Bilateral vestibulopathy is the failure or loss of function of the vestibular systems on both sides. The degree of involvement may differ. The hearing may be normal. It leads to imbalance and visual problems. Patients with this condition are severely handicapped. The incidence is 1% of the population with an increased risk in the elderly.
In the majority of patients a cause cannot be established. Other causes include ototoxicity due to medication (such as Gentamycin), autoimmune ear disease (AIED), bilateral temporal bone fractures, Meniere’s disease, meningitis, Neurofibromatosis type (NF2), HIV/AIDS and cerebellar disease. Recently the CANVAS syndrome was described. In this syndrome patients suffer from a combination of cerebellar ataxia, neuropathy and vestibular areflexia.They can present with bilateral vestibulpathy. In South Africa I see this condition in tuberculosis and AIDS patients. Unfortunately it is often missed and unrecognized.
The vestibular system has three main functions:
- It is part of the vestibulo-ocular reflex (VOR) that helps to stabilize vision during head movement.
2 It helps to maintain balance when standing and walking.
3 It helps with spatial orientation.
Patients have difficulty to balance when walking in the dark or on uneven surfaces. Furthermore they complain of osillopsia (jumbling of the panorama). Oscillopsia is the blurring and inability to focus on objects whilst moving. It manifest as the difficulty to read road signs when driving or recognize faces when walking. Oscillopsia occurs when both the vestibulo ocular reflexes (VOR) fail. Vertigo (spinning dizziness) is not common.
Some tests may be ordered to confirm the diagnosis. These tests include vestibular testing such as videonystagmography (VNG) and rotation testing such as the rotation chair or VORTEQ.
Blood tests, high resolution computed tomography (CT) scans and magnetic resonance imaging (MRI) may further be of value.
Bilateral vestibulopathy is managed with a vestibular rehabilitation program. In the majority of cases the damage is irreversible. Even if the cause is treated the weakness is usually permanent. There is no medication that helps.
Research is currently conducted on a vestibular implant. It is not commercially available yet.