Neurotization of motor nerves innervating the lower extremity by utilizing the lower intercostal nerves

An animal model in the rat was developed to study the reinnervation of ventral roots contributing to lower-extremity nerves by use of intercostal nerves. Intercostal nerves and distal cauda equina roots were anastomosed, using a collagen tube and microsurgical technique. Most experimental animals could lift their previously paralyzed legs and could walk with a severe limp by 9 months postoperatively. Recordings of nerve action potentials (NAPs) and muscle action potentials (MAPs) indicated that the intercostal and sciatic nerves had some functional connections. Histologic analysis 12 months after repair demonstrated axonal regeneration extending from the intercostal nerves to and down lumbar ventral roots. Most of the regenerated fibers were moderately well-myelinated. Connections between the neurons of the anterior horn cells in the lower thoracic spinal cord and the reinnervated sciatic nerve were confirmed by retrograde tracer, using fast blue.