Denervation and reinnervation in congenital brachial palsy

Motor unit number estimation (MUNE) was shown to be useful in assessing the neurophysiological status of 18 subjects with congenital brachial palsy. T his was especially so since conventional M-wave measurements may give misle ading impressions as to the extent of motor axon regeneration. In most subj ects the involvement of sensory nerve fibers indicated that the traumatic l esions included postganglionic segments of the fibers, with or without preg anglionic damage. In a minority the lesions were purely preganglionic. Digi tal sensory nerve involvement was more in a mediolateral direction, consist ent with greater damage to the uppermost elements in the brachial plexus. I n 5 individuals, MUNE and sensory testing showed that there had been trauma to the supposedly unaffected arm. Discrepancies between sensory and motor results suggested that reinnervation of the biceps brachii muscle was great er than that of the intrinsic muscles of the hand. In one subject examined serially, reinnervation of the hand muscles was detected by 10 months and c ontinued in the hypothenar muscles for the next 6 years. (C) 1999 John Wile y & Sons, Inc.