Microsurgical management of the old birth-related brachial plexus injuries

Introduction: The potential for nerve regeneration in children is much greater than in adults. However, the longest period elapsed from injury where regeneration can still occur in a child is unknown. Material and Methods: This preliminary study evaluates the efficacy of microsurgical approach in the management of 7 children suffering from old birth-related brachial plexus injuries. The average age at surgery was 5.3 years (ranging from 1.2 to 10 years after birth-related injury). The whole brachial plexus was involved in 5 patients and C5 or C5-C7 levels were involved in 2 patients. The patients were evaluated and subsequently treated by external and interfascicular neurolysis and/or autogenous interfascicular nerve grafts. In cases of preganglionic or whole brachial plexus injury, neurotization from the C4 nerve root was performed in order to promote reinnervation of the avulsed posterior cord. Somatosensory evoked potential (SSEP's) response on the scalp during root stimulation was used for identification of the preganglionic nerve root avulsion. During external and interfascicular neurolysis, intraoperative Compound Muscle Action Potentials (CMAP's) were recorded from corresponding muscles during selected stimulation of plexus elements to identify functional nerve roots, trunks, divisions, cords and nerves. Results: During external and interfascicular neurolysis in 5 of the 7 patients, the: increasing amplitude(mV) of CMAP's from 0.40 +/- 0.33 to 1.036 +/- 0.66 and decreasing latency (msec) from 4.15 +/- 1.74 to 3.62 +/- 1.64 were recorded. Four of the 5 patients with previously paralyzed or minimal finger flex ion movement demonstrated the start of antigravity function or improvement. Four of the 7 patients demonstrated the appearance of or improvement of forearm and or shoulder movements achieving improvement of muscle resistance during antigravity movements. Postoperative EMG clearly demonstrated improvement of electrophysiological muscle function. Conclusion: I) Intraoperative electrophysiological findings after external and interfascicular neurolysis suggested that viability of nerve tissue is longer than previously considered. 2) This study suggests that the use of microsurgical techniques, even in long term cases, promotes partial functional improvement of patients suffering from old birth-related brachial plexus injuries. Microsurgical brachial plexus exploration should be considered in treating this selected group of patients.