Osmophobia in primary headaches

This study evaluates osmophobia (defined as an unpleasant perception, during a headache attack, of odours that are non–aversive or even pleasurable outside the attacks) in connection with the diagnosis of primary headaches. We recruited 775 patients from our Headache Centre (566 females, 209 males; age 38±12 years), of whom 477 were migraineurs without aura (MO), 92 with aura (MA), 135 had episodic tension–type headache (ETTH), 44 episodic cluster headache (ECH), 2 chronic paroxysmal hemicrania (CPH) and 25 other primary headaches (OPHs: 12 primary stabbing headaches, 2 primary cough headaches, 3 primary exertional headaches, 2 primary headaches associated with sexual activity, 3 hypnic headaches, 2 primary thunderclap headaches and 1 hemicrania continua). Among them, 43% with MO (205/477), 39% with MA (36/92), and 7% with CH (3/44) reported osmophobia during the attacks; none of the 135 ETTH and 25 OPH patients suffered this symptom. We conclude that osmophobia is a very specific marker to discriminate adequately between migraine (MO and MA) and ETTH; moreover, from this limited series it seems to be a good discriminant also for OPHs, and for CH patients not sharing neurovegetative symptoms with migraine. Therefore, osmophobia should be considered a good candidate as a new criterion for the diagnosis of migraine.