術後著しい聴力改善を認めた小脳橋角部髄膜腫症例

Hearing Improvement after Conservative Approach for Large C-P Angle Meningioma

I．はじめに

　小脳橋角部腫瘍は難聴をきたすことが多く，手術により蝸牛神経機能を温存することも容易ではない。今回，術前に失聴した髄膜腫症例に対し腫瘍摘出術を施行したところ，術後に聴力が改善し正常聴力となった症例を経験したので報告する。

　A 42-year-old woman with dramatic recovery of hearing after the removal of a 5.5cm C-P angle meningioma was presented. She had a six-years'history of hearing loss in her right ear,which was later accompanied by dizziness and headache. Her pure tone average（PTA）in October 1999 revealed scale out. She also had Bruns nystagmus and no caloric response with 0℃ice water in her right ear. Most of the tumor was surgically removed during two operations. One week after the second operation,her PTA was 38.8dB and her speech discrimination score（SDS）was 30％. Bruns nystagmus was disappeared but there was still no caloric response. Four months later,her PTA and SDS improved to 23.8dB and 90％respectively. Eight months later,her caloric response improved to a level of moderate CP. Hearing improvement after the removal of the tumor indicates hearing loss in this case could be caused by the cochlear nerve conduction block.