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  • Association of cognitive and P50 suppression deficits in chronic patients with schizophrenia
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-17
    Luyao Xia; Dongmei Wang; Jiesi Wang; Hang Xu; Lijuan Huo; Yang Tian; Qilong Dai; Shuochi Wei; Wenjia Wang; Guangya Zhang; Xiangdong Du; Qiufang Jia; Xiaomin Zhu; Li Wang; Wei Tang; Xiang Yang Zhang

    Objective Cognitive deficits are core symptoms of schizophrenia; however, their pathophysiological mechanisms are still unclear. A sensory gating deficit, as reflected by P50 suppression, has been repeatedly shown in schizophrenia patients, which may be associated with cognitive deficits in this disorder. The present study was to examine the relationship between the P50 suppression and cognitive deficits in patients with schizophrenia, which is still under-investigated. Method We recruited 38 chronic schizophrenia patients and 32 matched healthy controls, and assessed their cognition with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and P50 suppression with the electroencephalography system. Results The total and its 4 index scores (all p<0.05) except for the visuospatial/ constructional index of RBANS were significantly lower in patients compared with healthy controls. However, only the language and attention passed Bonferroni corrections. Patients displayed a significantly higher P50 ratio, higher S2 amplitude, and lower S1 amplitude (all p<0.05) than healthy controls. Interestingly, only in the patients, the S1 amplitude was associated with both language and attention, and the S2 amplitude with both visuospatial/ constructional and language (all p<0.05), although all of these significances did not pass the Bonferroni corrections. The P50 ratio was not associated with any of the RBANS scores (all p>0.05). Conclusions Our results suggest the P50 suppression deficits in Chinese patients with schizophrenia, which may be associated with cognitive impairments of this illness. Moreover, the amplitude of S1 and the amplitude of S2 may be involved in the different cognitive domain deficits in schizophrenia patients. Significance This study suggests that the P50 components may possibly be effective biomarkers for cognitive deficits in patients with schizophrenia.

    更新日期:2020-01-17
  • Nerve ultrasound reference data in children from two to seven years
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-16
    Charlotte Schubert; Anna-Sophie Grimm; Jan-Hendrik Stahl; Hanna Küpper; Josua Kegele; Julia Wittlinger; Lina Serna-Higuita; Natalie Winter; Samuel Groeschel; Alexander Grimm

    Objective We examined selected peripheral and spinal nerves of children aged between two and seven years. Method High resolution ultrasound was performed in 116 children (2-7 years of age) at 20 predefined landmarks of median, ulnar, tibial, fibular, sural and radial nerves, the vagus as well as cervical spinal nerve 5 and 6. Further, side-to-side measuring and grey-scale analysis was done at selected nerve sites. Results Nerves of children were on average smaller than those of adults. Nerve growth correlates significantly with age in all nerves, the mean values were similar in the age of two to four years and five to seven years. Body mass index (BMI) and gender showed moderate effect at some nerve sites, however not uniformly in all. A side-to-side difference of up to 30% in median, and up to 20% in tibial nerve can occur in healthy individuals. Grey-scale analysis for echointensity has been performed in median, ulnar and tibial nerves. Conclusion Nerve size increases with age, BMI and gender have moderate effect. A side-to-side-difference of up to 30% can exist. Significance Reference values of nerve cross-sectional area, side-to-side-difference and echo intensity are necessary to detect nerve pathology in children as well as in adults.

    更新日期:2020-01-16
  • Prediction of Treatment Resistance in Obsessive Compulsive Disorder Patients Based on EEG Complexity as a Biomarker
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-13
    Tuğçe Ballı Altuğlu; Barış Metin; Emine Elif Tülay; Oğuz Tan; Gökben Hızlı Sayar; Cumhur Taş; Kemal Arikan; Nevzat Tarhan

    Objective This study aimed to identify an Electroencephalography (EEG) complexity biomarker that could predict treatment resistance in Obsessive compulsive disorder (OCD) patients. Additionally, the statistical differences between EEG complexity values in treatment-resistant and treatment-responsive patients were determined. Moreover, the existence of correlations between EEG complexity and Yale-Brown Obsessive Compulsive Scale (YBOCS) score were evaluated. Methods EEG data for 29 treatment-resistant and 28 treatment-responsive OCD patients were retrospectively evaluated. Approximate entropy (ApEn) method was used to extract the EEG complexity from both whole EEG data and filtered EEG data, according to 4 common frequency bands, namely delta, theta, alpha, and beta. The random forests method was used to classify ApEn complexity. Results ApEn complexity extracted from beta band EEG segments discriminated treatment-responsive and treatment-resistant OCD patients with an accuracy of 89.66% (sensitivity: 89.44%; specificity: 90.64%). Beta band EEG complexity was lower in the treatment-resistant patients and the severity of OCD, as measured by YBOCS score, was inversely correlated with complexity values. Conclusions The results indicate that, EEG complexity could be considered a biomarker for predicting treatment response in OCD patients. Significance The prediction of treatment response in OCD patients might help clinicians devise and administer individualized treatment plans.

    更新日期:2020-01-13
  • An Automatic Detection Method for 40-Hz Auditory Steady State Response and its Application in Prognosis of Comatose Patients
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-13
    Tingting Chen; Shiqi Lu; Ping Qian; Guolin Chen; Nan Hu

    Objective We proposed a 40-Hz auditory steady-state response (ASSR) automatic detection method, and studied the prognosis of comatose patients by combining the 40-Hz ASSR detection results of multiple paradigms of auditory stimulation. Methods The 40-Hz ASSR elicitation experiments were carried out on 32 comatose patients, with the detection results used as prognosis predictors. To achieve automatic detection, the detection was modeled as a binary hypothesis test for a sinusoidal waveform with unknown amplitude and phase, based on the generalized likelihood ratio test (GLRT). The patients were followed up for 6 months, and each patient’s outcome was classified as either favorable outcome (severe disability, moderate disability or good recovery) or unfavorable outcome (vegetative state / unresponsive wakefulness syndrome or death) according to the Glasgow outcome scale (GOS). The performance of the prognosis predictors was assessed using the area under the receiver operating characteristic curve (AUC-ROC). Results The largest AUC in univariate analysis involving a single stimulation paradigm was 0.849, while the AUC obtained by combining multiple predictors was increased to 0.966. Conclusions For comatose patients, the absence of 40-Hz ASSR in multiple stimulation paradigms may indicate an unfavorable prognosis. Furthermore, the combination of multiple auditory stimulation paradigms may increase the outcome prediction accuracy. Significance The combination of multi-paradigm 40-Hz ASSR automatic detection results may provide a feasible automatic outcome prediction method for comatose patients.

    更新日期:2020-01-13
  • Frontal theta and beta oscillations during lower-limb movement in Parkinson’s disease
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-13
    Arun Singh; Rachel C. Cole; Arturo I. Espinoza; Darin Brown; James F. Cavanagh; Nandakumar Narayanan

    Objectives Patients with Parkinson’s disease (PD) have deficits in lower-limb functions such as gait, which involves both cognitive and motor dysfunction. In PD theta and beta brain rhythms are associated with cognitive and motor functions, respectively. We tested the hypothesis that PD patients with lower-limb abnormalities would exhibit abnormal theta and beta rhythms in the mid-frontal cortical region during lower-limb action. Methods This study included thirty-nine participants; 13 PD patients with FOG (PDFOG+), 13 without FOG (PDFOG-), and 13 demographically-matched controls. We recorded scalp electroencephalograms (EEG) during a lower-limb pedaling motor task, which required intentional initiation and stopping of a motor movement. Results FOG scores were correlated with disease severity and cognition. PDFOG+ patients pedaled with reduced speed and decreased acceleration compared to PDFOG– patients and controls. PDFOG+ patients exhibited attenuated theta-band (4-8 Hz) power and increased beta-band (13-30 Hz) power at mid-frontal electrode Cz during pedaling. Frontal theta- and beta-band oscillations also correlated with motor and cognitive deficits. Conclusion Frontal theta and beta oscillations are predictors of lower-limb motor symptoms in PD and could be used to design neuromodulation for PD-related lower-limb abnormalities. Significance: These data provide insight into mechanisms of lower-limb dysfunction in PD with FOG.

    更新日期:2020-01-13
  • Classification of autism spectrum disorder based on sample entropy of spontaneous functional near infra-red spectroscopy signal
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-13
    Lingyu Xu; Qianling Hua; Jie Yu; Jun Li

    Objectives To assess the possibility of distinguishing autism spectrum disorder (ASD) based on the characteristic of spontaneous hemodynamic fluctuations and to explore the location of abnormality in the brain. Methods Using the sample entropy (SampEn) of functional near-infrared spectroscopy (fNIRS) from bilateral inferior frontal gyrus (IFG) and temporal cortex (TC) on 25 children with ASD and 22 typical development (TD) children, the pattern of mind-wandering was assessed. With the SampEn as feature variables, a machine learning classifier was applied to mark ASD and locate the abnormal area in the brain. Results The SampEn was generally lower for ASD than TD, indicating the fNIRS series from ASD was unstable, had low fluctuation, and high self-similarity. The classification between ASD and TD could reach 97.6% in accuracy. Conclusions The SampEn of fNIRS could accurately distinguish ASD. The abnormality in terms of the SampEn occurs more frequently in IFG than TC, and more frequently in the left than in the right hemisphere. Significance The result in this study may help to understand the cortical mechanism of ASD and provide a fNIRS-based diagnosis for ASD.

    更新日期:2020-01-13
  • Mismatch negativity to different deviant changes in autism spectrum disorders: A meta-analysis
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-01
    Tzu-Ching Chen; Ming H. Hsieh; Yi-Ting Lin; Pei-Ying S. Chan; Chia-Hsiang Cheng

    Objective Mismatch negativity (MMN) has been continuously used to evaluate the functional integrity of central auditory processing. However, it still remains inconclusive whether patients with autism spectrum disorder (ASD) demonstrate reduced MMN responses in all deviant types. Methods To reconcile the previous controversial findings, we performed a meta-analysis of peer-reviewed MMN articles concerning ASD. The potential moderators regarding different deviant types, diagnosis, and age on the effect sizes (Hedges’s g) were also assessed. Results Compared to the controls, ASD patients showed reduced MMN amplitudes (g = -0.37, p = 0.001) and prolonged latencies (g = -0.33, p = 0.041) in response to speech-sound deviants. Children/adolescents with ASD manifested reduced MMN amplitudes in response to tone-duration deviants (g = -0.46, p = 0.014). Furthermore, the results showed significantly shortened MMN latencies to tone-frequency deviants in patients with autism (g = 0.29, p = 0.038) and, in contrast, prolonged MMN latencies (g = -0.74, p = 0.001) in patients with Asperger syndrome. Conclusion MMN deficits are robust in ASD patients, suggesting an altered central ability in auditory discrimination. Significance MMN alterations were displayed in different profiles with respect to frequency, duration and phoneme changes.

