Olfactory hallucination in childhood primary headaches: case series

Area of Science:

• Neurology
• Neuroscience
• Ophthalmology

Background:

• Olfactory hallucination (OH) is a reported symptom in primary headache patients.
• However, olfactory aura is not yet recognized by the International Classification of Headache Disorders (ICHD-2).

Purpose of the Study:

• To investigate the frequency and characteristics of olfactory hallucinations in children and adolescents experiencing primary headaches.
• To determine if olfactory hallucinations are associated with specific headache types, particularly migraine.

Main Methods:

• A cohort of 839 neurologically normal patients with primary headaches, including 537 with migraine, were assessed for olfactory hallucination.
• Diagnosis adhered to the International Classification of Headache Disorders (ICHD) criteria.
• Data were collected prospectively through clinic visits and headache diaries.

Main Results:

• Olfactory hallucination (OH) was reported by 2.5% of patients (21/839) exclusively during headache attacks, all diagnosed with migraine.
• The prevalence of OH was 3.9% in migraineurs and 6.5% in those with migraine aura.
• OH episodes lasted 15-50 minutes, often occurring simultaneously with or preceding migraine aura (visual, somatosensory, motor).

Conclusions:

• Olfactory hallucination is a feature that occurs in migraine patients.
• The characteristics of olfactory hallucination suggest similarities to migraine aura, warranting further investigation and potential inclusion in headache classifications.