三叉神経第2枝より生じた頭蓋内神経鞘腫の1例

A Case of Intracranial Neurinoma Arising from the Maxillary Branch of the Trigeminal Nerve

Ⅰ．はじめに

　三叉神経鞘腫は全頭蓋内神経鞘腫の0.8～8％を占める比較的稀な腫瘍である^9,11,13)．その好発部位は，三叉神経根やgasserian ganglionであり，それぞれ後頭蓋窩や中頭蓋窩を中心に増大する．一方，さらに末梢部の三叉神経枝より生じた神経鞘腫の症例も散見されるが^1,2,4,9-12)，このような三叉神経枝神経鞘腫の臨床像については不明な点が多い．今回われわれは，三叉神経第2枝より生じた稀な頭蓋内神経鞘腫を経験したので，その臨床症状，画像所見，および治療について既存の報告例と比較検討し，若干の考察を加えて報告する．

The intracranial portion of the trigeminal branches is rarely involved in neurinomas. The clinical characteristics including symptoms,neuroradiological findings and results of surgical excision of the previously reported 11 neurinomas and the present case arising from the intracranial trigeminal branches are reviewed.

　A 59-year-old female patient complained of paresthesia and hypesthesia in the infraorbital region with no other neurological abnormalities. Neuroradiological examinations revealed a round cyst-like tumor located at the middle fossa with enlargement of the foramen rotundum and pterygopalatine fossa. No vascular abnormalities were found by angiography. At surgery,the solid tumor with no cystic component arising from the intracranial maxillary nerve was removed totally via a frontotemporal extradural and interdural approach with zygomatic osteotomy. Histopathology revealed a typical neurinoma. The paresthesia disappeared following surgery.

　Clinical features of neurinomas arising from the trigeminal branches are varied but distinct depending upon the site of origin of the tumors. These tumors can be removed totally in most cases through the extradural and interdural approach without critical morbidity. Special care should be taken not to cause injuries to the surrounding neurovascular structures such as cranial nerves and internal carotid artery. A small amount of residue is acceptable in cases of tumors with tenacious adhesion to these critical structures.