    更新日期:2020-01-01
  • Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS): An update (2014–2018)
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2020-01-01
    Jean-Pascal Lefaucheur; André Aleman; Chris Baeken; David H. Benninger; Jérôme Brunelin; Vincenzo Di Lazzaro; Saša R. Filipović; Christian Grefkes; Alkomiet Hasan; Friedhelm C. Hummel; Satu K. Jääskeläinen; Berthold Langguth; Letizia Leocani; Alain Londero; Raffaele Nardone; Jean-Paul Nguyen; Thomas Nyffeler; Albino J. Oliveira-Maia; Ulf Ziemann

    A group of European experts reappraised the guidelines on the therapeutic efficacy of repetitive transcranial magnetic stimulation (rTMS) previously published in 2014 [Lefaucheur et al., Clin Neurophysiol 2014;125:2150–206]. These updated recommendations take into account all rTMS publications, including data prior to 2014, as well as currently reviewed literature until the end of 2018. Level A evidence (definite efficacy) was reached for: high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the painful side for neuropathic pain; HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC) using a figure-of-8 or a H1-coil for depression; low-frequency (LF) rTMS of contralesional M1 for hand motor recovery in the post-acute stage of stroke. Level B evidence (probable efficacy) was reached for: HF-rTMS of the left M1 or DLPFC for improving quality of life or pain, respectively, in fibromyalgia; HF-rTMS of bilateral M1 regions or the left DLPFC for improving motor impairment or depression, respectively, in Parkinson’s disease; HF-rTMS of ipsilesional M1 for promoting motor recovery at the post-acute stage of stroke; intermittent theta burst stimulation targeted to the leg motor cortex for lower limb spasticity in multiple sclerosis; HF-rTMS of the right DLPFC in posttraumatic stress disorder; LF-rTMS of the right inferior frontal gyrus in chronic post-stroke non-fluent aphasia; LF-rTMS of the right DLPFC in depression; and bihemispheric stimulation of the DLPFC combining right-sided LF-rTMS (or continuous theta burst stimulation) and left-sided HF-rTMS (or intermittent theta burst stimulation) in depression. Level A/B evidence is not reached concerning efficacy of rTMS in any other condition. The current recommendations are based on the differences reached in therapeutic efficacy of real vs. sham rTMS protocols, replicated in a sufficient number of independent studies. This does not mean that the benefit produced by rTMS inevitably reaches a level of clinical relevance.

    更新日期:2020-01-01
  • The evolving role of surface electromyography in amyotrophic lateral sclerosis: a systematic review
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-27
    J. Bashford; K. Mills; C. Shaw

    Objective Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease that leads to inexorable motor decline and a median survival of three years from symptom onset. Surface EMG represents a major technological advance that has been harnessed in the development of novel neurophysiological biomarkers. We have systematically reviewed the current application of surface EMG techniques in ALS. Methods We searched PubMed to identify 42 studies focusing on surface EMG and its associated analytical methods in the diagnosis, prognosis and monitoring of ALS patients. Results A wide variety of analytical techniques were identified, involving motor unit decomposition from high-density grids, motor unit number estimation and measurements of neuronal hyperexcitability or neuromuscular architecture. Some studies have proposed specific diagnostic and prognostic criteria however clinical calibration on large ALS cohorts is currently lacking. The most validated method to monitor disease is the motor unit number index (MUNIX), which has been implemented as an outcome measure in two ALS clinical trials. Conclusion Surface EMG offers significant practical and analytical flexibility compared to invasive techniques. To capitalise on this fully, emphasis must be placed upon the multi-disciplinary collaboration of clinicians, bioengineers, mathematicians and biostatisticians. Significance Surface EMG techniques can enrich effective biomarker development in ALS.

    更新日期:2019-12-27
  • Pain-related evoked potentials in patients with large, mixed, and small fiber neuropathy
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-26
    Gabriela Siedler; Claudia Sommer; Nurcan Üçeyler

    Objective To investigate A-delta fiber pathways in patients with large, mixed, and small fiber neuropathies using pain-related evoked potentials (PREP). Methods We prospectively examined consecutive and unselected 108 patients with neuropathies using PREP. Patients were stratified according to impaired fiber types in those with large fiber neuropathy (LFN, n=23), mixed fiber neuropathy (MFN, n=80), and small fiber neuropathy (SFN, n=5). Additionally, medical history, nerve conduction studies, quantitative sensory testing (QST), and skin punch biopsy were applied. Data was compared with those of 49 healthy controls. Results Patients with MFN showed a distal loss of PREP (16/80, 20%) and prolonged PREP latencies after stimulation at the foot (MFN: 225.8 [135-293.6] ms, controls: 218 [135-394] ms, p<0.05). Patients with demyelinating neuropathies had prolonged PREP latencies after stimulation at the hand (p<0.05 each). QST showed an impairment of small and large fiber function in patients with MFN. PREP were mostly absent in patients at advanced stages of neuropathies: in 10/31(30%) patients with no recordable sural nerve action potential (SNAP, preserved SNAP: 8/76, 10% missing) and in 4/17 (24%) patients with loss of distal epidermal innervation (preserved epidermal innervation: 7/60, 24%) PREP was not recordable. PREP peak-to-peak amplitude after stimulation at the face was lowered in patients with reduced proximal intraepidermal nerve fiber density (p<0.02). Conclusion PREP is a useful screening method for A-delta fiber pathology also in patients with simultaneous large fiber pathology. Loss of PREP indicates advance stages of nerve fiber damage. Significance PREP may be useful as a complementary method for detection of small fiber impairment also in patients with mixed fiber neuropathy and in advanced stages.

    更新日期:2019-12-27
  • A Neurophysiological Brain Map: Spectral Parameterization of the Human Intracranial Electroencephalogram
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-26
    Giridhar P. Kalamangalam; Sarah Long; Mircea I. Chelaru

    Objective A library of intracranial electroencephalography (iEEG) from the normal human brain has recently been made publicly available (Frauscher et al., 2018). The library – which we term the Montreal Neurological Institute Atlas (MNIA) - comprises 30 hours of iEEG from over a hundred epilepsy patients. We present a Fourier spectrum-based model of low dimension that summarizes all of MNIA into a neurophysiological ‘brain map’. Methods Normalized amplitude spectra of the MNIA data were modelled as log-normal distributions around individual canonical Berger frequencies. The latter were concatenated to yield the composite spectrum with high accuracy. Key model parameters were color-coded into a visual representation on cortical surface models. Results Each brain region has its own spectral characteristics that together yield a novel composite intracranial EEG brain map. Conclusions iEEG from normal brain regions can be accurately modelled with a small number of independent parameters. Our model is based in the canonical Berger bands and naturally suits clinical electroencephalography. Significance Due to its applicability to iEEG from all sampled regions, the model suggests a certain universality to brain rhythm generation that is independent of precise cortical location. More generally, our results are a novel abstraction of resting cortical dynamics that may help diagnostics in epileptology, in addition to informing structure-function relationships in the field of human brain mapping.

    更新日期:2019-12-27
  • Effects of Ramped-Frequency Thalamic Deep Brain Stimulation on Tremor and Activity of Modeled Neurons
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-26
    Brandon D. Swan; David T. Brocker; Robert E. Gross; Dennis A. Turner; Warren M. Grill

    Objective We conducted intraoperative measurements of tremor to quantify the effects of temporally patterned ramped-frequency DBS trains on tremor. Methods Seven patterns of stimulation were tested in nine subjects with thalamic DBS for essential tremor: stimulation ‘off’, three ramped-frequency stimulation (RFS) trains from 130→50 Hz, 130→60 Hz, and 235→90 Hz, and three constant frequency stimulation (CFS) trains at 72, 82, and 130 Hz. The same patterns were applied to a computational model of the thalamic neural network. Results Temporally patterned 130→60 Hz ramped-frequency trains suppressed tremor relative to stimulation ‘off,’ but 130→50 Hz, 130→60 Hz, and 235→90 Hz ramped-frequency trains were no more effective than constant frequency stimulation with the same mean interpulse interval (IPI). Computational modeling revealed that rhythmic burst-driver inputs to thalamus were masked during DBS, but long IPIs, concurrent with pauses in afferent cerebellar and cortical firing, allowed propagation of bursting activity. The mean firing rate of bursting-type model neurons as well as the firing pattern entropy of model neurons were both strongly correlated with tremor power across stimulation conditions. Conclusion Frequency-ramped DBS produced equivalent tremor suppression as constant frequency thalamic DBS. Tremor-related thalamic burst activity may result from burst-driver input, rather than by an intrinsic rebound mechanism. Significance Ramping stimulation frequency may exacerbate thalamic burst firing by introducing consecutive pauses of increasing duration to the stimulation pattern.

    更新日期:2019-12-27
  • Recursive independent component analysis-decomposition of ictal EEG to select the best ictal component for EEG source imaging
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-24
    Mohammad Ashfak Habib; Fatimah Ibrahim; Mas S. Mohktar; Shahrul Bahyah Kamaruzzaman; Kheng Seang Lim

    Objective This study aimed to present a new ictal component selection technique, named as recursive ICA-decomposition for ictal component selection (RIDICS), for potential application in epileptogenic zone localization. Methods The proposed technique decomposes ictal EEG recursively, eliminates a few unwanted components in every recursive cycle, and finally selects the most significant ictal component. Back-projected EEG, regenerated from that component, was used for source estimation. Fifty sets of simulated EEGs and 24 seizures in 8 patients were analyzed. Dipole sources of simulated-EEGs were compared with a known dipole location whereas epileptogenic zones of the seizures were compared with their corresponding sites of successful surgery. The RIDICS technique was compared with a conventional technique. Results The RIDICS technique estimated the dipole sources at an average distance of 12.86 mm from the original dipole location, shorter than the distances obtained using the conventional technique. Epileptogenic zones of the patients, determined by the RIDICS technique, were highly concordant with the sites of surgery with a concordance rate of 83.33%. Conclusions Results show that the RIDICS technique can be a promising quantitative technique for ictal component selection. Significance Properly selected ictal component gives good approximation of epileptogenic zone, which eventually leads to successful epilepsy surgery.

    更新日期:2019-12-25
  • Stimulus Probability Affects the Visual N700 Component of the Event-related Potential
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-23
    H. Althen; T. Banaschewski; D. Brandeis; S. Bender

    Objective To examine whether the occipito-temporal visual N700 component of the event-related potential is sensitive to stimulus probabilities. Methods P1, N1, P3, and, in particular, the occipito-temporal N700 component of the event-related potential were analysed in response to frequent and rare non-target letters of a continuous performance task in 200 healthy adolescents. Additionally, amplitude habituation with time was examined for the occipito-temporal N700 and N1 components. Results The visual P1, N1, and occipito-temporal N700 components were significantly larger in response to rare letters than to frequent letters, whereas the P3 component demonstrated no amplitude difference. Over time, the occipito-temporal N700 amplitude decreased in response to the rare letters, while the N1 amplitude increased, to both, frequent and rare letters. Conclusions This study provides first evidence that the visual occipito-temporal N700 is sensitive to stimulus probabilities, suggesting an enhanced post-processing of rare stimuli in secondary visual areas. The distinct habituation patterns of occipito-temporal N700 and N1 amplitudes distinguish repetition effects on stimulus post-processing (N700) from those on perception (N1). Significance The enhanced N700 component to rare stimuli might reflect an orienting response and underlying attentional processes. The N700 sensitivity to stimulus probabilities should be examined in patient groups with attentional deficits.

