上眼窩神経鞘腫の1例

Intraorbital Schwannoma Arising from the Supraorbital Nerve

Ⅰ．はじめに

　眼窩内神経鞘腫は眼窩内腫瘍の約1～4％を占める比較的稀な腫瘍である^{3,10,14,15,17)}．上眼窩神経より発生した症例の報告は，われわれが渉猟し得た限りではこれまで10例を認めるのみであり，神経線維腫症を合併しない症例についての報告は2例を認めるのみで，極めて稀である^1,7)．今回われわれは，神経線維腫症を伴わない上眼窩神経鞘腫の1例を経験したので報告する．

　A 67-year-old man presented a three-month history of double vision and slight numbness at his right forehead. Neurological examination on admission demonstrated diplopia at lower gaze and mild hypesthesia at right frontal. MRI disclosed an extraconal cystic mass,centered over the superior rectus muscle,in the superior part of the right orbit. 3D-CT scan in bone window image showed an erosion of the right orbital roof. An operation was performed by a transcranial extradural anterior orbitotomy. It was noticed that the supraorbital nerve entered the cyst wall of the tumor. The mass was dissected from the surrounding intraorbital fat and was removed completely. Pathologically,diagnosis of schwannoma was made. Postoperatively,the diplopia diminished,although numbness at the right forehead remained. Orbital schwannomas constitute 1 to 4% of all orbital tumours. Identification of the nerve of origin of the tumours is difficult. Including this present case,only 11 cases of supraorbital nerve schwannoma,and only three cases of the tumour without neurofibromatosis,have been reported.