McCombe Waller, S & Whitall, J; University of Maryland, Baltimore, MD, USA. smccombewaller@som.umaryland.edu.

PURPOSE: Upper extremity hemiparesis is a major limiting factor in the recovery of function in 80% of patients who survive stroke. One less explored issue in recovery is the side of hemispheric damage. The present study expands the baseline comparison of deficits in left versus right-sided lesion and compares the responsiveness to a bilateral training intervention. SUBJECTS: 16 subjects with chronic hemiparetic stroke, all right-hand dominant prior to stroke (8 left & 8 right hemispheric lesion). METHODS AND MATERIALS: We compared baseline and post-treatment responses for arm impairment and function. The training protocol was 6 weeks of non-progressive repetitive bilateral arm training with rhythmic auditory cueing or BATRAC (see Whitall et al, 2000 for details). Measures included the Fugl-Meyer UE test, Wolf Motor Arm Test, isometric strength and A/PROM for both sides. ANALYSES: One-way analysis of variance was used to compare baseline measures for both groups. One-way repeated measures analysis of variance was used to compare pre and post training results. Alpha was set at .05. RESULTS: Baseline: Across 40 different measures, there were no baseline differences in the arm impairment and functional measures for subjects with left versus right-sided lesion. Training response: Both groups demonstrated significant improvement after BATRAC training in Fugl Meyer. Patients with left-sided stroke but not right-sided, made significant improvements in nonparetic wrist flexion/extension strength, nonparetic shoulder flexion and in the Wolf Motor Arm Test (a time based test of paretic arm function). Seven of 8 left lesioned patients improved in paretic wrist flexion, shoulder extension and shoulder abduction with a trend towards significance (.06). CONCLUSIONS: The unexpected lack of differential baseline deficits may be due to the nature of our measures compared to other studies. However, this finding strengthens the training response advantage to BATRAC for right-handed subjects with left-sided stroke. This advantage may relate to interhemispheric inhibitory circuits that exist between motor dominant and motor nondominant hemispheres. Bilateral activation, such as bilateral training, may partially disinhibit these pathways permitting overflow. Damage to the motor dominant hemisphere may show increased responses to disinhibition since there is differential inhibitory control prior to stroke. These preliminary findings have implications for future training approaches in upper extremity rehabilitation. FUNDING SOURCE: Claude D. Pepper Center Pilot Grant.

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