    更新日期:2019-12-23
  • Early focality and spread of cortical dysfunction in amyotrophic lateral sclerosis: a regional study across the motor cortices
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-23
    Thanuja Dharmadasa; José M. Matamala; James Howells; Steve Vucic; Matthew C. Kiernan

    Objective To characterise the regional cortical patterns underlying clinical symptomatology in amyotrophic lateral sclerosis (ALS). Methods 138 patients prospectively underwent transcranial magnetic stimulation studies from hand and leg cortical regions of each hemisphere, obtaining motor evoked potentials from all four limbs. Patients were categorised by clinical phenotype and underwent clinical and peripheral evaluation of disease. Results Cortical dysfunction was evident across the motor cortices, with reduction in short-interval intracortical inhibition (SICI) suggesting the presence of widespread cortical hyperexcitability, most prominently from clinically affected regions (hand p<0.0001; leg p<0.01). In early disease, cortical abnormalities were asymmetric between hemispheres, focally corresponding to clinical site-of-onset (p<0.05). Degrees of cortical dysfunction varied between phenotypes, with the bulbar-onset cohort demonstrating greatest reduction in SICI (p=0.03). Conclusions The pattern of cortical dysfunction appears linked to clinical evolution in ALS, with early focal asymmetry preceding widespread changes in later disease. Cortical differences across phenotypes may influence clinical variability. Significance This is the first study to extensively map cortical abnormalities from multiple motor regions across hemispheres. The early cortical signature mirrors symptom laterality, supporting a discrete region of disease onset. Phenotypes appear to exist within a pathophysiological continuum, but cortical heterogeneity may mediate observed differences in clinical outcome.

    更新日期:2019-12-23
  • The eyes wake up: Screening for benign paroxysmal positional vertigo with polysomnography
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-23
    Yulia Valko; Esther Werth; Lukas L. Imbach; Philipp O. Valko; Konrad P. Weber

    Objective While positional nystagmus of benign paroxysmal positional vertigo (BPPV) has been shown to be detectable in electrooculography (EOG) tracings of polysomnography (PSG), the frequency of undiagnosed BPPV in patients referred for sleep-wake examination has never been investigated. Methods Prospective evaluation of positional nystagmus in 129 patients, referred to a neurological sleep laboratory for sleep-wake examination with PSG. Both in the evening and morning, patients had diagnostic positioning maneuvers under ongoing EOG-PSG registration, followed by visual inspection of EOG for positional nystagmus. Results In 19 patients (14.7%), we found patterns of positional nystagmus, typically appearing few seconds after changes in head position. In 9 of these patients (47%), the nystagmus was also provoked by the positioning maneuvers. Nystagmus only occurred during wakefulness, not during sleep. In a patient with severe cupulolithiasis, we observed disappearance of nystagmus while entering N1 sleep stage. Nocturnal positional nystagmus was independently associated with positive positioning maneuvers. Conclusions Inspection of EOG-PSG demonstrated that positional nystagmus is common, occurring only when wake, and independently associated with positive positioning maneuvers. Significance By routinely searching for positional nystagmus in PSG, sleep physicians may substantially contribute to the identification of patients with so-far undiagnosed BPPV.

    更新日期:2019-12-23
  • Posteroanterior cervical transcutaneous spinal stimulation targets ventral and dorsal nerve roots
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-13
    Yu-Kuang Wu; Jonah M. Levine; Jaclyn R. Wecht; Matthew T. Maher; James M. LiMonta; Sana Saeed; Tiffany M. Santiago; Eric Bailey; Shivani Kastuar; Kenneth S. Guber; Lok Yung; Joseph P. Weir; Jason B. Carmel; Noam Y. Harel

    Objective We aim to non-invasively facilitate activation of spared neural circuits after cervical spinal cord injury (SCI) and amyotrophic lateral sclerosis (ALS). We developed and tested a novel configuration for cervical transcutaneous spinal stimulation (cTSS). Methods cTSS was delivered via electrodes placed over the midline at ∼T2-T4 levels posteriorly and ∼C4-C5 levels anteriorly. Electromyographic responses were measured in arm and hand muscles across a range of stimulus intensities. Double-pulse experiments were performed to assess homosynaptic post-activation depression (PAD). Safety was closely monitored. Results More than 170 cTSS sessions were conducted without major safety or tolerability issues. A cathode-posterior, 2 ms biphasic waveform provided optimal stimulation characteristics. Bilateral upper extremity muscle responses were easily obtained in subjects with SCI and ALS. Resting motor threshold at the abductor pollicis brevis muscle ranged from 5.5 to 51.0 mA. As stimulus intensity increased, response latencies to all muscles decreased. PAD was incomplete at lower stimulus intensities, and decreased at higher stimulus intensities. Conclusions Posteroanterior cTSS has the capability to target motor neurons both trans-synaptically via large-diameter afferents and non-synaptically via efferent motor axons. Significance Posteroanterior cTSS is well tolerated and easily activates upper extremity muscles in individuals with SCI and ALS.

    更新日期:2019-12-17
  • Neural correlates of performance monitoring in adult patients with Gilles de la Tourette syndrome: A study of event-related potentials
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-12
    Claire Warren; Caroline Seer; Florian Lange; Bruno Kopp; Kirsten Müller-Vahl

    Objectives Gilles de la Tourette syndrome (GTS) is a neuropsychiatric condition characterized by motor and vocal tics. There is undoubtedly basal ganglia involvement, which are also important for cognitive processes including performance monitoring and interference resolution. We investigated these functions in adult patients with GTS compared to healthy controls (HCs). Methods We compared a group of N = 23 adult patients with GTS to N = 27 HC on a flanker task during an EEG recording. Reaction times and error rates were recorded, as well as N2 and Ne/ERN amplitudes. The N2 is an index of interference resolution. The Ne/ERN is a negative fronto-central component, occurring when participants make mistakes. Results Patients’ reaction times were enhanced on incongruent trials compared to HC. Electrophysiological data revealed more frontal components, as well as significantly increased Ne/ERN amplitudes in patients with GTS compared to HC (p = .026). Conclusions Altered electrophysiological correlates of error processing in adult patients with GTS compared to HC cannot be attributed to differential error probabilities. Potentially, patients recruit compensatory resources from frontal networks to maintain behavioural performance. Significance This study gives further insight into cognitive deficits of patients with GTS, and the underlying neural processes of these functions.

    更新日期:2019-12-13
  • Neuronal oscillations of the pedunculopontine nucleus in Progressive Supranuclear Palsy: influence of levodopa and movement
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-12
    Imke Galazky; Tino Zaehle; Catherine M. Sweeney-Reed; Jens Neumann; Hans-Jochen Heinze; Jürgen Voges; Andreas Kupsch; Herrmann Hinrichs

    Objective The pedunculopontine nucleus (PPN) has been proposed as a new deep brain stimulation (DBS) target for the treatment in idiopathic Parkinson’s syndrome (IPS) and progressive supranuclear palsy (PSP). In IPS, levodopa has been shown to induce alpha activity in the PPN, indicating a possible physiological role for these oscillations in movement control. Despite shared clinical features, the PPN is more severely affected in PSP than IPS. Here we investigated neuronal oscillations in the PPN in PSP and the influence of levodopa and movement. Methods Local field potentials were recorded bilaterally from the PPN of 4 PSP patients at rest, with levodopa and during self-paced leg movements. Results During rest, levodopa administration was associated with significantly increased alpha and reduced gamma activity in the PPN. Without levodopa, continuous movements were associated with reduced alpha and beta power. These differences between oscillatory power during movement and resting state were not observed with levodopa administration. Conclusion In PSP the changes in neuronal oscillations in the PPN region on levodopa administration are similar to those reported in IPS. The enhancement of lower frequency oscillations in the PPN is possibly influenced by a dopaminergic activation of the striatal pathway and a reduced pallidal inhibition. Significance Levodopa influences neuronal oscillations at low and high frequencies in the PPN region in Parkinsonian disorders.

    更新日期:2019-12-13
  • Sleep related epilepsy in focal cortical dysplasia type 2: insights from sleep recordings in presurgical evaluation
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-12
    Christin M. Eltze; Elisabeth Landre; Christine Soufflet; Francine Chassoux

    Objective To determine the relationship between seizure onset, sleep stage and focal cortical dysplasia type 2 (FCD2) location in sleep related epilepsy (SRE). Methods We reviewed scalp video-EEG data of 77 patients with SRE among 130 surgically treated patients with histologically confirmed FCD2. Seizure onset was classified as occurring during NREM, REM and after arousal. Results Sleep recordings were available for 65 patients (37 males, 7- 49 years old). FCD2 was located in frontal lobe in 46 (71%) and in extra-frontal regions in 19, including the temporal lobe in 6. MRI was negative/doubtful in 35 cases. Interictal rhythmic/pseudorhythmic spike rate increased from 31% during waking to 65% during sleep. Seizure onset occurred from NREM in 46 cases (71%), mostly from stage 2, and after arousal in 14 (22%). Seizures occurring from NREM/REM sleep were significantly more frequent in frontal (89%) compared to extra-frontal location (42%), whilst arousal preceded seizure onset more often in extra-frontal (58%) compared to frontal location (7%). Conclusions NREM seizure onset is the most common ictal pattern in SRE due to frontal FCD2 whereas preceding arousal points to extra-frontal regions. Significance Sleep recordings may help for FCD2 localisation and suggest topography dependent impact on sleep related epileptic networks.

    更新日期:2019-12-13
  • A novel method for extracting interictal epileptiform discharges in multi-channel MEG: Use of fractional type of blind source separation
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-12
    Teppei Matsubara; Naruhito Hironaga; Taira Uehara; Hiroshi Chatani; Shozo Tobimatsu; Kuniharu Kishida

    Objective Visual inspection of interictal epileptiform discharges (IEDs) in multi-channel MEG requires a time-consuming evaluation process and often leads to inconsistent results due to variability of IED waveforms. Here, we propose a novel extraction method for IEDs using a T/k type of blind source separation (BSST/k). Methods We applied BSST/k with seven patients with focal epilepsy to test the accuracy of identification of IEDs. We conducted comparisons of the results of BSS components with those obtained by visual inspection in sensor-space analysis. Results BSST/k provided better signal estimation of IEDs compared with sensor-space analysis. Importantly, BSST/k was able to uncover IEDs that could not be detected by visual inspection. Furthermore, IED components were clearly extracted while preserving spike and wave morphology. Variable IED waveforms were decomposed into one dominant component. Conclusions BSST/k was able to visualize the spreading signals over multiple channels into a single component from a single epileptogenic zone. BSST/k can be applied to focal epilepsy with a simple parameter setting. Significance Our novel method was able to highlight IEDs with increased accuracy for identification of IEDs from multi-channel MEG data.

    更新日期:2019-12-13
  • An Update on Retinal Prostheses
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-10
    Lauren N. Ayton, Nick Barnes, Gislin Dagnelie, Takashi Fujikado, Georges Goetz, Ralf Hornig, Bryan W. Jones, Mahiul M.K. Muqit, Daniel L. Rathbun, Katarina Stingl, James D. Weiland, Matthew A. Petoe

    Retinal prostheses are designed to restore a basic sense of sight to people with profound vision loss. They require a relatively intact posterior visual pathway (optic nerve, lateral geniculate nucleus and visual cortex). Retinal implants are options for people with severe stages of retinal degenerative disease such as retinitis pigmentosa and age-related macular degeneration. There have now been three regulatory-approved retinal prostheses. Over five hundred patients have been implanted globally over the past 15 years. Devices generally provide an improved ability to localize high-contrast objects, navigate, and perform basic orientation tasks. Adverse events have included conjunctival erosion, retinal detachment, loss of light perception, and the need for revision surgery, but are rare. There are also specific device risks, including overstimulation (which could cause damage to the retina) or delamination of implanted components, but these are very unlikely. Current challenges include how to improve visual acuity, enlarge the field-of-view, and reduce a complex visual scene to its most salient components through image processing. This review encompasses the work of over 40 individual research groups who have built devices, developed stimulation strategies, or investigated the basic physiology underpinning retinal prostheses. Current technologies are summarized, along with future challenges that face the field.

