Olfaction in migraineurs.

Many investigators have described olfactory dysfunction among migraineurs. Olfactory stimuli can precipitate migraine, and olfactory hallucinations can occur as auras of migraines or as part of the symptom complex. Despite many reports linking olfactory phenomena and migraine, no evaluations of the olfactory abilities of migraineurs have been documented. To begin such assessments, sixty-seven consecutive migraine patients were given Pyridine odor threshold tests. Twelve of them (18%) scored as hyposmic or anosmic. In comparison, 1% of the general population of the U.S. is hyposmic or anosmic. Aside from possible diagnostic or methodological error, several possibilities may account for our result: migraine may induce olfactory pathology; olfactory pathology may induce migraine, or; a common pathogen may induce both olfactory dysfunction and migraine. The association of migraine with the emotional component of the limbic system has long been recognized, and our results strengthen its association with the olfactory component as well. Headache patients should be tested for olfactory loss and warned of such risks as inability to detect gas leaks and spoiled food.