[Hearing disturbances in multiple sclerosis (author's transl)].

Dizziness and provoked or even spontaneous nystagmus are common findings in multiple sclerosis. Disturbances of hearing are thought to be rare, and there are few case reports in the literature. The importance of characterizing the audiometric abnormalities of disseminated encephalomyelitic disease of uncertain neurological aetiology is stressed. They may be defined as follows: 1. The pure tone threshold level may be normal or may be seen as a flat loss. 2. Pulse tones are better heard that continuous tones (Bekesy, tone decay tests). 3. Recruitment or its equivalents demonstrate hearing impairment at neural or neuronal levels. 4. The acoustico-facial reflex (impedance audiometry) cannot be elicited or is obviously reduced on the affected side. 5. Intelligibility of numbers in speech audiometry is not altered or may be better than that expected on the pure tone threshold findings. The intelligibility of monosyllabic words is obviously bad. 6 Dichotic discrimination of speech may be completely absent on one side even though the pure tone threshold is near normal. Multiple sclerosis primarly involves the central nerve fibres. The presence of remissions distinguishes the disease from vascular lesions and from acoustic neuromas. An audiological approach offers a new application of otology in neurological practice.