    更新日期:2019-12-11
  • Upper limb motor evoked potentials as outcome measure in progressive multiple sclerosis
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-10
    M. Pisa, R. Chieffo, A. Giordano, S. Gelibter, M. Comola, G. Comi, L. Leocani

    Objective To assess the usefulness of upper limb (UE) motor evoked potential (MEPs) as a marker of motor impairment in a cohort of people with progressive multiple sclerosis (PwPMS). Methods we evaluated UE and lower extremities (LE) MEPs, 6-minutes walk-test (6MWT), 10-meter walk-test (10MWT), EDSS, 9-hole peg-test (9HPT), and measures of strength (MRC) and tone (MAS) to the UE and LE in 50 PwPMS (EDSS 4.0-6.5; P≥3, C≤2). Results Bilateral absence of LE-MEPs, found in 74% of cases, was associated with worse 10MWT and 6MWT. UE-MEPs were rarely absent (8%) but often delayed (74%). Abnormal UE-MEPs were associated with worse performance at 9HPT (25.8 vs 33.2 sec). UE-MEPs latency correlated with 10MWT (rho=0.597), 6MWT (rho=-0.425) and EDSS (rho=0.296). Conclusion UE-MEPs may represent a clinically relevant outcome measure to quantify corticospinal tract integrity in PwPMS, at least when LE-MEPs cannot provide a measurable response. Significance the strive for novel remyelination strategies in MS points to the need for quantitative conduction measurements in addition to clinical outcomes. The frequent absence of MEPs to the lower limbs in PwPMS may greatly limits their usefulness in monitoring progression or response to therapies. With this respect, the upper extremities may represent a better target.

    更新日期:2019-12-11
  • Intraoperative Erb's Point-Vertex Recording Increases Brainstem Auditory Evoked Potential Wave V Amplitude
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-10
    Tobias Greve, Finja Beyer, Andrea Szelényi

    Objective Recording derivations for intraoperative brainstem auditory evoked potential (BAEP) monitoring consist of a preauricular electrode referenced to Cz’. These derivations are prone to unfavorable signal amplitude. This study analyses whether an alternative noncephalic electrode positioned over ipsilateral Erb’s point, thereby generating a new Erb’s point-vertex recording derivation, improves BAEP recordings. Methods Electrodes were placed preauricularly (A1/A2) and at left and right Erb’s point (EP1/EP2). They were referenced to Cz’. Click sound stimulation (80 – 95 dB above hearing level) was applied. At intraoperative baseline conditions, latencies and amplitudes of waves I – V of all derivations were analyzed. Results Data of 30 patients (54±15 years / 17 females) with normal hearing or mild symmetrical presbycusis undergoing infratentorial surgeries (15 microvascular decompressions) were analyzed. Using EP1-Cz’ / EP2-Cz’ derivations compared to A1-Cz’ / A2-Cz’, amplitudes for wave IV (left +65%, p < 0.001; right + 43%, p = 0.002) and wave V (left +54%, p < 0.001; right + 48%, p < 0.001) were significantly increased. Only in the left (EP1) derivation, there was a tendency towards less reproducibility of wave I, resulting in a decrease of amplitude (-35%, p = 0.005). Conclusions Adding an Erb’s point electrode derivation resulted in larger amplitudes of waves IV to V. whereas conventional preauricular or mastoid derivation is preferential for wave I assessment. Significance Increased wave amplitudes facilitate detection of pathologically reduced wave forms (wave V in particular) which represents a significant advancement.

    更新日期:2019-12-11
  • Visualization of electrophysiological activity at the carpal tunnel area using magnetoneurography
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-10
    Toru Sasaki, Shigenori Kawabata, Yuko Hoshino, Kensuke Sekihara, Yoshiaki Adachi, Miho Akaza, Isamu Ozaki, Koji Fujita, Akimoto Nimura, Toshitaka Yoshii, Yuki Miyano, Yuki Mitani, Taishi Watanabe, Shinji Sato, Sukchan Kim, Atsushi Okawa

    Objective To establish a noninvasive method to measure the neuromagnetic fields of the median nerve at the carpal tunnel after electrical digital nerve stimulation and evaluate peripheral nerve function. Methods Using a vector-type biomagnetometer system with a superconducting quantum interference device, neuromagnetic fields at the carpal tunnel were recorded after electrical stimulation of the index or middle digital nerve in five healthy volunteers. A novel technique for removing stimulus-induced artifacts was applied, and current distributions were calculated using a spatial filter algorithm and superimposed on X-ray. Results A neuromagnetic field propagating from the palm to the carpal tunnel was observed in all participants. Current distributions estimated from the magnetic fields had five components: leading and trailing components parallel to the conduction pathway, outward current preceding the leading component, inward currents between the leading and trailing components, and outward current following the trailing component. The conduction velocity and peak latency of the inward current agreed well with those of sensory nerve action potentials. Conclusion Removing stimulus-induced artifacts enabled magnetoneurography to noninvasively visualize with high spatial resolution the electrophysiological neural activity from the palm to the carpal tunnel. Significance This is the first report of using magnetoneurography to visualize electrophysiological nerve activity at the palm and carpal tunnel.

    更新日期:2019-12-11
  • Altered Effective Connectivity Network in Patients with Insular Epilepsy: A High- frequency Oscillations Magnetoencephalography Study
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-06
    Chunli Yin, Xiating Zhang, Jing Xiang, Zheng chen, Xin li, Siqi Wu, Peiyuan Lv, Yuping Wang

    Objective The project aimed to determine the alterations in the effective connectivity (EC) neural network in patients with insular epilepsy based on interictal high-frequency oscillations (HFOs) from magnetoencephalography (MEG) data. Methods We studied MEG data from 22 insular epilepsy patients and 20 normal subjects. Alterations in spatial pattern and connection properties of the patients with insular epilepsy were investigated in the entire brain network and insula-based network. Results Analyses of the parameters of graph theory revealed the over-connectivity and small-world configuration of the global connectivity patterns observed in the patients. In the insula-based network, the insular cortex ipsilateral to the seizure onset displayed increased efferent and afferent EC. Left insular epilepsy featured strong connectivity with the bilateral hemispheres, whereas right insular epilepsy featured increased connectivity with only the ipsilateral hemisphere. Conclusions Patients with insular epilepsy display alterations in the EC network in terms of both whole-brain connectivity and the insula-based network during interictal HFOs. Significance Alterations of interictal HFO-based networks provide evidence that epilepsy networks, instead of epileptic foci, play a key role in the complex pathophysiological mechanisms of insular epilepsy. The dysfunction of HFO networks may prove to be a novel promising biomarker and the cause of interictal brain dysfunctions in insular epilepsy.

    更新日期:2019-12-07
  • Electrical impedance myography as a biomarker of inclusion body myositis: a cross-sectional study
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-06
    Bhaskar Roy, Seward B. Rutkove, Richard J. Nowak

    Objective To assess the value of electrical impedance myography (EIM) in inclusion body myositis (IBM). Methods Patients with clinically defined IBM and healthy controls (HC) of similar age group were recruited. Each participant underwent manual muscle testing (MMT), 6-minute walk test (6MWT), handgrip dynamometry, and IBM-functional rating scale assessment (IBM-FRS). EIM measurements were obtained from bilateral deltoid, biceps, forearm-flexors, quadriceps, tibialis anterior, and medial gastrocnemius. Results Fourteen IBM patients and 12 HCs with mean age 68.6 ± 6 and 67.4 ± 5.4 years were included in the final analysis. Averaged phase value at 50 kHz (EIM50) and ratio of phase value at 50 kHz/200 kHz (EIMPR) from six-muscles were significantly lower in IBM patients when compared to HC (5.23 ± 1.34 vs 7.88 ± 1.9, p-value 0.002, and 0.55 ± 0.09 vs. 0.68 ± 0.09, p-value 0.004, respectively). A strong correlation was noted between IBM-FRS, 6MWT, disease-duration and the averaged value of EIM50 and EIMPR in the IBM patients (Spearman |rho|>0.7, p-values <0.01). Conclusions EIM can differentiate between IBM patients and HCs and EIM parameters correlate with clinical outcome measures. Significance EIM may be a potential objective biomarker for IBM. A longitudinal validation study is warranted.

    更新日期:2019-12-07
  • Complexity changes in preclinical Alzheimer’s disease: an MEG study of subjective cognitive decline and mild cognitive impairment
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-06
    Elizabeth Shumbayawonda, David López-Sanz, Ricardo Bruña, Noelia Serrano, Alberto Fernández, Fernando Maestú, Daniel Abasolo

    Objective To analyse magnetoencephalogram (MEG) signals with Lempel-Ziv Complexity (LZC) to identify the regions of the brain showing changes related to cognitive decline and Alzheimeŕs Disease (AD). Methods LZC was used to study MEG signals in the source space from 99 participants (36 male, 63 female, average age: 71.82 ± 4.06) in three groups (33 subjects per group): healthy (control) older adults, older adults with subjective cognitive decline (SCD), and adults with mild cognitive impairment (MCI). Analyses were performed in broadband (2-45Hz) and in classic narrow bands (theta (4-8Hz), alpha (8-12Hz), low beta (12-20Hz), high beta (20-30Hz), and, gamma (30-45Hz)) Results LZC was significantly lower in subjects with MCI than in those with SCD. Moreover, subjects with MCI had significantly lower MEG complexity than controls and SCD subjects in the beta frequency band. Lower complexity was correlated with smaller hippocampal volumes. Conclusions Brain complexity – measured with LZC – decreases in MCI patients when compared to SCD and healthy controls. This decrease is associated with a decrease in hippocampal volume, a key feature in AD progression. Significance This is the first study to date characterising the changes of brain activity complexity showing the specific spatial pattern of the alterations as well as the morphological correlations throughout preclinical stages of AD.

    更新日期:2019-12-07
  • Ulnar neuropathy at the elbow: reappraisal of the wrist-upper arm latency difference between ulnar and median nerves
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-06
    G. Di Virgilio, A.M. Grapperon, J. Fayerstein, M. Goudot, S. Nollet, F. Ochsner, M. Théaudin, A. Truffert, P. Tsouni, C. Vial, FC. Wang, J. Pasquier, L. Tatu, S. Attarian, T. Kuntzer

    Objectives To evaluate the sensitivity and specificity of the latency difference (DLat) between ulnar and median nerves of the arm after stimulation at the wrist; one of the easiest techniques proposed for recognizing ulnar neuropathy at the elbow (UNE). As latency difference is not a standardized technique, we set up a multicenter study to recruit large numbers of normal subjects and patients with UNE or generalized neuropathy. Methods Six centers participated in the study with data obtained from three groups of participants, controls (CTRLs), patients with UNE and patients with generalized neuropathy (GNP). We first verified the anatomical superposition of the ulnar and median nerves in cadaver examination. The optimal recording site for these two nerves was found to be 10 cm above the medial epicondyle. We then standardized the position of the arm with full extension of the elbow and stimulated first the median and then the ulnar nerves at the wrist. CTRLs were examined on both arms at two consecutive visits. Results We recorded 32 idiopathic UNE cases, 44 GNP patients and 62 controls. We demonstrated that a DLat cut-off value of 0.69 ms brings a sensitivity of 0.86 and specificity of 0.89 to discriminate CTRLs from UNE. We also validated that intra-examiner reproducibility was good. Conclusion We report a lower normal value for DLat than reported in several non-standardized studies2,8 and CTRL and UNE groups have clearly separated DLat values. Significance Due to its high sensitivity, our standardized technique could be used as a first-line diagnostic tool when UNE is suspected.

