Kawakami M, Weinstein J N, Chatani K, Spratt K F, Meller S T, Gebhart G F
Department of Orthopedic Surgery, Wakayama Medical College, Japan.
Spine (Phila Pa 1976). 1994 Aug 15;19(16):1795-802. doi: 10.1097/00007632-199408150-00002.
The recently proposed animal model of lumbar radiculopathy was used to investigate behavioral consequences and histologic changes in spinal nerve roots, dorsal root ganglia, and spinal nerves after the L4, L5, and L6 nerve roots were loosely ligated with either silk or chromic gut sutures in an attempt to better understand the pathophysiologic mechanisms that give rise to pain associated with lumbar radiculopathy.
Little is known about the pathophysiologic mechanisms that give rise to pain associated with lumbar radiculopathy. The recently proposed animal model of unilateral lumbar radiculopathy, which demonstrated an association with motor paresis and thermal hyperalgesia of the affected hind limb and showed evidence of spontaneous pain has been demonstrated, may serve as a vehicle to allow direct investigation of the nature of the pathophysiological mechanisms associated with lumbar radiculopathy.
Three distinct treatments of the nerve roots were initially investigated: 1) a sham intervention, where the surgery simply exposed the nerve roots and dorsal root ganglion followed by standard closing procedures; 2) 4-0 silk ligature, where two loose ligatures of 4-0 silk were placed around the nerve roots; and 3) 4-0 chromic gut 2, where four 0.3 cm pieces of 4-0 chromic gut were laid adjacent to the nerve roots and secured by two loose ligatures of 4-0 chromic gut.
ANOVA techniques were used to test for differential effects across time for the three treatment groups in terms of animal function. A qualitative analysis of the histology of the ipsilateral and contralateral nerve roots, dorsal root ganglia, and spinal nerves was done to correlate histologic changes with behavioral changes.
Behavioral results were consistent with the previous study. Rats treated with chromic gut, but not silk, reliably demonstrated a prolonged thermal hyperalgesia that was maximal 2 weeks after surgery and lasted for up to 12 weeks. These behavioral changes, however, were not correlated with histologic changes in myelinated fiber content in the L4, L5, and L6 nerve roots, dorsal root ganglia and spinal nerves, the ipsilateral spinal nerved, dorsal root ganglia, and nerve roots of rates ligated with silk or chromic gut showed similar, significant, decreased in the number of large diameter myelinated fibers.
These results suggest that mechanical constriction of the L4, L5, and L6 spinal nerve roots, as evidenced by a loss of myelinated fibers, is not sufficient to produce the behavioral effects associated with this model of lumbar radiculopathy. It is hypothesized that chemical factors from the chromic gut play a role in the pathophysiology and development of the behavioral, but not histological, changes in this model of lumbar radiculopathy.
采用最近提出的腰椎神经根病动物模型，研究在L4、L5和L6神经根用丝线或铬制肠线进行松弛结扎后，脊髓神经根、背根神经节和脊神经的行为后果及组织学变化，以更好地理解导致与腰椎神经根病相关疼痛的病理生理机制。
对于导致与腰椎神经根病相关疼痛的病理生理机制知之甚少。最近提出的单侧腰椎神经根病动物模型，已证明与受影响后肢的运动麻痹和热痛觉过敏有关，并显示出存在自发痛的证据，可作为一种手段，用于直接研究与腰椎神经根病相关的病理生理机制的本质。
最初研究了三种不同的神经根处理方法：1）假手术干预，即手术仅暴露神经根和背根神经节，随后进行标准的缝合操作；2）4-0丝线结扎，即在神经根周围放置两根4-0丝线进行松弛结扎；3）4-0铬制肠线2，即将四根0.3厘米长的4-0铬制肠线放置在神经根旁，并用两根4-0铬制肠线进行松弛结扎固定。
采用方差分析技术，以检验三个治疗组在动物功能方面随时间的差异效应。对同侧和对侧神经根、背根神经节和脊神经的组织学进行定性分析，以将组织学变化与行为变化相关联。
行为学结果与先前的研究一致。用铬制肠线而非丝线处理的大鼠，可靠地表现出延长的热痛觉过敏，在手术后2周达到峰值，并持续长达12周。然而，这些行为变化与L4、L5和L6神经根、背根神经节和脊神经中髓鞘纤维含量的组织学变化无关，用丝线或铬制肠线结扎的大鼠同侧脊神经、背根神经节和神经根中，大直径髓鞘纤维数量均出现类似的显著减少。
这些结果表明，L4、L5和L6脊神经根的机械性压迫，如髓鞘纤维的丧失所证明的，不足以产生与该腰椎神经根病模型相关的行为效应。据推测，铬制肠线中的化学因素在该腰椎神经根病模型的病理生理学和行为学变化（而非组织学变化）的发展中起作用。
