Can Viral Infection Cause Vertigo and Hearing Loss?
The relation of viral infection to subsequent hearing loss and vertigo symptoms is a subject of concern. Proper function of the inner ear is essential for both hearing and balance. Vestibular neuritis and labyrinthitis are the two major conditions that result from inflammation caused by infection of the inner ear. Both can have devastating effects. Such infections are usually of viral origin; less commonly the cause may be bacterial.
Vestibular neuritis and labyrinthitis are disorders thought to result from an infection that inflames the inner ear or the nerves connecting the inner ear to the brain. This inflammation disrupts normal transmission of sensory information from the ear to the brain. Vertigo, dizziness and difficulties with balance, vision or hearing may result.
In the inner ear both vestibular neuritis and and labyrinthitis affect one specific nerve, the vestibulocochlear nerve. This nerve sends balance and head position information from the inner ear to the brain. When swollen or inflamed, though, it disrupts the way the information would normally be interpreted by the brain.
Vestibular neuritis is a common cause of vertigo, labyrinthitis less so. Typically, though, they both produce disturbances of balance to varying degrees and may affect one or both ears.
Definition
Vestibular neuritis and labyrinthitis are closely-related disorders. Vestibular neuritis results from the swelling of one branch of the vestibulocochlear nerve (the vestibular portion) that affects balance. Labyrinthitis, in contrast, involves the swelling of both branches of the vestibulocochlear nerve (the vestibular portion and the cochlear portion) and impacts both balance and hearing.
Cause
Researchers think the most likely cause involves a viral infection of the inner ear, swelling around the vestibulocochlear nerve (usually caused by a virus) or a viral infection that has occurred somewhere else in the body. Some examples of viral infections in other areas of the body include herpes virus (causes cold sores, shingles, chickenpox), measles, flu, mumps, hepatitis and polio. Genital herpes, though, is not a cause of vestibular neuritis.
Even though the exact cause is not yet clear, evidence clearly shows that labyrinthitis and vestibular neuritis are likely to develop after a viral infection or, more rarely, after an infection caused by bacteria. Either condition seemingly can be triggered by an upper respiratory infection such as the flu or a cold. Less often, it may start after a middle ear infection. Other causes may include allergies or certain drugs that are risky for the inner ear.
When infection inflames the vestibular nerve, it sends incorrect messages to the brain signaling that the body is moving. The other senses –such as vision — do not detect the same movement however. The resulting confusion in signals can then make a sufferer feel as if the room is spinning or that he or she has lost balance (vertigo).
Risk factors:
- Drinking large amounts of alcohol
- Fatigue
- History of allergies
- Recent viral illness, respiratory infection or ear infection
- Smoking
- Stress
- Using certain prescription or nonprescription drugs (e.g., aspirin)
Symptoms
Symptoms of viral neuritis can be mild or severe, ranging from subtle dizziness to the violent spinning/whirling sensation of vertigo. They can also include nausea, vomiting, unsteadiness and imbalance, difficulty with vision and impaired concentration. In some cases symptoms become so severe that they affect the ability to stand up or walk.
The symptoms of labyrinthitis are the same as those of vestibular neuritis often with the additional symptoms of tinnitus (ringing in the ears) and/or hearing loss.
Typically this type of vertigo begins without warning, its onset often commencing one to two weeks after a bout of the flu or a cold. The most severe symptoms generally last only a couple days but, while present, make it extremely difficult to perform even routine activities of daily living. After the worst symptoms lessen, most patients make a slow but full recovery over the next several weeks. For a month or longer, though, a sufferer may still get vertigo symptoms when moving the head in a certain way. In a few cases some patients may experience balance and dizziness problems that last for several months.
Epidemiology
Dizziness is the primary complaint in 3.3% of all U.S. hospital emergency department visits. Approximately 5.6% of these patients are eventually diagnosed with vestibular neuritis or labyrinthitis. The annual incidence of the two combined diagnoses in the United States computes to be approximately 150,000 patients.
Vestibular neuritis is the third most common cause of peripheral vestibular vertigo. It has an annual incidence of 3.5 per 100,000 population and accounts for 7% of the patients at outpatient clinics specializing in the treatment of vertigo. Vestibular neuritis can affect both adults and children but has a peak age of onset between 40 and 50 years.
Viral labyrinthitis is the most common form of labyrinthitis. It usually occurs in adults aged 30 to 60 years but rarely in children. It most frequently appears in the fourth decade of life with women patients outnumbering men by about 2:1. Bacterial labyrinthitis is rare now in the post-antibiotic era.
