片側性難聴を呈した脳幹・小脳梗塞の1例

Unilateral Sudden Deafness as a Primary Symptom of Brainstem and Cerebellar Infarction

　症例は74歳男性。飲酒後に浮動性めまいと右難聴が突然出現し耳鼻咽喉科を受診した。突発性難聴が疑われステロイドが投与されたが，その後めまい症状と難聴が増悪し，右顔面のしびれ感と口角下垂，複視も出現したため，頭蓋内病変を疑われて当科を紹介された。来院時には左注視方向性眼振・右顔面知覚障害・右外転神経麻痺・右末梢性顔面神経麻痺・右感音性難聴および小脳失調が確認された。頭部MRIでは右中小脳脚を中心に小脳片葉を含む散在性の虚血巣が確認され，前下小脳動脈領域の血栓症と診断された。突発的に片側性難聴をきたす症例の場合には，一般に内耳性疾患が疑われる。しかし類似した症状は脳血管障害でも生じることがあり，臨床的に突発性難聴が疑われた症例でも，脳血管障害の危険因子を有する場合には，前下小脳動脈症候群を念頭においた注意深い神経症状の観察と早期の画像診断が重要と考えられた。

　We report a case with a unilateral sudden sensorineural hearing loss caused by an infarction of brainstem and cerebellum. The patient was a 74-year-old male presented with a sudden onset of hearing loss and tinnitus in the right ear and dizziness. Steroid was administered on suspicion of idiopathic sudden deafness. However, the initial symptoms were deteriorated approximately 2 weeks later. He newly complained of the numbness of the right face and double vision, and he was transferred to our hospital for further evaluation. Neurological examination demonstrated horizontal nystagmus, diminution in the right facial sensation, right peripheral facial palsy, right hearing loss and cerebellar ataxia. Urgent MRI disclosed fresh infarctions of the right middle cerebellar peduncle and cerebellum localized in the territory of anterior inferior cerebellar artery. In general, idiopathic sudden deafness and Meniers's disease are frequent diagnosis in cases of sudden hearing loss with vertigo, but these symptoms may rarely be caused by cerebrovascular disorder. In patients with risk factors for arteriosclerosis, cerebrovascular disorder should be taken into consideration even if idiopathic sudden deafness may be suspected clinically. We emphasize the diagnostic importance of careful observation on neurological findings and early detection of radiological abnormalities on MRI.