    更新日期:2019-12-07
  • Conscious and unconscious expectancy effects: a behavioral, scalp and intracranial electroencephalography study
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-05
    Camille Rozier, Tal Seidel Malkinson, Dominique Hasboun, Michel Baulac, Claude Adam, Katia Lehongre, Stéphane Clémenceau, Vincent Navarro, Lionel Naccache

    Objective The scope of unconscious cognition stretched its limits dramatically during the last 40 years, yet most unconscious processes and representations that have been described so far are fleeting and very short-lived, whereas conscious representations can be actively maintained in working memory for a virtually unlimited period. In the present work we aimed at exploring conscious and unconscious lasting (>1 second) expectancy effects. Methods In a series of four experiments we engaged participants in the foreperiod paradigm while using both unmasked and masked cues that were informative about the presence/absence of an upcoming target. We recorded behavioral responses, high-density scalp EEG (Exp.2a), and intra-cranial EEG (Exp. 2b). Results While conscious expectancy was associated with a large behavioral effect (∼150ms), unconscious expectancy effect was significant but much smaller (4ms). Both conscious and unconscious expectancy Contingent Negative Variations (CNVs) originated from temporal cortices, but only the late component of conscious CNV originated from an additional source located in the vicinity of mesio-frontal areas and supplementary motor areas. Finally, only conscious expectancy was accessible to introspection. Conclusions Both unmasked and masked cues had an impact on response times and on brain activity. Significance These results support a two-stage model of the underlying mechanisms of expectancy.

    更新日期:2019-12-05
  • Heart Rate Variability (HRV): From brain death to resonance breathing at 6 breaths/minute
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-04
    Andreas R. Schwerdtfeger, Gerhard Schwarz, Klaus Pfurtscheller, Julian F. Thayer, Marc N. Jarczok, Gert Pfurtscheller

    Heart rate variability (HRV) has been associated with various diseases and reflects autonomic cardiac control sensitive to central nervous system function. Examples of the heart-brain interaction are illustrated by extreme clinical conditions such as brain death, orthotopic heart transplantation, weaning from respirator support, and brain maturation in preterm infants. Interactions with the immune system document the importance of HRV for tumor growth and prognosis. Research linking HRV to the regulation of negative emotions including depression and anxiety document the sensitive influence of central commands on cardiac activity. Moreover, 0.1 Hz oscillations in the heart and the brain seem to be coupled, thus indicating central pacemakers on the heart rhythm. Moreover, low frequency oscillations in heart rate seem to be composed of two subcomponents presumably signaling different central-autonomic functions. We conclude by showing that breathing at 6 breaths/minute could induce coherence of the 0.1 Hz oscillations, thus facilitating physical and psychological function. The reviewed findings impressively demonstrate that central nervous system function modifies the rhythm of the heart and vice versa, suggesting that HRV could be a useful indicator of central-autonomic integration and that 0.1 Hz oscillations play a major role in physical and mental health via optimizing energy supply.

    更新日期:2019-12-04
  • Significant group-level hotspots found in deep brain regions during transcranial direct current stimulation (tDCS): A computational analysis of electric fields
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-02
    Jose Gomez-Tames, Akihiro Asai, Akimasa Hirata

    Objective Transcranial direct current stimulation (tDCS) is a neuromodulation scheme that delivers a small current via electrodes placed on the scalp. The target is generally assumed to be under the electrode, but deep brain regions could also be involved due to the large current spread between the electrodes. This study aims to computationally evaluate if group-level hotspots exist in deep brain regions for different electrode montages. Methods We computed the tDCS-generated electric fields (EFs) in a group of subjects using interindividual registration methods that permitted the projection of EFs from individual realistic head models (n = 18) to a standard deep brain region. Results The spatial distribution and peak values (standard deviation of 14%) of EFs varied significantly. Nevertheless, group-level EF hotspots appeared in deep brain regions. The caudate had the highest field peaks in particular for F3-F4 montage (70% of maximum cortical EF), while other regions reach field peaks of 50%. Conclusions tDCS at deeper regions may include not only modulation via underlying cortical or subcortical circuits but also modulation of deep brain regions. Significance The presented EF atlas in deep brain regions can be used to explain tDCS mechanism or select the most appropriate tDCS montage.

    更新日期:2019-12-03
  • Mechanism of visual network dysfunction in relapsing-remitting multiple sclerosis and its relation to cognition
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-02
    Gerald K. Cooray, Mathias Sundgren, Tom Brismar

    Objective To investigate if changes in brain network function and connectivity contribute to the abnormalities in visual event related potentials (ERP) in relapsing-remitting multiple sclerosis (RRMS), and explore their relation to a decrease in cognitive performance. Methods We evaluated 72 patients with RRMS and 89 healthy control subjects in a cross-sectional study. Visual ERP were generated using illusory and non-illusory stimuli and recorded using 21 EEG scalp electrodes. The measured activity was modelled using Dynamic Causal Modelling. The model network consisted of 4 symmetric nodes including the primary visual cortex (V1/V2) and the Lateral Occipital Complex. Patients and controls were tested with a neuropsychological test battery consisting of 18 cognitive tests covering six cognitive domains. Results We found reduced cortical connectivity in bottom-up and interhemispheric connections to the right lateral occipital complex in patients (p<0.001). Furthermore, interhemispherical connections were related to cognitive dysfunction in several domains (attention, executive function, visual perception and organization, processing speed and global cognition) for patients (p<0.05). No relation was seen between cortical network connectivity and cognitive function in the healthy control subjects. Conclusion Changes in the functional connectivity to higher cortical regions provide a neurobiological explanation for the changes of the visual ERP in RRMS. Significance This study suggests that changes in connectivity to higher cortical regions partly explain visual network dysfunction in RRMS where a lower interhemispheric connectivity may contribute to impaired cognitive function.

    更新日期:2019-12-03
  • Naming processes in reading and spelling disorders: an electrophysiological investigation
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-12-02
    Sarolta Bakos, Heike Mehlhase, Karin Landerl, Jürgen Bartling, Gerd Schulte-Körne, Kristina Moll

    Objective Reading fluency deficits characteristic for reading disorders (RD; F81.0) have been shown to be strongly associated with slow naming speed (e.g. in rapid automatized naming tasks). In contrast, children with an isolated spelling disorder in the context of unimpaired reading skills (iSD; F81.1) show naming speed task performances that are similar to typically developing (TD) children. However, the exact nature of the naming speed deficit and its relation to RD and the question whether children with iSD are also on the neurophysiological level similar to TD children is still unresolved. Methods The time-course and scalp topography of event-related potentials (ERP) activity recorded during a delayed digit-naming task was investigated in ten-year-old children with RD and iSD compared to a TD group. Results ERP activity differed between the RD and the TD group at around 300 ms after stimulus presentation (left occipito-temporal P2). In contrast, there were no neurophysiological differences between the TD and the iSD group. The P2 component correlated with behavioural performance on the RAN task. Conclusions Slow naming speed in RD might result from a slowed-down access and prolonged processing of the word (lexical) form. Significance The study establishes a relation between neurophysiological processes of naming tasks and RD.

    更新日期:2019-12-03
  • Test-Retest Reliability of the N2 Event-Related Potential in School-Aged Children with Autism Spectrum Disorder (ASD)
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-25
    Amanda Cremone-Caira, Akshita Vaidyanathan, Danielle Hyatt, Rachel Gilbert, Tessa Clarkson, Susan Faja

    Objective The N2 ERP component is used as a biomeasure of executive function in children with autism spectrum disorder (ASD). The aim of the current study was to evaluate the test-retest reliability of N2 amplitude in this population. Methods ERPs were recorded from 7 to 11-year-old children with ASD during Flanker (n = 21) and Go/Nogo tasks (n = 14) administered at two time points separated by approximately three months. Reliability of the N2 component was examined using intraclass correlation coefficients (ICCs). Results Reliability for mean N2 amplitude obtained during the Flanker task was moderate (congruent: ICC = 0.542, 95% CI [0.173,0.782]; incongruent: ICC = 0.629, 95% CI [0.276,0.831]). Similarly, reliability for the Go/Nogo task ranged from moderate to good (‘go’: ICC = 0.817, 95% CI [0.535,0.937]; ‘nogo’: ICC = 0.578, 95% CI [0.075,0.843]). Conclusions These findings support the use of N2 amplitude as a biomeasure of executive function in school-aged children with ASD. Significance This research addresses a critical gap in clinical neurophysiology, as an understanding of the stability and reliability of the N2 component is needed in order to differentiate variance explained by repeated measurement versus targeted treatments and interventions.

    更新日期:2019-11-26
  • Computational modelling in source space from scalp EEG to inform presurgical evaluation of epilepsy
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-22
    Marinho A. Lopes, Leandro Junges, Luke Tait, John R. Terry, Eugenio Abela, Mark P. Richardson, Marc Goodfellow

    Objective The effectiveness of intracranial electroencephalography (iEEG) to inform epilepsy surgery depends on where iEEG electrodes are implanted. This decision is informed by noninvasive recording modalities such as scalp EEG. Herein we propose a framework to interrogate scalp EEG and determine epilepsy lateralization to aid in electrode implantation. Methods We use eLORETA to map source activities from seizure epochs recorded from scalp EEG and consider 15 regions of interest (ROIs). Functional networks are then constructed using the phase-locking value and studied using a mathematical model. By removing different ROIs from the network and simulating their impact on the network’s ability to generate seizures in silico, the framework provides predictions of epilepsy lateralization. We consider 15 individuals from the EPILEPSIAE database and study a total of 62 seizures. Results were assessed by taking into account actual intracranial implantations and surgical outcome. Results The framework provided potentially useful information regarding epilepsy lateralization in 12 out of the 15 individuals (p=0.02, binomial test). Conclusions Our results show promise for the use of this framework to better interrogate scalp EEG to determine epilepsy lateralization. Significance The framework may aid clinicians in the decision process to define where to implant electrodes for intracranial monitoring.

    更新日期:2019-11-22
  • Influence of reference electrode position on the compound muscle action potential
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-22
    Sanjeev D. Nandedkar, Paul E. Barkhaus

    Objective When the compound muscle action potential (CMAP) is recorded in motor nerve conduction studies, the reference (E2) electrode can make a significant contribution to the CMAP. This study investigates the E2 recorded signal and its effect on CMAP measurements when E2 electrode is placed at different sites. Methods The CMAP was recorded using the active electrode on the muscle belly and 4 different E2 electrodes placed at distal and proximal sites. The signal recorded by each electrode was also measured using a reference electrode on the contralateral limb. Signals were recorded from the abductor pollicis brevis, abductor digiti minimi, tibialis anterior and biceps muscles. Results The E2 recorded a smaller signal when it was placed near or off the proximal tendon or muscle origin. This affected CMAP latency, duration for tibialis anterior. Contrary to expectation, initial upward deflection was noted for E2 signal. Conclusion A proximal E2 position records a lower volume conducted signal and yields a CMAP that is more representative of the muscle over which the E1 (active) electrode is placed. Significance The proposed ‘Proximal E2’ montage may be better suited to assess pathology.

