Olfactory abnormalities in patients with migraine: a narrative review of a symptom commonly overlooked by neurologists

Nausea, vomiting, photophobia, and phonophobia are common concomitant symptoms in patients with migraine and provide valuable information for headache specialists during consultations. Clinical observations have identified various olfactory abnormalities in patients with migraine, such as osmophobia, olfactory hallucinations, hyperosmia and hyposmia, which are often overlooked by neurologists. These olfactory abnormalities may interact with the trigeminal vascular system, parasympathetic nervous system, and cortical spreading depression. This review aimed to examine the mechanisms underlying olfactory abnormalities in patients with migraine and the clinical correlations between these abnormalities and migraine. Additionally, olfactory training is highlighted as a promising non-pharmacological treatment for migraine.