[Gait analysis of idiopathic normal pressure hydrocephalus].

Normal pressure hydrocephalus (NPH) is a clinical syndrome associated with dementia, gait disturbance and urinary incontinence. Gait disturbance is usually the initial sign and most important symptom, but its objective evaluation has not been established. We analyzed the gait of an idiopathic NPH before and after ventricular shunting with the gait analysis system. Before shunting, the stride was short and irregular, and the truncal movement was unsteady. Three-dimensional patterns of angular relationships between 3 joints, namely the ankle, knee and hip were small and irregular. The vector profile of floor reaction force showed a monophasic pattern with absence of the peak at toe-off. After shunting, the step enlarged and the truncal movement was steady. The three-dimensional patterns of angular relationships between the 3 joints were nearly normalized. The vector profile of floor reaction force showed an appearance of the peak at toe-off, which formed a biphasic pattern, similar to the pattern of a normal person. The gait analysis is a useful method to evaluate gait disturbance in idiopathic NPH.