Hirabayashi Y, Shimizu R, Fukuda H, Saitoh K, Furuse M
Department of Anaesthesiology, Jichi Medical School, Tochigi, Japan.
Br J Anaesth. 1995 Jul;75(1):6-8. doi: 10.1093/bja/75.1.6.
To assess the changes in the curvature of the spinal column in the supine position during pregnancy, we studied seven pregnant (32-37 weeks of pregnancy) and seven non-pregnant women using magnetic resonance imaging. T1-weighted sagittal midline magnetic resonance images of the spinal column were obtained with subjects in the supine position with left tilt. There was no significant difference in the maximum angle of decline of the lumbar spinal canal between the pregnant (mean 12.4 (SD 3.3) degrees) and non-pregnant (13.4 (3.9) degrees) groups. The maximum angle of incline of the upper thoracic spinal canal was smaller in the pregnant (15.8 (2.9) degrees) than in the non-pregnant (22.7 (6.0) degrees) group. The highest point of the lumbar spinal canal was located at a lower lumbar region in the pregnant (median L4-5 (range L4 to L4-5)) than in the non-pregnant (L4 (L3-4 to L4)) group. The lowest point of the thoracic spinal canal was located at a higher thoracic region in the pregnant (T6-7 (T6 to T7-8)) than in the non-pregnant (T8 (T6-7 to T9)) group. This study revealed that the apex of lumbar lordosis was caudad and thoracic kyphosis was reduced in the supine position in the later stages of pregnancy. These changes in the curvature of the spinal column may explain, in part, the enhanced cephalad spread of subarachnoid hyperbaric anaesthetic solutions in the later stages of pregnancy.
为评估孕期仰卧位时脊柱曲率的变化，我们使用磁共振成像研究了7名孕妇（妊娠32 - 37周）和7名非孕妇。在受试者左侧倾斜的仰卧位获取脊柱的T1加权矢状位中线磁共振图像。孕妇组（平均12.4（标准差3.3）度）和非孕妇组（13.4（3.9）度）腰椎管最大下降角度无显著差异。孕妇组（15.8（2.9）度）上胸椎椎管最大倾斜角度小于非孕妇组（22.7（6.0）度）。孕妇组腰椎管最高点位于较低的腰椎区域（中位数L4 - 5（范围L4至L4 - 5）），而非孕妇组位于L4（L3 - 4至L4）。孕妇组胸椎管最低点位于较高的胸椎区域（T6 - 7（T6至T7 - 8）），而非孕妇组位于T8（T6 - 7至T9）。本研究表明，妊娠后期仰卧位时腰椎前凸顶点向尾侧移动，胸椎后凸减小。脊柱曲率的这些变化可能部分解释了妊娠后期蛛网膜下腔高压麻醉溶液向头侧扩散增强的现象。
