Assessment of the Peripheral Performance and Cortical Effects of SHADE, an Active Device Promoting Ankle Dorsiflexion

Abstract

Acute post-stroke rehabilitation protocols include passive mobilisation as a means to prevent contractures, but this technique could also help preserve neuromuscular activation patterns through proprioceptive information. This paper presents SHADE, an active orthosis that provides repetitive passive motion to a flaccid ankle by using shape memory alloy wire actuators. SHADE was studied to assess the promoted passive range of motion (PROM), acceptability and cortical effects. PROM and tolerability was assessed on 3 acute post-stroke patients (58±5y/o) by means of optoelectronic cinematic analysis. EEG/MEG instrumentation was utilised to evaluate sensorimotor cortical involvement during passive mobilization induced by SHADE in 7 healthy subjects (30.3±6.9y/o). These data were compared with voluntary movement (VM). SHADE produced good mobilisation across the available PROM (typically, from 5° plantarflexion to 15° dosiflexion). Acceptability in patients was also good. Suitable functional sources were identified for the primary sensorimotor areas. Cortico-muscular coherence was high not only in primary motor but also in primary somatosensory cortex. The cerebral involvement in these regions during the use of SHADE was similar to VM and significantly different from rest. This suggests that passive stimulation with SHADE could have clinical implications in supporting recovery of active functionality in stroke patients.