Immune-mediated disorders associated with idiopathic sudden sensorineural hearing loss

Different immune disorders are involved in the development of sudden sensorineural hearing loss (SSNHL). This includes a wide spectrum of immune-mediated disorders such as immune complexes, production of autoantibodies to the inner ear proteins, production of anticardiolipin (aCL) antibodies, and cellular immune defects. Some studies have also found an elevation of total IgE levels and a type 1 immune reaction. Our objective was to establish the association of "idiopathic" SSNHL (ISSNHL) with various autoantibodies, and to analyze the persistence over time of existing aCL and anti-beta2 glycoprotein 1 (anti-beta2 GP1) antibodies in such patients. Finally, we sought to establish a possible association between ISSNHL and total IgE elevation and whether this elevation is due to a specific type I immune reaction. In this prospective follow-up study, 51 patients considered as having ISSNHL were compared with 35 age-sex matched healthy volunteers over a 3-year period. All participants were tested for serum antinuclear antibodies, antithyroid antibodies, aCL, and rheumatoid factor. All patients who were positive for aCL antibodies were reanalyzed 3 months later for aCL antibody persistence and for the coexistence and persistence of anti-beta2 GP1 antibodies. Skin prick tests were performed in patients in whom total IgE was elevated. Antinuclear antibodies were positive in 9 of 51 (17%) and antithyroid antibodies in 11 of 51 (21%) ISSNHL patients, as compared to 1 of 35 (3%) and 2 of 35 (6%), respectively, in the control group. Rheumatoid factor was positive in 6 of the 51 patients (12%) and in none of the control group. Positive aCL antibodies were present in 16 of 51 patients (31%), 6 of whom (12%) were also positive for anti-beta2 GP1 antibodies. Three months later, aCL antibodies persisted in 7 patients (14%), and anti-beta2 GP1 in 4 patients. Only 2 of the normal subjects (6%) were positive for aCL antibodies, which persisted in only 1 of them (3%). The level of total IgE was elevated in 14 of 51 patients (27%), in contrast to 3 of 35 controls (8%). Six of them (42%) demonstrated a positive skin test to at least 1 allergen, but only 3 presented allergy symptoms. Our findings support the reported existence of multiple immune-mediated disorders in patients with ISSNHL. The lack of aCL antibody persistence in as many as half of our patients strongly suggests that transient phenomena (eg, viral infection) may trigger aCL antibody activity. However, the presence of aCL antibodies, especially in conjunction with anti-beta2 GP1 antibodies, suggests that in some patients, SSNHL is included among the rare symptoms of the antiphospholipid syndrome.