The histologic effects of posterior lumbar surgery and retained extradural foreign bodies on the cauda equlna were investigated in rats over time. The following four groups of rats were provided: Group 1, sham operation (Iaminar exposure alone); Group 2, laminectomy alone; Group 3, iaminectomy with retained extradural silk thread; Group 4, laminectomy with exradural kaolin; and the control. Histological study was performed on the transverse sections of laminectomized (L5) and nonlarninectomized (L4) areas. In Group 1, adhesive changes involving the cauda equlna, consisting of dilatetion of nutrlent vessels, and eosinophilic exudative changes between the adhering cauda rootlests were seen the day after surgery, but the fibrinous adhesion was resolved spontaneously in all rats after 1 week without pormanent sequelse. In Groups 2 and 3, postoperative adhesion of the cauda equina roots was conspicuous, but it resolved by 6 weeks. In Group 4, obvious adhesion persisted through the 12th week after surgery, Destruction of the myelin sheath and axonal loss of the cauda equlna occurred in the first week after surgery in all the experimental groups except in the sham group. The severity and extent of the neural degeneration were mostly parallel to the severlty of inflammatory chaanges in the epidural areas, At the nonlaminectomized are (L4) In each group, the arachnoid and cauda equina tended to congregate the day after surgery, but these changes were all transitory. The severity and persistency of the arachnoiditis and neural degeneration directly corresponded to the magnitude of the inflammation and wound healing processes. This seems to imply that careful surgical intervention with no use of foreign bodies is necessary to reduce postoperative adhesive arachnoiditis.
展开▼
