Deafness following mumps: the possible pathogenesis and incidence of deafness.

Mumps is thought to be the most common cause of unilateral acquired sensorineural deafness in children. Mumps deafness is usually sudden in onset, profound or complete, and may be associated with vestibular symptoms. The authors' clinical survey of 55 patients with unilateral deafness which could reasonably be ascribed to mumps indicates that the hearing loss is exclusively unilateral, severe or total and permanent, and that approximately 45% of the patients experienced dysequilibrium of vestibular origin. An analysis of the present series of mumps deafness also suggests that the primary route of invasion of the virus is hematogenous, and thus the term "viral endolymphatic labyrinthitis" is proposed as the possible pathogenesis of the deafness, since both tympanogenic and meningogenic routes of viral invasion to the labyrinth can be excluded on the basis of the clinical and cerebrospinal fluid studies. This view of the pathogenesis, particularly that mumps meningitis is not associated with deafness, is supported by several reports including those of Vuori et al. (1962), Azimi et al., (1969), Lindsay (1973), Nadol (1978), etc. The incidence of deafness following mumps appears to be extremely low, approximately 1:20,000, as estimated by Everberg (1957).