What are the steps for differential diagnosis and assessment of headache?

Differential Diagnosis and Assessment Steps for Headache

The differential diagnosis of headache requires a structured approach that prioritizes identifying life-threatening secondary causes through recognition of red flag symptoms, followed by systematic evaluation of primary headache disorders using established diagnostic criteria. 1

Red Flag Assessment - Emergency Evaluation First

Always begin by screening for these critical danger signs requiring immediate medical attention:

• Thunderclap headache: Sudden, severe headache reaching maximal intensity within seconds to minutes 1
• Focal neurological deficits: Any weakness, numbness, vision changes, or speech disturbance 1
• Altered mental status: Confusion, drowsiness, or decreased level of consciousness 1
• Neck stiffness and fever: Potential signs of meningitis 1
• Recent head/neck trauma: May indicate traumatic brain injury 1, 2
• New onset headache in patients >50 years: Higher risk of secondary causes 1, 3
• Headache during pregnancy or postpartum period: Risk of pre-eclampsia, venous thrombosis 2
• Headache in immunocompromised patients: Risk of CNS infection or malignancy 2
• Headache worsened by Valsalva maneuver or exertion: May indicate increased intracranial pressure 4
• Headache associated with sexual activity: Risk of subarachnoid hemorrhage 4

Immediate Diagnostic Testing for Red Flag Symptoms

When red flags are present, proceed with:

1. Non-contrast head CT: First-line for thunderclap headache or suspected subarachnoid hemorrhage (98% sensitivity for acute SAH) 1
2. Lumbar puncture: If CT is negative but clinical suspicion for SAH remains high 1, 3
   • Xanthochromia detection with spectrophotometry has 100% sensitivity for SAH at 12 hours to 2 weeks post-event 3
3. MRI with MRA/MRV: Preferred for suspected stroke or vascular abnormality 1

Systematic Assessment for Primary Headache Disorders

If no red flags are present, evaluate for primary headache disorders using ICHD-3 criteria:

Migraine Assessment

• Duration: Typically 4-72 hours untreated 1
• Characteristics (need at least 2): 1
  • Unilateral location
  • Pulsating quality
  • Moderate to severe intensity
  • Aggravation by routine physical activity
• Associated symptoms (need at least 1): 1
  • Nausea and/or vomiting
  • Photophobia and phonophobia
• Aura assessment: Visual, sensory, speech/language, motor, brainstem, or retinal symptoms 1

Tension-Type Headache Assessment

• Bilateral location
• Pressing/tightening quality
• Mild to moderate intensity
• Not aggravated by routine physical activity
• No nausea/vomiting (mild nausea may be present)
• No more than one of photophobia or phonophobia 5

Cluster Headache Assessment

• Severe unilateral orbital, supraorbital, and/or temporal pain
• Duration 15-180 minutes
• Accompanied by ipsilateral autonomic features (conjunctival injection, lacrimation, nasal congestion, rhinorrhea, eyelid edema, facial sweating, miosis, ptosis) 5

Neuroimaging Considerations

• When to image without red flags: 3

  • New-onset headache in patients over 50
  • Change in established headache pattern
  • Headaches that wake patient from sleep
  • Headaches always occurring on the same side
  • Headaches affected by posture changes

• Yield of neuroimaging: The diagnostic yield in patients with headache and normal neurological examination is low (brain tumors 0.8%, AVM 0.2%, aneurysm 0.1%) 3

Common Pitfalls to Avoid

1. Failure to obtain neuroimaging for red flag symptoms: Most common diagnostic error in subarachnoid hemorrhage 1
2. Dismissing sentinel headaches: Can lead to delayed diagnosis of subarachnoid hemorrhage 1
3. Misdiagnosis of chronic migraine: Often confused with frequent episodic migraine or tension-type headache 1
4. Overlooking medication overuse: Can complicate diagnosis and management 1
5. Cardiac risk with triptans: Serious adverse cardiac events including MI and arrhythmias have been reported; contraindicated in patients with coronary artery disease 6
6. NSAID cardiovascular risks: Increased risk of serious cardiovascular thrombotic events with prolonged use 6
7. Serotonin syndrome: Risk when combining triptans with SSRIs or SNRIs 6

Special Population Considerations

• Children and adolescents: Different treatment approaches including bed rest, ibuprofen for acute treatment 1
• Older adults: Higher risk of secondary headache and adverse medication events 1
• Pregnant women: Limited medication options; acetaminophen safest for acute treatment 1

Remember that while most headaches evaluated in primary care are benign, a systematic approach to assessment is essential to identify the potentially life-threatening causes that require immediate intervention.