Headache Syndromes: Primary and Secondary Headache Evaluation

Headache disorders represent one of the most common neurological complaints, affecting up to 96% of the population at some point in their lives. The International Classification of Headache Disorders (ICHD-3) categorizes headaches into primary and secondary types.

[KEY_CONCEPT] Primary headaches have no underlying structural cause and include:

• Migraine (with and without aura)
• Tension-type headache
• Cluster headache and other trigeminal autonomic cephalalgias

[KEY_CONCEPT] Secondary headaches result from underlying pathology and require immediate evaluation for potentially life-threatening conditions.

Epidemiology

[CLINICAL_PEARL] The "POUND" mnemonic helps identify migraine features: Pulsating, One day duration, Unilateral, Nausea/vomiting, Disabling intensity.

Pathophysiology of primary headaches involves dysfunction of the trigeminovascular system, with activation of trigeminal afferents innervating cranial blood vessels, leading to neurogenic inflammation and pain transmission through the trigeminal nucleus caudalis.

[HIGH_YIELD] Red flag symptoms require immediate evaluation: sudden onset "thunderclap" headache, fever with neck stiffness, focal neurological deficits, papilledema, and headache with altered mental status.

Migraine Clinical Features

[KEY_CONCEPT] Migraine without aura (85% of cases):

• Duration: 4-72 hours if untreated
• Quality: Pulsating, throbbing
• Location: Unilateral (but can be bilateral)
• Intensity: Moderate to severe
• Associated symptoms: Nausea, vomiting, photophobia, phonophobia
• Aggravating factors: Physical activity

Migraine with aura (15% of cases) includes visual, sensory, or speech disturbances lasting 5-60 minutes, typically preceding headache.

[CLINICAL_PEARL] Typical aura features include scintillating scotomata (zigzag lines), fortification spectra, or spreading visual disturbances that develop gradually over 5+ minutes.

Cluster Headache Features

[HIGH_YIELD] Cluster headaches are characterized by:

• Timing: Strictly unilateral, orbital/temporal location
• Quality: Severe, boring, non-pulsating pain
• Duration: 15 minutes to 3 hours
• Frequency: 1-8 attacks per day during cluster periods
• Associated symptoms: Ipsilateral autonomic features (lacrimation, rhinorrhea, ptosis, miosis)
• Behavior: Restlessness and agitation (unlike migraine patients who prefer stillness)

Tension-Type Headache

• Quality: Pressing, band-like, non-pulsating
• Location: Bilateral
• Intensity: Mild to moderate
• Duration: 30 minutes to 7 days
• Associated symptoms: Minimal (mild photophobia OR phonophobia, not both)

[CLINICAL_PEARL] Circadian patterns are pathognomonic for cluster headaches, often occurring at the same time daily, frequently awakening patients from sleep.

Primary Headache Diagnosis

Migraine without aura diagnostic criteria (requires ≥2 of A, plus B and C):

A. Headache characteristics (≥2 required):

• Unilateral location
• Pulsating quality
• Moderate to severe intensity
• Aggravated by physical activity

B. Associated symptoms (≥1 required):

• Nausea and/or vomiting
• Photophobia and phonophobia

C. Duration: 4-72 hours (untreated)

Secondary Headache Red Flags

[HIGH_YIELD] SNOOP10 mnemonic for red flag features:

S - Systemic symptoms/illness N - Neurologic symptoms/signs O - Onset sudden (thunderclap) O - Older age (>50 years new onset) P - Pattern change P - Precipitated by Valsalva P - Papilledema P - Progressive headache P - Pregnancy/postpartum P - Painful eye with autonomic features

Diagnostic Algorithm

New Headache Presentation ↓ Red Flag Present? ↙ ↘ YES NO ↓ ↓ Immediate Primary headache workup evaluation ↓ ↓ • CT/MRI Pattern recognition: • LP if • Migraine criteria indicated • Cluster features • Labs • Tension-type

[CLINICAL_PEARL] Neuroimaging indications include: first/worst headache, focal neurologic signs, altered mental status, headache with fever, or significant pattern change.

Essential diagnostic questions:

1. Onset pattern (gradual vs. sudden)
2. Location and quality
3. Duration and frequency
4. Associated symptoms
5. Triggers and relieving factors
6. Response to previous treatments

Migraine Acute Treatment

[KEY_CONCEPT] Stratified care approach based on headache severity and disability:

Mild-Moderate Migraine:

• NSAIDs: Ibuprofen 400-800mg, Naproxen 220-550mg
• Combination analgesics: Acetaminophen + Aspirin + Caffeine

Moderate-Severe Migraine:

• Triptans (first-line): Sumatriptan 25-100mg PO, Rizatriptan 10mg PO
• Contraindications: Coronary artery disease, cerebrovascular disease, uncontrolled hypertension

[HIGH_YIELD] Triptan mechanism: Selective 5-HT1B/1D receptor agonists causing vasoconstriction and inhibition of neuropeptide release.

