Viral Etiology of Sudden Sensorineural Hearing Loss: Historical Development and Current Evidence

Sudden sensorineural hearing loss (SSNHL) is an otological emergency with complex and heterogeneous etiologies, and most cases remain unexplained and are therefore classified as idiopathic. Viral infection has long been considered an important potential cause of SSNHL; however, the mechanisms underlying virus-associated hearing loss and the causal relationship between viral infection and SSNHL have not been fully elucidated. Current evidence suggests that viruses may induce acute hearing loss through direct invasion of the inner ear, reactivation of latent viruses, immune-mediated injury, and cellular stress and inflammatory responses. This review describes the major viruses associated with SSNHL and their epidemiological and clinical characteristics; summarizes evidence from serological testing, molecular virology, imaging, temporal bone histopathology, and animal studies; and discusses recent advances in the pathogenic mechanisms, etiological diagnosis, and antiviral treatment of virus-associated SSNHL. This review aims to systematically clarify the current evidence and controversies surrounding the viral etiology of SSNHL and to provide a reference for etiological identification, patient stratification, and targeted treatment of virus-associated SSNHL.