MRIによる腰椎術後硬膜外血腫の評価

MRI Evaluation of Postoperative Epidural Hematoma after Lumbar Spine Surgery

　抄録：腰椎術後に下肢痛やしびれなどが遺残したり，新たに発生することは稀ではない．これらが術後硬膜外血腫により引き起こされている可能性について検討するため，術後MRIを撮影した66症例で血腫の有無により術後症状に差があるか否か，後向き研究を行った．MRI上，血腫を認めた症例（以下，陽性群）は30例，血腫を認めない症例（以下，陰性群）は36例であった．これら2つの群の間で殿部痛の割合は陽性群40.0％，陰性群16.7％と有意差を認め（P＝0.034），下肢痛の割合も陽性群40.0％，陰性群16.7％と有意差を認めた（P＝0.034）．腰痛，下肢しびれ，MRI撮影時および退院時における術前と比較した筋力低下の有無，および退院時のJOAスコアの改善率においては有意差を認めなかった．術後硬膜外血腫は強い痛みや筋力の低下を来して血腫除去術を必要とする以外に自然消失する血腫があり，殿部痛や下肢痛の遺残など術後早期の経過を不良にしていることが考えられる．

　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 postoperative 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 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.