Skeletal muscle changes following myelotomy in paraplegic patients.

Pourpre's dorsal T-shaped myelotomy was performed on three paraplegic patients in which medical and electro-physiological procedures proved to be ineffective concerning muscle spasms. The myelotomy led to the elimination of spasms and of muscle hypertonicity in the lower limbs. Biopsies of the rectus femoris muscles were performed bilaterally one year before and two months following myelotomy. The first biopsy revealed fascicular atrophy, with type I fibre preferential atrophy, which is usually found in paraplegic patients. After myelotomy some histological differences were seen: reduction of type II fibre diameter and the presence of target-targetoid fibres and of atrophic dark fibres. There was a difference of fibre pattern type in hypertonic spastic muscles compared to that seen in spasm relieved by myelotomy. The morphological changes seen after myelotomy are interpreted as denervation changes because of the surgical lesion by the myelotomy on the anterior horn cells.