Experimental Study of Spinal Deformity Produced in Dogs with Syringomyelia

为探讨高岭土诱发犬脊髓侧凸的病因，对9只出生后6 ~ 8周的比格犬进行枕大池内注射高岭土。为了通过染色评价骨生长，在生长期间皮下给予钙黄绿素和四环素。分别于注射高岭土后8周（2只）、10周（1只）、14周（2只）、18周（1只）、26周（2只）、52周（1只）处死动物。获得X线片、CT扫描和MRI。对脊髓进行组织学检查，并对脊柱结构变化进行组织形态计量学分析。4只犬出现交通型脊髓空洞症并伴有脑积水。脊髓的组织学研究显示急性或亚急性炎症变化，包括室管膜细胞的拉伸和变薄，室管膜周围水肿的形成，以及室管膜周围组织内的海绵状变化。在注射高岭土后10周和14周，2只犬出现轻度脊柱侧凸，1只犬在注射高岭土后14周出现显著脊柱侧凸，主曲率为66 °。在一只患有显著脊柱侧凸的狗中，异常的脊柱建模，表明骨生长试图纠正而不是产生畸形，组织形态计量学显示，将高岭土注射到枕大池中会产生基底动脉蛛网膜炎，导致脑积水和脊髓积水。然而，目前尚未见高岭土诱发脊髓损伤导致脊柱侧凸畸形的报道，脊柱侧凸畸形的椎旁肌组织学检查有待进一步研究。

The purpose of this study is to investigate the etiology of scoliosis produced in dogs with kaolin-induced syringomyelia.Kaolin was injected into the cisterna magna of 9 beagles from 6 to 8 weeks after birth. To evaluate bony growth by staining, calcein and tetracycline subcutaneously administered during the growth period. The animals were sacrificed 8 weeks (2dogs), 10(1), 14(2), 18(1), 26(2), 52(1) after injection of kaolin. Roentgenograms, CT scans, and MRI were obtained. The spinal cord was histologically examined, and the structural changes of the vertebral column were analyzed histomorphometrically.Hydrocephalus was noted in 7 dogs. A comunicating-type syringomyelia was appeared in 4 dogs in association with hydrocephalus. The histological study of the spinal cord revealed acute or subacute inflammatory changes, including stretching and thinning of the ependymal cells, formation of periependymal edema, and spongy changes within the periependymal tissues. Mild scoliosis were recognized in 2 dogs at 10 and 14 weeks, and a significant scoliosis with main curvature of 66ﾟ was noted in 1 dog at 14 weeks after kaolin injection. In a dog with significant scoliosis, abnormal spinal modeling, suggesting that the bone growth was attempting to correct rather than produce deformity, was shown histomorphometrically.It has been shown that kaolin injection into the cisterna magna produced basilar arachnoiditis leading to hydrocephalus and syringomyelia. However, there is no report on the scoliotic deformity associated with kaolin-induced syringomyelia.The paravertebral muscle of scoliotic deformity will be histologically examined in future.