Valerie, a 26-year-old legal assistant who lives in Rockville, Maryland:
I have suffered from migraine headaches for over 10 years. While I’ve noticed that riding on the subway during a migraine can make me feel dizzy, more nauseated and generally uncomfortable until today I’d never experienced anything remotely like this. I awoke in the morning with a pretty bad migraine headache, and while I was standing in the subway car, feeling miserable and hanging onto a strap, I looked out the window at the tunnel lights whizzing by and suddenly felt like everything around me was spinning out of control. A stranger kindly offered me his seat, but I was so sick and so dizzy that I was unable even to sit. I had to lie down on the floor of the subway car, but then I became so nauseated that I started to vomit. Truly humiliating, but I was too frightened to be embarrassed! I literally crawled off the train at the next stop and lay down on a concrete bench. After about 20 minutes the dizziness began to lessen, and with a lot of effort, I was able to take the escalator up to the street level and call for a ride. An hour later I was okay except for my usual headache. What happened to me? Did I have a stroke?
Migraineurs often report experiencing "dizziness" during migraine attacks, but in medical jargon "dizziness" is a highly non-specific symptom. In many cases, the "dizziness" migraineurs describe simply implies they are dehydrated from migraine-associated nausea and vomiting or a general disinterest in taking fluids by mouth. The resulting volume depletion and consequent drop in blood pressure may cause them to become lightheaded and feel as if they might faint, especially when arising from bed, couch or chair.
Not infrequently, however, migrainous "dizziness" indicates a very different symptom: disequilibrium (loss of balance) or even vertigo (the hallucination of movement). Pressed for details, patients may describe the symptoms as "feeling like I just stepped off a merry-go-round" (vertigo) or "like trying to stand steady on a boat that’s rocking" (disequilibrium). Disequilibrium/vertigo results from a disturbance in the vestibular system, a circuit that links together balance centers in the inner ear and brain with clusters of cells in the brainstem that control eye movement. This circuit is critical to our maintaining balance between the eyes, head, and body when we change position or there is movement in the environment around us.
The many causes of "vestibulopathy" (a disturbance within this circuit) range from disorders as benign and transient as a viral infection of the inner ear to stroke, tumor or multiple sclerosis. Because both migraine and vestibulopathy are so common, many migraineurs may experience vertigo/disequilibrium that is entirely unrelated to their headache disorder. In a sizable percentage of migraineurs who experience vertigo/disequilibrium, however, and especially in those who have recurrent episodes of vestibulopathy over a prolonged period with complete resolution of vestibular symptoms during the intervals between episodes, the migraine and the vestibulopathy may be clinically and biologically linked. When this occurs, the symptom complex bears the name vestibular migraine.
There is no blood test, imaging procedure or other diagnostic study that can confirm the diagnosis of vestibular migraine. This is a clinical diagnosis that’s based on the patient's history, and diagnostic studies assist only by excluding disorders that may mimic vestibular migraine.