植物状態3症例の他覚的検索—聴覚・視覚誘発反応を中心に

THE OBJECTIVE EVALUATION OF THREE VEGETABLE CASES

I．はじめに

　近年「脳死の判定」と関連して，失外套症候群や無動性無言なもの，いわゆる「植物状態の本態」について医学的見地から取りあげられることが多くなつた。われわれは「植物状態」という病態について，聴性誘発反応を組み合せることで他覚的に把握することを目的とし，主に聴性脳幹反応によつて脳幹の機能を検索し，さらに中間潜時反応，頭頂部緩反応，視覚誘発反応を記録し，比較検討を行つてみた。さらに神経学的所見，神経耳科学的所見脳波所見を加えることで状態像の把握を試みた。これらの検査方法の中では聴性脳幹反応と神経学的所見の相関を特に重視した。この反応はJewett^5），Sohmer^12）らによつて発見された聴性誘発反応の早期成分で脳幹の聴神経路に由来し^2），睡眠や意識障害，通常の麻酔ではほとんど影響されないが^7），脳幹疾患では各波の成分の消失や潜時の延長などの異常が生じる^6,13）。したがって，他の，起源の異る誘発反応と併用すれば，末梢から大脳に至る聴神経路の機能部位診断の可能性がある。

The objective evaluation of three vegetative cases was undertaken by auditory and visual evoked potentials.

Case I was a seven-year-old boy who manifested apallic syndrome one year after bleeding of the left frontal lobe caused by Hennoch's purpura. Case 2 was a 27-year old woman with apallic syndrome due to Creutzfeldt-Jakob disease. Case 3 was a 67-year-old man who showed akinetic mutism after subarachnoidal bleeding caused by rupture of an aneurysm. For the purpose of the objective evaluation of these cases, recordings of auditory brain-stem response (BSR), middle latency com-ponent (MLC), slow vertex potential (AER) visual evoked response (VER) were undertaken. The results were as follows : BSR wave form was normal in all three cases; MLC showed a myogenic res-ponse in Case 1, normal wave form in Case 2 and no response in Case 3 ; AER was absent in all three cases, while VER was normal in Case 1 and 2 but absent in Case 3.

These results were correlated with neurological as well as neurotological findings of the three cases. BSR, accordingly when taken together with recor-dings of other evoked potentials, is considered to be useful for evaluation of pathology and prognosis of a vegetative state.