New motor control assessment techniques for evaluating individuals with severe handicaps: a case study

Prescription of assistive devices for motor-handicapped individuals requires assessment of their motor capabilities. When patients' motor deficits are particularly severe, wide individual differences in the location and type of abnormalities complicate the assessment process. The precision of assessment has been greatly increased in recent years by the use of quantitative, computer-aided motion analysis, which facilitates statistical examination and comparison with normal individuals. This paper discusses a case study wherein a 24-year-old male nonvocal cerebral palsy patient was assessed for his ability to operate assistive communication devices. Three computer-aided measurement protocols were employed to evaluate the patient and two controls: performance using the patient's existing communication aid was evaluated in terms of rate and accuracy of communication using standardized spelling and response time tasks; volitional myoelectric activity was surveyed to identify possible myoelectric control sites for communication aid operation; a study of head position and its time derivatives was conducted to explore the feasibility of proportional control of a communication aid. Comparison of handicapped and control subject data indicated that, despite several characteristic motor control deficits, the handicapped subject was capable of proportional control of lateral head rotation and binary control of frontalis myoelectric signals. These movements could be used to operate a proportionally-controlled, direct-selection communication aid that could substantially increase the subject's communication rate. Work in progress includes the expansion of the handicapped and unimpaired subject databases and further development of the techniques discussed here to include three-dimensional motion analysis and objective measurement of muscle fatigue.