Utility of neuropsychological tests in assessing response to cerebrospinal fluid drainage in idiopathic normal pressure hydrocephalus

Introduction: Cognitive impairment is a key characteristic of idiopathic normal pressure hydrocephalus (iNPH) and may improve following cerebrospinal fluid (CSF) diversion. Neuropsychological tests can be used to aid diagnosis and assessment. The objective of this study was to assess the utility of these tests in patients undergoing CSF drainage.

Methods: A retrospective review was conducted of consecutive patients undergoing CSF drainage for suspected iNPH through a dedicated multidisciplinary (MDT) clinic. All patients underwent either high volume lumbar puncture (LP) or extended lumbar drain test (ELD) and had a repeatable battery of neuropsychological testing in memory, attention, motor speed, language, and executive function, along with a 10-m gait assessment. Following MDT evaluation, patients considered to be ‘responsive’ were offered a ventriculoperitoneal shunt.

Results: A total of 26 (15 male, 11 female, mean age 74 years) patients underwent CSF drainage with 20 (77%) demonstrating a positive response (13 following ELD and 7 following LP). Of the cognitive tests undertaken pre and post drainage, there was significant improvement in RBANS Immediate Story Recall (pre = 10.68, post = 13.21, p < 0.05), and Delayed Story Recall (pre = 3, post = 4.1, p < 0.05) but no significant change in WMS-III Mental Control, Trail Making Task, 9-Hole Pegboard or RBANS Semantic Fluency tests. Mean 10 m walk time improved from 26.51 s to 15.25 s (p < 0.05).

Conclusions: Tests of memory demonstrated significant change following CSF drainage whereas tests of other cognitive domains did not. Further investigation of the clinical utility of neuropsychological tests is planned.