    更新日期:2019-11-22
  • Deriving pediatric nerve conduction normal values in the very young (<3 years)
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-22
    Joe F. Jabre, Matthew C. Pitt, Ralph Smith

    Objective This work describes our efforts to obtain nerve conduction studies normal values in a pediatric cohort between birth and 3 years of age using the extrapolated norms or e-norms method. Interpretation of these studies poses major challenges when no reliable normal values can be found in the literature. Methods The e-norms method was used to derive a reference range of upper and lower extremity sensory and motor nerve conductions normal values from a pediatric cohort referred to an EMG Laboratory for nerve conduction studies. Results E-norms were calculated for Median, Ulnar, Superficial Peroneal, Sural, and Medial Plantar sensory studies, and for Median, Ulnar, Peroneal, and Tibial motor studies. Conclusions Pediatric electrodiagnostic testing is a very challenging undertaking. The ability to obtain and use normal values from the neurophysiologist’s own referral pool adds great value to their diagnostic work-up. Significance EMG and nerve conduction studies can yield invaluable information in the diagnostic work-up of young infants. Using the e-norms method improves on the analysis and interpretation of electrophysiological studies in this age group.

    更新日期:2019-11-22
  • Tripolar concentric EEG electrodes reduce noise
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-22
    Anahita Aghaei-Lasboo, Katherine Inoyama, Adam S. Fogarty, Jonathan Kuo, Kimford J. Meador, Jessica J. Walter, Scheherazade T. Le, Kevin D. Graber, Babak Razavi, Robert S. Fisher

    Objective To assay EEG signal quality recorded with tripolar concentric ring electrodes (TCREs) compared to regular EEG electrodes. Methods EEG segments were recorded simultaneously by TCREs and regular electrodes, low-pass filtered at 35 Hz (REG35) and 70 Hz (REG70). Clips were rated blindly by nine electroencephalographers for presence or absence of key EEG features, relative to the “gold-standard” of the clinical report. Results TCRE showed less EMG artifact (F =15.4, p < .0001). Overall quality rankings were not significantly different. Focal slowing was better detected by TCRE and spikes were better detected by regular electrodes. Seizures (n=85) were detected by TCRE in 64 cases (75.3%), by REG70 in 75 (88.2%) and REG35 in 69 (81.2%) electrodes. TCRE detected 9 (10.6%) seizures not detected by one of the other 2 methods. In contrast, 14 seizures (16.5%) were not detected by TCRE, but were by REG35 electrodes. Each electrode detected interictal spikes when the other did not. Conclusions TCRE produced similar overall quality and confidence ratings versus regular electrodes, but less muscle artifact. TCRE recordings detected seizures in 7% of instances where regular electrodes did not. Significance The combination of the two types increased detection of epileptiform events compared to either alone.

    更新日期:2019-11-22
  • A skew-based method for identifying intracranial EEG channels with epileptic activity without detecting spikes, ripples, or fast ripples
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-22
    Anne H. Mooij, Birgit Frauscher, Jean Gotman, Geertjan J.M. Huiskamp

    Objective To develop a method for identifying intracranial EEG (iEEG) channels with epileptic activity without the need to detect spikes, ripples, or fast ripples. Methods We compared the skew of the distribution of power values from five minutes non-rapid eye movement stage N3 sleep for the 5-80 Hz, 80-250 Hz (ripple), and 250-500 Hz (fast ripple) bands of epileptic (located in seizure-onset or irritative zone) and non-epileptic iEEG channels recorded in patients with drug-resistant focal epilepsy. We optimized settings in 120 bipolar channels from 10 patients, compared the results to 120 channels from another 10 patients, and applied the method to channels of 12 individual patients. Results The distribution of power values was more skewed in epileptic than in non-epileptic channels in all three frequency bands. The differences in skew were correlated with the presence of spikes, ripples, and fast ripples. When classifying epileptic and non-epileptic channels, the mean accuracy over 12 patients was 0.82 (sensitivity: 0.76, specificity: 0.91). Conclusions The ‘skew method’ can distinguish epileptic from non-epileptic channels with good accuracy and, in particular, high specificity. Significance This is an easy-to-apply method that circumvents the need to visually mark or automatically detect interictal epileptic events.

    更新日期:2019-11-22
  • Practice-dependent motor cortex plasticity is reduced in non-disabled Multiple Sclerosis patients
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-21
    Mario Stampanoni Bassi, Fabio Buttari, Pierpaolo Maffei, Nicla De Paolis, Andrea Sancesario, Luana Gilio, Luigi Pavone, Gabriele Pasqua, Ilaria Simonelli, Francesco Sica, Roberta Fantozzi, Paolo Bellantonio, Diego Centonze, Ennio Iezzi

    Objectives Skill acquisition after motor training involves synaptic long-term potentiation (LTP) in primary motor cortex (M1). In multiple sclerosis (MS), LTP failure ensuing from neuroinflammation could contribute to worsen clinical recovery. We therefore addressed whether practice-dependent plasticity is altered in MS. Methods Eighteen relapsing-remitting (RR)-MS patients and eighteen healthy controls performed 600 fast abductions of index finger in 30 blocks of 20 movements. Before and after practice, transcranial magnetic stimulation (TMS) was delivered over the hot spot of the trained first dorsal interosseous muscle. Movements kinematics, measures of cortical excitability, and the input/output curves of motor evoked potentials (MEPs) were assessed. Results Kinematic variables of movement improved with practice in patients and controls to a similar extent, although patients showed lower MEPs amplitude increase after practice. Practice did not change the difference in RMT values observed between patients and controls, nor did modulate SICI. Clinical/radiological characteristics were not associated to practice-dependent effects. Conclusions Practice-induced reorganization of M1 is altered in non-disabled RR-MS patients, as shown by impaired MEPs modulation after motor learning. Significance These findings suggest that in RR-MS physiological mechanisms of practice-dependent plasticity are altered.

    更新日期:2019-11-22
  • Sensory evoked potentials in patients with Rett syndrome through the lens of animal studies: systematic review
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-21
    Olga V. Sysoeva, Kirill Smirnov, Tatiana A. Stroganova

    Objective Systematically review the abnormalities in event related potential (ERP) recorded in Rett Syndrome (RTT) patients and animals in search of translational biomarkers of deficits related to the particular neurophysiological processes of known genetic origin (MECP2 mutations). Methods Pubmed, ISI Web of Knowledge and BIORXIV were searched for the relevant articles according to PRISMA standards. Results ERP components are generally delayed across all sensory modalities both in RTT patients and its animal model, while findings on ERPs amplitude strongly depend on stimulus properties and presentation rate. Studies on RTT animal models uncovered the abnormalities in the excitatory and inhibitory transmission as critical mechanisms underlying the ERPs changes, but showed that even similar ERP alterations in auditory and visual domains have a diverse neural basis. A range of novel approaches has been developed in animal studies bringing along the meaningful neurophysiological interpretation of ERP measures in RTT patients. Conclusions While there is a clear evidence for sensory ERPs abnormalities in RTT, to further advance the field there is a need in a large-scale ERP studies with the functionally-relevant experimental paradigms. Significance The review provides insights into domain-specific neural basis of the ERP abnormalities and promotes clinical application of the ERP measures as the non-invasive functional biomarkers of RTT pathophysiology.

    更新日期:2019-11-22
  • Thalamo-cortical network dysfunction in temporal lobe epilepsy
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-20
    Giovanni Assenza, Jacopo Lanzone, Angelo Insola, Giulia Amatori, Lorenzo Ricci, Mario Tombini, Vincenzo Di Lazzaro

    Objectives Imaging and neurophysiological data shows that the cortical disfunction caused by focal epilepsy is not limited to the epileptic focus, thus raising the modern vision of focal epilepsy as a network disorder. The involvement of deep thalamo-cortical projections in temporal lobe epilepsy is a clear example. We aimed at demonstrating the interictal functional impairment of thalamo-cortical network in drug-naïve TLE patients through the study of high frequency oscillations of somatosensory evoked potentials (HF-SEP). Methods Twelve healthy controls (HC; 8 females, 52.2±17.3 years-old) and 12 drug-naïve TLE patients (8 females, 55.5±21.5 years-old) underwent bilateral median HF-SEP, recorded by scalp electrodes. Cp3’-Fz and Cp4’-Fz traces were filtered (400-800 Hz) to evidence HF-SEP. Results HF-SEP duration in the affected hemisphere was significantly longer when compared to that of both the unaffected hemisphere and HC hemispheres. No significant inter-hemispheric differences were found in areas, powers and latencies of HF-SEP wavelets. Conclusion Our results demonstrate that TLE induces early interictal functional impairments of the thalamo-cortical network. Significance Our data strongly corroborates the vision of focal epilepsy as a network disorder and offers a new neurophysiological tool to test pharmacological, surgical and neuromodulatory therapies.

    更新日期:2019-11-20
  • Natural alpha frequency components in resting EEG and their relation to arousal
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-20
    Robert J. Barry, Frances M. De Blasio, Jack S. Fogarty, Adam R. Clarke

    Objective Global EEG alpha activity is negatively correlated with skin conductance level (SCL), supporting alpha as an inverse marker of arousal. Frequency Principal Components Analysis (f-PCA) of resting EEG amplitude spectra has demonstrated natural components in the alpha band of healthy persons. This is a preliminary exploration of whether such components differ with arousal, possibly underpinning the anomalous ADHD hypoarousal link to reduced alpha. Method Twenty-seven right-handed undergraduate students participated in three 2 minute blocks of resting eyes-open/closed EEG and SCL: EO1, EC, EO2. For each condition, mean EEG spectra were submitted to separate f-PCAs. Results The inverse alpha/SCL relationship was confirmed for band amplitudes. EO had two alpha components; both correlated negatively with SCL. EC alpha contained four components, but only one had a substantial negative correlation with SCL; two had no relationship, suggesting natural alpha components with different non-arousal functionality in EC. Conclusion Some alpha components in both EC and EO reflect arousal, with other non-arousal components in EC. Our f-PCA approach offers insight into previously-noted alpha anomalies in disorders such as ADHD. Significance This proof of concept demonstration in typical participants may provide the basis for a new research effort in clinical disorders involving atypical arousal patterns.

    更新日期:2019-11-20
  • Effects of Ventral Intermediate Nucleus Deep Brain Stimulation Across Multiple Effectors in Essential Tremor
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-20
    B.J. Wilkes, A. Wagle Shukla, A. Casamento-Moran, C.W. Hess, E.A. Christou, M.A. Okun, D.E. Vaillancourt

    Objective Essential tremor (ET) prominently affects the upper-limbs during voluntary movements, but can also affect the lower-limbs, head, and chin. Although deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of thalamus improves both clinical ratings and quantitative measures of tremor, no study has quantified effects of DBS on tremor across multiple body parts. Our objective was to quantify therapeutic effects of DBS across multiple body parts in ET. Methods We performed quantitative assessment of tremor in ET patients who had DBS for at least one year. We assessed tremor on and off VIM-stimulation using triaxial accelerometers on the upper-limbs, lower-limbs, head and chin during seated and standing tasks. Results VIM-DBS significantly reduced tremor, but there was no statistical difference in degree of tremor reduction across the measured effectors. Compared to healthy controls, ET patients treated with DBS showed significantly greater tremor power (4-8 Hz) across all effectors during seated and standing tasks. Conclusions VIM-DBS reduced tremor in ET patients. There was no significant difference in the degree of tremor reduction across the measured effectors. Significance This study provides new quantitative evidence that VIM-DBS is effective at reducing tremor across multiple parts of the body.

