Hemifacial spasmで発見されたCP angle epidermoid

CP ANGLE EPIDERMOID PRESENTING AS HEMIFACIAL SPASM

　抄録　著者らは，現在まで，半側顔面痙攣（hemifacial spasm）に対して425例の後頭蓋窩神経血管減圧術を行っている。このシリーズ中，小脳橋角部のepidermoid tumorが原因であったものが1例ある。患者は，48歳，女性で，4年来の左hemifacial spasmを訴えて来院した。術前CTにてepidermoidの確定診断はつかず，microvascular decompressionを目的とした手術で初めてtumorが確認された。Epider—moid tumorは同じアプローチで全摘され，16ヵ月後の現在，神経症状を有さず，hemifacial spasmは完全に消失している。文献的検索より，hernifacial spasmの原因としてepidermoidが発見される頻度は1.2〜0.24％であり，逆に，CP angle epidermoidが存在するとき，hemifacial spasm　は10〜7.7％の頻度で出現することが推定される。

A rare case of CP angle epidermoid presenting as hemifacial spasm was reported. The patient was a 48-year-old woman with left hemifacial spasm of 4 years duration. Preoperative CT films showed some low density area in the left CP angle, how-ever, this finding was thought to be within nor-mal variation. The diagnosis of CP angle epider-moid was made at the time of craniectomy aimed for microvascular decompression. The epidermoid was extending from the lower cranial nerves up to the midbrain level and successfully removed with the same craniectomy opening. Postoperative follow up during 16 months period disclosed complete disappearance of hemifacial spasm and no other neurological deficit.

So far, the authors have experienced 425 cases of microvascular decompression for hemifacial spasm and there was only 1 case in whom a CP angle epidermoid was found (O.24%).

A review of the literature revealed that hemi-facial spasm due to CP angle epidermoid was very rare (1.2%). It was also reported that if there is CP angle epidermoid, hemifacial spasm may appear n the incidence of 7.7-10%.

A possibility of CP angle epidermoid should be kept in mind when performing microvascular decompression for hemifacial spasm particularly in yonger patients.