Gait Improvement Following CSF Tap Test in NPH Patients With and Without Striatal Dopaminergic Deficit: A Preliminary Study.

Background and objectives: Recent studies have highlighted the occurrence of reduced striatal signal intensity on dopamine transporter (DAT) scans in patients with idiopathic normal pressure hydrocephalus (iNPH). The aim of our study was to investigate whether the extent of symptom improvement after a CSF tap test (TT) differs between iNPH patients with reduced striatal DAT uptake and those with normal uptake.

Methods: We conducted gait analysis on 44 patients with iNPH who underwent DAT scans at Seoul National University Bundang Hospital (SNUBH) and Kyungpook National University Chilgok Hospital (KNUCH) both before and after a CSF TT. A positive response to the TT was defined as an improvement in walking speed of 10% or greater compared with baseline. We compared TT response rates between iNPH patients with and without striatal dopaminergic deficit using logistic regression models, with the medical institution (SNUBH, KNUCH) as a stratification variable.

Results: Among 36 patients without striatal dopaminergic deficit, 22 patients (61.11%) exhibited a response after the TT, whereas among 8 patients with striatal dopaminergic deficit, 5 patients (62.5%) exhibited a response after the TT. The response rate after TT was not significantly different between the iNPH patients with and without striatal dopaminergic deficit (odds ratio 0.46; p value = 0.4048).

Discussion: Our findings suggest that gait improvement after a CSF TT in patients with iNPH remains consistent regardless of the presence or absence of reduced striatal DAT uptake. Further research involving a larger cohort is necessary to validate these observations.