No dawn yet of a new age in spinal cord rehabilitation

Sir,Recently Angeli et al. (2014) reported that tonic epidural electrical stimulation of lumbar spinal cord in four near completely motor paralysed subjects with spinal cord injury revealed some limited voluntary movements in lower limbs. The idea is put forward that electrical stimulation evokes neuronal activities which sum with intention-related spinal locomotor programs to become supra-threshold. Are these the first steps on the way to a ‘spinal neuroprosthesis’ or even a training device to relearn walking as the authors enthusiastically envisage (Harkema et al. , 2011; Angeli et al. , 2014)? The present comment is a critical view on the achievements and the projected perspectives in light of previous findings.What is so significantly new to allow these goals to be claimed at all? Not really much indeed when expecting new mechanisms: enhancement or ‘appearance’ of residual voluntary activity, here achieved under tonic electrical stimulation of the spinal cord, can also be obtained by other ‘unspecific’ means: mechanical stimulation (e.g. bare-foot walking and pinching) and electrical stimulation of the skin, reduction of body weight support (Harkema et al. , 2011), enhanced excitability of the spinal cord (spasticity; reduction in antispastic medication) and others. In particular ‘Jendrassik manoevures’ (see examples for vivid application in Angeli et al. ’s Supplementary Video 3 and moderate action in Supplementary Video 4) not only acutely and time-locked elevate residual voluntary muscle activity (Supplementary Videos 1 and 2 in Harkema et al. , 2011), but can ‘willingly’ evoke seemingly all-or-nothing multi-joint flexion ‘mass’ movements in near completely motor-paralysed limbs (Dimitrijevic et al. …