Gait analysis in idiopathic normal pressure hydrocephalus - which parameters respond to the CSF tap test?

Objectives: Normal pressure hydrocephalus (NPH) is an often underestimated cause of hypokinetic gait disorders in the elderly. Diagnosing NPH is a com plex problem, since many symptoms overlap with other neurological diseases. The purpose of the present study was to characterize the gait pattern in N PH quantitatively. Additionally, we analyzed the improvement of gait parame ters following tapping of cerebrospinal fluid (CSF). Methods: Gait analysis was performed in 10 patients and 12 age-matched heal thy controls during overground and treadmill locomotion. Results: Compared to healthy controls, patients with NPH walked significant ly slower, with shorter and more variable strides and a somewhat lower cade nce. The feet were not lifted to a normal height and the dorsal extension o f the forefoot prior to heel-strike was insufficient. Balance-related gait parameters such as step width and the foot rotation angles were significant ly increased in NPH, while their variability was lower. Only some gait para meters improved after tapping 30 mi CSF. Gait velocity increased by about 2 3% due to an increased stride length, while the cadence remained unchanged. Balance-related gait parameters and the foot-to-floor clearance during swi ng were not affected by the treatment. Conclusions: In conclusion, we found a triad of decreased stride length, de creased foot-to-floor clearance and a broad-based gait to be the typical fe atures of the gait abnormality in NPH. Only the stride length improved foll owing a diagnostic spinal tap. These results may help to more reliably diag nose the condition of NPH in a routine clinical setting. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.