F29. Recovery of sensory modalities after peripheral nerve lesions associated with mechanoreceptor and sensory nerve fiber function

Abstract

Introduction Sensation is essential for recovery after peripheral nerve injury. However, the relationship between sensory modalities and function of regenerated fibers and reinnervated sensory receptors is uncertain. We have investigated the relationships between touch threshold, tactile gnosis and mechanoreceptor and sensory fiber function after nerve regeneration. Methods Twenty-one median or ulnar nerve lesions were repaired by a collagen nerve conduit or direct suture. Quantitative sensory hand function using a modified Rosen score and sensory conduction studies by near-nerve needle technique including tactile stimulation of mechanoreceptors were followed for 2 years, and results were compared to non-injured hands. Results At both repair methods, touch thresholds at the finger tips recovered to 81 ± 3% whereas tactile gnosis only recovered to 20 ± 4% (P Conclusion The recovered function of regenerated peripheral nerve fibers and reinnervated mechanoreceptors may differentially influence recovery of sensory modalities. Touch was affected by the number and function of regenerated fibers and mechanoreceptors. In contrast, tactile gnosis depends on the input and plasticity of the CNS, which may explain the absence of a direct relation between electrophysiological parameters and poor recovery. Dispersed maturation of sensory nerve fibers with desynchronized inputs to the CNS also contributes to the poor recovery of tactile gnosis.