治療に難渋したガンマナイフ照射後聴神経鞘腫の1例

Surgery for Acoustic Neurinoma Treated by Gamma-knife Radiosurgery : A Case Report

I．はじめに

　聴神経腫瘍に対してガンマナイフ治療が広く行われるようになった．一般にその適応は腫瘍径が3cm程度までとされている^9）．今回われわれは，腫瘍径3.2cmの聴神経鞘腫へのガンマナイフ治療後1年4カ月の経過で腫瘍径の軽度増大および水頭症を来し，治療に難渋した1例を経験したので報告する．

A 52-year-old woman had a history of left hearing loss for 5 years. An acoustic neurinoma with 3.2 cm in diameter was diagnosed and treated with gamma-knife radiosurgery (19 Gy of marginal dose) 1 year and 4 months ago. She developed headache, nausea, and visual disturbance 1 month prior to admission. Slight left facial palsy appeared after radiosurgery. Magnetic resonance imaging demonstrated the tumor with central necrosis in the left cerebellopontine angle cistern, increasing in size to 3.5 cm in diameter, and hydrocephalus. Tumor removal was performed incompletely, because of the fibrous appearance of the tumor and severe adherence with the surrounding cerebellar tissue. Facial palsy did not worsen after surgery. Since the hydrocephalus was not resolved, a right ventriculo-peritoneal shunt was inserted. The clinical course in this case suggests that tumor removal followed by radiosurgery was an approximately effective treatment for large acoustic neurinoma.