    更新日期:2019-11-20
  • Neurophysiological markers of cue reactivity and inhibition subtend a three-month period of complete alcohol abstinence
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-20
    Salvatore Campanella, Elisa Schroder, Hendrik Kajosch, Catherine Hanak, Johannes Veeser, Maud Amiot, Tatiana Besse-Hammer, Nabil Hayef, Charles Kornreich

    Objective Finding new tools for conventional management of alcohol disorders is a challenge for psychiatrists. Brain indications related to cognitive functioning could represent such an add-on tool. Methods Forty alcohol-dependent inpatients undertook two cognitive event-related potential (ERP) tasks at the beginning and at the end of a 4-week detoxification program. These comprised a visual oddball task investigating cue reactivity and a Go/No-go task tagging inhibition using oddball P3d and No-go P3d ERP components. Three months after discharge, the patient group (N = 40) was split into two subgroups: patients who remained abstinent during this post-treatment period (90 days; n = 15), and patients who relapsed (mean time: 28.5 ± 26.2 days; n = 25). Pattern changes of both ERP markers (oddball P3d and No-go P3d) during the detoxification were compared to differentiate these populations. Results Abstinent patients exhibited similar P3d responses devoted to alcohol cues in Sessions 1 and 2, but an increased No-go P3d devoted to No-go trials in alcohol-related contexts in Session 2 compared to Session 1. Conclusions Specific cue-reactivity and inhibitory neurophysiological markers subtend a further three-months of complete abstinence. Significance Monitoring these ERP changes during detoxification may provide important clues regarding patients’ future abstinence vs. relapse. The present data were derived from secondary analyses related to the Clinical Trial NCT02107352 entitled “Effect of Anti-craving Medication on Cognitive Functions in Alcohol Dependence: an ERP Study”. URL: https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0004LNJ&selectaction=Edit&uid=U0001RBA&ts=2&cx=-mw5fp4

    更新日期:2019-11-20
  • Repeater F-waves in amyotrophic lateral sclerosis: electrophysiologic indicators of upper or lower motor neuron involvement?
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-11
    Emel Oguz Akarsu, Nermin Gorkem Sirin, Elif Kocasoy Orhan, Bahar Erbas, Hava Ozlem Dede, Mehmet Baris Baslo, Halil Atilla Idrisoglu, Ali Emre Oge

    Objective To extract insight about the mechanism of repeater F-waves (Frep) by exploring their correlation with electrophysiologic markers of upper and lower motor neuron dysfunction in amyotrophic lateral sclerosis (ALS). Methods The correlations of Frep parameters with clinical scores and the results of neurophysiological index (NI), MScanfit MUNE, F/M amplitude ratio (F/M%), single and paired-pulse transcranial magnetic stimulation (TMS), and triple stimulation technique (TST) studies, recorded from abductor digiti minimi (ADM) and abductor pollicis brevis (APB) muscles of 35 patients with ALS were investigated. Results Frep parameters were correlated with NI and MScanfit MUNE in ADM muscle and F/M% in both muscles. None of the Frep parameters were correlated with clinical scores or TST and TMS measures. While the CMAP amplitudes were similar in the two recording muscles, there was a more pronounced decrease of F-wave persistence in APB, probably heralding the subsequent split hand phenomenon. Conclusion Our findings suggest that the presence and density of Freps are primarily related to the degree of lower motor neuron loss and show no correlation with any of the relatively extensive set of parameters for upper motor neuron dysfunction. Significance Freps are primarily related to lower motor neuron loss in ALS.

    更新日期:2019-11-13
  • Detection of mesial temporal lobe epileptiform discharges on intracranial electrodes using deep learning
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-11
    Maurice Abou Jaoude, Jin Jing, Haoqi Sun, Claire S. Jacobs, Kyle R. Pellerin, M. Brandon Westover, Sydney S. Cash, Alice D. Lam

    Objective Develop a high-performing algorithm to detect mesial temporal lobe (mTL) epileptiform discharges on intracranial electrode recordings. Methods An epileptologist annotated 13,959 epileptiform discharges from a dataset of intracranial EEG recordings from 46 epilepsy patients. Using this dataset, we trained a convolutional neural network (CNN) to recognize mTL epileptiform discharges from a single intracranial bipolar channel. The CNN outputs from multiple bipolar channel inputs were averaged to generate the final detector output. Algorithm performance was estimated using a nested 5-fold cross-validation Results On the receiver-operating characteristic curve, our algorithm achieved an area under the curve (AUC) of 0.996 and a partial AUC (for specificity > 0.9) of 0.981. AUC on a precision-recall curve was 0.807. A sensitivity of 84% was attained at a false positive rate of 1 per minute. 35.9% of the false positive detections corresponded to epileptiform discharges that were missed during expert annotation. Conclusions Using deep learning, we developed a high-performing, patient non-specific algorithm for detection of mTL epileptiform discharges on intracranial electrodes. Significance Our algorithm has many potential applications for understanding the impact of mTL epileptiform discharges in epilepsy and on cognition, and for developing therapies to specifically reduce mTL epileptiform activity.

    更新日期:2019-11-13
  • Could we have missed out the seizure onset: A study based on intracranial EEG
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-11
    P.A. Karthick, Hideaki Tanaka, Hui Ming Khoo, Jean Gotman

    Objective Intracranial EEG covers only a small fraction of brain volume and it is uncertain if a discharge represents a true seizure onset or results from spread. We therefore assessed if there are differences between characteristics of the ictal onset when we are likely to have a true onset, and characteristics of the discharge in regions of spread. Methods Wavelet based statistical features were extracted in 503 onset and 390 spread channels of 58 seizures from 20 patients. These features were used as predictors in models based on machine learning algorithms such as k-nearest neighbour, logistic regression, multilayer perceptron, support vector machine, random and rotation forest. Results Statistical features (mean, variance, skewness and kurtosis) associated with all wavelet scales were significantly higher in onset than in spread channels. The best classifier, random forest, achieved accuracy of 79.6% and precision of 82%. Conclusions The signals associated with onset and spread regions exhibit different characteristics. The proposed features are able to classify the signals with good accuracy. Significance Using our classifier on new seizures could help clinicians gain confidence in having recorded the real seizure onset or on the contrary be concerned that the true onset may have been missed.

    更新日期:2019-11-13
  • Direct cortical stimulation with cylindrical depth electrodes in the interhemispheric fissure for leg motor evoked potential monitoring
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-11
    Liberto Brage, Pedro Javier Pérez-Lorensu, Julio Plata-Bello, Ángel Saponaro-González, Luis Pérez-Orribo, Mario García-Conde, Pablo Febles-García, Héctor Roldán-Delgado, Víctor García-Marín

    Objective To evaluate cylindrical depth electrodes in the interhemispheric fissure as an alternative to subdural strip electrodes for direct cortical stimulation (DCS) leg motor evoked potential (MEP) monitoring. Methods A cylindrical depth electrode was positioned in the interhemispheric fissure of 37 patients who underwent supratentorial brain surgery. Leg sensory and motor cortices were localized by highest tibial nerve somatosensory evoked potential amplitude and lowest DCS leg MEP threshold; the lowest-threshold electrode was then used for DCS leg MEP monitoring. Results Intraoperative leg MEPs were obtained from all the patients in the series. The mean intensity applied for leg MEP monitoring with the cylindrical depth electrode was 15.2 ± 4.0 mA. No complications secondary to neurophysiological monitoring were detected. Conclusions Lower extremity MEPs were consistently recorded using a multi-contact cylindrical depth electrode in the interhemispheric fissure by DCS. Significance Cylindrical depth electrodes may be a safe and effective alternative for DCS in the interhemispheric fissure, where subdural strips are difficult to place.

    更新日期:2019-11-13
  • Prognostic value of phrenic nerve conduction study in amyotrophic lateral sclerosis: Systematic review and meta-analysis
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-11
    Cláudia S. Silva, Filipe B. Rodrigues, Gonçalo S. Duarte, João Costa, Mamede de Carvalho

    Objectives To assess the prognostic value of phrenic nerve conduction (PNC) in amyotrophic lateral sclerosis (ALS). Methods We conducted a systematic review to identify studies reporting on PNC, and mortality and/or forced vital capacity (FVC) in patients with ALS. We searched Medline, EMBASE, and Web of Science. Two independent authors selected studies and extracted data. Risk of bias was assessed using the QUIPS tool. Hazard-ratios and correlation coefficients were pooled using a random effects generic inverse-variance model. Evidence quality was evaluated with GRADE. Results In the pooled analysis, patients with CMAP-amplitude equal or below 0.4mV are 2.021 more likely to die over the studied period (95%CI 1.161 to 3.522; I2=55.9%; 338 participants). CMAP-amplitude showed a moderate positive correlation with FVC (r=0.400, 95%CI= 0.226 to 0.550; I2=69.77%; 381 participants). However, there was a weak negative correlation between CMAP-latency and FVC (r=-0.235; 95%CI= -0.447 to -0.024; I2=15.92%; 112 participants). Conclusions There is moderate-quality evidence that CMAP-amplitude of the PNC is correlated with FVC. Results favour a predictive value for mortality, but the risk of bias is high. Significance PNC is a simple test that should be considered to assess respiratory function in ALS, especially in patients with bulbar involvement or cognitive impairment.

    更新日期:2019-11-13
  • Association of corneal nerve loss with markers of axonal ion channel dysfunction in type 1 diabetes
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-11
    Shyam Sunder Tummanapalli, Tushar Issar, Natalie Kwai, Ann Poynten, Arun V. Krishnan, Mark Willcox, Maria Markoulli

    Objective Corneal confocal microscopy (CCM) has been identified as a non-invasive technique to assess corneal nerve fiber morphology. It is not known how corneal nerve changes relate to measures of peripheral nerve function in diabetic peripheral neuropathy (DPN). The present study investigates the relationship between nerve structure and function in DPN. Methods Fifty participants with type 1 diabetes (T1DM) and 29 healthy controls underwent CCM to assess corneal nerve fiber density (CNFD), branch density (CNBD), fiber length (CNFL), total branch density (CTBD), nerve fractal dimension (CNFrD) and inferior whorl length (IWL). The severity of DPN was assessed as Total Neuropathy Score (TNS). Motor nerve axonal excitability tests were conducted to assess axonal function. Results Significant correlations were noted between CNFD (rho = -0.783; P < 0.01) or superexcitability (rho = 0.435; P < 0.01) and TNS.  CNFrD was significantly correlated with peak response to stimulus (r = 0.414; P < 0.01) and superexcitability (r = -0.467; P < 0.01) measurements. Conclusion Corneal nerve loss demonstrates a significant association with axonal ion channel dysfunction in T1DM. Significance Detection of altered corneal nerve morphology may lead to the earlier diagnosis of DPN.

    更新日期:2019-11-13
  • A standardised assessment schemefor conventional EEG in preterm infants
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-09
    E. Elena Pavlidis, Rhodri O. Lloyd, Vicki Livingstone, John M. O'Toole, Peter M. Filan, Francesco Pisani, Geraldine B. Boylan

    Objective To develop a standardised scheme for assessing normal and abnormal electroencephalography (EEG) features of preterm infants. To assess the interobserver agreement of this assessment scheme. Methods We created a standardised EEG assessment scheme for 6 different post-menstrual age (PMA) groups using 4 EEG categories. Two experts, not involved in the development of the scheme, evaluated this on 24 infants <32 weeks gestational age (GA) using random 2 hour EEG epochs. Where disagreements were found, the features were checked and modified. Finally, the two experts independently evaluated 2 hour EEG epochs from an additional 12 infants <37 weeks GA. The percentage of agreement was calculated as the ratio of agreements to the sum of agreements plus disagreements. Results Good agreement in all patients and EEG feature category was obtained, with a median agreement between 80% and 100% over the 4 EEG assessment categories. No difference was found in agreement rates between the normal and abnormal features (p = 0.959). Conclusions We developed a standard EEG assessment scheme for preterm infants that shows good interobserver agreement. Significance This will provide information to Neonatal Intensive Care Unit (NICU) staff about brain activity and maturation. We hope this will prove useful for many centres seeking to use neuromonitoring during critical care for preterm infants.

