Combined Injury-site & Lumbosacral Epidural Spinal Cord Stimulation

Combined Injury-site & Lumbosacral Epidural Stimulation for Spinal Cord Injury - a Pilot Study.

Spinal cord stimulation (SCS) has been shown in previous studies to be capable of restoring motor and autonomic function in patients with chronic complete spinal cord injury (SCI). Clinical studies have demonstrated that SCS enables activation of previously paralyzed muscles, leading to functional improvements in patients in the chronic stage of paralysis through the delivery of activity-based interventions. For most previous studies on SCS in SCI, stimulation was invariably applied to lumbrosacral plexus only. In this study, after signing the consent form, the patient will be assigned for standard surgery with additional implant of the spinal cord stimulator. The investigators propose to conduct the SCS with three phases. For the first phase, SCS over lumbrosacral spinal cord will be activated for 3 months with appropriate stimulation of lower limb muscles for walking together with physiotherapy of individual muscle groups for walking. For the second phase, SCS over lumbrosacral spinal cord will be stopped. SCS over the injury site will be activated for 3 months with appropriate stimulation of lower limb muscles. For the third phase, SCS over both lumbrosacral spinal cord and injury site of spinal cord will be activated for another 3 months with appropriate stimulation of lower limb muscles.

Spinal cord injury (SCI) causes damage to motor, sensory, and autonomic function below the level of injury. This can have a huge impact on the daily function of the patients, with devastating effects on their quality of life, especially those with paralysis. Surgical treatment including decompression surgery is an option to improve the neurological outcome of these patients if the paralysis or limb weakness were surgically correctable. However, even with surgical treatment, there are still many patients with residual neurological deficits, which may greatly impair their activities of daily living. Patients with post-SCI may also develop chronic debilitating pain, because of neurophysiological changes in the somatosensory system.

Spinal cord stimulation (SCS) has increasingly been used as a potential method of improving motor function and for pain relief in patients with spinal cord injury. SCS is a well-established therapeutic treatment with robust evidence, in the management of chronic neuropathic and ischaemic pain syndromes, including persistent back pain after surgery, complex regional pain syndrome, and chronic ischemic pain condition. Its proposed mechanism of analgesic effects includes the gate control theory of pain, and enhancement of GABAergic systems of dorsal horn cells by stimulating their dendrites. Currently, there is a lack of mechanistic studies of SCS for SCI pain and its effectiveness is not well established.

SCS has been shown in previous studies to be capable of restoring motor and autonomic function in patients with chronic complete spinal cord injury. Clinical studies have demonstrated that SCS enables activation of previously paralyzed muscles, leading to functional improvements in patients in the chronic stage of paralysis through the delivery of activity-based interventions. For most previous studies on SCS in SCI, stimulation was invariably applied to lumbrosacral plexus only. The proposed mechanism for the effects of relate to the increased excitability of the central pattern generators (CPG) and enhance tonic and rhythmic motor patterns in persons after SCI and results in the activation of lower extremity muscles for standing and stepping with and without assistive devices. It was also shown that SCS in combination with locomotor training provides sensorimotor training of the spinal circuitry and facilitates standing stepping to enhance neuroplasticity.

In this study the investigators hypothesize that the application of SCS to the injury site can provide a neuromodulatory effect to the recovering neurons, allowing for improved neurological function caudal to the injury site. The investigators propose to conduct a clinical trial to determine whether the application of SCS to both injury site and lumbrosacral spinal cord, instead of SCS over lumbrosacral spinal cord alone, can further improve motor function in patients with motor-complete subacute and chronic spinal cord injury. The investigators will also assess longer term secondary outcomes including lower limb functional scores, chronic pain, and health related quality of life.

Inclusion Criteria:

1. American Society of Anesthesiologist (ASA) status I-III
2. Age 18-70 years old
3. Patients with SCI more than 2 years
4. Traumatic or atraumatic spinal cord injury
5. American Spinal Injury Association (ASIA) Impairment Scale A and B
6. Have previous MRI to document extent of spinal cord injury before recruitment

Exclusion Criteria:

1. Chronic opioid user
2. Presence of chronic pain condition (pain duration over 3 months)
3. Alcohol or substance abuse
4. active and unaddressed psychiatric diseases