Olfactory function in migraine both during and between attacks

Abstract

Introduction People with migraine often report being osmophobic, both during and between acute migraine attacks. It is not clear, however, whether such reports are associated with changes in olfaction such as hyperosmia, as measured by psychophysical testing. In this case-control study we quantitatively assessed olfactory identification ability, which correlates with threshold tests of olfactory acuity, in patients with migraine at baseline (no headache), during migraine episodes, and after a treated attack and compared the test scores to those of matched control subjects. Methods Fifty episodic migraine subjects and 50 and sex- and age-matched controls without headache were tested. All completed the University of Pennsylvania Smell Identification Test (UPSIT), a standardized and well-validated olfactory test. Results At baseline, the UPSIT scores did not differ significantly between the migraine and control study groups (median paired score difference: −1, p = 0.18). During migraine attacks, a minority of migraine subjects (eight of 42) developed microsmia (i.e. lower test scores by at least four points), suggesting that, as compared to their matched controls, olfactory acuity was somewhat impaired during migraine attacks ( p = 0.02). This difference was less pronounced and not statistically significant after a successfully treated attack ( p = 0.15). Discussion People with episodic migraine were found to have similar olfactory function as age- and sex-matched controls, but a minority exhibit microsmia or hyposmia during acute attacks. The cause of this dysfunction is unknown, but could relate to autonomic symptoms, limbic system activation, or disorders of higher order sensory processing.

Osmophobia in allodynic migraineurs: cause or consequence of central sensitization?

“…The presence of ictal osmophobia also in patients with episodic forms of migraine in which CA is not present seems to reinforce this second physiological explanation. On the contrary, a recent work on episodic migraineurs [9] did not found differences between patients and controls in term of ''olfactory identification ability'', apparently in contrast with the hypothesis that the hypersensibility to olfactory stimulation may contribute to the sensitization process. In fact, this statement is not entirely true: the study was limited to episodic migraineurs and it did not separate osmophobic migraineurs from non-osmophobic neither clinically hyperosmic from non-hyperosmic.…”

The Insula

“…While around 20% of migraineurs have been reported to be anosmic or hyposmic (Hirsch, 1992), positron emission tomography (PET) studies show hypersensitivity to olfactory stimuli (Demarquay et al, 2008) with activations in a number of brain regions such as the temporal lobe, anterior cingulate, and locus coeruleus, but not the insula. Interictal olfactory hypersensitivity is reported (Marmura et al, 2014; Stankewitz and May, 2011) to be present in about 35% of migraineurs (Demarquay et al, 2006) and seems to be a predictor of olfactory triggers for migraine attacks. In addition, during a migraine attack some migraineurs have olfactory symptoms of microsmia or hyposmia (Marmura et al, 2014).…”

“…Interictal olfactory hypersensitivity is reported (Marmura et al, 2014; Stankewitz and May, 2011) to be present in about 35% of migraineurs (Demarquay et al, 2006) and seems to be a predictor of olfactory triggers for migraine attacks. In addition, during a migraine attack some migraineurs have olfactory symptoms of microsmia or hyposmia (Marmura et al, 2014). During spontaneous migraine attacks, there is increased activation induced by olfactory stimuli (rose odor) in the amygdala and insula (Stankewitz and May, 2011).…”

Migraine with aura is associated with impaired colour vision: Results from the cross-sectional German DMKG headache study

“…Only recently Marmura and colleagues reported impaired olfactory ability during migraine attacks in MwoA and MA patients as determined with the University of Pennsylvania Smell Identification Test (UPSIT) (28). While baseline olfaction did not differ from a healthy control group, UPSIT scores shortly after an attack were numerically lower than at baseline.…”