Differential Diagnosis for Migraine-Type Head Pain
The differential diagnosis for migraine-type head pain must systematically distinguish between other primary headache disorders (tension-type headache, cluster headache) and potentially life-threatening secondary causes (meningitis, subarachnoid hemorrhage, mass lesions) using clinical features and red flags to guide further investigation. 1
Primary Headache Disorders
Tension-Type Headache (TTH)
The most common primary headache disorder that mimics migraine. Key distinguishing features include:
- Bilateral location (vs. often unilateral in migraine)
- Pressing or tightening quality (vs. pulsating in migraine)
- Mild to moderate intensity (vs. moderate to severe in migraine)
- Not aggravated by routine physical activity
- Lacks the characteristic migraine features: no photophobia, phonophobia, nausea, or vomiting 1
Cluster Headache
A rare but distinctive primary headache affecting ~0.1% of the population. Highly characteristic features make it readily distinguishable:
- Strictly unilateral headache
- Very severe intensity
- Short duration: 15-180 minutes (vs. 4-72 hours in migraine)
- Ipsilateral cranial autonomic symptoms: conjunctival injection, lacrimation, nasal congestion
- Frequently recurrent attacks 1
Medication-Overuse Headache (MOH)
A critical differential, especially for chronic migraine. This secondary headache disorder develops from overuse of acute migraine medications and often coexists with migraine, making differentiation challenging. Consider MOH when:
- Headache frequency increases despite medication use
- Pattern of daily or near-daily headache emerges
- History of escalating acute medication use 1
Secondary Headache Disorders Requiring Urgent Evaluation
Red Flags in History
These features mandate immediate investigation for life-threatening causes:
- Thunderclap headache (sudden, severe onset)
- Atypical aura features
- Recent head trauma
- New headache in patients >50 years
- Progressive worsening or change in headache pattern 1
Red Flags on Physical Examination
- Unexplained fever (consider meningitis, encephalitis)
- Impaired memory or consciousness
- Focal neurological symptoms
- Papilledema (suggests increased intracranial pressure)
- Meningeal irritation signs 1, 2
Life-Threatening Secondary Causes
When red flags are present, consider:
- Subarachnoid hemorrhage (thunderclap onset)
- Meningitis/encephalitis (fever, meningeal signs)
- Intracranial mass lesions (progressive symptoms, focal signs)
- Cerebral venous thrombosis
- Acute glaucoma (eye pain, visual changes) 1, 2
Cervicogenic Headache
An often-overlooked mimic of migraine that can present with migraine-like features due to trigeminocervical convergence:
- Fixed unilateral headache
- Cervical onset with trigeminal radiation
- Reduced neck mobility and flexion strength
- May include nausea, photophobia, phonophobia (mimicking migraine)
- History of whiplash injury is common
- Pain duration: days to weeks 3
Diagnostic Approach Algorithm
Step 1: Clinical Assessment
Apply ICHD-3 diagnostic criteria and use validated screening tools:
- ID-Migraine questionnaire (3 items: nausea, photophobia, disability)
- Migraine Screen Questionnaire (5 items, sensitivity 0.93) 1
Step 2: Screen for Red Flags
Use the SNNOOP10 mnemonic for systematic evaluation of concerning features 2
Step 3: Neuroimaging Decision
Neuroimaging is NOT routinely indicated for typical migraine with normal examination. Only pursue imaging when:
- Red flags are present in history or examination
- Atypical features that don't fit migraine pattern
- Change in established headache pattern
- New-onset headache in older adults 1
When imaging is needed:
- Emergent cases (thunderclap, focal signs): Non-contrast CT head to exclude hemorrhage or mass effect, followed by lumbar puncture if CT is normal to rule out subarachnoid hemorrhage 2
- Non-emergent cases: MRI brain preferred (higher resolution, no radiation exposure) 1
Common Pitfalls to Avoid
Overuse of neuroimaging: Routine imaging in typical migraine with normal examination is unnecessary, potentially harmful (radiation exposure), and may reveal clinically insignificant findings (white matter lesions, arachnoid cysts) that cause patient alarm and trigger unnecessary further testing 1
Missing MOH: When evaluating chronic or increasing headache frequency, always assess acute medication use patterns, as MOH commonly develops from treating migraine attacks 1
Assuming bilateral headache excludes migraine: Population-based data shows ~40% of migraine patients report bilateral pain during attacks 1
Overlooking cervicogenic headache: The presence of migraine-like features (nausea, photophobia) doesn't exclude cervicogenic headache; assess neck mobility and history of neck trauma 3