急性高度難聴の側頭骨病理

Histopathology in Acute Deafness

緒言

　急激に高度の感音難聴を生じる病因として，ウイルス感染，聴器毒，内耳出血，側頭骨骨折，内耳窓破裂などがあるが，ほかに原因のまったく不明な突発性難聴がある。これら急性高度難聴については，臨床的な研究は進んでいるが，その病理所見はヒトにおいてはなお充分に検討されているわけではない。

　今回，原因の明らかな，急激に高度難聴を起こす疾患として，腫瘍転移，内耳出血，カナマイ難聴と，原因不明の突発性難聴の内耳病理を検索し，急性高度難聴の機序にこつき考案した。対象は，急激に高度感音難聴を起こした8例，14耳（内耳への腫瘍転移1例2耳，内耳出血1例2耳，カナマイ難聴1例2耳，突発性難聴5例8耳）である。このうちの4例についてはすでに報告してあるが^1,2），これらをまとめた。また，聴力にこついては聴力損失を聴力レベルに換算した。

Histopathological studies were performed on 14 temporal bones from 8 patients who suffered from deafness of acute onset.

In 3 cases, histopathological studies revealed metastatic lung cancer, inner ear hemorrhage and hair cell degeneration by kanamycin, while 5 cases were diagnosed as sudden deafness of which the etiology were not clarified.

In 2 cases of sudden deafness (3 ears), the hearing impairment was completely recovered by treatment. There were no remarkable pathological findings in the inner ears of the patients. The histopathological findings in 4 temporal bones from 2 bilateral irreversible sudden deafness showed atrophy of organ of Corti, missing hair cells, rol-led-up tectorial membrane and atropy of the stria vascularis. These pathological changes were more likely to be due to viral infection than those to following vascular lesion. A temporal bone in the irreversible sudden deafness showed complete loss of the cochlear nerves and spiral ganglions, but some part of organ of Corti were relatively well-preserved, suggesting neuritis of the cochlear nerve.

The causes of sudden deafness were considered as viral infections, vasculr disorders, window rup-ture etc, but the present study of the temporal bones suggested the possibility of viral infection, especially in the irreversible case of sudden deafness.