Sudden sensorineural hearing loss (SSNHL) can have varying causes and etiologies and is considered a syndrome rather than a diagnosis. It is estimated that a cause is identified in only 10 % of patients diagnosed with the syndrome. Historically, there have been several proposed mechanisms for idiopathic SSNHL and today there are still questions and considerable debate regarding its etiology. Among the varied proposed mechanisms are immune-mediated disease, viral infection, vascular abnormalities, or a combination of multiple factors. This chapter reviews the current state of the science regarding idiopathic SSNHL, diagnosis, comorbidity, current therapeutic interventions, and emerging opportunities for disease management and treatment that are based on evidence-based practice. These include steroid treatment, hyperbaric oxygen therapy, drug therapy for viruses, intervention for vascular or ischemic etiology, salvage therapy, and posttherapy rehabilitation in cases of permanent hearing loss as well as the inherent challenges of providing intervention with varied evidence of efficacy.