Submitted by: Hristelina Ilieva, MD, PhD
Edited by: Niranjan N. Singh, MD
Wagner FB, et al. Targeted neurotechnology restores walking in humans with spinal cord injury
The authors report a novel, targeted, spatio-temporal spinal cord stimulation in 3 patients with chronic spinal cord injuries (4 years post trauma) who had permanent motor deficits or complete paralysis despite extensive physical therapy. The authors mapped carefully in each of the 3 patients the pools of different lumbo-sacral motor neurons (those controlling hip flexion, ankle extension, etc.) and placed 16 electrode paddle array over the respective dorsal roots. Then they delivered via wireless communication epidural electrical stimulation (EES) in real-time, spatially selective (i.e. stimulating first hip flexors, then ankle extensors, etc) trains that coincided with intended movement. Within a week that led to establishing an adaptive control over the paralyzed muscles. The paradigm included 5 months of physical therapy including overground assisted walking. Locomotor performance improved during rehabilitation. Patients progressed from stepping on a treadmill to supported walking on the ground (while receiving EES), and were able to adjust their step elevation and stride length. Over time, patients could walk for up to 1 hour on the treadmill with EES. Following rehabilitation, the 3 patients could walk independently (either partially supported or with a walker) with EES, and regained voluntary leg movements without EES.
In an accompanying paper published in Nature Neuroscience
, the same group reports the importance of using burst stimulation and spatiotemporal stimulation profiles versus continuous stimulation to be able to preserve proprioception stimulation. In continuous stimulation, the proprioceptive inputs get cancelled reducing or abolishing the conscious perception of leg position, which limits the success of the rehabilitation.
This is a breakthrough discovery which sets the stage for trials with a large patient population with varying degrees of trauma (complete versus partial spinal cord transection injuries). Experience in more laboratories will help confirm the initial observations and bring those discoveries to a wider range of patients. It will be interesting to see if cervical spinal cord injuries are amenable to a similar approach and if earlier initiation (before 4 years) offers better chances for a more complete recovery. These results establish a technological framework for improving neurological recovery and supporting the activities of daily living after spinal cord injury.