癒着性くも膜炎に続発したpresyrinx stateの1例

The Presyrinx State Due to Adhesive Arachnoiditis:A Case Report

　要旨　症例は66歳女性。1年前に左椎骨動脈，後下小脳動脈の解離性動脈瘤によるくも膜下出血の既往がある。術後半年より両下肢の筋力低下，Th6-7以下の感覚障害が出現した。術前の胸椎MRIではTh3-4レベルで脊髄が腫大，髄内はT2強調画像で高信号，T1強調画像で軽度の低信号（脳脊髄液よりは高信号）を示した。Th5以下ではくも膜囊胞による脊髄の圧排を認めた。手術ではTh3-4付近でくも膜が全周性に激しく癒着しており，癒着の剝離と癒着部の上下の髄液腔のシャントを行った。術後1ヵ月では感覚障害が改善し，歩行時のふらつきが残存。胸椎MRIで脊髄の腫大や異常信号も減少，Th5以下のくも膜囊胞も縮小した。presyrinx stateは脊髄空洞症へ進行する前の可逆的な状態であり，病態としては浮腫，静脈性の うっ血，虚血などの可能性がある。本症例は癒着性くも膜炎に続発するpresyrinx stateであったと推測され，早期の手術で脊髄空洞症への進行を防げた症例と考えられる。

　We report a 66-year-old woman with a presyrinx state due to adhesive arachnoiditis. She had a history of subarachnoid hemorrhage one year ago. She became aware of gait disturbance and abnormal sensation at the chest 6 months ago. Neurological examination revealed weakness of the both lower extremities and sensory disturbance below the T6 level. MR images of the thoracic spine revealed swelling of the thoracic cord at the T3-4 level, with an intramedullary hyperintensity on T2-weighted images（WI）and hypointensity on T1-WI. The intramedullary hypointensity on T1-WI was less than the CSF intensity. In addition, the thoracic cord lower than T5 level was compressed by an arachnoid cyst in the spinal canal. The preoperative diagnosis was the presyrinx state due to adhesive arachnoiditis. An operation for detachment of arachnoidal adhesion and restoration of CSF flow pathway was performed. After one month from the operation, neurological findings were improved. Postoperative MR images revealed improvement of swelling of the thoracic cord and intramedullary abnormal intensity. The arachnoid cyst in the spinal canal was decreased in the size. The presyrinx state is recently recognized condition before the formation of syringomyelia and that is known to resolve with proper treatment. We wish to emphasize we could prevent a progression to syringomyelia by a proper treatment for the presyrinx state.