Idiopathic scoliosis: a complex model of neuromuscular growth disturbances
(1989) Combined meeting SRS & ESDS — Location: Amsterdam (17.September.1989)
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- Authors
Maréchal, Georges 
- et. al.
- Abstract
- Investigations on idiopathic scoliosis can be interpreted on the basis of at least 4 major interacting factors : GROWTH-Segmental spinal DEFORMATION-Segmental spinal IMMOBILIZATION - Disturbances in the neural AFFERENCES. The contribution of each to the "inducing mechanism" of idiopathic scoliosis has been studied using four experimental models in 50 dogs. In group A, deafferentation was performed by a dorsal rhizotomy (extramedullar and preganglionic) on 5 consecutive thoracic levels in growing (n=22) and adult dogs (n=4). In group B, segmental spinal deformation was obtained by a curved metallic plate inserted through a two level thoracotomy and fixed to 8 vertebral bodies in young (n=4) and adult (n=4) dogs with no injury to the paravertebral muscles. In group C, segmental spinal immobilization was obtained by a straight rigid plate fixed to 8 vertebral bodies also through a two level thoracotomy in adult dogs (n=4). In group D, a multilevel laminectomy was performed in young (n=4) and adult (n=4) animals. The dorsal roots were approached surgically on five consecutive levels but were not severed. Electromyography of the superficial and deep paravertebral muscles was performed on both sides of the spine before surgery, 4 weeks later and at sacrifice (3 to 6 months post-surgery). Denervation and reinnervation were detected already at 4 weeks post-op. Histological sections of the spinal chord (transverse and frontal) were performed at the apex and on both extremities of the deafferented segment. Three months post-rhizotomy demyelination was only found in the fasciculus cuneatus of group A. The number of motoneurons was reduced in the homolateral anterior horn exclusively in young animals. Chromatolysis of motoneurons without demyelination was already observed at 7 days post-rhizotomy (n=4).muscles biopsies from both sides were examined by histochemical methods (ATPase pH 9.4, NADH and PAS) and by biochemical measurement: soluble (SO) and sedimentable (SE) protein concentration, lactico-deshydrogenase (LDH) and isocitricodehydrogenase activities (ICDH). In conclusion of detailed analyses, the changes observed in muscles of scoliotic dogs were primarily due to immobilization of the spine in a curved configuration during growth. An imbalance in the sensory afferents to the motoneurons affects the mechanism of neuromuscular maturation.
Citations
Lokietek, W., Maréchal, G., Plaghki, L., & et al. (1989). Idiopathic scoliosis: a complex model of neuromuscular growth disturbances. Combined meeting SRS & ESDS, p. 358-359. https://hdl.handle.net/2078.5/231314