A lost track in ICHD 3 beta: A comprehensive review on osmophobia

Area of Science:

• Neurology
• Headache Medicine

Background:

• Osmophobia (Os) is notably more prevalent in migraine (M) than other primary headaches.
• Its high specificity for differentiating M from tension-type headache (TTH) has been previously reported.
• Os was previously an appendix diagnostic criterion for M in ICHD II but was omitted in ICHD-3 beta.

Purpose of the Study:

• To systematically review the literature published after 2004 regarding osmophobia (Os).
• To evaluate the prevalence and diagnostic utility of Os in migraine (M) and tension-type headache (TTH).
• To assess the justification for Os's exclusion from the ICHD-3 beta diagnostic criteria for migraine.

Main Methods:

• A systematic literature review was conducted using PubMed, MEDLINE, and the Cochrane library.
• Search terms included "osmophobia", "odour/odorphobia AND headache", "odour/odor hypersensitivity AND headache", and "olfactory hypersensitivity AND headache".
• Pooled prevalence and diagnostic values (sensitivity and specificity) were calculated from data in 40 selected articles.

Main Results:

• Osmophobia was cited in 112 papers as a headache symptom, with 16 focusing on its role in M diagnosis.
• Pooled prevalence of Os in M was 48.5% in adults and 23.4% in pediatric patients.
• In differentiating M from TTH, Os demonstrated high specificity (94.1% in adults, 92.0% in pediatric patients) but lower sensitivity (51.4% in adults, 22.1% in pediatric patients).

Conclusions:

• The reviewed literature supports the inclusion of osmophobia (Os) within the diagnostic criteria for migraine (M).
• The omission of Os from the ICHD-3 beta criteria appears unjustified based on its prevalence and diagnostic specificity.
• A revision of the ICHD-3 beta criteria regarding osmophobia is recommended.