Laboratory Studies
Laboratory studies generally do not help determine the etiology or type of vertigo. However, laboratory studies may be useful to help distinguish between vertigo and other types of dizziness such as light-headedness.
Consider abnormal serum glucose, anemia, or any ongoing cardiac dysrhythmia when patients report feeling light-headed.
Imaging Studies
Cerebral imaging may be necessary to assess causes of central vertigo.
Possible causes of central vertigo include the following:
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Cerebellar bleeds
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Infarcts and tumors
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Lesions of the brain stem
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Cerebellopontine angle tumors
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Multiple sclerosis
Because significant bony artifacts degrade CT images of the posterior fossa, MRI is the preferred imaging modality when available.
Imaging generally is not indicated in patients with isolated vertigo, in those with no history or physical findings that suggest any diagnosis other than vestibular neuritis, and in those without cerebrovascular disease risk factors. A lower threshold for imaging should be maintained for elderly patients or those with risk factors for cerebrovascular disease. These patients have a higher risk for a central cause of vertigo, even when no other symptoms manifest. In one study, 10% of patients with cerebellar infarction presented with isolated prolonged vertigo suggestive of vestibular neuritis. [16]
Procedures
Perform the Hallpike maneuver on all patients who complain of vertigo but do not exhibit nystagmus on routine examination of the extraocular muscles.
Hallpike maneuver requires patient to lie back from sitting to supine position 3 times. The first time, have the patient lie back with the head facing forward and the neck slightly extended; repeat this movement with the patient's head turned 45 degrees to the right and a third time with the head turned 45 degrees to the left.
Instruct patient to keep both eyes open each time he or she lies back.
Check for nystagmus and ask patient about any symptoms of vertigo.
Among the characteristics of an elicited nystagmus that would suggest disease of peripheral origin are a pause before nystagmus appears (latency), unidirectional nystagmus, and fatiguing of nystagmus after approximately 1 minute or repeated inductions.
Failure either to observe or to provoke unidirectional nystagmus casts doubt on whether the process is localized to the peripheral vestibular system. Either finding suggests a need to consider other diagnostic alternatives.
Other Tests
Bedside tests (head-impulse, head-heave, head-shake, and vibration tests) are effective in the diagnosis and prediction of the time to recovery from vestibular neuritis. [9]
