Cervical spinal cord stimulation for treatment of upper limb paralysis: a narrative review

Recent advances in cervical spinal cord stimulation (SCS) have demonstrated improved efficacy as a therapeutic intervention for restoring hand functions in individuals with spinal cord injuries or stroke. Accumulating evidence consistently shows that cervical SCS yields significant improvements in grip force, proximal arm strength and muscle activation, with both immediate and sustained effects. This review synthesizes the evidence that electrical stimulations modulate the spinal and supraspinal organization of uninjured descending motor tracts, primarily the residual corticospinal tract, reticulospinal tract and propriospinal network of neurons, as well as increasing the sensitivity of spinal interneurons at the stimulated segments to these inputs. Additionally, we examine contemporary strategies aimed at achieving more precise patterned stimulations, including intraspinal microstimulation, ventral cord stimulation and closed-loop neuromodulation, and discuss the potential benefits of incorporating cervical SCS into a multimodal treatment paradigm. Level of evidence: V