Vestibular neuronitis is a type of unilateral and temporarily vestibular dysfunction, which is believed to be secondary to an inner ear infection caused by virus, or a viral infection of the vestibular nerve, which travels from the inner ear to the brainstem. The inner ear is made up of two parts: the semicircular canals, which control our sense of equilibrium, and the cochlea, which is the auditory portion of the inner ear. In vestibular neuronitis, involvement of the semicircular canals causes spinning dizziness, nausea, and sometimes vomiting; involvement of the cochlea produces hearing loss, ear ringing, or ear fullness.
It is not known which virus in particular causes vestibular neuronitis. It is believed that different types of viruses may be capable of infecting the vestibular nerve. Some patients will report having an upper respiratory infection or a flu prior to the onset of the symptoms of vestibular neuronitis, others will have no viral symptoms prior to the vertigo attack. The main symptom of vestibular neuronitis is vertigo, which appears suddenly, often with nausea and vomiting. Vertigo usually lasts for several days or weeks. In rare cases it can take months to go away entirely. Vestibular neuronitis does not lead to a permanent loss of hearing.