High prevalence of cervical myelopathy in patients with idiopathic normal pressure hydrocephalus

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Highlights

  • There was a 17 % rate of cervical stenosis with myelopathy in a consecutively treated series of patients shunted for iNPH.

  • Cervical imaging could be considered prior to shunt placement in iNPH, especially with upper motor neuron signs.

  • Consider obtaining a cervical MRI in patient with iNPH who have not improved following shunt placement.

Abstract

Background

Both idiopathic normal pressure hydrocephalus (iNPH) and cervical myelopathy may result in progressive gait impairment. Some patients who do not respond to shunting despite a positive tap test may have gait dysfunction from cervical myelopathy. The objective of this study was to determine the prevalence of cervical myelopathy in patients with iNPH.

Methods

A consecutive series of patients undergoing shunt placement for iNPH were screened for cervical stenosis. Clinical manifestations of iNPH and cervical myelopathy, grade of cervical stenosis, cervical spine surgical intervention, timing of intervention, and outcomes were recorded.

Results

Fifty-two patients shunted for treatment of iNPH were included for analysis. 58 % were male with a mean age of 75.2 years (SD 7.3 years). All patients presented with gait disturbances. 39/52 (75 %) had cervical stenosis, and 9/52 (17.3 %) had significant (grade 2−3) cervical stenosis with myelopathy and were subsequently treated with surgical decompression. There was an association between increasing grade of stenosis and disproportionately enlarged subarachnoid space hydrocephalus (DESH). All patients with grade 2−3 cervical stenosis and symptoms of cervical myelopathy in addition to iNPH underwent cervical decompression surgery.

Conclusions

Clinically significant cervical myelopathy was prevalent in patients with iNPH and was associated with increased rate of DESH, a finding that requires validation in a larger cohort. Based on these results, cervical imaging could be considered preoperatively in patients with iNPH, particularly when upper motor neuron findings are identified. Additionally, concomitant cervical stenosis should be ruled out in patients whose gait does not improve after shunt placement.

Introduction

Idiopathic normal pressure hydrocephalus (iNPH) is a progressive neurological disorder characterized by gait abnormalities and imbalance, cognitive decline, urinary incontinence, ventriculomegaly, and normal cerebrospinal fluid (CSF) pressure [1,2]. The reported incidence of iNPH is 0.5–5.5 per 100,000 people per year, with the prevalence of iNPH increasing exponentially as a function of age [[3], [4], [5]]. Idiopathic NPH often poses a diagnostic dilemma since there can be considerable overlap in the symptomatology between iNPH and several neurodegenerative diseases including Parkinson’s and Alzheimer’s disease [6,7], and the cardinal symptoms may be associated with aging as well [8]. Therefore diagnosis relies on response to high volume lumbar tap or extended lumbar drainage trial, in addition to radiographic evidence of ventriculomegaly [9]. Treatment for iNPH involves CSF diversion via shunting, which is most effective in ameliorating gait dysfunction, although 15–20 % of patients fail to report full resolution of gait abnormalities 3 years after shunting [10,11].

Cervical spondylotic myelopathy is a progressive degenerative process in which compression of the cervical spinal cord causes gait disturbances and imbalance, dexterity loss and weakness of the hands, and urinary dysfunction at late stages [12,13]. Like iNPH, the incidence and prevalence of cervical myelopathy increase with age and the mainstay of treatment is by surgical decompression of the cervical spinal cord, either from an anterior or posterior approach [13,14]. Thus, iNPH and cervical myelopathy may both present with progressive gait impairment and urinary symptoms, particularly in the elderly. Given the overlapping clinical presentation between iNPH and cervical myelopathy and the relatively high percentage of patients with persistent gait disturbances despite shunting, the objective of this study was to investigate the prevalence of cervical myelopathy in patients with iNPH.

Section snippets

Patient selection and variables of interest

This study was approved by the institutional review board (IRB no. 19-000836). A consecutive series of 52 patients who underwent ventriculoperitoneal (VP) shunt placement for iNPH over an 18 month period, between December 1, 2017, and June 30, 2019, by the senior author at a single institution were included in the analysis. All patients had an MRI of the cervical spine 2 years before or after of shunt placement. Electronic medical records were reviewed retrospectively. Basic demographic

Results

Among these 52 patients, there was roughly a 3:2 male to female ratio with 30 males and 22 females (Table 1). The average age of the cohort was 75.2 ± 7.3 years, and the average BMI was 30.0 ± 4.3 kg/m2. Nearly 70 % of the overall cohort were former or current smokers. One hundred percent of patients presented with gait instability, 81 % with urinary incontinence, and 88 % with cognitive decline. In total, 36 of 52 patients (69 %) were found to have DESH.

There were 13 patients (25 %) with grade

Discussion

In this study, we retrospectively reviewed iNPH patients who underwent VP shunting at a single institution by a single surgeon to assess the prevalence of cervical myelopathy in this population. Of 52 iNPH patients, 17 % of patients had grade 2 or 3 spinal stenosis and underwent surgical treatment for both myelopathy and iNPH. All patients in this study presented with gait disturbance. The incidence of cognitive dysfunction and response to lumbar tap test were independent of the degree of

Conclusion

Due to high coincidence of iNPH and cervical myelopathy reported here, a screening MRI of the cervical spine could be considered in all patients with suspected iNPH, though in this study, only those with upper motor neuron findings on clinical examination required surgical intervention. Future studies with larger sample sizes are clearly warranted to better understand the unique clinical presentation of patients with iNPH and concurrent cervical myelopathy. Interestingly, there was an

Disclosure of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

CRediT authorship contribution statement

Ryan M. Naylor: Investigation, Data curation, Writing - original draft, Writing - review & editing. Karina A. Lenartowicz: Data curation, Writing - original draft, Writing - review & editing. Jonathan Graff-Radford: Conceptualization, Methodology, Writing - original draft, Writing - review & editing, Supervision. David T. Jones: Conceptualization, Methodology, Writing - original draft, Writing - review & editing, Supervision. Jeremy K. Cutsforth-Gregory: Conceptualization, Methodology, Writing

Declaration of Competing Interest

None.

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    These authors contributed equally.

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