Concept: Also known as epidemic vertigo, vestibular labyrinthitis. Etiology: Atrophy of all or part of the vestibular nerve and the scaipa ganglion. Degeneration. Or lesions of the labyrinth itself. Some believe it is a viral infection. Some people think it is caused by ischemic disorder of small vestibular arteries. Clinical manifestations: spring and early summer, with a history of episodic illness. 30–40 years of age. Single episode type: sudden intense rotational vertigo attacks and ataxia or balance disorders, nausea and vomiting, and horizontal rotational nystagmus with a fast phase to the healthy side. Optokinetic nystagmus presents with a dominant bias toward the healthy side, without auditory or central pathology. Days or weeks, usually resolving after a few days, with complete resolution for 6 months. Multiple-episode type: recurrent episodes of rotational vertigo attacks and ataxia or balance disorders and a feeling of unsteadiness. Neurologic dysfunction or partial atrophy of the vestibular nerve results. Diagnosis: sudden and intense rotational vertigo attacks, nystagmus fast phasing to the healthy side, marked vestibular hypoplasia on hot and cold vestibular test. No cochlear symptoms. No other neurologic abnormalities. Increased cerebrospinal fluid protein levels. Treatment: Early rest. Avoid light and sound stimulation. Anti-vertigo medication.