investigations
Last reviewed 01/2018
To exclude systemic conditions.
- renal function, glucose - metabolic disturbances
- FBC, ESR, CRP - infections
- TFT - hormonal imbalances (1)
For testing of hearing
- pure tone audiometry:
- to assess the level of hearing loss
- initially, low frequencies are lost whihch resolves after an attack
- later, loss of higher frequencies occurs, causing a more flattened audiogram
- typically indicates a sensory type of hearing loss in the affected ear
- speech discrimination is often diminished in the affected ear
For testing of balance
- ENG (electronystagmograph) or video nystagmography
- may be performed to evaluate balance function
- procedure:
- it is done in a darkened room
- recording electrodes are placed near the eyes
- warm and cool water or air are gently introduced into each ear canal
- measurement of eye movements is used to test the balance system
- in about 50% the balance function is reduced in the affected ear.
- rotational testing (balance platform)
In addition, patients who are suspected of having Meniere's disease, should rule out acoustic neuroma (vestibular schwannoma) by having a magnetic resonance imaging of the internal auditory meatus.
Other tests which are used in specialist clinics include:
- the bithermic caloric testing an objective test of unilateral peripheral vestibular disease
- ectrocochleography (ECoG) – measures the electrical activity of the inner ear
- the vestibular evoked myogenic potential -
- the video head-impulse test- to identify peripheral vestibular deficits
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