[Acute inner ear deafness]

Sudden inner ear hearing loss initially might suggest a psychogenic disorder of hearing, particularly when it is bilateral and simultaneous. The differential diagnosis includes disseminated encephalitis, syphilitic labyrinthitis and Cogan's syndrome. The history and cause of acute bilateral deafness in meningitis are easy to recognise. Furthermore, unilateral acute inner ear deafness should not be regarded as idiopathic without further consideration. A acoustic neuroma is a possible cause even of a low-tone hearing loss. More controversial is rupture of the round window membrane as a cause of sudden deafness. The deafness after epidemic parotitis obviously leads to a total unilateral hearing loss in every case. Even labyrinthine apoplexy with loss of hearing and vestibular function can be caused by a tumour of the cerebellopontine angle. Idiopathic sudden deafness should be defined as an acute sensory hearing loss whose anatomical basis in an acute vascular endolymphatic hydrops of unknown cause. The sudden deafness affects only one ear; tinnitus and brief vertigo can be accompanying symptoms. A sudden hearing disorder due to other causes should be distinguished from idiopathic lesions.