AAO-HNSF Primary Care Otolaryngology Handbook

DIZZINESS

Vestibular Testing Additional testing can be performed to help determine whether the problem exists within the vestibular system. This may include an audio- gram, video- or electronystagmography (ENG), rotational chair test, posturography, and electrocochleography (ECOG), depending on the clinical situation. There are four main parts to ENG testing : the calibration test, which measures rapid eye movements; the tracking test, which evaluates the ability of the eyes to track a moving target; the positional test, which measures responses to head movements; and the caloric test, which measures responses to warm and cold air or water introduced to the ear canal. ENG is the most useful for detecting unilateral peripheral vestibular disorders. In contrast, rotatory chair testing is most helpful for evaluating bilateral vestibular weakness. The patient is slowly spun in a rotating chair and dizziness is measured with optokinetic testing and a fixation test. Moving platform posturography is a method of quantifying balance but should not be used alone to diagnose vestibular disorders. It is most useful in quantifying balance improvement (or worsening) following treatment for a particular problem and can help identify the functional dizzy patient. ECOG is not really a test of the vestibular system but is a useful test of cochlear function in the evaluation of Ménière’s disease. The test is a variant of brainstem audio-evoked response and, if possible, should be BPPV is the most common cause of vertigo . This disorder is caused by sediment, such as otoconia (calcium carbonate crystals), that has become free-floating within the semicircular canals. When patients turn their heads quickly into certain positions, this free-floating material moves the semicircular canal fluid (endolymph) and stimulates the vestibular nerve, creating an intense feeling of vertigo that lasts less than 60 seconds and passes when the material settles. Patients are usually able to describe the precise motion that precipitates the vertigo. Rolling over in bed is one movement that frequently initiates an episode. The name of the syndrome comes from the intense, episodic (parox- ysmal) vertigo initiated by certain head positions (positional) that is not related to a central nervous system tumor (benign). This disorder can occur without any specific inciting event but is often seen after head trauma or an episode of vestibular neuronitis. performed during active Ménière’s attacks. Benign Paroxysmal Positional Vertigo

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