Longitudinal improvement in postural instability is distinct from gait in treated adult hydrocephalus

Abstract

Background: Ventriculoperitoneal shunting improves gait in patients with normal pressure hydrocephalus. Postural instability is a major concern, but mostly ignored in the evaluation and treatment of these patients. This study quantified postural instability using kinematics via a prospective cohort design. Methods: Seventeen patients with suspected normal pressure hydrocephalus and twenty age-matched, healthy controls underwent quantitative pull test and gait examinations while wearing inertial measurement units at baseline. Patients with suspected normal pressure hydrocephalus who were shunted (n=13) and not shunted (n=4) underwent further testing after a lumbar drain trial and at follow-up visits 6 and 12 months post-operatively. Results: While most gait improvement in patients who were shunted was seen immediately after the lumbar drain trial, measures of their postural response continued to improve after the lumbar drain trial through one year of follow-up. Patients who were not shunted showed no statistically significant changes in gait and postural instability measures. Conclusions: After shunting, postural instability improves continuously over one year. In contrast, a large improvement in gait is seen immediately with minimal change over the subsequent year. This difference in timing may implicate two distinct neurophysiological mechanisms of recovery and provides novel evidence that postural instability improves in response to long-term CSF diversion.

Utilizing kinematic analysis of postural instability as an objective measure to aid in distinguishing between normal pressure hydrocephalus and Parkinson's disease

“… 2 Given the primacy of gait and balance symptoms in NPH, a more quantitative method of assessment theoretically carries the benefit of being able to distinguish between the two diseases. In addition, postural instability in NPH improves with surgical treatment via VPS 13 while there are essentially no effective treatments for postural instability in PD. Previous work has demonstrated that the use of quantitative kinematics is helpful in examining gait and postural instability before and after surgery for patients with NPH and should be further investigated for patients with PD.…”

“…While these patient groups undergo different surgical intervention (VPS for NPH and DBS for PD), the overall goal of surgical intervention improving postural instability remains the same and an important next step to investigate. 13 Quantitative methods allow for the possibility of detailing small changes in the postural response when assessing new treatments or understanding the pathophysiology of postural instability. Canonically, ordinal rating scales have been used in the clinical assessment of these patients, but with the limitations of between- and within-provider variability and subjectivity.…”

“…We are currently in the process of demonstrating that postural instability in NPH patients improves with VPS which can be demonstrated using kinematics. 13 However, there are no known effective treatments for postural instability in PD including dopaminergic medication and DBS 14 although LSVT-BIG therapy may improve certain aspects of postural instability. 15 , 16 This provides an ideal comparison between two patient groups with essentially kinematically identical postural responses as seen in this study, but differing treatment responses.…”