PubMed1985
A group of 37 patients (total 41 nerves) with a traumatic transection of median or ulnar nerves at the wrist were reinvestigated clinically and electrophysiologically 4-59 months after primary or secondary suture or grafting. Clinically there was no relation between the time after the operation, and sensory recovery determined according to the schedule of Nicholson and Seddon (1957), two-point discrimination, vibration threshold. There was also no relationship between the time after suture, and the motor latencies as well as amplitudes of evoked muscle action potentials from the abductor pollicis brevis or hypothenar muscles. In sensory nerve fibres there was a statistically significant increase of the maximum amplitude and of the cumulative amplitude during the period after operation, due to an increasing number of regenerated nerve fibres. Sensory nerve conduction velocities showed no relation to the time after suture. Cumulative amplitudes were significantly related to two-point discrimination and to restitution of sensibility. As indicated by the great scatter, however, this parameter is merely a moderate predictor for the degree of clinical recovery. Somatosensory evoked potentials can be helpful in some cases to indicate nerve regeneration when nerve action potentials in peripheral nerves cannot be recorded. However, latencies and amplitudes of the individual peaks did not reveal any relationship to either clinical findings or to period of time after operation. Needle electromyography also yielded highly variable findings. A constant finding was a persistent loss of motor units. Most of these were increased sin size, as indicated by prolonged duration of their action potentials during slight voluntary effort.