Neurophysiological Recovery Following Nerve Transfer Surgery to Restore Upper Limb Function after Cervical Spinal...

Nerve transfer is a promising intervention for restoring hand and upper limb function after cervical spinal cord injury (SCI), but the timeline of neurophysiological recovery in humans remains unclear. This study aimed to define recovery profiles after nerve transfers to restore upper limb function.

Individuals with traumatic cervical SCI who received nerve transfer surgery in at least 1 limb were evaluated during routine clinical visits for up to 2 years post-transfer. The primary outcome was the time to detect reinnervation, defined as the appearance of voluntary motor unit potentials on needle electromyography. Representative muscles were assessed for 5 nerve transfer procedures: (1) supinator to posterior interosseous nerve; (2) brachialis to anterior interosseous nerve (AIN); (3) extensor carpi radialis longus to AIN; (4) extensor carpi radialis brevis to AIN; and (5) axillary to triceps. In a subset of participants who continued needle electromyography after reinnervation was detected, an ordinal grading system characterized motor unit potential maturity and the presence of pathological spontaneous activity over time.

A total of 44 individuals with traumatic cervical SCI were enrolled. Mean times to detect reinnervation were 6.9 months (supinator-posterior interosseous nerve), 10.4 months (brachialis-AIN), 9.6 months (extensor carpi radialis longus-AIN), 9.6 months (extensor carpi radialis brevis-AIN), and 9.0 months (axillary-triceps). Over time, reinnervated muscles showed reduced pathological spontaneous activity and progression from nascent to mature motor unit potentials.

These findings establish benchmark timelines for first detection of neurophysiological reinnervation after nerve transfer in cervical SCI, providing a foundation for setting clinical expectations, planning rehabilitation, and designing future interventional studies. ANN NEUROL 2026.