Effect of video feedback on the performance of a weight shifting controlled tracking task in subjects with parkinsonism and neurologically intact individuals.

This study compared the performance of a visual motor task, accomplished by standing weight shifting, of 34 people with Parkinson's disease (P.D.) and 34 neurologically intact (N.I.) subjects. Twenty of the P.D. subjects were in Stage 1 and 14 were in Stage 2. The performance of ten, 10-s trials was each examined under two feedback (FB) conditions: continuous video display of performance and end of trial position. Visual FB was composed of displaying a target and cursor on a video monitor, with the cursor controlled by the subject through weight shifting on a platform interfaced with a microprocessor. Once the cursor was centered, the computer then transferred the target to the upper right quadrant of the monitor, and the subject was required, through weight shifting, to relocate the cursor inside the target. ANOVA with repeated measures was used for data analysis. The visual motor performance of P.D. subjects was significantly worse than that of N.I. (P less than 0.01), as well as between FB conditions (P less than 0.01). The interaction of the FB condition by trial segment was significant (P less than 0.01), as was the interaction of group membership by the trial segment (P less than 0.01). FB condition and group membership did not significantly interact, confirming that performance was worse under end of trial position FB, regardless of group membership (P less than 0.01). Post hoc analysis yielded significant differences (P less than 0.05) in task performance between N.I. and P.D. subjects after the first second of the trials regardless of FB condition. In either group, significant differences between continuous visual FB and end of trial position FB (P less than 0.05) were verified after the fourth second. Performance between N.I., Stage 1, and Stage 2 P.D. subjects revealed significant differences (P less than 0.01) among all three groups, regardless of FB condition. One of the revealing aspects of this investigation was the establishment of significant differences in visual motor performance of individuals in the early stages of the disease compared to previous reports of extremity deficits in the later stages.

Visually displayed EMG feedback: single case studies of hemiplegic upper extremity rehabilitation.

The efficacy of visually displayed EMG feedback in treating hemiplegic upper limb motor disorders was investigated in 5 patients (0.5-4 years poststroke). A single case experimental method "multiple-baseline across target behaviors" was used to compare performance during the feedback phase to that occurring in the monitored baseline phase. The nonfeedback baseline phase was followed by the staggered introduction of audiovisual feedback for each of the targeted pairs of muscles. EMG feedback obtained from muscle pairs (shoulder: anterior deltoid and upper trapezius; elbow: brachial triceps and biceps; digits: extensor digitorum communis and digit flexors) was displayed as two distinct waveforms on a videomonitor during therapy. Nonfeedback assessment of each of the three pairs was performed during each session. The effects of feedback were not uniformly distributed. Elbow control responded best, and statistical tests confirmed the effects of intervention observed clinically in all 5 patients. Clinical improvements in shoulder flexion were observed in 4 patients but could be statistically attributed to EMG gains in just 1. Improvement in finger extension observed clinically in 3 patients was statistically attributable to EMG gains in 2. All patients regained control of at least one target activity. EMG gains were accompanied by increases in active range of motion and by varying functional improvement. Marked functional gains in 3 patients were obtained with recovery of finger control.

Nerve conduction studies in patients with cervical spinal cord injuries.

Twenty-nine patients with cervical spinal cord lesions were tested extensively by upper extremity nerve conduction between 7 days and 15 years postinjury. Certain patients were retested serially to determine if slow progressive lesions occur in this population. Statistically significant abnormalities were found in the periphery, with a time-scale tentatively established as to when these lesions become detectable. Possible late anterior horn cell or motor root lesions were found in 17% of extremities tested.