I asked the following question after awalkerphoenix’s belief that his problems were mainly due to VN and not migraine:
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“Is it possible or have you seen a caloric test result come back showing strong unilateral hypofunction in a migraineur? One might assume that a 70 or 80% deficit would indicate that some sort of vestibular damage had occurred previously, possibly through a viral attack for example. In your opinion can a person with only migrainous vertigo show such a deficit solely as a result of the migraine condition?”
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[size=150]Steven D. Rauch, MD[/size]
In most all other vestibulopathies, both central and peripheral, test abnormalities tend to “cluster”, showing all peripheral dysfunction or all central. Migraine does not cluster, but shows “scattered” abnormalities that have some elements of peripheral dysfunction and some elements of central dysfunction. Cases of scattered abnormalities are almost diagnostic of migraine – or at least highly suggestive. There also seems to be greatly increased test-retest variation rather than consistent findings. Finally, migraineurs are highly intolerant of vestibular function testing — they are MUCH more likely to have vomiting during the testing and MUCH more likely to have lingering dizziness and vertigo for days (or weeks) after testing than any other dizzy patients.
As for your specific patient, remember that in caloric testing we use Jongkees formula* to calculate a % asymmetry. We always report the result as “weakness” on the side with less activity. However, there are occasional cases, e.g. very shortly after a Meniere attack or in a migraineur, when one side may actually be “HYPERactive”. This would get reported as weakness on one side when it is actually hyperactivity on the other side.
That said, there is certainly mounting evidence that migraineurs can gradually develop peripheral injury – sensorineural hearing loss (SNHL) and/or caloric weakness. This is probably due to abnormal activity/signalling in the trigeminovascular innervation of the inner ear. Robert Baloh (otoneurologist at UCLA) has reported that 20% of patients with MAV develop SNHL. Patients with both MAV and SNHL can be indistinguishable from Meniere’s disease. They can be considered “migrainous Meniere’s.”
*Jongkees formula:
(right warm + right cool) - (left warm + left cool)
____________________________________________ X 100 = % asymmetry
(right warm + right cool) + (left warm + left cool)
I hope that helps.
Steve