Animal Study on Intercostal Neurotization in Avulsion Brachial Plexus Injury

Microsurgical reconstruction of brachial plexus was performed on twelve monkeys using the ipsilateral intercostal nerves (T3-9). Reinnervation of the individual nerves was evaluated monthly by observation of neuromuscular and electromyographic improvement. The electromyographic studies revealed the reappearance of motor unit potentials. According to a motor scale ranging from 0 to 4, the mean muscle power six months, after the operation had improved to 2.75 in the deltoid muscles, 2 in the biceps muscles, 1.22 in the triceps muscles, 1.13 in the flexor carpi radialis muscles, and 1.6 in the intrinsic muscles of the hands. Retrograde transport of horseradish peroxidase (HRP) from the neuromuscular junctions of the reconstructed musculocutanenus nerves at six months following a complete brachial plexus lesion in four animals demonstrated HRP-labeled neurons in the anterior horn, spinal ganglia and sympathetic ganglia of the thoracic spinal cord. It suggested that the regenerated afferent and efferent circuits in the thoracic cord innervating the transected brachial plexuses were able to generate some movement in the paralyzed upper limbs.