Selander D, Sjöstrand J
Acta Anaesthesiol Scand. 1978;22(6):622-34. doi: 10.1111/j.1399-6576.1978.tb01346.x.
Unexpected spinal anesthesia, occurring after peripheral nerve blocks close to the spine, may be caused by a centripetal spread of the local anesthetic along the injected nerve to the spinal cord. In order to analyze the pathway of such a spread, a radioactive local anesthetic mixed with a fluorescent dye was injected into difrerent compartments of the rabbit sciatic nerve, and the early distribution of these tracers was studied by scintillation counting and fluorescence microscopy. Epineurial (extrafascicular) injections were of low injection pressure (25-60 mmHg) (3.3-7.9 kPa) and limited spread, while endoneurial (intrafascicular) injections reached higher pressures (300-750 mmHg) (39.9-99.7 kPa) and caused a rapid spread over long distances within the fascicle. The sacral plexus seemed difficult to pass. However, 20% of endoneurial injections reached the spinal cord, where the injectate primarily spread in the thin subpial space. Our experimental findings suggest that intraneural injections of local anesthetics are responsible for the reported cases of unexpected spinal anesthesia due to inadvertent intrafascicular spread. Although intrafascicular injections are rarely made, we recommend that intraneural injections of local anesthetics or other solutions close to the spine should be avoided, as they may cause unexpected spinal anesthesia or lesion of the cord.
在靠近脊柱的周围神经阻滞之后发生的意外脊髓麻醉，可能是由于局部麻醉药沿注入的神经向心性扩散至脊髓所致。为了分析这种扩散的途径，将一种与荧光染料混合的放射性局部麻醉药注入兔坐骨神经的不同部位，并通过闪烁计数和荧光显微镜研究这些示踪剂的早期分布。神经外膜（束外）注射的注射压力较低（25 - 60 mmHg）（3.3 - 7.9 kPa）且扩散有限，而神经内膜（束内）注射达到更高的压力（300 - 750 mmHg）（39.9 - 99.7 kPa），并导致在束内迅速远距离扩散。骶丛似乎难以通过。然而，20%的神经内膜注射到达了脊髓，注射物主要在薄的软膜下间隙扩散。我们的实验结果表明，局部麻醉药的神经内注射是因意外束内扩散导致的意外脊髓麻醉报告病例的原因。尽管很少进行束内注射，但我们建议应避免在靠近脊柱处进行局部麻醉药或其他溶液的神经内注射，因为它们可能导致意外脊髓麻醉或脊髓损伤。
