Gait rehabilitation by nociceptive withdrawal reflex-based functional electrical therapy

The nociceptive withdrawal reflex (NWR) can be used for supporting gait as the spinal stepping generator circuits can also be triggered by robust afferent input [36]. This has been utilised in many assistive functional electrical stimulation devices since the first reports by Liberson [32] who found a functional benefit when stimulating electrically the peroneal nerve during the swing phase. The NWR response is an integrated movement generated by a coordinated activation of several muscles in the limb when the body receives a potentially tissue damaging stimulus. The NWR is generated to ensure adequate and sufficient withdrawal while maintaining balance and ensuring continuation of the ongoing motor programs [4, 41, 49]. This obviously leads to involvement of the contralateral limb to ensure upright posture and balance control. During rhythmic movements like gait, the spinal pattern generators are involved in reflex modulation as the reflex responses are strongly modulated by the phases of the gait cycle [17, 56].