In our study, 68% of patients with migraine had osmophobia. Although studies have shown that the frequency of osmophobia is similar in migraine patients, the frequency of osmophobia in migraine patients is reported to be between 25% and 95%. (2, 12, 13)
Some studies investigating osmophobia during attacks have reported that osmophobia is observed only in migraine patients and not in TTH patients, and it has been concluded that osmophobia during attacks is specific to migraines (1, 2). In our study, although there were TTH patients who experienced osmophobia both during attacks and during the interattack period, the number of these patients was significantly lower than that of migraine patients. Considering these findings, it seems to be a more appropriate protocol in clinical practice to consider migraine first in patients who describe intense osmophobia and whose diagnosis is in doubt and to organize first-line treatment according to migraine.
In a study of 113 migraine patients, osmophobia was most frequently observed with the smell of perfume, and no significant difference was found between the migraine with and without aura groups (14). Similarly, we found that osmophobia in patients with migraine who participated in our study was most frequent in perfume scents. In patients with TTH, the most common sensitivity was for food odors. Perfumes ranked third among these patients. During patient evaluation, detailed questioning of which odors the patient is sensitive to may support the differential diagnosis. However, it may be useful to warn and inform patients with migraine and their relatives about osmophobia and smells that may trigger attacks. Perhaps, in detailed studies to be conducted in larger populations, the scents to which migraine patients are sensitive can be determined, and the cosmetics industry can focus on perfumes and unscented cosmetics that migraine patients can use more easily.
Although our study did not show a relationship between disease duration and osmophobia in migraine and TTH patients, there are publications that find a significant relationship, especially in migraine patients (5). It would be appropriate to keep in mind that patients who do not have osmophobia in the first years of migraine diagnosis may develop osmophobia as the duration of the disease increases and to question osmophobia at every examination.
The MIDAS scores of those with osmophobia in the migraine group were slightly greater than those of those without osmophobia, but the difference was not statistically significant. Many studies have shown that the frequency of osmophobia increases as the MIDAS score increases (5, 6, 15). We believe that more definitive results can be obtained with studies in which the number of patients is increased.
When age, education level, disease duration, pain frequency, attack duration, and VAS score were examined in both groups of patients, no statistically significant differences were found between any of these parameters and osmophobia. The perception of scents is an extremely subjective experience. This is a limitation of this study. Even a patient's current mood can affect his response. Therefore, the results of studies evaluating migraine-triggering scents have yielded controversial interpretations.
In studies conducted with functional MRI, increased activity was detected in olfactory brain regions, such as the prefrontal, cingulate, and temporal cortices, of migraine patients with osmophobia. This activity is suppressed by typical antipsychotics (16, 17). Although olfactory hallucinations and phantosmia are symptoms particularly associated with temporal lobe epilepsy, these symptoms were detected in a small number of patients in a headache center. Patients with normal electroencephalograms respond positively to antiepileptic treatment (18). Recently, a hospital-based study in Taiwan reported that patients with osmophobia were more likely to have higher levels of depression and anxiety than were those without osmophobia (19).
For the differential diagnosis and treatment of headache, in-depth questioning should be conducted while taking anamnesis, and the characteristics of osmophobia and its accompanying conditions should be questioned. The aim should be to increase the patient's quality of life through strict control by using treatment agents that can cover the patient's comorbidities and reduce osmophobia.
We hope that new studies that question the sense of taste, which is a close accompaniment of smell, in patients with migraine and tension-type headaches, including anxiety and depression scales, will shed light on the literature.