Kirihara Yumiko, Saito Yoji, Sakura Shinichi, Hashimoto Keishi, Kishimoto Tomomune, Yasui Yukihiko
Department of Anesthesiology, Shimane Medical University, Izumo, Japan.
Anesthesiology. 2003 Oct;99(4):961-8. doi: 10.1097/00000542-200310000-00032.
Although there is a considerable difference in the number of clinical reports of neurologic injury between spinal anesthesia and other regional techniques, there are no animal data concerning a difference in the local anesthetic neurotoxicity between intrathecal and epidural administration. In the current study, the functional and morphologic effects of lidocaine administered intrathecally and epidurally were compared in rats.
Male rats were implanted with an intrathecal or epidural catheter through L4-L5 vertebra in the caudal direction. In experiment 1, to determine relative anesthetic potency, 16 rats received repetitive injections of 2.5% lidocaine into intrathecal or epidural space in different volumes and were examined for tail flick test for 90 min. In experiment 2, to ascertain whether the relative potency obtained in experiment 1 would apply to other concentrations of lidocaine, additional rats received saline, 1%, 2.5%, or 5% lidocaine in a volume of 20 or 100 microl through the intrathecal or epidural catheter, respectively. In experiment 3, additional rats that received saline, 2.5% lidocaine, or 10% lidocaine in a volume of 20 or 100 microl through the intrathecal or epidural catheter, respectively, were examined for persistent functional impairment and morphologic damage.
In experiment 1, the two techniques produced parallel dose-effect curves that significantly differed from each other. The potency ratio calculated was approximately 4.72 (3.65-6.07):1 for intrathecal:epidural lidocaine. In experiment 2, every lidocaine solution produced a similar increase in tail flick latency for the two techniques. In experiment 3, five of eight rats given 10% intrathecal lidocaine incurred functional impairment 4 days after injection, whereas no rats in the other groups did. Significantly more morphologic damage was observed in rats given 10% intrathecal lidocaine than in those given 10% epidural lidocaine.
Persistent functional impairment occurred only after intrathecal lidocaine. Histologic damage in the nerve roots and the spinal cord was less severe after epidural lidocaine than after intrathecal lidocaine. The current results substantiate the clinical impression that neurologic complications are less frequent after epidural anesthesia than after spinal anesthesia.
尽管脊髓麻醉与其他区域麻醉技术在神经损伤临床报告数量上存在显著差异，但尚无关于鞘内注射与硬膜外注射局部麻醉药神经毒性差异的动物数据。在本研究中，比较了大鼠鞘内和硬膜外注射利多卡因后的功能和形态学效应。
雄性大鼠通过L4-L5椎间隙向尾侧植入鞘内或硬膜外导管。在实验1中，为确定相对麻醉效能，16只大鼠以不同体积向鞘内或硬膜外间隙重复注射2.5%利多卡因，并在90分钟内进行甩尾试验检测。在实验2中，为确定实验1中获得的相对效能是否适用于其他浓度的利多卡因，另外的大鼠分别通过鞘内或硬膜外导管接受20或100微升的生理盐水、1%、2.5%或5%利多卡因。在实验3中，另外的大鼠分别通过鞘内或硬膜外导管接受20或100微升的生理盐水、2.5%利多卡因或10%利多卡因，检测其持续性功能损害和形态学损伤。
在实验1中，两种技术产生了相互显著不同的平行剂量-效应曲线。计算得出的鞘内：硬膜外利多卡因效能比约为4.72（3.65-6.07）：1。在实验2中，每种利多卡因溶液对两种技术的甩尾潜伏期产生了相似的增加。在实验3中，8只接受10%鞘内利多卡因的大鼠中有5只在注射后4天出现功能损害，而其他组无大鼠出现该情况。与接受10%硬膜外利多卡因的大鼠相比，接受10%鞘内利多卡因的大鼠观察到明显更多的形态学损伤。
仅在鞘内注射利多卡因后出现持续性功能损害。硬膜外注射利多卡因后神经根和脊髓的组织学损伤比鞘内注射利多卡因后更轻。目前的结果证实了临床印象，即硬膜外麻醉后神经并发症比脊髓麻醉后更少见。
