Spinal cord stimulation facilitates functional walking in a chronic, incomplete spinal cord injured

Abstract

Design: This paper describes a treatment paradigm to facilitate functional gait in a quadriplegic, ASIA C spinal cord injured (SCI), wheelchair-dependent subject who presented with some large ®ber sensation, sub-functional motor strength in all lower limb muscles, and moderate spasticity. The study utilizes partial weight bearing therapy (PWBT) followed by epidural spinal cord stimulation (ESCS) with the assumption that both treatments would be necessary to elicit a well organized, near eortless functional gait with a walker. Function is de®ned in terms of accomplishing task-speci®c activities in the home and community. Objectives: To demonstrate the feasibility and bene®ts of combined PWBT and ESCS therapies aimed at promoting functional gait in a wheelchair-dependent ASIA C SCI subject. Setting: The Clinical Neurobiology and Bioengineering Research Laboratories at Good Samaritan Regional Medical Center, Phoenix, Arizona, USA, and the Department of Bioengineering, Arizona State University, Tempe, Arizona, USA. Methods: The study began with the application of PWBT. The subject walked on the treadmill until a plateau in gait rhythm generation was reached. Subsequently, ESCS, applied to the lumbar enlargement, was utilized to facilitate PWBT and, later, over-ground walking for a standard distance of 15 m. Gait performance was analyzed by measuring average speed, stepping symmetry, sense of eort, physical work capacity, and whole body metabolic activity. Results: PWBT led to improved stereotypic stepping patterns associated with markedly reduced spasticity, but was insucient for over-ground walking in terms of safety, energy cost, and fatigue. ESCS with PWBT generated immediate improvement in the subject's gait rhythm when appropriate stimulation parameters were used. When compared to the non-stimulated condition, over-ground walking with ESCS across a 15 m distance was featured by a reduction in time and energy cost of walking, sense of eort, and a feeling of`lightness' in the legs. After a few months of training, performance in speed, endurance, and metabolic responses gradually converged with/without ESCS at this short distance, suggesting a learned response to these conditions. However, at longer distances (eg, 50 ± 250 m), performance with ESCS was considerably superior. The subject was able to perform multiple functional tasks within the home and community with ESCS. Conclusion: We propose that ESCS augments the use-dependent plasticity created by PWBT and may be a valuable adjunct to post-SCI treadmill training in ASIA C subjects. We also conclude that ESCS elicits greater activation of an oxidative motor unit pool, thereby reducing the subject's sense of eort and energetic cost of walking.

Neuropathology: the foundation for new treatments in spinal cord injury

“…69 Electrical stimulation is known to facilitate well-being in incomplete SCI. 70 It is also important to avoid pressure palsies of peripheral nerves so that the skeletal muscles do not undergo atrophy.…”

Supraspinal Control Predicts Locomotor Function and Forecasts Responsiveness to Training after Spinal Cord Injury

“…97,98 Also beginning in the 1980s, there were published reports of spinal cord stimulation with implanted epidural electrodes to improve motor function in persons with neurological conditions, 99 to elicit step-like behavior in persons with SCI, 30 and facilitate walking in persons with motor-incomplete injuries. 100 More recently, there have been reports wherein epidural stimulation has been used to increase the excitability of spinal circuits to a level that allows some volitional movement in persons with injuries clinically classified as motor complete. 101 While epidural spinal cord stimulation requires an invasive surgical procedure for the implantation of electrodes into the epidural space, more recent evidence indicates that transcutaneous spinal cord stimulation provides a non-invasive alternative for the stimulation of the spinal cord, using electrodes placed on the skin over the spine.…”

Functional electrical stimulation after spinal cord injury: current use, therapeutic effects and future directions

“…It has been further speculated that the normal neural circuitry within the spinal cord necessary for gait and other motor functions needs continuous maintenance by FES and/or body weight supported treadmill training (BWSTT) ambulation. 7 Others have suggested that such patterned neural activity may be important for both development and recovery of neurological functions. 8 Furthermore, there is substantial scientific evidence that shows that physical exercise not only stimulates production of endorphins, but contributes to the upregulation of brainderived neurotrophic factor (BDNF), which may promote synaptic and functional plasticity within the brain and spinal cord.…”

“…172 Other investigators have suggested that patterned neuronal activity with FES and/or BWSTT is important for development and even recovery of neurological functions 8 or by using both BWSTT and epidural spinal cord stimulation. 7,173 In general, it is now felt that the functional motor benefits of such exercise training does more than improve muscle strength and cardiovascular fitness in persons with SCI as animal studies have shown that it may also have an influence on synapses and motor neurons. 174 If and when a treatment will be found to reverse the neurological loss after SCI, it is unlikely that such treatment will result in complete reestablishment of all the descending and ascending projections within the spinal cord.…”

“…176 It has been shown that epidural spinal cord stimulation in conjunction with BWSTT can facilitate functional walking in persons with chronic SCI ASIA C, perhaps by eliciting greater activation of the oxidative motor unit pool. 7,173 Other investigators have shown in animal experiments that stimulation of motor neuron pools within the gray matter of the spinal cord by implanted microelectrode arrays can activate large number of individual muscle fibers in a relatively coordinated pattern. 177,178 These observations suggest that it may be possible to activate by electrical stimulation the natural neural circuitry in the spinal cord to generate functional muscle activity.…”