PO BOX 13305 · PORTLAND, OR 97213 · FAX: (503) 229-8064 · (800) 837-8428 · [email protected] · WWW.VESTIBULAR.ORG Vestibular Neuritis and Labyrinthitis Infections of the Inner Ear By Charlotte L. Shupert, PhD with contributions from Bridget Kulick, PT and the Vestibular Disorders Association Vestibular neuritis and labyrinthitis are Infections of the inner ear are usually disorders resulting from an infection that viral; less commonly, the cause is inflames the inner ear or the nerves bacterial. Such inner ear infections are connecting the inner ear to the brain. This not the same as middle ear infections, inflammation disrupts the transmission of which are the type of bacterial infections sensory information from the ear to the common in childhood affecting the area brain. Vertigo, dizziness, and difficulties around the eardrum. with balance, vision, or hearing may result. Inner ear structure and function The inner ear consists of a system of fluid-filled tubes and sacs (see diagram © Vestibular Disorders Association ◦ www.vestibular.org ◦ Page 1 of 6 on page 2) called the labyrinth. The Labyrinthitis (inflammation of the labyrinth serves two functions: hearing labyrinth) occurs when an infection and balance. affects both branches of the vestibulo- cochlear nerve, resulting in hearing The hearing function involves the cochlea, changes as well as dizziness or vertigo. a snail-shaped tube filled with fluid and sensitive nerve endings that transmit Bacterial and viral infections sound signals to the brain. Inner ear infections that cause vestibular neuritis or labyrinthitis are usually viral The balance function involves the rather than bacterial. Although the vestibular organs. Fluid and hair cells in symptoms of bacterial and viral infections the three loop-shaped semicircular canals may be similar, the treatments are very and the sac-shaped utricle and saccule different, so proper diagnosis by a provide the brain with information about physician is essential. head movement. Signals travel from the labyrinth to the brain via the vestibulo- Bacterial: In serous labyrinthitis, cochlear nerve (the eighth cranial nerve), bacteria that have infected the middle ear which has two branches. One branch (the or the bone surrounding the inner ear cochlear nerve) transmits messages from produce toxins that invade the inner ear the hearing organ, while the other (the via the oval or round windows and vestibular nerve) transmits messages inflame the cochlea, the vestibular from the balance organs. system, or both. Serous labyrinthitis is most frequently a result of chronic, The brain integrates balance signals sent untreated middle ear infections (chronic through the vestibular nerve from the otitis media) and is characterized by right ear and the left ear. When one side subtle or mild symptoms. is infected, it sends faulty signals. The brain thus receives mismatched Less common is suppurative labyrinthitis, information, resulting in dizziness or in which bacterial organisms themselves vertigo. invade the labyrinth. The infection originates either in the middle ear or in Neuritis (inflammation of the nerve) the cerebrospinal fluid, as a result of affects the branch associated with bacterial meningitis. Bacteria can enter balance, resulting in dizziness or vertigo the inner ear through the cochlear but no change in hearing. The term aqueduct or internal auditory canal, or neuronitis (damage to the sensory through a fistula (abnormal opening) in neurons of the vestibular ganglion) is also the horizontal semicircular canal. used. Viral: Viral infections of the inner ear are more common than bacterial infections, © Vestibular Disorders Association ◦ www.vestibular.org ◦ Page 2 of 6 but less is known about them. An inner symptoms can be very frightening; many ear viral infection may be the result of a people go to the emergency room or visit systemic viral illness (one affecting the their physician on the same day. rest of the body, such as infectious mononucleosis or measles); or, the Chronic phase: After a period of gradual infection may be confined to the labyrinth recovery that may last several weeks, or the vestibulo-cochlear nerve. Usually, some people are completely free of only one ear is affected. Some of the symptoms. Others have chronic dizziness viruses that have been associated with if the virus has damaged the vestibular vestibular neuritis or labyrinthitis include nerve. herpes viruses (such as the ones that cause cold sores or chicken pox and Many people with chronic neuritis or shingles), influenza, measles, rubella, labyrinthitis have difficulty describing their mumps, polio, hepatitis, and Epstein- symptoms, and often become frustrated Barr. Other viruses may be involved that because although they may look