What is Bilateral Vestibulopathy?

Bilateral vestibulopathy, or bilateral vestibular loss is rare and occurs in only 2-5% of patients with balance problems. Bilateral vestibulopathy occurs when the balance organs of both vestibular systems (inner ears) are damaged or destroyed. The symptoms of bilateral loss typically include dizziness, imbalance and visual disturbances when trying to track objects that are moving. People will often notice that their imbalance is worse in the dark or in situations where footing is un-even or uncertain.

People will often describe having dizziness and visual symptoms of blurriness called Oscillopsia. This usually occurs when the head is moving and is a common symptom among people suffering from Bilateral vestibulopathy. The illustration to the right shows what a person with bilateral vestibulopathy may see when driving down road and looking at an object like a road sign. Oscillopsia also often occurs when someone is walking and trying to concentrate on a stationary object.

What Causes Bilateral Vestibulopathy?

In many instances, exposure to ototoxic medication is found to be the predominant cause of bilateral vestibular loss. Gentamicin is an example of an ototoxic, and Gentamicin toxicity is known to be the single largest cause of bilateral vestibulopathy cases. Ototoxicity can also be due to infection like meningitis, sarcoidosis, congenital disorders, Ménière's disease, or bilateral ear surgeries for acoustic neuroma or bilateral vestibular neuritis. In persons with bilateral loss following meningitis, hearing is normally profoundly affected.

Bilateral vestibular neuritis is a known cause of bilateral vestibular loss. In most cases, the loss is not complete and residual vestibular function still occurs. Evidence of this occurs when the lateral canals may be unresponsive on both sides, but there is often evidence of retained posterior canal function as well as saccule function.

Aging also causes bilateral vestibulopathy, although it is only rarely severe. Advanced age is another risk factor because vestibular ganglion cell counts decrease with age. By the time someone has reached 80 years of age, only about 50% of vestibular neurons still remain.  This reduction presumably contributes to the invariable loss of balance function that occurs as people age. It has been proven that it can be diagnosed with rotary chair testing.

How do You Diagnose Bilateral Vestibulopathy?

The first step to diagnosing bilateral vestibulopathy is to have a medical exam from a specialist trained in diagnosing these types of conditions. A doctor will make the diagnosis based on a patients medical history, physical examination findings, and the results of the vestibular tests ENG/VNG or rotational chair. During the physical examination, the tandem Romberg test is sometimes administered along with the dynamic visual acuity test. This test uses a snellen chart, like pictured at right, or a computerized DVA version to access a persons visual acuity. Patients with bilateral vestibular loss will often lose 6-8 lines of visual acuity when administered one of these types of tests. As patients recover from bilateral loss, they perform better on this test.

The rotational chair test is an essential diagnostic test to determine if there are reduced responses to motion in both ears, and also assessing the degree of compensation or partial recovery that the patient has experienced. The results from this test generally improves with time and eventually high frequency gain becomes normal after several years. The recovery sometimes present at high frequencies is related to non-vestibular sensory input and does not necessarily correlate with severity of the vestibular injury.

Snellen Chart

How do Treat Bilateral Vestibulopathy?

The best course of treatment for bilateral loss generally involves finding out the cause and treating it if possible. Depending on what damage has been done, the primary focus of treatment is upon avoidance of vestibular suppressants and ototoxins and starting a comprehensive vestibular rehabilitation program are very important to aid in the recovery and prevent further problems. Most doctors will recommend that you tell your primary care doctor and staff that you are can't take any drugs that end in "mycin", because of possible reaction. This should help prevent accidental toxicity and will help you stay safe of the most common ototoxin medications.

Other medications that should be watched are Aspirin and nonsteroidal anti-inflammatory drugs that can affect your hearing. It's also wise if possible to avoid these drugs also or maintain only some doses. 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. Here is a list of the most common problem medications:

The potential problem medications for patients with bilateral vestibular loss

Vestibular Suppressants - These can cause temporary worsening of dizziness or hearing symptoms. Medications in this group are commonly taken to make vertigo better, but will likely make the symptoms of bilateral loss worse.

• Aspirin or NSAIDS: medications like ibuprofen and naproxen when taken in large doses
• Antihistamines: meclizine (antivert), dramamine and phenergan
• Antidepressants: amitriptyline, especially tricyclic type antidepressants
• Benzodiazepines: diazepam (valium), alprazolam (xanax), lorazepam (ativan), klonazepam (klonopin)
• Verapamil and other calcium channel blockers
  

Ototoxin Medications - These can cause permanent or temporary worsening of dizziness or hearing symptoms and should not be taken if you have been diagnosed with bilateral vestibular loss. Please consult your doctor before stopping any of these medications.

• Gentamicin and other "mycin" antibiotics: this includes large doses of erythromycin
• Platinum based drugs: Cis-Platinum, a chemotherapy medication and others in this group
• Diuretics: Furosemide (Lasix) and ethacrynic acid (Edecrin)
• Quinine group: medications that have a "quin" in their name

This group of medications should be avoided if possible. If any of these medications need to be taken, reasonable judgment should be exercised. The medications that cause only temporary unsteadiness (i.e. meclizine), may still be useful in some situations. The medications that are ototoxic (such as gentamicin), may still be useful in cases of bilateral vestibular loss when there is no reasonable alternative or when the damage done is already so extensive that there is nothing more to lose. Certain bacteria, such as methacillin-resistant staphylococcus aureus (MRSA) are so difficult to treat that ototoxic medications may be required to save a persons life. Nevertheless, as medicine progresses, we expect that newer drugs such as Linezolid will provide reasonable alternatives.