Manual dexterity and keyboard use in spastic hemiparesis: a comparison between the impaired hand and the ‘good’ hand on a number of performance measures

Objective: To assess the functional deficits in tapping performance of subjects with spastic hemiparesis.

Design: In a pilot study, typing performance on a computer keyboard was examined on a number of performance measures.

Setting: Department of Research and Development at the Werkenrode Institute.

Subjects: Four subjects (mean age 16.4 years, standard deviation 1.8 years) with cerebral palsy and diagnosed as having spastic hemiparesis.

Interventions: Subjects had to type a sequence of one or more keys as quickly as possible within an 8 second period with the fingers of both hands separately.

Main outcome measures: The average number of good and false responses were calculated. Within the false response category, four, mutually exclusive, types of errors were distinguished; wrong key, repetition, registrations under 75 ms and holding. Speed and regularity of the typing responses were also established.

Results: The ‘good’ hand outperformed the impaired hand on all performance measures except on the amount of repetition errors made. The holding error was only present for the impaired hand, and there was an increase in holding errors from the index to the little finger in this hand. In addition, the impaired hand performed the task with a slower speed and in a more irregular fashion.

Conclusions: The results are discussed with reference to keyboard design. It is concluded that the standard ‘QWERTY’ keyboard hampers typing performance extensively, especially for subjects with left spastic hemiparesis. A learning method is presented in which the role of an external pacer (e.g. metronome) is discussed. This device can initially be used to decrease movement variability and, eventually, for increasing movement speed.