Determinants of clinical response in possible normal pressure hydrocephalus.

Abstract

Objectives: This study aims to identify which clinical factors should be considered when determining a diagnosis of probable idiopathic Normal Pressure Hydrocephalus (iNPH) in patients with possible iNPH, and to explore alternative assessments that can complement lower extremity motor evaluations.

Patients and methods: We conducted a prospective observational study involving 41 patients with possible iNPH. The assessments included the 10-Meter Walk Test (10MWT), a comprehensive neuropsychological battery, the Finger Tapping Test, and radiological measurements. Patients who exhibited a 20% or greater reduction in 10MWT time following a cerebrospinal fluid (CSF) tap test (TT) were classified as responders; those with less than a 20% reduction were classified as non-responders.

Results: Of the 41 patients, 23 were classified as responders. Radiological findings showed no significant differences between the two groups. However, the presence of the DESH (Disproportionately Enlarged Subarachnoid Space Hydrocephalus) sign significantly influenced the rate of change in walking time following lumbar puncture across all patients (p = 0.037). Certain baseline subscores, such as the Clock Drawing and Semantic Fluency tests within the neuropsychological battery, demonstrated significant differences in responders. Most parameters of the Finger Tapping Test showed statistically significant improvements in responders (p = 0.03, p = 0.028), while changes in non-responders were not significant.

Conclusion: While radiological features are useful in identifying possible iNPH, they are not predictive of a probable iNPH diagnosis. In contrast, detailed cognitive assessments may help predict responsiveness to the TT without the need for invasive procedures. Additionally, upper extremity motor function tests may serve as valuable tools for detecting TT-related changes in this patient population.