New Type Of Cortical Neuroplasticity After Nerve Repair In Brachial Plexus Lesions

Background: In brachial plexus avulsion, a recent technique connects the ending of the disrupted musculocutaneous nerve to the side of the intact phrenic nerve to regain elbow flexion. This requires the phrenic nerve to perform a new double function: independent control of breathing and elbow flexion. Neuroplastic changes associated with acquisition of double nerve functions have not yet been investigated.Objective: To evaluate neuroplastic changes associated with acquisition of double nerve functions in a mono-functional nerve (phrenic nerve).Design: Clinical and functional magnetic resonance imaging investigations during arm movements, forced inspiration, and motor control tasks.Setting: Investigations at the Medical University of Vienna, Vienna, Austria.Participants: Three healthy control subjects, 2 patients with phrenic nerve end-to-side coaptation, and 1 control patient with C7 end-to-end coaptation (same clinical presentation but phrenic nerve unchanged).Results: Clinical documentation showed that both patients with phrenic nerve end-to-side coaptation were able to control the diaphragm and the biceps independently via the same phrenic nerve. In contrast to all controls, both patients with phrenic nerve end-to-side coaptation activated the cortical diaphragm areas with flexion of the diseased arm.Conclusion: Our functional magnetic resonance imaging data indicate that the patient's cortical diaphragm areas reorganize in such a way that independent control of breathing and elbow flexion is possible with the same neuronal population.