頭部外傷による両側脳幹性感音難聴と発声失行をきたした症例

Sensorineural Hearing Loss Caused by Brain Stem Lesion Willi Apraxia of Phonation

I．はじめに

　比較的広範囲な脳幹部の病変は，生命予後が不良であったり，あるいは意識障害を伴うことが多い。外傷によるものでも急性期の神経学的検討資料が多い割には，慢性化し，しかも意識障害が伴わない例についての機能検査成績についての報告がほとんど見あたらない。聴覚や発声の機能は脳幹部の病変の影響を受けることが多い。

　そこで筆者らは，交通事故による頭部外傷が原因で，中脳から橋にわたる脳幹背側部に障害が生じた症例について，聴覚機能，平衡機能，音声言語機能を中心とした神経学的検査を系統的に行うことができ，興味ある結果が得られたので報告した。

　A 19-year-old female resuscitated after 47 days' unconsciousness by blunt head injury was studied on the audiological, equilibrium and phonatory functions.

　The average hearing levels were 65 dB in the right and 76 dB in the left ear, however, in speech audiometry, any word was unable to discriminate at 90 dB in both ears. The stapedial reflex showed normal with no reflex decay phenomena. In auditory brain stem responses, wave I to III appeared clearly to the 90 dBnHL click sound, though wave IV was faint and no wave V was confirmed. The minimal threshold of wave III was 40 dBnHL. Saccadic eye movements were observed in electronystagmography and optokinetic nystagmus was impaired, however, the caloric tests were normal. After the resuscitation, apraxia of phonation had been present for five months, but was disappeared. CT scan revealed two low density lesions, one was in the left cerebellum and the other was in the dorsal half of the brain stem with widening of the anterior cerebral sulci and ventricular enlargement.