Changes in Cognitive Function Scores After Cerebrospinal Fluid Tap Testing in Patients with Suspected Idiopathic Normal-Pressure Hydrocephalus.

Background: In patients suspected of having idiopathic normal-pressure hydrocephalus (iNPH), improvement in impaired cognition is common after a diagnostic cerebrospinal fluid tap test (CSFTT). Measures used to evaluate cognitive function before and after a CSFTT include the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), and Trail Making Test (TMT). However, the time point at which cognitive function should be reevaluated after a CSFTT remains controversial.

Objective: To investigate differences in cognitive function 1 day and 1 week after a CSFTT (versus baseline) in patients with suspected iNPH.

Methods: This retrospective study, conducted between October 2012 and January 2017, involved 39 patients with suspected iNPH. We analyzed their MMSE, FAB, and TMT scores on tests conducted before and 1 day and 1 week after the CSFTT.

Results: Changes in MMSE scores were negligible 1 day after the CSFTT but began to appear 1 week later. Changes in FAB scores were observed from 1 day to 1 week after the CSFTT. Although no statistically significant differences in TMT scores were observed at either time point, the execution time for the test tended to be shorter on the day after the CSFTT. Changes in cognitive function were not associated with demographic or morphological parameters. More severe impairments at baseline, however, were associated with greater changes in cognitive function.

Conclusions: Performing several reevaluations using each test may enable more accurate assessment of cognitive function in patients with suspected iNPH. Our results highlight the need for long-term follow-up, regardless of the severity of cognitive impairment.