Migraine Prevention

Indications for preventive therapy:

• ≥4 headache days per month
• Significant disability despite acute treatment
• Contraindications to acute medications
• Medication overuse headache risk

Cluster Headache Treatment

Acute treatment:

• High-flow oxygen: 12-15 L/min for 15-20 minutes (first-line)
• Sumatriptan: 6mg subcutaneous (most effective route)

Preventive treatment:

• Verapamil: 240-480mg daily (first-line)
• Lithium: 600-900mg daily (alternative)
• Prednisone: Short-term bridge therapy

[CLINICAL_PEARL] Cluster headache acute treatment requires rapid-acting interventions due to the brief attack duration; oral medications are typically ineffective.

Migraine Complications

[HIGH_YIELD] Status migrainosus: Migraine lasting >72 hours, often requiring hospitalization for:

• IV medications (DHE, antiemetics)
• Hydration and electrolyte management
• Exclusion of secondary causes

Chronic migraine: ≥15 headache days per month for ≥3 months, with ≥8 days meeting migraine criteria. Often associated with medication overuse.

Medication Overuse Headache (MOH)

[KEY_CONCEPT] Diagnostic criteria:

• Headache ≥15 days per month
• Regular overuse of acute headache medication for >3 months:
  • Simple analgesics: ≥15 days/month
  • Triptans/combination analgesics: ≥10 days/month

Management: Withdrawal of overused medication with bridging preventive therapy.

Critical Secondary Headaches

Subarachnoid hemorrhage:

• Sudden onset "thunderclap" headache
• Sentinel bleeding in 30-50% before major rupture
• CT sensitivity decreases with time (95% at 12 hours, 85% at 24 hours)

Temporal arteritis (Giant Cell Arteritis):

• Age >50 years
• New temporal headache
• Jaw claudication, visual symptoms
• ESR >50 mm/hr, CRP elevated
• [CLINICAL_PEARL] Urgent ophthalmologic evaluation and steroid initiation to prevent irreversible vision loss

Increased intracranial pressure:

• Progressive headache worse in morning
• Nausea, vomiting
• Papilledema, sixth nerve palsy
• Associated with mass lesions, idiopathic intracranial hypertension

Meningitis/Encephalitis:

• Headache with fever, neck stiffness
• Altered mental status
• Photophobia, phonophobia
• Urgent lumbar puncture if no contraindications

[CLINICAL_PEARL] Post-concussion headache can develop after mild traumatic brain injury and may persist for months, requiring multidisciplinary management [5].

Primary Headache Prognosis

Migraine natural history:

• Peak prevalence in 30s-40s, often improves after menopause in women
• 20-30% of patients achieve sustained remission
• Chronic transformation occurs in 2-3% annually
• [HIGH_YIELD] Cardiovascular risk: Migraine with aura associated with increased stroke risk, especially in women using oral contraceptives

Cluster headache patterns:

• Episodic clusters (85%): Cluster periods lasting weeks to months, followed by remission periods
• Chronic clusters (15%): No remission periods >1 month
• Spontaneous remission possible but unpredictable

Monitoring and Follow-up

Headache diary components:

• Frequency, duration, intensity (1-10 scale)
• Triggers and associated symptoms
• Medication use and effectiveness
• Disability assessment (MIDAS score)

Preventive therapy monitoring:

• Monthly follow-up initially, then quarterly
• Assess efficacy (≥50% reduction in frequency)
• Monitor adverse effects and drug interactions
• Adjust dosing based on response and tolerability

[CLINICAL_PEARL] Treatment goals: Reduce attack frequency by ≥50%, decrease disability, improve quality of life, and prevent medication overuse.

Special Populations

Pregnancy considerations:

• Migraine often improves during pregnancy (especially second/third trimesters)
• Avoid teratogenic medications (valproate, topiramate)
• Safe options: acetaminophen, some beta-blockers
• [KEY_CONCEPT] New-onset headache in pregnancy requires careful evaluation for preeclampsia, cerebral venous thrombosis

Pediatric headache:

• Shorter duration attacks (1-48 hours)
• More often bilateral
• Prominent behavioral changes
• School attendance monitoring important

Elderly patients:

• New-onset headache after age 50 requires imaging
• Consider temporal arteritis, medication interactions
• Lower starting doses for preventive medications