Sun W M, MacDonagh R, Forster D, Thomas D G, Smallwood R, Read N W
Royal Adelaide Hospital, North Terrace, Australia.
Gastroenterology. 1995 Apr;108(4):990-8. doi: 10.1016/0016-5085(95)90194-9.
BACKGROUND/AIMS: The implantation of spinal stimulators to facilitate defecation in patients with complete spinal transection involves division of the posterior sacral nerve roots. The aim of this study was to investigate the role of spinal reflexes in anorectal function.
Anorectal manometry and electromyography were performed in 14 patients with supraconal spinal cord transection (C6-T12) before and after complete sacral posterior rhizotomy and in 30 normal controls.
Patients with spinal transection lost conscious control of the external anal sphincter. Reflex responses to intra-abdominal pressure and to rectal distention were eliminated after rhizotomy, indicating that they are spinal reflexes. Rhizotomy also eliminated giant rectal contractions induced by rectal distention in these patients. In contrast, the exaggerated sphincter relaxation induced by rectal distention was not influenced by rhizotomy. Discriminant rectal sensation was lost, but patients with thoracic cord lesions perceived a dull pelvic sensation during rectal distention even after rhizotomy.
The exaggerated anorectal smooth muscle responses and absent conscious control of the anorectum may explain why patients with complete spinal transection experience uncontrollable reflex defecation, and the persistence of external anal sphincter contraction during straining may impair fecal expulsion. The elimination of these responses after posterior rhizotomy prevented reflex defecation while facilitating manual evacuation.
背景/目的：植入脊髓刺激器以促进完全性脊髓横断患者排便，这涉及骶后神经根的切断。本研究的目的是探讨脊髓反射在肛门直肠功能中的作用。
对14例圆锥上脊髓横断（C6 - T12）患者在完全性骶后根切断术前和术后进行肛门直肠测压和肌电图检查，并与30名正常对照者进行比较。
脊髓横断患者失去了对肛门外括约肌的意识控制。根切断术后，对腹内压和直肠扩张的反射反应消失，表明它们是脊髓反射。根切断术还消除了这些患者中由直肠扩张引起的巨大直肠收缩。相比之下，由直肠扩张引起的过度括约肌松弛不受根切断术的影响。辨别性直肠感觉丧失，但胸段脊髓损伤患者即使在根切断术后，在直肠扩张时仍能感觉到钝性盆腔感觉。
肛门直肠平滑肌反应过度以及对肛门直肠缺乏意识控制，可能解释了完全性脊髓横断患者出现无法控制的反射性排便的原因，而用力时肛门外括约肌持续收缩可能会妨碍粪便排出。骶后根切断术后这些反应的消除可防止反射性排便，同时便于手法排便。
