馬尾ヘルニアを伴った仙骨囊腫の1例

Sacral Perineural Cyst with Cauda Equina Herniation. Case Report

　硬膜管終端近傍から仙骨囊腫内にくも膜・馬尾ヘルニアを生じていた1例を報告する．症例は44歳の女性で，症状は坐位にて増悪する会陰部～両大腿後面のしびれと排尿障害であった．MRIにてS2椎体レベルに囊腫像を認め，発症3カ月で手術を施行した．囊腫は左S3神経根膨大部を中心とした傍神経根囊腫であったが，囊腫近位部で硬膜管よりくも膜ヘルニアが囊腫内に形成され，同じS3馬尾が嵌頓していた．囊腫を部分切除・縫縮するとともに，嵌頓した馬尾はくも膜下腔に環納して硬膜を縫縮・パッチした．術後4カ月現在，MRIで再発を認めず，両大腿しびれは5割程度軽減し排尿障害は消失した．以前より存在した囊腫内に馬尾の嵌頓を併発したことが発症の一因となった可能性が推察された．

　We report a case of cauda equina herniation within a sacral perineural cyst. A 44-year-old woman experienced a bilateral sensory disturbance of the buttocks, perineal area, and lower extremities, and later developed a bladder disturbance. Magnetic resonance imaging demonstrated a sacral perineural cyst at the S2 level, and surgery was performed three months after the onset of symptoms. Intraoperatively we observed a sacral perineural cyst adjacent to the spinal ganglion of the S3 root associated with an arachnoid herniation containing the cauda equina at the same S3 level near the end of the dural sac. The cyst was incised and imbricated, and magnetic resonance imaging four months postoperatively demonstrated no recurrence of the cyst. The sensory disturbance had decreased to half its preoperative severity, and the bladder disturbance had resolved. We speculate that the occurrence of the cauda equina herniation within the existing sacral perineural cyst was one of the factors in the onset of symptoms.