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Simple exams work in vestibular testing: up to 50% of migraineurs have vestibular symptoms, including dizziness, motion sensitivity.

CHICAGO -- Three simple bedside exams are more accurate than most laboratory tests in eliciting objective evidence of vestibular abnormalities in patients with migraine, Dr. David Zee said at the annual meeting of the American Headache Society.

Some studies suggest that more than 50% of migraineurs have some type of vestibular symptoms, including dizziness, unsteadiness, and motion sensitivity. Specialized vestibular testing such as electronystagmography (ENG) is commonly used in patients with migraine and vestibular symptoms, but the results often are not specific, said Dr. Zee, director of the vestibular-eye movement clinic and testing laboratory at Johns Hopkins University, Baltimore.

"There are a couple of things you can do at the bedside that are far better than any vestibular function test you are going to get from a laboratory," he said.

The biggest issue is that quality control of ENG testing is extremely poor, so testing is subject to variability and artifact.

Dr. Zee urged caution when evaluating the results of vestibular function tests, including ENG and posturography, as he does even from his own lab. "Your bedside exam is far more accurate when there is a significant loss of vestibular function on one side."

Up to 25% of migraineurs with vestibular symptoms have been reported to have a reduced response to caloric stimulation upon laboratory testing, which suggests a decrease in labyrinthine sensitivity.

As many as 65% have been reported to have interictal central eye movement abnormalities such as gaze-evoked nystagmus or impaired pursuit.

Dr. Zee said he recommends three bedside exams that take about a minute to perform:

* Use an ophthalmoscope to detect spontaneous nystagmus. This test is performed during routine ophthalmoscopy, which is conducted on all migraine patients. The physician examines the optic nerve head for stability while covering and then uncovering one eye. This eliminates visual fixation and will bring out or exacerbate spontaneous nystagmus if present.

The patient also can be asked to move his or her head gently from side to side while covering each eye. If the optic nerve head is still, the vestibular system is intact.

If optic nerve head is oscillating, that could indicate a problem.

* Perform a head-thrust maneuver. This test requires that the patient's head to be rotated very rapidly while the physician watches the patient's eyes to see whether there is an appropriate smooth, slow-phase eye movement response that comes from stimulation of the labyrinth and compensates for the head perturbation, Dr. Zee said.

When normal, this eye movement reflex allows the patient to see clearly during head motion.

If there is an asymmetry to the response requiring a rapid catch-up movement called a saccade, it could be because the slow phase is inadequate, indicating a vestibular problem.

* Use a vibrator to elicit nystagmus. This test uses a vibrator pressed against the patient's mastoid bone for about 10 seconds. If a vestibular imbalance is present, the vibrator will elicit nystagmus.

Obtaining a family history is critical in patients with vestibular migraine. Family history is often positive, and attacks of vertigo may be the predominant symptom in some family members, Dr. Zee said.

The mean onset of vertigo in migraine is about 40 years of age, and headaches precede vertigo by almost 10 years. Symptoms usually last minutes to a day, but low-level symptoms may last days to weeks.

Migraine headaches often are an infrequent or long-forgotten symptom in vestibular migraine.

Migraine headaches may occur independently of vestibular symptoms and vice versa. In some patients, they never occur together, he noted.

Patients often have chronic motion sensitivity and may have hearing symptoms such as muffled sounds, ear pressure or pain, or tinnitus, according to Dr. Zee.

Panic, anxiety, and phobic behavior are common in patients with vertigo and migraine.

In addition, light sensitivity is common in migraineurs during their attacks of vertigo.

BY PATRICE G. W. NORTON

Contributing Writer
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Title Annotation:Pain Medicine
Author:Norton, Patrice G.W.
Publication:Clinical Psychiatry News
Date:Jan 1, 2004
Words:638
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