There is wide variability in reported prevalence worldwide for diseases causing vestibular dysfunction — from 3.1% one-year prevalence to 35.4%. In all studies, though, occurrence was found to increase with age of the patient.
Diagnosis
Inner ear infections that cause vestibular neuritis or labyrinthitis are usually viral rather than bacterial. The symptoms of bacterial and viral infections may be similar. Treatments, on the other hand, are very different; therefore, initial diagnosis by a qualified physician is essential.
No specific tests are yet able to diagnose vestibular neuritis or labyrinthitis. As a consequence the process of elimination is often necessary for a default diagnosis. Because the symptoms of an inner ear virus often mimic other medical problems, a thorough examination is necessary to rule out other causes of dizziness (stroke, head injury, cardiovascular disease, allergies, side effects of prescription or nonprescription drugs [including alcohol, tobacco, caffeine and many illegal drugs], neurological disorders and anxiety).
A physician will usually begin the diagnostic process by doing a physical exam and asking about symptoms and health history. If the cause of vertigo is still not clear, the doctor may order tests to rule out other causes of the symptoms. Such procedures are likely to include:
- EEG
- Videonystagmography or electronystagmography (caloric stimulation – warming and cooling the inner ear with air or water to test eye reflexes)
- Head CT scan
- Hearing tests (audiology/audiometry)
- MRI of the head
Treatment
Medications can usually help manage symptoms. Vestibular rehabilitation therapy, though, may be necessary in some cases.
When other illnesses have been ruled out and the diagnosis of either vestibular neuritis or labyrinthitis established, then medications can generally control the worst of symptoms. Drugs are often prescribed to relieve nausea and to suppress dizziness during the acute phase. Antiemetics, antihistamines and sedatives may all be helpful as well. If nausea has been severe enough to cause excessive dehydration, intravenous fluids also may be necessary to re-establish fluid and electrolyte balance.
Usually symptoms will improve on their own. Resolution typically takes several weeks. If the cause is a bacterial infection, the doctor almost certainly will prescribe antibiotics. Most cases, though, are caused by viral infections, which cannot be cured with antibiotics.
Vertigo usually gets better over time as the body adjusts to a new reality (compensation). In some cases the doctor may eventually prescribe steroid medicines to decrease inflamation in the vestibular system. Pharmaceuticals like antihistamines, too, can sometimes help to relieve symptoms, but they may also extend the time needed for the vertigo to resolve. In general it is probably best to use medicines only when they are needed and for as little time as possible.
Finally staying active can help to speed recovery. Specific vestibular rehabilitation therapy may be useful in some cases. Check with your doctor for a physical therapy referral or for information about balance exercises to try at home. The regimen usually includes simple head movements and practice at maintaining balance while standing and sitting. With repetition such maneuvers may reduce symptoms of vertigo.
Prognosis
In most patients (95% and greater) vestibular neuritis or labyrinthitis is a one-time experience. Sufferers generally recover fully within a few weeks with or without symptomatic treatment. Improvement happens because of a combination of the body fighting off the infection and the brain accommodating to the vestibular imbalance (compensation). A minority, though, may experience vertiginous episodes following rapid head movement for months or even years after onset. Anxiety disorders and depression occur more often, too, with self-reported vestibular vertigo, as does cognitive impairment.
Because a virus usually causes inner ear infection, the microbe can run its course and then go dormant in the nerve only to flare up again at some time in the future. There is currently no way to predict whether it will recur.
If treated promptly, many inner ear infections cause no lasting damage. In some cases, however, permanent loss of hearing can result, ranging from barely detectable to total. Permanent damage to the vestibular system can also occur. Positional dizziness or BPPV (Benign Paroxysmal Positional Vertigo) can later present as a secondary type of dizziness that develops from neuritis or labyrinthitis and may recur chronically on its own. Labyrinthitis may also cause endolymphatic hydrops (abnormal fluctuations in the endolymph) to develop several years later.
Disequilibrium or positional vertigo may be present for the long term following resolution of an acute infection. If symptoms have not resolved completely within two to three months, though, further testing (e.g., an ENG, an audiogram or others) may be necessary to confirm the original diagnosis.
Hearing loss associated with viral labyrinthitis may eventually reverse. Suppurative labyrinthitis, though, usually leaves permanent and profound hearing loss. With labyrinthitis the recovery of hearing loss is more variable.