Scoliosis induced by anterior and posterior rhizotomy

This paper presents the result and statistical analysis of an experiment in which selective anterior or posterior rhizotomy was carried out under microscopic surgery. The animals used for the experiment were 48 young rabbits, and they were divided into four groups. Group 1, which was used as control, was subjected to lower dorsal bilateral laminectomies with dural incision; Group II to laminectomies with three right posterior rhizotomies; Group III to laminectomies with three right anterior rhizotomies, and Group IV to laminectomies with three right anterior and posterior rhizotomies. Scoliosis was induced in Groups II, III, and IV. There was no significant statistical difference in the degree of curvatures among these three groups. The convexity of the curvature faced to the side of the divided roots. In Groups III and IV, scoliotic curvatures were obvious within 2 weeks, but there were no considerable changes thereafter. In Group II, the curves progressed slowly up to the 12th week. They were statistically significant at the fourth week and increased continuously thereafter. The histologic findings in Groups III and IV showed denervation atrophy of the paravertebral muscles at the apex of the curvature, but there was little or no muscle atrophy in Groups I and II. The experimental results indicate that scoliosis may be induced not only by anterior root paralysis but also by selective posterior root paralysis.