全身麻酔下の腹臥位での頸髄症手術後に無光覚に陥った1例

A case who became blind in one eye after surgery for cervical myelopathy under general anesthesia in the prone position

要約　目的：全身麻酔下で頸髄症の手術を受け，その直後に片眼が失明した症例の報告。症例：60歳男性に右眼視朦が突発し，院内往診を依頼された。整形外科で頸髄症の手術を受けた直後であった。手術は腹臥位による全身麻酔下で行われ，手術時間は2時間20分，麻酔時間は3時間20分であった。糖尿病の既往があり，12歳からインスリン治療が行われ，45歳で汎網膜光凝固を受けていた。所見：右眼には光覚弁がなく，眼球運動は全方向で制限されていた。右眼に結膜浮腫，眼瞼下垂，眼瞼腫脹があり，Hertelによる眼球突出度は右22mm，左16mmであった。右眼角膜に皺壁があり，眼底の色調は蒼白で桜実紅斑があった。CT検査で頭蓋内に異常所見はなく，MRIで右眼の外眼筋腫脹があった。眼窩圧上昇による網膜中心動脈閉塞症と診断した。1か月後の右眼視力は無光覚弁であった。結論：本症例は，全身麻酔中に眼窩が圧迫されたための，網膜中心動脈閉塞症を伴う虚血性眼窩コンパーメント症候群であると推定される。

Abstract.　Purpose：To report a case who became blind in one eye immediately after surgery for cervical myelopathy under general anesthesia. Case：A 60-year-old male presented with acute blindness in the right eye after surgery for cervical myelopathy. Surgery was performed in prone position under general anesthesia. Surgery lasted for 140 minutes. General anesthesia lasted for 200 minutes. The patient had diabetes mellitus and had been receiving insulin injection since 12 years of age. He had received panretinal photocoagulation in both eyes when 45 years old. Findings：Visual acuity in the right eye was no light perception. Eye movement was restricted in all directions. The right eye showed chemosis, blepharoptosis, and eyelid swelling. After Hertel, amount of protrusion was 22 mm right and 16 mm left. The right eye showed corneal folds, pale fundus and cherry-red fovea. Computed tomography showed no abnormal intracranial findings. Magnetic resonance imaging（MRI）showed swollen extraocular muscles in the right orbit. The patient was diagnosed with central retinal artery occlusion secondary to elevated orbital pressure. Visual acuity in the right eye remained no light perception one month later. Conclusion：This case illustrates that temporarily elevated orbital pressure during general anesthesia may induce central retinal artery occlusion as manifestation of ischemic orbital compartment syndrome.