Reciprocal tapping in spastic hemiparesis

Objective: To locate the source of slowness in typing movements in subjects with spastic hemiparesis and to examine whether enlargement of keys would facilitate typing. Design: Experimental within-subjects design. Setting. Werkenrode, a special school for physically disabled young childre n. Subjects: Eleven subjects (mean age 17.7 years) diagnosed as having spastic hemiparesis, most as a result of cerebral palsy. Interventions: Subjects made fast reciprocal tapping movements with one fin ger of both hands separately within a 10-second interval. Keys of 12 x 12 m m and 24 x 24 mm were used. Main outcome measures: Interkey response interval (IRI), dwell time (interv al during which the key is pressed) and forces were measured. Also, the sta ndard deviation and coefficient of variation of the variables were calculat ed to determine regularity of the movements. Results: The impaired hand tapped slower and more irregularly and exerted l ess force. In addition, the duration of the dwell phase was lengthened for this hand. However, the percentage dwell time as a function of IRI was not different between hands. Enlargement of the keys shortened flight time (i.e . time in which the finger moves through the air from one key to the next) of the impaired hand, but not dwell time. Conclusions: The entire movement is slower for the impaired hand. Disturban ces are not exclusively located at the inversion of the movement. With resp ect to keyboard design, enlarged keys and a locked repeat function of the k eys may be beneficial for subjects suffering from spasticity.