Last revision: 10/2012
- What is Bilateral Vestibulopathy?
- What Causes Bilateral Vestibulopathy?
- How is Bilateral Vestibulopathy Diagnosed?
- How is Bilateral Vestibulopathy Treated?
- How Might Bilateral Vestibulopathy Affect My Life?
- Research Studies in Bilateral Vestibulopathy
What is Bilateral Vestibulopathy?
Bilateral vestibulopathy occurs when the balance portions of both inner ears are damaged. The symptoms typically include imbalance and visual problems. The imbalance is worse in the dark or in situations where footing is uncertain. Spinning vertigo is unusual. The visual symptoms, called oscillopsia, only occur when the head is moving (J.C., 1952). The illustration to the right shows what a person with bilateral vestibulopathy may see when driving over a bumpy road. Oscillopsia is often common during walking (Kim et al., 2011). Quick movements of the head are associated with transient visual blurring.
A recent review of 255 patients found 25% to have cerebellar symptoms, such as poor coordination or nystagmus (patterned eye movements). There was also a high rate of peripheral neuropathy (18 to 32%), which was more common in bilateral vestibulopathy patients who also experienced cerebellar symptoms (Zingler 2007). Twenty-five percent of patients had bilateral hearing deficits.
What Causes Bilateral Vestibulopathy?
About 5% of all dizziness is due to bilateral vestibulopathy. In about 50% of cases, bilateral vestibulopathy is due to exposure to an ototoxic medication. Gentamicin is an antibiotic medication and gentamicin toxicity is the most common single known cause of bilateral vestibulopathy, accounting for 15 to 50% of all cases. Ototoxicity can also be due to infection (meningitis, about 5 to 10%); Meniere’s Disease; sarcoidosis; bilateral ear surgery, such as for certain forms of acoustic neuroma or bilateral vestibular neuritis; congenital disorders with deafness, such as the disorders of the immune system. It may be a genetic disorder inherited in an autosomal dominant manner (jen, 2004). One rare familial form, migraine associated vertigo (MAV),is associated with migraine. Advanced age is another risk factor because normally vestibular ganglion cell counts decrease with age so that by 80 years of age, only about 50% of vestibular neurons remain. In about one- third of all cases of bilateral vestibulopathy, no cause can be identified for bilateral vestibulopathy (Zingler et al., 2009). There is also accumulating evidence that free radical generation plays an important role in ototoxicity. This information is the basis of experimental treatments to prevent ototoxicity.
How is Bilateral Vestibulopathy Diagnosed?
Your physician can make the diagnosis based on your history, findings on physical examination, and the results of vestibular tests (rotatory chair). On physical examination, the tandem Romberg test, the dynamic visual acuity test, and the ophthalmoscope tests are the three most helpful confirmatory tests. The rotatory chair test is essential to document the characteristic reduced responses to motion of both ears. Based on rotatory chair testing in our laboratory, patients
are divided into three groups: mild, moderate, and severe (see Table 1). These categories have prognostic significance (see later). Other diagnostic studies may be helpful. Hearing testing (audiogram) is necessary. A test for syphilis (FTA), and an antibody test (ANA) for autoimmune inner ear disease may be performed. A chest X-ray and ACE test may be done if sarcoidosis is thought likely, and a Lyme titer may be obtained if there has been exposure (a tick bite in an endemic area).
|Rotatory Chair||ENG caloric responses|
|Mild||Increased phase, steeper than normal slope to gain vs. frequency plot||Normal and symmetric. Total response greater than or equal to 20.|
|Moderate||Increased phase, steep slope, gain greater than 0.2 at highest frequencies||Total response between 0 and 10|
|Severe||No response at all frequencies except (possibly) highest (0.64 Hz)||No response to usual temperatures as well as ice water|
The categories shown in Table 1 are based on testing done at the author’s institution, and might not be applicable to other protocols at other institutions. Pathologic correlation is minimal for these categories; however, recent data suggests that “severe” losses are associated with roughly an 80% or more loss of hair cells.
Treatment involves finding out the cause and treating it, if possible. If the damage has already been done, then the focus of treatment is upon avoidance of vestibular suppressants and ototoxins. Vestibular rehabilitation is important to speed recovery and prevent setbacks. We recommend that you tell health care workers that you cannot take drugs that end in mycin (like Azithromycin and Erythromycin), because of possible reaction. This will keep you from contact with the most common ototoxins. Asprin and nonsteroidal anti-inflammatory drugs can also affect hearing. It may be prudent to avoid these drugs, or at least large doses of them. Antihistamines,like Antivert (meclizine) or Dramamine, and benzodiazepines (Valium-like drugs like Klonopin, Xanax, and Ativan), are temporary vestibular suppressants. While they won’t permanently harm you, typically they make imbalance temporarily worse. A list of the most common problem medications follows.
Potential Problem Medications
Medications that can cause a temporary worsening of dizziness or hearing symptoms are generally vestibular suppressants, including the following:
- Antihistamines, such as meclizine and phenergan.
- Antidepressants, such as amitryptyline and other tricyclic type antidepressants.
- Aspirin or NSAIDS (drugs like ibuprofen and naproxen) in large doses
- Diazepam (Valium), alprazolam (Xanax), lorazepam (Ativan), klonazepam (Klonopin) and related drugs
- Verapamil and other calcium channel blockers
Medications that can cause permanent or temporary worsening of dizziness or hearing include the following:
- Cis-Platinum (a chemotherapy drug) and other platinum based drugs
- Gentamicin and other mycin antibiotics, including large doses of erythromycin (although this is actually in a different group than Gentamicin)
- Furosemide (Lasix) and ethacrynic acid (Edecrin) loop diuretics
- Quinine and related drugs (they usually have a “quin” in their name).
