Experimental bypass surgery between the spinal cord and caudal nerve roots for spinal cord injuries

Spinal cord injuries often cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate in adult mammalians. Re-establishing functional activity especially in the lower limbs by reinnervating the caudal infra-lesional territories could represent an attractive therapeutic strategy. For several years, we have studied and developed surgical bypasses using peripheral nerve grafts bridging the supra-lesional rostral spinal cord to the caudal infra-lesional lumbar roots. Main objectives were: 1- to overcome the spinal cord lesion and the consecutive glial barrier blocking the axonal regeneration; 2- to find and bring an alternative source of regenerating axons; 3- to guide those axons toward precisely definite targets (for example, lower limb muscles). We report here the results of our experimental research, which led us from animal experimental models (rodents, primates) to the first human experimentation. Limitations of the method (especially technical pitfalls) are numerous. However, we have obtained encouraging results in our attempts to “repair” the motor pathway. Functional recovery with strong evidence of centrifugal axonal regeneration from the spinal cord to the periphery has been observed. Regarding the sensory pathway, we have found evidence of centripetal axonal regeneration from the periphery toward the spinal cord. Further studies are obviously advocated, but our experimental model of spinal cord - nerve roots bypasses may be integrated in future “repair” strategies of both motor and sensory pathways following spinal cord injury. Les traumatismes de la moelle épinière sont responsables de troubles neurologiques souvent définitifs et inaccessibles à un traitement efficace. Cette atteinte définitive est directement liée à l’incapacité des axones médullaires interrompus par le traumatisme, de régénérer spontanément chez le mammifère adulte. Pour rétablir une activité fonctionnelle, notamment au niveau des membres inférieurs, ré-innerver les territoires sous-lésionnels constitue une voie d’approche séduisante. Les pontages radicello-médullaires entre le segment médullaire sus-lésionnel et les radicelles sous-lésionnelles à l’aide d’un greffon de nerf périphérique sont étudiés dans notre équipe depuis plusieurs années. Ces techniques ont pour objectif de ponter la lésion et la barrière gliale secondaire au traumatisme, d’apporter une source alternati