Anatomical and experimental investigntion on postoperative ralimlopattiy after postenior decompresion of the cervical spinal cord

通过对20名日本成年人和118名患者的颈脊髓和颈椎根的解剖和临床研究，我们阐明了以下事实。1)颈椎根减压后栓系效应有两个可能发生的部位，即硬膜内和硬膜外。2)硬脊膜外根通过神经周围粘连固定在椎间孔上，施加硬脊膜牵引力可引起硬脊膜外根牵引损伤。3)根的硬脊膜内和硬脊膜外部分的解剖特征提示硬脊膜外栓系效应可能是术后瘫痪的最可能原因，临床研究证实了这一点。4)作为预防这些栓系效应的方法，纵向硬膜切开术可以有效地减少硬膜外栓系效应，抑制硬膜管后部扩大到一定程度，使硬膜内根保持松弛，被认为是预防硬膜内栓系效应的有效方法。在另一组43例患者的后路减压中，使用直径0.3mm的2-9尼龙线测量C5根套后方的硬脑膜压力，其中9例患者硬脑膜压力高于40 g-weight/mm^2,4例患者术后出现C5麻痹。在29例硬脑膜压力低于40 g-weight/mm^2的患者中，1例发生术后C5麻痹。两组比较，差异有统计学意义（X^2=4.35, p<0.05）。这一结果表明，术中测量硬脑膜压力可能有助于检测术后瘫痪的可能性。需要进一步的研究来开发一种更准确的预测术后瘫痪的方法，以及一种比纵向硬膜切开术更简单的预防方法。

Based on anatomical and clinical studies on the cervical spinal cord and root using 20 Japanese adults and 118 patients, the following facts were elucidated. 1) There were two possible sites for the occurrence of post-decompressive tethering effects on cervical roots, i.e., intradural and extraural. 2) Extradural tethering effect could be induced by exertion of dural traction force on extradural roots which were anchored to the intervertebral foramina by perineural adhesion, resulting in traction injury of extradural roots. 3) Anatomical characteristics of intra-and extradural portions of a root indicated that the extradural tethering effect might be the most probable cause of post-operative palsy and it was verified by a clinical study. 4) As methods of prevention for each of these tethering effects, a longitudinal durotomy was effectivi in reducing extradural tehthering effect and a suppression of posterior enlargement of dural tube to that degree that allowed intradural rootlets remain relaxd was thought to be effective for prevention of intradural tethering effect. In another series of posterior decompression consisting with 43 patients, dural pressures just posterior to C5 root-sleeve were measured using a 2-9 nylon thread with a diameter of 0.3mm. of nine patients with a dural perssure higher than 40 g-weight/mm^2,4patients developed post-operative C5 palsy. Of twenty nine patients with a dural pressure lower than 40 g-weight/mm^2, one patient developed post-operative C5 palsy. There was a difference of statistical significance (X^2=4.35, p<0.05) between those two groups. This result showed that measurement of dural pressure during surgery might be useful to detect a possibility of post-operative palsy. Further studies are required to develop a more accurate method for predicting post-operative palsy and a simpler method of prevention of it than a longitudinal durotomy.