眼窩尖端症候群を呈した眼窩内神経鞘腫

Orbital neurinoma presenting orbital apex syndrome

I．はじめに

　眼窩内に出現する腫瘍として，偽腫瘍，涙腺混合腫瘍，血管腫，皮様嚢腫，リンパ腫などが多いとされている．神経鞘腫は比較的少なく^2,6），大きなシリーズによると眼窩内腫瘍のうちの2.1-6.8％を占めるに過ぎないとされている^3,11,12）．

　一方，眼窩尖端症候群は一側の動眼，滑車，外転ならび三叉神経第1枝の症状に視神経障害を伴うものであり，進行性の黒内障と視神経萎縮をきたす^9）．今回われわれは右眼窩尖端症候群を有した症例において，CT scanで眼窩尖端部にmassを認め，手術により神経鞘腫が発見され，術後より症状の著しい改善を認めた1例を経験したので報告する．

A 75-year-old man presented a twelve-day history of double vision and retro-ocular pain with rapid de-terioration of visual acuity. Neurological examination on admission demonstrated right oculomotor palsy and abducence palsy, visual loss in the right eye, and hypesthesia and pain in the right supraorbital nerve.CT scan and MRI disclosed a mass in the right orbital apex.

An emergency operation via a frontotemporal ex-tradural approach was performed to decompress the op-tic nerve. The anterior clinoid process and minor wing of the sphenoid were drilled to expose the optic canal and superior orbital fissure. When the periorbita just beside the optic sheath was opended, a grayish colored mass was observed beneath the superior rectus muscle. The mass was dissected from the surrounding intraor-bital tissue and was removed completely. The postop-erative course was uneventful. The patient experienced complete disappearance of the ocular pain and complete restoration of his visual acuity.

Orbital neurinoma is a benign tumor accounting for between 2.1 and 6.8% of all orbital tumors in the large series. The salient clinical symptom is exophthalmos followed by mass palpability. However, an orbital neurinoma presenting orbital apex syndrome is quite rare. In the case with orbital apex syndrome, it is some-times impossible to recover visual acuity even though the optic nerve decompression is promptly performed.In such a case, only an emergency approach to the le-sion can rescue the visual acuity.