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

Abstract

Migraine is a primary headache characterized by recurrent attacks of head pain associated with nausea or vomit, photophobia, phonophobia and osmophobia. The presence of osmophobia during migraine attacks seems to be a very specific complaint. Cutaneous allodynia (CA) is very common in migraineurs, and it is the most evident clinical manifestation of central sensitization, a mechanism involved in migraine chronification. This study was aimed at identifying the possible correlation between osmophobia and CA in migraineurs. 673 migraineurs were studied (492 episodic, 181 chronic). The prevalence of both CA and osmophobia was higher in chronic than in episodic migraineurs. The association between these two symptoms was significant in chronic migraineurs at Chi square test. The highlighted relationship between CA and osmophobia may be interpreted in different ways: central sensitization induced by recurrent pain stimulation may in parallel induce a distortion of both cutaneous sensitivity (CA) and olfaction (osmophobia); alternatively, the recurrent olfactory stimulation in subjects with a hypersensitivity to olfactory stimuli may co-work with repetitive pain stimulation to induce the central sensitization process.

Somatosensory temporal discrimination remains intact in tension-type headache whereas it is disrupted in migraine attacks

“…Migraine headache attacks are accompanied by characteristic symptoms of sensorial dysfunction. Tactile, visual, auditory and olfactory senses are all altered during the migraine attack and generate cutaneous allodynia, photophobia, phonophobia and osmophobia (4)(5)(6)(7)(8). These symptoms are independent from trigeminal nerve input (8) and reflect an altered cerebral cortical processing of sensorial information.…”

Osmophobia and Odour-triggered Headaches – Review of the Literature and Main Research Centres

“…There were 13 comparative studies between migraine and other primary headaches or controls without headache, 2,3,5,8,13,14,[17][18][19][20]22,28,31 and 10 that evaluated only migraine patients. 4,6,7,11,15,16,24,26,29,30 As for odour-triggered headache, there were six studies detected, two comparative studies between migraine and other primary headaches, 1,3 two with migraine patients, 7,24 and two case reports. 9,12 However, there were six other studies where pathophysiological aspects of the association between odours and migraine were studied.…”

“…Generally, we observed a severe intolerance to odours, pleasant or unpleasant, during headache attacks. 2,[4][5][6][7][8]10,11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] However, a limited number of studies showed that odours may trigger headache attacks in some patients, particularly in migraineurs 1,3,6,7,9,24 and occasionally in cluster headache patients. 12,18 This intolerance to odours is known as osmophobia, and according to two studies that investigated osmophobia in secondary headaches, it occurred during headache attacks only in the primary headaches.…”

“…2 Many researchers have confirmed that osmophobia is a symptom associated with migraine. 2,[4][5][6][7][8]10,11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Despite such research, osmophobia is still not part of the diagnostic criteria for migraine. 34 In recent years, these studies were carried out in several countries.…”

Constipation is associated with tension type headache in women

“…The exact mechanism for osmophobia is not known. In the attack period of headache in individuals, the sense of smell is different, which is related to the neuronal interaction between the olfactory and trigeminal nociceptive system, and this has been suggested to be caused by central sensitization 27, 28 . In mice it has been noticed that, if constantly given smell stimuli, hyperexcitability and anxiety develop as a result of overstimulation of the olfactory system 29,30 .…”