Sudden hearing loss following infectious mononucleosis: possible effect of altered immunoregulation.

Sudden, permanent hearing loss developed in three young patients. In an attempt to determine a viral etiology, their humoral and cell-mediated responses to a panel of seven viruses linked to deafness and altered immunity were measured. Although a specific viral cause was not determined, a mild Epstein-Barr virus infection was documented for each patient. It had preceded their hearing loss onset by 1 to 4 months. Evidence of altered cell-mediated responses to Epstein-Barr virus antigens was found in each patient. It is proposed that, in certain susceptible individuals, a temporary cellular immunosuppression, which accompanies normal recovery from Epstein-Barr virus infection, may provide an opportunity for a viral invasion of, or a latent viral reactivation in, the inner ear. This invasion or reactivation leads to deafness.