Sensation, mechanoreceptor, and nerve fiber function after nerve regeneration
The aim of the current study was to ascertain the relationships between clinical recovery and nerve fiber and mechanoreceptor function after surgical repair of ulnar or median nerve lesions by a collagen nerve guide or direct suture at the distal forearm level. Clinical recovery was measured by quantitative sensory hand function tests.14 Regeneration of nerve fibers and their functional characteristics were assessed by recording of the compound sensory nerve action potential (SNAP) using near‐nerve needle electrodes. However, electrical stimulation of digital nerves provides limited information about target reinnervation, because receptor function and the distal nerve fiber segment are excluded in these studies. To specifically assess target reinnervation, we have utilized a tactile probe to stimulate fast‐adapting mechanoreceptors at the fingertip.15 This method allows recording of a SNAP and analysis of the receptor‐associated responses16 to provide insight into recovery of mechanoreceptor function after reinnervation.
Our studies showed differential recovery of sensory modalities and that SNAPs remained extremely dispersed and polyphasic. These findings suggest that sensory fiber and receptor dysfunction influence the recovery of clinical perception. Clinical and sensory electrophysiological recovery were indistinguishable between repair types, supporting that regenerating nerve fibers in humans can traverse a short gap and correctly reinnervate the distal nerve stump and relevant mechanoreceptors.