These medications need not be avoided at all costs but reasonable judgment should be exercised. Medications that cause only temporary unsteadiness (for example, meclizine), may still be used in some situations. Medications that are ototoxic (such as gentamicin) may still be useful in cases of bilateral vestibulopathy when there is no reasonable alternative, or when the damage done is already so extensive that no more damage is possible.
How Might Bilateral Vestibulopathy Affect My Life?
This is a condition that realistically often causes some permanent disability. In patients with gentamicin-induced ototoxicity, the symptoms generally peak at three months from the last dose of gentamicin. In the long run however, (five years), most patients become substantially better. There are multiple reasons why people get better. First, there is evidence that the damaged vestibular hair cells in the inner ear can regenerate, although the extent to which this occurs and the degree to which they are functional is not presently clear (Staecker et al., 2011; Forge et al, 1993)). Some recovery presumably occurs because marginal hair cells recover, because the brain rewires itself to adapt to the new situation (plasticity), and because people change the way they do things to adjust to their situation.
One can predict prognosis based on the amount of damage done initially, modified by other factors such as age and other medical problems. Gillespie and Minor (1999) reported that recovery is related to various factors, including severity of lesion. In our experience, rotatory chair testing done at six months following onset (or later) helps to establish prognosis by dividing individuals into three categories. Individuals with mild abnormalities on rotatory testing, are nearly always subjectively normal at one year. Individuals with moderate vestibular loss are usually able to continue to work productively, with some modifications in their behavior. For example, most people with moderate or severe loss never return to driving at night. In situations where there is complete or near-complete loss of vestibular function, vision and balance usually remain impaired permanently; however, most individuals do return to work, especially if their job does not require good head/eye coordination or balance. Frequently, job modification or accommodation occurs.
While balance is poorer than normal, with normal vision and sensation in the feet and ankles present, most patients with bilateral loss appear, at least on casual inspection, to have a normal gait. Falls are more frequent in persons with bilateral vestibulopathy (Herdman et al, 2000). Reading is generally more difficult than for persons with normal vestibular systems, but quite feasible, as the head can be steadied during reading. Many people with bilateral vestibulopathy complain of a mild confusion or “brain fog,” which is attributed to the increased attention needed to maintain balance and vision. This reduces the amount of attention that is available for other thinking tasks.
While crutches, canes, walkers and wheelchairs may be necessary in the first three months, these appliances are rarely needed by one year. After 20 years, most patients have returned to near-normal for their age. To some extent this return to “normal” is related to the aging of the patient’s peers, since vestibular function normally declines with age. Other aspects of recovery involve use of other senses such as neck position sensors (the COR or cervico-ocular reflex), vision, and compensation through prediction.
You will want to change your life style to adjust to your reduced balance, and inability to see when your head is in motion. You will want to take precautions to avoid falls. You may need to change your occupation if your present one requires good balance, and an ability to see while the head is in motion. For example, it would not be safe to continue as a truck driver, construction worker, or a roofer if you developed a significant bilateral vestibulopathy. A job where you work at a desk is usually a good choice.
Research Studies in Bilateral Vestibulopathy
Considerable research is ongoing regarding bilateral vestibulopathy. Presently, Vestibular implants have, have shown promise for restoring function and a feasibility study for treatment in humans with Meniere’s Disease has begun (Rubinstein et al., 2012) Mechanisms to stimulate regeneration of hair cells within the inner ear are also currently being developed. Methods of preventing loss through protective agents and predicting susceptibility to gentamicin through genetic testing are also currently hot topics.
Help with research efforts is much needed to speed progress in this disorder. You may wish to volunteer to be a research subject, to contribute funds for research efforts aimed at treating or preventing ototoxicity, or to contribute your inner ear in the event of your death. As of 2012, donations of the inner ear of individuals with gentamicin toxicity are sorely needed by the National Temporal Bone Bank as no usable specimens presently exist in the collection.
Considerable research is ongoing regarding bilateral vestibulopathy. Presently, efforts are ongoing to develop a vestibular prosthesis (ARO abstracts 743-747, 2001) as well as mechanisms to stimulate regeneration of hair cells within the inner ear. Both of these projects seem likely to be successful within 10 years. Methods of preventing loss through protective agents and predicting susceptibility to gentamicin through genetic testing are also currently hot topics.
Help with research efforts is much needed to speed progress in this disorder. You may wish to volunteer to be a research subject, to contribute funds for research efforts aimed at treating or preventing ototoxicity, or to contribute your
inner ear in the event of your death. As of 2001, donations of the inner ear of individuals with gentamicin toxicity are sorely needed by the National Temporal Bone Bank as no usable specimens presently exist in the collection (Tsuji et al, 1999).
At the American Hearing Research Foundation (AHRF), we have funded basic research on bilateral vestibulopathy in the past, and are very interested in funding additional research on bilateral vestibulopathy in the future. We are particularly interested in projects that might lead to prevention of ototoxicity in those who are exposed to aminoglycosides. Learn more about donating to American Hearing Research Foundation (AHRF).
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- Johns Hopkins
- Lynn Brown, Gentamicin support group (firstname.lastname@example.org)
- VEDA’s bilateral loss page
- Recent references related to Ototoxicity