COMPUTERIZED MEASUREMENT OF MOTOR-PERFORMANCE AFTER STROKE

Background and Purpose Stroke scales usually convert motor status to a score along an ordinal scale and do not provide a permanent recording of motor performance. Computerized methods sensitive to small changes in neurological status may be of value for studying and measuring str oke recovery. Methods We developed a computerized dynamometer and test ed 23 stroke subjects and 12 elderly control subjects on three motor t asks: sustained squeezing, repetitive squeezing, and index finger tapp ing. For each subject, scores on the Fugl-Meyer and National Institute s of Health stroke scales were also obtained. Results Sustained squeez ing by the paretic hand of stroke subjects was weaker (9.2 kg) than th e unaffected hand (20.2 kg; P<.0005), as well as control dominant (23. 1 kg; P<.0005) and nondominant (19.9 kg; P<.005) hands. Paretic index finger tapping was slower (2.5 Hz) than the unaffected hand (4.2 Hz; P <.01), as well as control dominant (4.7 Hz; P<.0005) and nondominant ( 4.9 Hz; P<.0005) hands. Many features of dynamometer data correlated s ignificantly with stroke subjects' Fugl-Meyer scores, including sustai ned squeeze maximum force (rho=.91) and integral of force over 5 secon ds (rho=.91); repetitive squeeze mean force (rho=.92) and mean frequen cy (rho=.73); and index finger tap mean frequency (rho=.83). Correlati on of these motor parameters with National Institutes of Health stroke scale score was weaker in all cases, a consequence of the scoring of nonmotor deficits on this scale. Dynamometer measurements showed excel lent interrater (r=.99) and intrarater (r=.97) reliability. Conclusion s The degree of motor deficit quantitated with the dynamometer is stro ngly associated with the extent of neurological abnormality measured w ith the use of two standardized stroke scales. The computerized dynamo meter rapidly measures motor function along a continuous, linear scale and produces a permanent recording of hand motor performance accessib le for subsequent analyses.