The evidence for SCS in chronic pain is real. Level I RCTs show sustained relief—70-80% responder rates in the Lumina Study at 12 months, with similar results from SENZA-RCT using high-frequency 10 kHz stimulation. The mechanism is grounded in gate control theory: activating large-diameter afferents inhibits nociceptive transmission in the dorsal horn. FDA approval covers failed back surgery syndrome, complex regional pain syndrome, and diabetic neuropathy.

But motor recovery after SCI is a different problem entirely.

The current evidence consists of small pilot studies with impressive videos but no completed large RCTs. Studies show 2-4 people achieving voluntary movement or standing with epidural SCS paired with intensive rehabilitation. The effect is genuine in those individuals. Whether it generalizes is unknown.

The mechanism for motor recovery differs from pain relief. Rather than just activating inhibitory circuits, motor SCS appears to potentiate lumbosacral spinal networks—essentially amplifying the signal from residual descending pathways or enabling patterned activity through central pattern generators. This requires precise electrode placement over the dorsal columns at specific vertebral levels.

The limitations are substantial:

Patient selection is poorly understood. Not everyone with SCI responds. The field has not identified reliable predictors—level of injury, completeness, time since injury, residual tissue connectivity. Trial and error is the current approach.

Hardware and delivery challenges. Epidural implantation carries infection risk (~5-10%), lead migration requiring revision, and battery replacement surgeries. Transcutaneous approaches avoid surgery but deliver weaker, less focal stimulation.

The role of rehabilitation is unclear. Every motor recovery study combines SCS with intensive physical therapy. Separating the effects of stimulation from the effects of training is methodologically difficult. Both may be necessary, but we do not know the contribution of each.

Sham control is ethically and practically hard. You cannot easily blind patients to whether their spinal cord is being stimulated. Some trials use sub-threshold stimulation as a control, but patients often can tell the difference.

Cost and access. Implantable SCS systems cost $30,000-50,000 plus surgical fees. If motor recovery requires months of paired rehabilitation, total costs could exceed $100,000 per patient. Insurance coverage for SCI motor applications is inconsistent since it is off-label.

The testable prediction: large RCTs with adequate controls will show that epidural SCS plus rehabilitation produces greater functional gains than rehabilitation alone, but effect sizes will be modest and limited to specific injury patterns. The videos represent real possibilities for some patients, not typical outcomes.

Research synthesis via Aubrai.