What is the diagnostic and treatment approach for a patient suspected of having chronic migraines?

Diagnostic Approach for Chronic Migraine

Chronic migraine is diagnosed when a patient experiences ≥15 headache days per month for >3 months, with ≥8 days per month meeting migraine criteria or responding to triptans/ergots. 1

Initial Clinical Assessment

Rule Out Secondary Causes First

Before diagnosing chronic migraine, exclude secondary headache disorders through careful history and examination. 1 Look specifically for these red flags that mandate urgent investigation:

• Thunderclap headache ("worst headache of life") suggesting subarachnoid hemorrhage 2
• New-onset headache after age 50 (consider giant cell arteritis) 2, 3
• Progressive worsening headache or headache awakening patient from sleep 2, 3
• Headache with Valsalva, cough, or exertion (increased intracranial pressure) 2, 3
• Focal neurological symptoms/signs 2, 3
• Unexplained fever with neck stiffness (meningitis) 2
• Recent head/neck trauma 2, 3

If any red flags are present, proceed immediately to neuroimaging (MRI preferred) and/or emergency referral. 2, 3

Establishing the Diagnosis of Chronic Migraine

Step 1: Confirm Headache Frequency Pattern

Ask directly: "Do you feel like you have a headache of some type on 15 or more days per month?" 1 This simple question is more reliable than asking patients to recall exact headache counts, as patients often underreport milder headaches and only mention severe days. 1

Alternatively, ask about headache-free days or "crystal-clear days" (days with no headache and no accompanying symptoms), which can be more informative for quantifying true headache burden. 4

Critical diagnostic requirement: Headaches must occur ≥15 days/month for >3 months, with each headache day defined as >4 hours of headache. 1, 2, 4

Step 2: Verify Migraine Features on Sufficient Days

On ≥8 days per month for >3 months, the headaches must meet one of these criteria: 1, 2

• Migraine without aura criteria: At least 2 pain characteristics (unilateral, pulsating, moderate-to-severe intensity, aggravated by routine activity) AND at least 1 accompanying symptom (nausea/vomiting OR both photophobia and phonophobia) 1, 2
• Migraine with aura criteria: Fully reversible aura symptoms (visual, sensory, speech, motor, brainstem, or retinal) with gradual spread over ≥5 minutes, lasting 5-60 minutes 1, 2
• Believed by patient to be migraine at onset and relieved by triptan or ergot derivative 1

Step 3: Obtain Essential Historical Details

Document systematically: 1

• Age at onset (migraine typically begins at/around puberty) 1, 2
• Duration of each headache episode (4-72 hours for migraine) 1
• Pain location (unilateral favors migraine) 1, 2
• Pain quality (pulsating favors migraine) 1, 2
• Pain severity (moderate-to-severe favors migraine) 1, 2
• Aggravating factors (routine physical activity worsens migraine) 1, 2
• Accompanying symptoms (nausea, vomiting, photophobia, phonophobia) 1, 2
• Family history (migraine has strong genetic component; positive family history strengthens diagnosis) 1, 2
• Complete medication history (acute and preventive medications) 1

Step 4: Rule Out Medication-Overuse Headache

Medication-overuse headache is a distinct diagnosis that can coexist with or complicate chronic migraine. 1, 2 It requires:

• Headache ≥15 days/month 1, 2
• Regular overuse for >3 months: Non-opioid analgesics on ≥15 days/month OR any other acute medication (triptans, ergots, combination analgesics, opioids) on ≥10 days/month 1, 2

Common pitfall: Patients often fail to report over-the-counter medication use unless specifically asked. 1 Directly inquire about all acute medications including acetaminophen, NSAIDs, and combination products.

Diagnostic Tools to Support Clinical Diagnosis

Headache Diary

Implement a headache diary immediately to document pattern and frequency, accompanying symptoms, acute medication use, triggers, and menstrual cycle relationship. 2, 5 Diaries reduce recall bias and increase diagnostic accuracy; if diary entries consistently fail to meet ICHD-3 criteria over multiple attacks, chronic migraine is ruled out. 2

Validated Screening Questionnaires

• ID-Migraine (3-item): Sensitivity 0.81, specificity 0.75, positive predictive value 0.93 2, 5
• Migraine Screen Questionnaire (5-item): Sensitivity 0.93, specificity 0.81, positive predictive value 0.83 2, 5

These tools support but do not replace clinical diagnosis based on ICHD-3 criteria. 2, 5

When to Order Investigations

Neuroimaging is NOT routinely indicated for chronic migraine diagnosis. 2, 6, 5 The diagnosis is clinical, based on history and systematic application of ICHD-3 criteria. 1, 5

Order MRI brain with and without contrast (preferred over CT for higher resolution and no ionizing radiation) only when: 2, 3

• Red flags are present 2, 3
• Atypical features suggest secondary causes 2, 6
• Diagnosis remains uncertain after thorough history 2

Additional investigations only if clinically indicated: 2

• ESR/CRP if temporal arteritis suspected (new headache in patient >50 years with scalp tenderness, jaw claudication) 2
• Morning TSH and free T4 if hypothyroidism suspected (cold intolerance, lightheadedness) 2
• Non-contrast CT head if presenting <6 hours from acute severe headache onset (subarachnoid hemorrhage) 2

Treatment Approach for Chronic Migraine

Acute Treatment

Every chronic migraine patient requires both acute and preventive treatment. 1

For acute attacks: 7

• NSAIDs or acetaminophen for mild-to-moderate attacks 2, 7
• Triptans for moderate-to-severe attacks or when NSAIDs fail 2, 7
• Antiemetics for nausea/vomiting 2, 7

Critical caveat: Monitor acute medication use carefully to avoid medication-overuse headache (limit non-opioid analgesics to <15 days/month, other acute medications to <10 days/month). 1, 2

Preventive Treatment

All patients with chronic migraine should be offered preventive treatment. 1, 4, 8

OnabotulinumtoxinA (Botox) is the only FDA-approved preventive treatment specifically for chronic migraine (not episodic migraine). 9, 8 It is indicated to prevent headaches in adults with chronic migraine who have ≥15 days each month with headache lasting ≥4 hours each day. 9

Alternative preventive options used off-label for chronic migraine include: 10, 8

• Propranolol (FDA-approved for migraine prophylaxis, though original studies were in episodic migraine) 10
• Other beta-blockers, anticonvulsants, antidepressants 8

Referral Criteria

Refer to neurology or headache specialist when: 1

• Diagnosis uncertain after systematic evaluation 2
• First-line treatments fail 2
• Rapid clinical deterioration 2
• Patient requires specialized preventive therapies 1

Emergency admission if: 2

• Any red flag present 2
• Patient unable to self-care without help 2

Key Diagnostic Pitfalls to Avoid

1. Ordering routine neuroimaging: Chronic migraine is a clinical diagnosis; imaging is only for suspected secondary causes. 2, 6, 5

2. Conflating medication-overuse headache with chronic migraine: These are distinct diagnoses that require different management approaches. 1, 2

3. Failing to ask about milder headaches: Patients typically report only severe headache days, leading to underdiagnosis. 1

4. Not documenting medication use: Medication-overuse headache cannot be diagnosed without detailed acute medication history. 1

5. Missing the diagnosis entirely: Only 20-25% of individuals meeting criteria for chronic migraine receive correct diagnosis. 1, 4 Assume chronic migraine until proven otherwise in any patient presenting with frequent disabling headaches having migraine features. 4