||There are probably several different conditions that can cause a sudden sensorineural hearing loss. Two of the most likely causes are an acute viral infection of the inner ear (viral cochleitis) or an acute vascular obstruction. Serologic conversion studies have suggested that multiple viral agents may be involved, including influenza virus Group B, rubeola, herpes simplex type I, mumps, influenza Group A3, rubella, and cytomegalovirus. The incidence of viral seroconversion and sudden hearing loss are closely correlated, and this relationship suggests that viral infection is probably the major cause of sudden deafness.
The results of clinical trials with carbogen (a mixture of 5% C02 and 95% 02, which has been shown to increase the level of oxygen in the perilymph) suggest that the lesion in those cases of sudden sensorineural hearing loss that are of vascular origin is distal to the arterioles of the cochlea and most likely involves the stria vascularis.