||The term labyrinthitis encompasses a broad spectrum of pathologic changes within the labyrinth. These changes include evidence of damage and repair and they arise in response to a variety of injuries, including those caused by infectious, inflammatory, and traumatic agents. The areas of the labyrinth involved and the degree to which damage results depend on the specificity of the injuring agent as well as its route of entry.
An in utero German measles viral infection produces a labyrinthitis with a specificity for the neuroepithelial elements and a sparing of the general architecture of the inner ear. By contrast, a bacterial suppurative labyrinthitis causes a widespread and nonspecific destruction of neural epithelium, supporting soft tissues, and even endosteal bone. The clinical manifestations of labyrinthitis depend on the severity and extent of the pathologic changes. The slight vertigo that sometimes accompanies an upper respiratory viral infection probably results from a transient reactive serous labyrinthitis which resolves with no sequelae. By contrast, suppurative labyrinthitis invariably causes severe vertigo with irritative and destructive nystagmus and a permanent profound sensorineural hearing loss.
Labyrinthitis may be classified into five categories on the basis of the pathologic changes seen within the labyrinth: serous, suppurative, chronic, ossifying, and viral.