Labyrinthitis is a term denoting inflammation and infection of the labyrinth, the constitutive anatomical part of the inner ear. Viral pathogens are rarely the underlying cause, as labyrinthitis is primarily associated as a complication of bacterial acute otitis media or meningitis. Principal symptoms include vertigo, dizziness and hearing loss, as both parts of the vestibulocochlear nerve are affected. The diagnosis rests on clinical criteria and several diagnostic procedures.
An infection of the labyrinth and both the vestibular and cochlear nerves by viral pathogens is termed viral labyrinthitis, a term rarely used in the literature because of its poorly understood etiology and pathogenesis   . It is distinguished from vestibular neuronitis, in which only the vestibular portion of the vestibulocochlear nerve is affected, thus a different clinical presentation is observed in the two syndromes   . So far, several viruses that have been identified as possible agents of labyrinthitis - herpes simplex virus (HSV) type 1, cytomegalovirus (CMV), adenovirus, strains of influenza A and B, as well as Epstein-Barr virus (EBV)  . In addition, measles, mumps, and rubella viruses have also been implicated in the pathogenesis of viral labyrinthitis . The main clinical features are vertigo and sensorineural hearing loss, developing as a consequence of cochlear and vestibular nerve damage, respectively   . Both symptoms appear in an abrupt fashion and are more frequently unilateral, while tinnitus is present in a number of patients   . Unlike bacterial infections of the inner ear, which are more common in the pediatric population, viral labyrinthitis is primarily encountered in adults between 30-70 years of life .
The diagnosis of labyrinthitis may not be easy to make without adequate clinical suspicion, which can only be created by a thorough physical examination and a detailed patient history. The simultaneous presence of vertigo and hearing loss should prompt the physician to perform a complete neurological examination and confirm lesions of both segments of the vestibulocochlear nerve. Furthermore, several tests are recommended to support the diagnosis  :