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 monofunctional 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.