Anatomical and physiological assessments of peripheral nerve grafts in the dorsal columns of the spinal cord

Abstract

Portions of 1 cm length of the sensory radial nerve from the cat forelimb were used to replace an excised portion of the dorsal columns in the upper lumbar spinal cord. Observations were made on the clinical recovery of the animals, and cine recordings were made of their ability to traverse a horizontal ladder 5 months after the grafting procedure. Evoked sensory potential studies performed 6 months after grafting showed that an impulse arising from a stimulus applied to the sciatic nerve could be recorded in the spinal cord caudal to the graft, in the graft and in the spinal cord rostral to the graft in 5 out of 8 animals. Tracing of nerve connections with injection of horseradish peroxidase into the grafts resulted in labelling of nerve cell bodies in dorsal root ganglia and the grey matter of the lumbar spinal cord up to a distance of 10 mm away from the graft. These results confirm that peripheral nerve grafts can provide a satisfactory environment for the regrowth of ascending fibres in the dorsal columns of the spinal cord. However, there is as yet no evidence that the regenerated fibres succeed in forming useful synaptic connections with other nerve cell bodies.