Predicting recovery of bilateral upper extremity muscle strength after stroke.

OBJECTIVE To investigate the recovery pattern of bilateral upper extremity muscle strength and to predict the recovery of strength early after stroke using a logarithmic regression model. DESIGN Longitudinal study. SUBJECTS Twenty-one inpatients with post-stroke hemiparesis were enrolled. The mean time after stroke event was 7.1 days (standard deviation (SD) 3.5 days). METHODS Bilateral elbow flexion and extension strengths were assessed separately with a hand-held dynamometer.Grip strength was also assessed with a Jamar dynamometer.These measurements were carried out on 4 occasions: baseline assessment within 2 weeks following stroke onset, and at weeks 1, 2 and 3 following baseline evaluation. Recovery off lexion and extension strengths was predicted using a logarithmic model using scores at the initial 2 evaluations. RESULTS The time course of recovery for bilateral upper extremities resembled a logarithmic function. Moreover, on the basis of a logarithmic regression model, baseline measures of bilateral strengths sampled from 2 time-points during recovery could be applied to predict the pattern of recovery accurately during the subacute stroke phase (R(2) = 0.74–0.95,p < 0.0001). CONCLUSION Upper extremity muscle strength improved significantly in a similar pattern on the sides contralateral and ipsilateral to the brain lesion. Moreover, a logarithmic regression model accurately predicted both measures.