Maximal grip force in chronic stroke subjects and its relationship to global upper extremity function

Objectives: Previous studies have shown that recovery of recordable grip strength in acute stroke subjects is one of the most sensitive assessments of initial upper limb recovery and a good prognostic factor for latter recovery. The objectives of this study were to test the reliability of maximal voluntary grip force (MVGF) measures and evaluate the relationship between paretic grip strength deficit and paretic upper extremity function in chronic stroke subjects. Design: Over a three-week period, bilateral MVGF was assessed three times with a modified strain gauge dynamometer in 15 chronic stroke subjects and 10 control subjects. The paretic MVGF deficit was expressed in relation to the MVGF of the nonaffected hand. Outcome measures: Upper extremity function in stroke subjects was measured using the Fugl-Meyer, the upper extremity performance test for the elderly (TEMPA), Box and Block and finger-to-nose tests. Results: MVGF measures in both groups of subjects demonstrated good reliability (intraclass correlation, ICC >0.86) and low standard error measurements (SEM). The paretic MVGF of the stroke subjects was greatly impaired in comparison to the control subjects. Results of linear and quadratic regressions analyses show that this impairment was significantly correlated (p <0.01) with the performance of the stroke subjects on the four upper extremity function tests. The percentages of variances explained by the MVGF deficit on all four upper extremity tests varied from 62% to 78% for the linear regressions and from 72% to 93% for the quadratic regressions. Conclusions: These results suggest that the paretic maximal grip strength, normalized with the maximal grip strength on the nonaffected side, appears to be a valuable outcome measure of upper extremity function in chronic stroke subjects.