healthy, are as yet unidentified because of they don’t feel well. Without necessarily difficulties in sampling the labyrinth understanding the reason, they may without destroying it. observe that everyday activities are fatiguing or uncomfortable, such as walking around in a store, using a Symptoms and onset of viral neuritis computer, being in a crowd, standing in or labyrinthitis the shower with their eyes closed, or Symptoms of viral neuritis can be mild or turning their head to converse with severe, ranging from subtle dizziness to a another person at the dinner table. violent spinning sensation (vertigo). They can also include nausea, vomiting, Some people find it difficult to work unsteadiness and imbalance, difficulty because of a persistent feeling of with vision, and impaired concentration. disorientation or “haziness,” as well as Sometimes the symptoms can be so difficulty with concentration and severe that they affect the ability to stand thinking. up or walk. Viral labyrinthitis may produce the same symptoms, along with Diagnosis and treatment tinnitus (ringing or noises in the ear) No specific tests exist to diagnose and/or hearing loss. vestibular neuritis or labyrinthitis. Therefore, a process of elimination is Acute phase: Onset of symptoms is often necessary to diagnose the condition. usually very sudden, with severe Because the symptoms of an inner ear dizziness developing abruptly during virus often mimic other medical problems, routine daily activities. In other cases, the a thorough examination is necessary to symptoms are present upon awakening in rule out other causes of dizziness, such as the morning. The sudden onset of such © Vestibular Disorders Association ◦ www.vestibular.org ◦ Page 3 of 6 stroke, head injury, cardiovascular further testing may be appropriate to disease, allergies, side effects of help determine whether a different prescription or nonprescription drugs vestibular disorder is in fact the correct (including alcohol, tobacco, caffeine, and diagnosis, as well as to identify the many illegal drugs), neurological disorders, specific location of the problem within the and anxiety. vestibular system. These additional tests will usually include an audiogram (hearing Treatment during the acute phase: test); and electronystagmography (ENG) When other illnesses have been ruled out or videonystagmography (VNG), which and the symptoms have been attributed may include a caloric test to measure any to vestibular neuritis or labyrinthitis, differences between the function medications are often prescribed to of the two sides. Vestibular evoked control nausea and to suppress dizziness myogenic potentials (VEMP) may also be during the acute phase. Examples include suggested to detect damage in a Benadryl (diphenhydramine), Antivert particular portion of the vestibular nerve. (meclizine), Phenergen (promethazine hydrochloride), Ativan (lorazepam), and Physicians and audiologists will review Valium (diazepam). Other medications test results to determine whether that may be prescribed are steroids (e.g., permanent damage to hearing has prednisone), an antiviral drug (e.g., occurred and whether hearing aids may Acyclovir), or antibiotics (e.g., be useful. They may also consider amoxicillin) if a middle ear infection is treatment for tinnitus if it is present. present. If nausea has been severe enough to cause excessive dehydration, If symptoms of dizziness or imbalance intravenous fluids may be given. are chronic and persist for several months, vestibular rehabilitation If treated promptly, many inner ear exercises (a form of physical therapy) infections cause no permanent damage. may be suggested in order to evaluate In some cases, however, permanent loss and retrain the brain’s ability to adjust to of hearing can result, ranging from barely the vestibular imbalance. Usually, the detectable to total. Permanent damage to brain can adapt to the altered signals the vestibular system can also occur. resulting from labyrinthitis or neuritis in a In addition, endolymphatic hydrops process known as compensation. (abnormal fluctuations in the inner ear Vestibular rehabilitation exercises fluid called endolymph) can develop facilitate this compensation. several years after either serous or suppurative labyrinthitis. In order to develop effective retraining exercises, a physical therapist will assess how well the legs are sensing balance Testing and treatment during the (that is, providing proprioceptive chronic phase: If symptoms persist, © Vestibular Disorders Association ◦ www.vestibular.org ◦ Page 4 of 6 information), how well the sense of vision optimum inner ear function, while others is used for orientation, and how well the can stop doing the exercises altogether inner ear functions in maintaining