Denervation findings on EMG in amyotrophic lateral sclerosis and correlation with prognostic milestones: Data from a retrospective study
Introduction
Amyotrophic lateral sclerosis (ALS) is an invariable fatal disease. The condition has an incidence of 2–3/100,000 per year and is slightly more common in men than in women (M/F 1.2–1.5). (Al-Chalabi and Hardiman 2013) Prevalence has been estimated to be about 5/100,000 per year. (Mehta et al., 2016)
The life time cumulative risk is 1/350 for men and 1/400 for women. (Johnston et al., 2006)
Recently a prospective multicenter (Westeneng et al., 2018) study has identified seven main prognostic factors in the condition: age of onset, diagnostic delay, progression rate on the revised ALS Functional Rating Scale (ALSFR-R), forced vital capacity (FVC), bulbar onset, definite ALS (according to Brooks et al., 2000), frontotemporal dementia, C9Orf72 repeat extension. The nutritional status of the patient also influences prognosis. (Chiò et al., 2009) Although some specific biomarkers showed promising results in ALS (Lu et al., 2015, Jacobsen et al., 2017), their application in clinical practice is still not universally widespread. Conversely, EMG is routinely used in clinical practice to confirm diagnostic suspicion of ALS.
The aim of our study was to verify whether a quantification of denervation activity (DA) at the time of diagnosis of ALS could provide clinicians information about the progression rate of the condition. In order to assess this, we conducted a retrospective study in a cohort of patients affected by ALS with scheduled follow-up visits.
Section snippets
Methods
We retrospectively studied all the patients discharged with a diagnosis of ALS in the time interval between January 2009 and January 2017. All the patients had a diagnosis performed under our observation. Diagnosis was supported by an elecrodiagnostic examination confirming the clinical suspicion in all patients.
To be considered for the study, inclusion criteria were:
- (a)
Diagnosis of ALS (possible, probable or definite) according to previously described criteria, the Awaji criteria. (de Carvalho et
Discussion
Our results support the importance of a careful EMG investigation in patients with suspected ALS because it can provide prognostic information, as soon as the diagnosis is made, about the hazards of ventilatory dysfunction and survival. Although some sources in literature (Gordon et al., 2009) showed advantages in separating death from other prognostic measures of outcome in ALS, other classical studies had considered NIV > 22 hours per day and/or tracheostomy equivalent to death in the
Conclusion
EMG assessment of DA, especially in cranial nerves innervated muscles, may be important not just for the diagnosis of ALS but also for its intrinsic prognostic value, regardless of the clinical phenotype of presentation. This is relevant because it could provide additional information about the rate of progression of the disease as early as the diagnosis is made. Nevertheless, there are a few limitations of our study which need to be mentioned, the most important being related to its
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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2021, Clinical NeurophysiologyCitation Excerpt :Interestingly, this allows a prompt diagnosis, due to the earlier neurophysiological involvement compared to the clinical signs of disease (de Carvalho et al., 2008). A previous study revealed an association between the severity of the denervation findings in the three body regions (bulbar, cervical and lumbosacral regions) at EMG at diagnosis and the survival in ALS patients (Fileccia et al., 2020). Notably, the degree of denervation findings in the bulbar region was associated with the time to respiratory failure and survival.
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