Effects of pulse modulation on FES-induced ankle dorsiflexion in adults with spastic diplegia

The application of function electrical stimulation (FES) has recently been extended to patients with cerebral palsy. To ensure a functional gain from the electrically elicited movement, a reproducible response with sufficient magnitude is desired. In this study, the effects of varying pulse parameters on the motor response were investigated. FES-induced ankle dorsiflexion of seven adults with spastic diplegia under constant current stimulation but with varied pulsewidths and frequencies was measured. The stimulation pattern that produced a desired motor response was determined for each individual subject. Despite the diversity of the conditions caused by cerebral palsy, a common trend was observed from the identified patterns. The characterization results suggested that the FES-induced ankle dorsiflexion in adults with spastic diplegia could be controlled by employing a constant current with frequency at 20 or 30 Hz using pulsewidth modulation ranged from 100 to 400 μs