GAIT VARIABILITY AND BASAL GANGLIA DISORDERS - STRIDE-TO-STRIDE VARIATIONS OF GAIT CYCLE TIMING IN PARKINSONS-DISEASE AND HUNTINGTONS-DISEASE

The basal ganglia are thought to play an important role in regulating motor programs involved in gait and in the fluidity and sequencing of movement. We postulated that the ability to maintain a steady gait, wi th low stride-to-stride variability of gait cycle timing and its subph ases, would be diminished with both Parkinson's disease (PD) and Hunti ngton's disease (HD). To test this hypothesis, we obtained quantitativ e measures of stride-to-stride variability of gait cycle timing in sub jects with PD (n = 15), HD (n = 20), and disease-free controls (n = 16 ). All measures of gait variability were significantly increased in PD and HD. In subjects with PD and HD, gait variability measures were tw o and three limes that observed in control subjects, respectively. The degree of gait variability correlated with disease severity. In contr ast, gait speed was significantly lower in PD, but not in HD, and aver age gait cycle duration and the time spent in many subphases of the ga it cycle were similar in control subjects. HD subjects, and PD subject s. These findings are consistent with a differential control of gait v ariability, speed, and average gait cycle timing that may have implica tions for understanding the role of the basal ganglia in locomotor con trol and for quantitatively assessing gait in clinical settings.