Auditory cues can modify the gait of persons with early-stage Parkinson's disease: a method for enhancing parkinsonian walking performance?

OBJECTIVE: To investigate whether systematically adjusting the rate of auditory cues induces corresponding modulations of the temporal and spatial parameters of gait of patients with early-stage Parkinson's disease. DESIGN: Subjects performed a series of 15 9-metre walks along a level floor under uncued and four cued conditions; the order of cued conditions was randomized. SETTING: A physiotherapy gymnasium, Manchester, UK. SUBJECTS: Eleven subjects with early-stage idiopathic Parkinson's disease. INTERVENTIONS: Preferred pace was established from the initial three uncued walks. The rate of auditory cues delivered throughout subsequent walks was systematically adjusted for each subject, representing 85, 92.5, 107.5 and 115% of their mean cadence at preferred walking pace. MAIN OUTCOME MEASURES: Mean cadence, mean stride length and mean velocity. RESULTS: Repeated measures ANOVA indicated that the mean velocity and mean cadence of subjects' gait significantly (p < or = 0.01) increased relative to baseline values at cue rates of 115 and 107.5% of cadence at preferred pace and decreased at cue rate of 85%. Mean stride length was unaffected by variations in cue rate. CONCLUSION: The rate of auditory cues, within the range tested, can modulate cadence and thus velocity of gait of subjects with early-stage Parkinson's disease. The provision of auditory cues provides a potential strategy for enhancing walking performance in these patients.

Increased dependence upon visual information of movement performance during visuo-motor tracking in cerebellar disorders.

The effect of temporarily suppressing the visual display of either the target (desired) trajectory or the actual movement trajectory upon the accuracy of visuo-motor tracking was studied in 6 patients with cerebellar syndromes and 6 healthy subjects. Subjects made extension and flexion movements of the wrist to superimpose a cursor displaying their actual movement (movement cursor) upon one indicating the target (target cursor) on a VDU screen. The target trajectory consisted of a sawtooth pattern of slow (4 deg/sec) ramp extension and instantaneous flexion return phases. Following practice, the tracking of cerebellar patients was significantly less accurate than that of healthy subjects for each phase (P = 0.02). Temporary suppression of the movement cursor during both the mid-section of the ramp phase (P = 0.05) and around the reversal phase (P = 0.04) caused a significant increase in tracking errors in the patients whereas suppression of the target cursor did not alter their performance. Suppression of neither cursor altered the tracking accuracy of healthy subjects during the ramp extensions whilst suppression of either caused reduced (P = 0.02) performance for the reversal phase. We interpret the increased dependence of patients upon visual information of their movements during slow trajectories as indicating an impairment of proprioceptive guidance.