Cochlear hearing loss and viral infection.

A group of about 100 consecutive patients admitted to an otorhinolaryngological outpatient department for treatment of cranial nerve affections underwent detailed neurological, audiological and laboratory examinations. Of 34 patients with hearing loss, objective signs of viral infection were found in 12. The hearing loss was sensorineural of the cochlear type, in 7 cases of the high-frequency type, in 5 cases of the low-frequency (Menière) type. Within one year after the onset of the disease the hearing loss had disappeared in all but 2 cases. Reversible dysfunction of two or more cranial nerves was found in 7 of 8 cases examined. In the cerebrospinal fluid the cell count and the total protein and gamma-globulin values were increased in most patients. Our findings indicate a reversible sensorineural hearing loss to be part of a viral-induced meningoencephalitis and cranial polyneuropathy. The mechanism of the reversible low- and high-frequency hearing loss is discussed.