ABSTRACT
Sudden sensorineural hearing loss (SSNHL) is an otological emergency for which a definitive aetiology and treatment remains controversial, but prompt recognition and management have been shown to improve hearing outcomes and quality of life. Several factors have been postulated as central to the aetiology of idiopathic sudden sensorineural hearing loss (ISSNHL). Possible causes include labyrinthine viral infection, vascular insult, intracochlear membrane rupture and autoimmune inner-ear disease. Animal studies experimentally inducing a vascular cause of hearing loss have resulted in cochlear fibrosis and inner ear ossification, which has not been seen in the temporal bone studies of SSNHL patients. Changes in blood viscosity could lead to cochlear ischaemia and hearing loss. However, patients with ISSNHL are no more likely than the general population to have a hyperviscosity disorder. Although heat shock protein (hsp)70 antibodies are elevated in autoimmune sensorineural hearing loss (SNHL), they are not thought to be the underlying cause of hearing loss.
