Proximal median and ulnar nerve injuries produce severe morbidity with loss of digital and palmar sensation for prehension and tissue protection, as well as intrinsic muscle weakness and atrophy. Traditional methods of nerve repair or grafting at the level of injury rely on antegrade regeneration to restore sensation and motor function, with significant delays and incomplete muscle recovery due to the excessive distances the regenerating axons must travel to reach their distal targets.
This paper presents two cases treated by the authors utilizing distal radial sensory nerve transfers to median and ulnar digital nerves in the digits for restoration of sensation after proximal median and ulnar nerve injuries. In both cases, proximal nerve injuries were repaired with nerve grafts or conduits. In separate operations, transfers of the radial sensory nerve branches to the thumb and index fingers were performed to recipients in the digital nerves of the thumb and index fingers. In one patient a transfer of the ulnar digital nerve of the ring finger to the radial digital nerve of the index finger was performed to restore sensation on the prehensile side of the digit. Proximal ends of the recipient injured nerves were implanted into the distal lumbricals and thenar muscles to provide neurotization after regeneration of the primarily grafted proximal nerves. In both patients, early sensory return was noted in the recipient territories. Comparison of sensory return in the radial sensory nerve transfers (distal) versus the primary nerve grafts (proximal) revealed an acceleration of sensory recovery in the distal transfers. The second patient was lost to follow-up at 18 months, so that differential timing of renervation and sensory return between the two repairs was not possible. The first patient experienced a 14 month difference in return of sensation to the distal digital territories.
This paper presents an interesting and creative solution to the problem of proximal nerve injuries in the upper extremity. Long regeneration times were circumvented by transferring the relatively less important radial sensory nerve branches in the digits to the distal median nerve branches, with rapid return of significant sensation, as measured by 2-point discrimination and the "ten test." Comparison of the transferred territories with traditional grafting of the proximal stumps revealed substantial delay in return of sensation in the grafted nerves. Thus, sensibility was restored faster in the distal transfers.
No statistical analysis of the results was offered, which is likely due to the small sample size and the lack of long term follow-up in one of the patients. Also, no mention is made of motor recovery, despite neurotization of the intrinsic muscles concomitant with the nerve transfers. However, this technique does appear to offer clear benefits in time to return of sensibility when compared with traditional proximal nerve grafting. More work is needed to determine the degree to which this benefits patients functionally as they recover sensation after these injuries.
Journal of Reconstructive Microsurgery