    更新日期:2019-11-11
  • Ultrasound guidance increases diagnostic yield of Needle EMG in plegic muscle
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-09
    Luca Gentile, Daniele Coraci, Costanza Pazzaglia, Filippo Del Tedesco, Carmen Erra, Domenica Le Pera, Luca Padua

    Objectives To increase the specificity of motor unit potential (MUPs) detection by using ultrasound guided electromyography (USG-EMG) in patients with muscle plegia due to traumatic nerve lesions. Methods Forty-six patients with recent nerve trauma underwent baseline standard EMG (ST-EMG) evaluation with evidence of absent MUPs. In 41 of them, ST-EMG was repeated after 2-3 months (T1) and the patients were accordingly divided in two groups: ST-EMG+ (if MUPs were detected) or ST-EMG- (MUPs not detected). Then, ST-EMG- patients underwent muscle ultrasound evaluation (M-US) and, if isles of muscular contractility were found, they also had USG-EMG. The same protocol was repeated 4-6 months after baseline (T2). Results At T1, 22/41 patients were ST-EMG+. While 19/41 were ST-EMG-; 9 of these patients had M-US consistent with residual muscular activity, for that reasons underwent USG-EMG with 7 of 9 demonstrating MUPs (at T2 all of these 7 patients resulted ST-EMG). In the other 2 patients, we found no MUPs at T1 but they became ST-EMG+ or USG-EMG positive at T2. The remaining 10 ST-EMG- patients had no EMG or US evidence of muscle contraction at T1, but at T2 2 of 10 became ST-EMG+ and 2 had USG-EMG showing MUPs. In the remaining 6 patients still M-US negative at T2, complete denervation was diagnosed. Concerning the 22 patients who were ST-EMG + at T1, all but one showed increase of MUPs at T2. Conclusions In this study, we demonstrated the utility of US guidance when performing EMG evaluation in locating isles of muscular contractility in patients who have no detectable MUPs on EMG after nerve trauma. Significance USG-EMG significantly increases the specificity of needle EMG allowing earlier detection of MUPs.

    更新日期:2019-11-11
  • The role of blink reflex R1 latency as an electrophysiological marker in diabetic distal symmetrical polyneuropathy
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-05
    Yun-Ru Lai, Chih-Cheng Huang, Wen-Chan Chiu, Rue-Tsuan Liu, Nai-Wen Tsai, Hung-Chen Wang, Wei-Che Lin, Ben-Chung Cheng, Yu-Jih Su, Chih-Min Su, Sheng-Yuan Hsiao, Pei-Wen Wang, Jung-Fu Chen, Jih-Yang Ko, Cheng-Hsien Lu

    Objective Studies showed a relatively prolonged blink R1 latency in patients with diabetic distal symmetrical polyneuropathy (DSPN) compared to that without DSPN. We tested the hypothesis that blink R1 latency would provide a diagnostic alternative to nerve conduction studies (NCS) in DSPN and act as a marker of the severity of NCS abnormalities in DSPN. Method A total of 109 patients with type 2 diabetes underwent blink reflex studies and NCS. We used the composite amplitude scores of nerve conductions (CAS), which consisted of motor (tibial, peroneal and ulnar) and sensory (sural and ulnar) amplitudes for estimating the severity of NCS Results Patients with DSPN had longer blink R1, R2, and contralateral R2 latencies (P < 0.0001, P = 0.001, and P = 0.031, respectively) and higher CAS (P < 0.0001). Area under curve on receiver operating characteristic curve analysis in diagnosing occurrence of DSPN in blink R1 latency was 0.772 (P < 0.0001). Multiple linear regression analysis showed that blink R1 latency was independently associated with CAS. Conclusion Blink R1 latency may be valuable in auxiliary diagnosis and in determining the severity of NCS abnormalities in DSPN Significance Blink R1 latency can be added as a supplemental marker of severity of NCS in DSPN, especially if the patient’s sural amplitudes has a floor effect

    更新日期:2019-11-06
  • Standards of instrumentation of EMG
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-05
    Hatice Tankisi, David Burke, Liying Cui, Mamede de Carvalho, Satoshi Kuwabara, Sanjeev D. Nandedkar, Seward Rutkove, Erik Stålberg, Michel J.A.M. van Putten, Anders Fuglsang-Frederiksen

    Standardization of Electromyography (EMG) instrumentation is of particular importance to ensure high quality recordings. This consensus report on “Standards of Instrumentation of EMG” is an update and extension of the earlier IFCN Guidelines published in 1999. First, a panel of experts in different fields from different geographical distributions was invited to submit a section on their particular interest and expertise. Then, the merged document was circulated for comments and edits until a consensus emerged. The first sections in this document cover technical aspects such as instrumentation, EMG hardware and software including amplifiers and filters, digital signal analysis and instrumentation settings. Other sections cover the topics such as temporary storage, trigger and delay line, averaging, electrode types, stimulation techniques for optimal and standardised EMG examinations, and the artefacts electromyographers may face and safety rules they should follow. Finally, storage of data and databases, report generators and external communication are summarized.

    更新日期:2019-11-06
  • Improved Detection of Parkinsonian Resting Tremor with Feature Engineering and Kalman Filtering
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-05
    Lin Yao, Peter Brown, Mahsa Shoaran

    Objective Accurate and reliable detection of tremor onset in Parkinson’s disease (PD) is critical to the success of adaptive deep brain stimulation (aDBS) therapy. Here, we investigated the potential use of feature engineering and machine learning methods for more accurate detection of rest tremor in PD. Methods We analyzed the local field potential (LFP) recordings from the subthalamic nucleus region in 12 patients with PD (16 recordings). To explore the optimal biomarkers and the best performing classifier, the performance of state-of-the-art machine learning (ML) algorithms and various features of the subthalamic LFPs were compared. We further used a Kalman filtering technique in feature domain to reduce the false positive rate. Results The Hjorth complexity showed a higher correlation with tremor, compared to other features in our study. In addition, by optimal selection of a maximum of five features with a sequential feature selection method and using the gradient boosted decision trees as the classifier, the system could achieve an average F1 score of up to 88.7% and a detection lead of 0.52s. The use of Kalman filtering in feature space significantly improved the specificity by 17.0% (p=0.002), thereby potentially reducing the unnecessary power dissipation of the conventional DBS system. Conclusion The use of relevant features combined with Kalman filtering and machine learning improves the accuracy of tremor detection during rest. Significance The proposed method offers a potential solution for efficient on-demand stimulation for PD tremor.

    更新日期:2019-11-06
  • Biophysical Reconstruction of the Signal Conduction Underlying Short-Latency Cortical Evoked Potentials Generated by Subthalamic Deep Brain Stimulation
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-05
    Kabilar Gunalan, Cameron C. McIntyre

    Objective Direct activation of the hyperdirect (HD) pathway has been linked to therapeutic benefit from subthalamic deep brain stimulation (DBS) for the treatment of Parkinson’s disease (PD). We sought to quantify the axonal conduction biophysics of corticofugal axons directly stimulated by subthalamic DBS and reconcile those findings with short-latency cortical evoked potential (EP) results. Methods We used a detailed computational model of human subthalamic DBS to quantify axonal activation and conduction. Signal propagation to cortex was evaluated for medium (5.7 µm), large (10.0 µm), and exceptionally large (15.0 µm) diameter corticofugal axons associated with either internal capsule (IC) fibers of passage or the HD pathway. We then compared the modeling results to human cortical EP measurements that have described an exceptionally fast component (EP0) occurring ∼1 ms after the stimulus pulse, a fast component (EP1) at ∼3 ms, and a slower component (EP2) at ∼5 ms. Results Subthalamic stimulation of the HD pathway with large and medium diameter axons propagated action potentials to cortex with timings that coincide with the EP1 and EP2 signals, respectively. Only direct activation of exceptionally large diameter fibers in the IC generated signals that could approach the EP0 timing. However, the action potential biophysics do not generally support the existence of a cortical EP less than 1.5 ms after DBS onset. Conclusions The EP1 and EP2 signals can be biophysically linked to antidromic activation of the HD pathway. Significance Theoretical reconstruction of cortical EPs from subthalamic DBS demonstrate a convergence of anatomical, biophysical, and electrophysiological results.

    更新日期:2019-11-06
  • Interictal epileptiform discharges vary across age groups
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-04
    Eivind Aanestad, Nils Erik Gilhus, Jan Brogger

    Objective To investigate whether the occurrence and morphology of interictal epileptiform discharges (IEDs) in scalp-EEG change by age. Methods 10547 patients who had a standard or sleep deprived EEG recording reported using the SCORE standard were included. 875 patients had at least one EEG with focal IEDs. Focal IED morphology was analyzed by age using quantitative measures in EEGLAB and by visual classification based on the SCORE standard. We present distributions of IED measures by age group, with medians, interquartiles, 5th and 95th percentiles. Results Focal IEDs occurred most frequently in children and elderly. IED morphology and localization depended on age (p<0.001). IEDs had higher amplitudes, sharper peaks, larger slopes, shorter durations, larger slow-wave areas and wider distributions in children. These morphological characteristics diminished and the IEDs became more lateralized with increasing age. Spike asymmetry was stable across all age groups. Conclusions IEDs have age-dependent characteristics. A spike detector, human or computer, should not operate with the same set of thresholds for patients at various age. With increasing age, focal IEDs are less sharp, have lower amplitudes, have less prominent slow-waves and they become more lateralized. Our findings can help EEG readers in detecting and correctly describing IEDs in patients of various age. Significance EEG readers should always consider patient age when interpreting interictal epileptiform discharges.

    更新日期:2019-11-04
  • In pursuit of a sensitive EEG functional connectivity outcome measure for clinical trials in Alzheimer’s disease
    Clin. Neurophysiol. (IF 3.675) Pub Date : 2019-11-04
    C.T. Briels, C.J. Stam, P. Scheltens, S. Bruins, I. Lues, A.A. Gouw

    Objective In clinical trials in Alzheimer’s Disease (AD), an improvement of impaired functional connectivity (FC) could provide biological support for the potential efficacy of the drug. Electroencephalography (EEG) analysis of the SAPHIR-trial showed a treatment induced improvement of global relative theta power but not of FC measured by the phase lag index (PLI). We compared the PLI with the amplitude envelope correlation with leakage correction (AEC-c), a presumably more sensitive FC measure. Methods Patients with early AD underwent 12 weeks of placebo or treatment with PQ912, a glutaminylcyclase inhibitor. Eyes-closed task free EEG was measured at baseline and follow-up (PQ912 n=47, placebo n=56). AEC-c and PLI were measured in multiple frequency bands. Change in FC was compared between treatment groups by using two models of covariates. Results A significant increase in global AEC-c in the alpha frequency band was found with PQ912 treatment compared to placebo (p=0.004, Cohen’s d=0.58). The effect remained significant when corrected for sex, country, ApoE ε4 carriage, age, baseline value (model 1; p=0.006) and change in relative alpha power (model 2; p=0.004). Conclusions Functional connectivity in early AD, measured with AEC-c in the alpha frequency band, improved after PQ912 treatment. Significance AEC-c may be a robust and sensitive FC measure for detecting treatment effects.

    更新日期:2019-11-04
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