When smells become a burden for people with migraines - new migraine study and therapeutic approaches
05.09.2022 16:04
A third of people with severe and long-term migraines apparently have a permanent hypersensitivity to smell - even between their migraine attacks. They most often find sweet perfume (36 percent), food smells (22 percent) and cigarette smoke (12 percent) annoying. The longer and the more severely you suffer from your illness, the more often this hypersensitivity to smells, called osmophobia, occurs. Around 30 percent of patients also cite smells as a trigger for migraine attacks. This is reported by private lecturer Dr. medical Gudrun Goßrau at a press conference for the “Attack! Together against headaches” initiative.
The new data comes from a joint study by the University Pain Center (USC) and the Interdisciplinary Olfactory Center at the University Hospital Dresden1, which was recently published in the Journal of Headache and Pain. “These findings can lead to new therapeutic approaches, such as structured smell training for desensitization, which is already being developed in Dresden,” said the Vice President of the German Migraine and Headache Society.
It is estimated that 8 to 10 million people in Germany are affected by migraines.2 Migraine ranks first among all diseases in the 15-49 age group in terms of years lived with disability.3 It is well known that migraine sufferers are often sensory sensitive not only to smells, but also to light and noise.
It was previously known that smells can trigger migraine attacks. What is new is that patients with migraine for a longer period of time and greater migraine-related limitations in everyday life show olfactory hypersensitivity more often than those less affected. In forms of migraine with aura, sensitivity to smell occurs twice as often as in forms without aura.
In addition to sweet perfume, food smells and cigarette smoke, the study participants also mentioned exhaust gases, stale room air, the smell of flowers, and the smell of paint and gas particularly frequently.
Activation of an entire pain system
The study suggests that the unpleasant smells activate not only the olfactory nerve (olfactory nerve), but also the trigeminal nerve, which is responsible for the perception of pain in the head. The olfactory and trigeminal systems are connected at the neural level. For example, experiments can show that stimulation of the trigeminal nerve triggers activity in the olfactory areas of the brain, i.e. those responsible for smell perception. The olfactory mucosa is also permeated by sensory fibers from the trigeminal nerve. This close connection between the scent and trigeminal pain systems offers an explanation for why scents can trigger headaches. It was observed that people infected with corona had longer and more severe migraine attacks. It is believed that the worsening of migraines is caused by SARS Cov-2 through infection of the olfactory mucous membranes and inflammation of the trigeminal nerve fibers.
Desensitization therapy in research
Avoiding odor triggers could be an approach for new forms of therapy. However, the currently researched approach of desensitization to unpleasant smells is more promising and sustainable, according to the head of the headache clinic at the University Hospital Dresden. Therapeutic studies also take place there. Test subjects regularly trained their sense of smell with, for example, rose and lemon scents. As a result, the intensity of the headache did not decrease, but the pain perception threshold increased. This means that after smell training, those affected were less sensitive to painful stimuli. These data from a study with children with migraine have recently been confirmed in a therapy study with adults with migraine. The investigation of the underlying brain mechanisms using MRI is currently the subject of scientific research.
methods
The currently published cross-sectional study1 is based on a survey of 113 people (99 female, 14 male) aged 19 to 78 with episodic or chronic migraine. The disease was assessed using the International Classification of Headache Disorders III by a specialized neurologist. The severity of migraine was determined using the Migraine disability assessment score (MIDAS).
Sources
1 Gudrun Gossrau, Marie Frost, Anna Klimova, Thea Koch, Rainer Sabatowski, Coralie Mignot, Antje Haehner. J Headache Pain. 2022 Jul 15;23(1):81. Interictal osmophobia is associated with longer migraine disease duration. doi: https://doi.org/10.1186/s10194-022-01451-7
2 Pfaffenrath V, Fendrich K, Vennemann M, et al. Regional variations in the prevalence of migraine and tension-type headache applying the new IHS criteria: the German DMKG Headache Study. Cephalalgia. 2009;29(1):48-57. doi:10.1111/j.1468-2982.2008.01699.x
3 Steiner T, Stovner L, Vos T, Jensen R, Katsarava Z. Migraine is first cause of disability in under 50s: will health politicians now take notice? J Headache Pain. 2018;19(1):17. doi:10.1186/s10194-018-0846-2v