Study design: Experimental animal study.
Objective: To evaluate motor and sensitive axonal regrowth after multiple intercosto-lumbar neurotizations in a sheep model.
Methods: Fifteen sheep were separated into three groups. Five sheep had multiple intercosto-lumbar neurotizations and a spinal cord lesion, five sheep were neurotized without any spinal cord lesion and five sheep had a spinal cord lesion without any neurotizations. Six months after the initial surgery, histological study of the neurotized roots was performed.
Results: The length of the three rerouted intercostal nerves was sufficient in the 10 sheep to perform an intercosto-lumbar neurotization in good conditions. Eight sheep out of the 15 had postoperative complications responsible for the animal's death in five cases. Histological cross-sections of all the neurotized L2, L3 and L4 roots showed numerous myelinated regenerated axons. Dorsal root ganglions of neurotized roots showed both large and small neurons with normal nucleus and cytoplasm. The fluorescent retrograde labeling of 18 roots revealed labeled motor neurons in five cases.
Conclusions: This study demonstrates the technical feasibility of intercosto-lumbar neurotizations in a big mammalian model. Intercostal nerve harvesting and rerouting was successfully performed in all the cases. Our histological results proved, in all the animals studied, the ability of motor and sensitive neurons to regenerate through the neurotization area. In the context of the future clinical application of strategies aimed at promoting axonal regeneration after severe spinal cord injury, the present data suggest that multiple intercosto-lumbar neurotization could be helpful to promote lower limb muscular strength recovery after spinal cord injuries.