Abnormalities of the spatiotemporal characteristics of gait at the onset of freezing in Parkinson's disease

We investigated the spatiotemporal variables of gait leading up to freezing . Gait analysis was carried out on 14 patients with Parkinson's disease in the off phase of the medication cycle. A computerised, three-dimensional ga it analysis system was used to treasure the walking pattern. After several trials of normal walling with voluntary stopping. distracting manoeuvres an d obstacles on the walkway were used to provoke freezing or festination. Th e gait variables of normal (off phase), festinating, prestop, and prefreezi ng strides were analysed using analysis of variance for repeated-measures. Cadence was excessively increased (68%) and stride length decreased (69%) d uring festination compared with normal off walking; a pattern which remaine d pronounced When comparing prefreezing strides with normal stopping. Analy sing in more detail the three steps before a freeze, we found a progressive decrease of stride length and stable cadence rates and proportions of doub le support pleases. The relationship between cadence and stride length exhi bited an exponential increase of cadence with a decreasing stride length du ring festination and freezing. Results suggest that freezing is caused by a combination of an increasing inability to generate stride length superimpo sed on a dyscontrol of the cadence: of walking. (C) 2001 Movement Disorder Society.