Photo-, osmo- and phonophobia in the premonitory phase of migraine: mistaking symptoms for triggers?

Background: Certain environmental stimuli are frequently reported as typical triggers of migraine pain. Whether these so-called triggers are independent precipitators of migraine pain or mere symptoms of the premonitory phase of migraine remains to be elucidated. Methods: In this retrospective cohort study of 1010 migraine patients of a tertiary headache center we assessed the frequency of common trigger factors, premonitory symptoms and accompanying symptoms as well as basic headache characteristics and demographic data. Results: Premonitory symptoms with an onset of 2 or more hours prior to the headache were present in 38.9% of migraine patients, the most frequent being a tense neck, phonophobia and difficulty concentrating. There was a clear overlap of certain trigger factors and the presence of corresponding premonitory symptoms: flickering or bright light as a trigger was associated with higher frequency of photophobia in the premonitory phase. The same applied to the presence of food craving and osmophobia in the premonitory phase and certain foods or odours as trigger factors. Conclusions: Our data thus support the view that commonly reported trigger factors of migraine are not so much independent precipitators of migraine pain, but that they are most likely just misinterpreted results of enhanced attention to certain stimuli mediated by typical premonitory symptoms of migraine pain.