特発性脊髄ヘルニアの1例

Idiopathic Spinal Cord Herniation : Case Report

　抄録：特発性脊髄ヘルニアの1例を経験したので報告する．症例は，63歳，女性．20年前から左下肢のしびれを自覚．下肢知覚障害，下肢筋力低下の進行により1年前より歩行不能となり，膀胱直腸障害も認めるようになった．MRIでは，T4/5高位で脊髄陰影の欠損途絶とその頭尾側で腹側への偏位を認め，CTMでは，脊髄は腹側に痕跡的に認めるのみであった．椎弓切除，硬膜切開した後，左側第4胸髄神経根と第4，5胸椎高位の両側歯状靱帯を切離し脊髄腹側部を観察した．硬膜欠損部に陥入した脊髄は絞扼され可動性を認めなかった．硬膜内層を切開切除することにより，赤褐色に変色した舌状の嵌頓脊髄は背側へ移動した．術後，知覚障害，下肢筋力，膀胱直腸障害は改善した．極めて稀とされてきた本疾患であるが，MRIの普及とこの疾患の認識の広まりにより報告は100例を超えた．

　We report a case of spontaneous spinal cord herniation and review the relevant literature. A 63-year-old female had a 20-year history of Brown-Séquard syndrome. Her symptoms were mainly muscle atrophy in the left lower extremity and bilateral sensory disturbance below the level of the 7th thoracic veretbra. A magnetic resonance imaging scan of the thoracic spine revealed anterior displacement and tethering of the cord at T4-T5 and a dorsal intradural arachnoid cyst. Computerized tomography following myelography showed displacement of the spinal cord. Surgery was performed via a four-level laminectomy. The left T4 nerve root and both the left and right dentate ligaments at T4 and T5 were sectioned under a microscope. The spinal cord was gently rotated, and examination of the ventral aspect of the cord revealed a defect (10×20mm) in the inner layer of the duplicated ventral dura mater through which the spinal cord had herniated. After resection of the dura around the oval hole in both the cranial and caudal directions, the spinal cord moved dorsally, and a ventral mass-like projection of the spinal cord was observed. Operative reduction of the spinal cord improved motor strength, the sensory disturbance, and bladder function. Reports of spinal cord herniation have been increasing recently and now exceed one hundred worldwide. More cases are being reported mostly because of the development of magnetic resonance imaging and increased awareness of this entity.