Chronic daily headache. How should it be included in the IHS classification?

Area of Science:

• Neurology
• Headache Medicine

Background:

• Patients with chronic daily headaches are common in specialty centers.
• These headaches are often misclassified under current International Headache Society (IHS) criteria, typically as chronic tension-type headache.
• Many patients originally suffered from episodic migraine, which evolved over time.

Purpose of the Study:

• To examine the nature of chronic daily headaches.
• To evaluate the current International Headache Society (IHS) classification's ability to diagnose these headaches.
• To advocate for the recognition of "transformed migraine" as a distinct diagnostic category.

Main Methods:

• Review of clinical observations and existing literature on chronic daily headache.
• Analysis of patient histories, focusing on the evolution from episodic to chronic headache patterns.
• Comparison of patient presentations with International Headache Society (IHS) diagnostic criteria.

Main Results:

• The majority of chronic daily headaches appear to be transformed migraine, not tension-type headaches.
• Current International Headache Society (IHS) criteria inadequately classify many chronic daily headache patients.
• A distinct clinical entity, "transformed migraine," has emerged from clinical experience.

Conclusions:

• Chronic daily headache is frequently a manifestation of transformed migraine.
• The International Headache Society (IHS) classification requires revision to accommodate transformed migraine.
• Accurate diagnosis of transformed migraine necessitates understanding the headache's evolution, not just individual attack characteristics.