硬膜外脊髄くも膜嚢腫の3例

Extradural Spinal Arachnoid Cysts. Report of Three Cases

　硬膜外くも膜嚢腫は他覚的，神経学的異常所見に乏しく，慢性腰痛症候群として漫然と治療されることが多い稀な疾患である．今回，手術を行った3例を報告した．症例1：24歳，男性．主訴は腰痛と腰部灼熱感．MRIではTh11～L2に硬膜外嚢腫様病変があった．Th12，L1椎弓形成的片側椎弓切除により嚢腫を摘出し，交通孔を閉鎖した．症例2：66歳，男性．主訴は1年前よりの腰痛と両大腿部痛．MRIではTh11～L2に硬膜外嚢腫様病変があり，CTミエログラムでは骨侵食を認めた．Th11～L2片側椎弓切除し，嚢腫を切除した．Th12神経根尾側に交通孔を確認し，閉鎖した．症例3：65歳，男性．主訴は10年来の両鼡径部以遠のしびれ，灼熱感．MRIでは，Th11～12レベルに硬膜外嚢腫様病変があり，ミエログラムでは嚢腫も造影された．Th10～12の部分椎弓切除で嚢腫を切除した．交通孔は確認できなかった．いずれの症例でも術後，症状は消失した．

　We report three cases of symptomatic extradural arachnoid cyst that involved the thracolumbar junction. The chief compliments varied and included low back pain and numbness or pain in the legs in the absence of obvious neurological deficits. Typical MR findings were observed in all three patients. MR images were helpful in making an early diagnosis and planning the surgical procedure. The lesions appeared as hypointense on the T1 images and hyperintense on the T2 images, and the myelography was useful for detecting the location of the communications between subarachnoid space and the cyst. Hemilaminectomy and hemilaminoplasty were performed, the extradural arachnoid cysts were resected, and the communications were closed. The patients have been symptom-free for 2 to 5 years postoperatively. The keys to less invasive surgery are closure of the communicating pathway and reduction of the cyst volume by aspiration.