Diagnostic Criteria for Chronic Migraine
According to the International Classification of Headache Disorders (ICHD-3), chronic migraine is defined as headache occurring on 15 or more days per month for more than 3 months, with features of migraine on at least 8 days per month. 1
ICHD-3 Diagnostic Criteria for Chronic Migraine
- Headache (migraine-like or tension-type-like) occurring on ≥15 days/month for >3 months that fulfill criteria 2 and 3
- Attacks occur in an individual who has had at least five attacks fulfilling criteria for migraine without aura and/or migraine with aura
- On ≥8 days/month for >3 months, any of the following criteria are met:
- Criteria for migraine without aura (at least two of: unilateral location, pulsating quality, moderate/severe intensity, aggravation by physical activity; plus at least one of: nausea/vomiting, photophobia and phonophobia)
- Criteria for migraine with aura (fully reversible aura symptoms plus specific characteristics)
- Believed by the patient to be migraine at onset and relieved by a triptan or ergot derivative
- Not better accounted for by another ICHD-3 diagnosis 1
Important Clinical Considerations
Distinguishing from Other Headache Disorders
- Chronic migraine must be differentiated from other primary chronic daily headaches including chronic tension-type headache, new daily persistent headache, and hemicrania continua 2
- Medication-overuse headache must be ruled out or addressed, defined as:
- Headache on ≥15 days/month in a person with pre-existing headache disorder
- Regular overuse for >3 months of acute headache medications (non-opioid analgesics on ≥15 days/month or other medications like triptans on ≥10 days/month)
- Not better accounted for by another ICHD-3 diagnosis 1
Evolution and Risk Factors
- Chronic migraine typically develops as a complication of episodic migraine after a period of increasing headache frequency 2
- Risk factors for transformation from episodic to chronic migraine include:
- Non-modifiable: age, race, genetic factors
- Modifiable: obesity, snoring, head injury, stressful life events, and overuse of opioids and barbiturates 2
Disease Burden
- Chronic migraine affects approximately 2% of the general population 3
- Patients with chronic migraine are significantly less likely to be employed full-time and almost twice as likely to be occupationally disabled compared to those with episodic migraine 2
- Higher rates of comorbidities including anxiety, chronic pain, depression, and cardiovascular conditions 2
Clinical Pearls and Pitfalls
Common Pitfalls
- Failing to recognize that chronic migraine is not a static entity - patients may revert to episodic migraine or transform back to chronic migraine over time 1
- Missing medication overuse, which can perpetuate and complicate chronic migraine 1
- Inadequate documentation of headache frequency and characteristics, which is essential for accurate diagnosis
Important Considerations
- A thorough headache diary is essential for accurate diagnosis, documenting frequency, duration, intensity, associated symptoms, and medication use 1
- Family history should be assessed as migraine has a strong genetic component 1
- Patients with chronic migraine require preventive treatment, not just abortive therapy 4
By systematically applying these diagnostic criteria and considering the clinical context, chronic migraine can be accurately diagnosed, allowing for appropriate treatment strategies to reduce disability and improve quality of life.