Sudden Unilateral Hearing Loss and Vertigo in an Adolescent: Viral Labyrinthitis Versus Idiopathic Sudden Sensorineural Hearing Loss.

Labyrinthitis and idiopathic sudden sensorineural hearing loss (SSNHL) are uncommon in children and are both considered otologic emergencies, as delayed diagnosis can lead to permanent disability. We describe a 15-year-old boy with a history of focal cortical dysplasia and a single remote seizure who presented with abrupt left-sided hearing loss, tinnitus, vertigo, nausea, and headache. Neurologic examination revealed no focal deficits; however, marching Romberg testing demonstrated instability, and otoscopy revealed only a small left middle-ear effusion. Laboratory studies, including complete blood count and C-reactive protein, were unremarkable. Non-contrast computed tomography (CT) of the head showed no acute intracranial abnormality. Magnetic resonance imaging (MRI) of the brain and internal auditory canals with and without contrast demonstrated normal labyrinthine structures and stable right frontal cortical dysplasia. The working diagnosis, established by pediatric neurology and otolaryngology, was acute viral labyrinthitis or idiopathic SSNHL with vestibular involvement. The patient received high-dose systemic corticosteroids, vestibular suppressants, antiemetics, and empiric oral acyclovir. Vertigo and nausea improved substantially, but profound left-sided hearing loss persisted at discharge. Outpatient audiometry and possible intratympanic steroid therapy were planned. This case emphasizes the diagnostic overlap between labyrinthitis and SSNHL in adolescents, the limited role of routine head CT for peripheral vestibulocochlear presentations, and the importance of early guideline-directed corticosteroid therapy. It also illustrates that MRI may be normal in clinically significant labyrinthitis and that careful follow-up is required to determine the need for salvage intratympanic steroid treatment.