MRI evaluation of postoperative epidural hematoma after lumbar spine surgery

Pain or numbness in the lower extremities often persists after lumbar spine surgery and it is not rare for such symptoms to occur anew. We performed a retrospective comparative study in 66 cases to determine whether there were differences in post-operative symptoms based on the presence of an epidural hematoma diagnosed by postoperative MRI. An epidural hematoma was identified in 30 of the cases, but not in the other 36 cases. The incidence of buttocks pain was 40.0% in the epidural hematoma group (EH group), as opposed to 16.7% among those without an epidural hematoma (non-EH group), and the difference between the two groups was significant (P=0.034). The incidence of pain in the lower extremities was 40.0% in the EH group, as opposed to 16.7% in the non-EH group, and the difference between the two groups was significant (P=0.034). However, there were no difference between the groups in low back pain, lower extremity numbness, presence of muscular weakness, or rate of improvement in Japanese Orthopedic Association (JOA) score. All of the postoperative hematomas resolved spontaneously. The result of the study showed that some epidural hematomas cause postoperative symptoms to persist and make the short-term outcome unsatisfactory even through the long-term results are ultimately satisfactory. (author)