Réparation médullaire des avulsions radiculaires du plexus brachial: vers de nouvelles stratégies chirurgicales ?

Abstract

Avulsion of nerve roots associated with the brachial plexus results in dramatic lesions with a prognosis which remains poor to this day. These lesions are considered as involving the central nervous system and therefore not amenable to surgical repair. However, the results of many experiments in animals have shown that if continuity can be re-established between the cervical cord and a denervated muscle or the distal end of its nerve, spinal motor neurons can regrow into a peripheral nerve graft, ultimately leading to the restoration of functional contraction. A preliminary experiment was attempted in humans but the outcomes were modest. In light of all the controversy raised by these preliminary results, we sought to demonstrate that axons can indeed regrow after intra-spinal re-implantation of an avulsed nerve root, that such re-growth can lead to the recovery of function, and that the phenomenon should be focused upon for the development of new surgical modalities to correct this serious condition. We first studied the anatomy of the intradural compartment and developed a posterior approach to the brachial plexus for implantation in the ventrolateral aspect of the spinal cord. The fact that the white matter of the central nervous system is not propitious for axon re-growth led us to investigate the advantages of directly implanting the graft in the ventrolateral sulcus of the spinal cord in order that it might reach the anterior horn of the gray matter. In order to do this, we developed in the laboratory a direct surgical approach to the anterior horn, an approach which we subsequently used in patients with avulsion of multiple nerve roots at different levels. Intraspinal re-implantation did not induce any neurological complications and co-contraction of different muscles was not observed in any of the patients. Partial re-innervation was obtained of the triceps, biceps and deltoid muscles, the exact pattern depending on the type of lesion and the type of graft. Treatment with neurotrophic factors represents a parallel line of research which might well help improve outcomes in spinal surgery to repair nerve root avulsion.