Creation and analysis of the animal models with chronic compression myelopathy.

为了确定慢性脊髓压迫后早期的功能变化，我们用骨形态发生蛋白(BHP)建立了兔黄韧带骨化(OYL)模型，并监测了诱发脊髓电位(ESCP)。67只兔子被用于这些实验。对16只OYL和6只健康对照兔进行了脊髓造影、ESCP测量和组织学检查。在OYL模型的平均40.6周后，发现平均脐带压缩率为15.3%。刺激坐骨神经时，OYL兔的ESCP第一波潜伏期与对照组无显著差异，而刺激运动区时，OYL兔脊髓压迫率为10%时，两组第一波潜伏期有显著差异(P&lt；0.005)。4只Oyl兔中有3只脊髓压迫率为*20%，组织学改变主要表现为背柱大纤维减少。我们的结果表明：(1)轻度脊髓压迫导致慢性脊髓压迫者ESCP改变大于急性脊髓压迫者，(2)慢性脊髓背侧压迫导致背柱和背外侧柱浅层损伤，(3)ESCP变化先于瘫痪和组织学改变。

To determine the functional changes occurring in the early period after the development of chronic cord compression, we created an ossification of the yellow ligament(OYL)model, which is a model of chronic cord compression, in domestic rabbits using bone morphogenetic protein(BHP), and monitored evoked spinal cord potentials(ESCP). Sixty-seven rabbits were used for these experiments. Myelography, ESCP measurements, and histological examinations were performed in 16 of the OYL and 6 of the healthy control rabbits.At an average of 40.6 weeks after creitio, of the OYL model, a mean cord compression ratio of 15.3% was found. When the sciatic nerve was stimulated, no significant differences were found in the latency of the ESCP first wave between the OYL and control rabbits, whereas with stimulation delivered to the motor area the first wave latency differed significantly(P<0.005)between the 2 groups when the cord compression ratio in the OYL rabbits was *10%. Histological changes consisting primarily of a reduction in the number of large fibers in the dorsal column were found in 3 of the 4 OYL rabbits showing a cord compression ratio of *20%.Our results demonstrate that(1)mild degrees of cord compression produce greater ESCP alterations in chronic than in acute cord compression, (2)chronic cord compression from the dorsal side produces injury in the superficial layer of the dorsal column and dorso-lateral column, and(3)changes in ESCP precede the development of paralysis and histological changes.