How should a secondary headache be evaluated and managed?

Secondary Headache Evaluation and Management

The evaluation of secondary headache must begin with immediate identification of red-flag features that indicate life-threatening conditions requiring urgent neuroimaging or emergency referral, followed by targeted diagnostic workup based on the specific suspected etiology. 1

Immediate Red-Flag Assessment

The first priority is to identify features that mandate urgent investigation or emergency admission:

History Red Flags Requiring Immediate Action

• Thunderclap headache (sudden onset reaching maximum intensity within seconds to minutes) suggests subarachnoid hemorrhage and requires immediate non-contrast CT if presenting within 6 hours, followed by lumbar puncture if CT is negative 1, 2
• "Worst headache of life" with abrupt onset indicates serious vascular pathology 1, 2
• New-onset headache after age 50 carries approximately 12-fold higher risk of serious pathology and warrants consideration of temporal arteritis, mass lesions, or other secondary causes 1, 2, 3
• Progressive headache worsening over weeks to months suggests intracranial space-occupying lesion 1, 2
• Headache awakening patient from sleep may indicate increased intracranial pressure 1, 2, 3
• Headache aggravated by Valsalva maneuver, coughing, sneezing, or exercise suggests intracranial hypertension or space-occupying lesion 1, 2
• Persistent headache following head trauma may indicate subdural hematoma or other intracranial injury 1, 2
• Atypical aura (focal neurological symptoms lasting >60 minutes) may indicate stroke, TIA, or arteriovenous malformation 1, 2, 3

Physical Examination Red Flags

• Focal neurological deficits (unilateral weakness, sensory loss, coordination problems) markedly increase likelihood of serious intracranial pathology (likelihood ratio ≈5.3) and mandate immediate neuroimaging 1
• Neck stiffness or limited neck flexion indicates meningitis or subarachnoid hemorrhage and requires immediate evaluation 1, 2
• Unexplained fever suggests meningitis and necessitates urgent workup 1, 2
• Papilledema on fundoscopic examination indicates raised intracranial pressure from mass lesion or idiopathic intracranial hypertension 1
• Altered consciousness, impaired memory, or personality change signals possible secondary causes 1, 2
• Uncoordination may indicate cerebellar pathology 1, 2

Ottawa SAH Rule for Acute Severe Headache

For alert patients >15 years with new severe non-traumatic headache reaching maximum intensity within 1 hour, investigate for subarachnoid hemorrhage if ANY of the following are present:

• Age ≥40 years 1
• Neck pain or stiffness 1
• Witnessed loss of consciousness 1
• Onset during exertion 1
• Thunderclap headache (instantly peaking pain) 1
• Limited neck flexion on examination 1

Diagnostic Imaging Algorithm

Acute Presentations (<6 hours from onset)

• Non-contrast CT head is first-line for suspected subarachnoid hemorrhage presenting within 6 hours (sensitivity 95% on day 0, declining to 74% by day 3 and 50% at 1 week) 1, 3
• If CT is negative and SAH is still suspected, perform lumbar puncture with spectrophotometric analysis for xanthochromia (100% sensitive from 12 hours to 2 weeks after bleed) 3
• CT head is also indicated for acute trauma or abrupt-onset severe headache 2, 3

Subacute Presentations or Suspected Specific Etiologies

• MRI brain with and without contrast is the preferred modality for subacute presentations, suspected tumor, inflammatory processes, or when higher resolution is needed (no ionizing radiation) 1, 2, 3
• MRI without contrast is indicated for suspected seizure-related headache 4
• MRI with sagittal T2-weighted sequence of cranio-cervical junction (with optional phase-contrast CSF flow study) is the study of choice for suspected Chiari I malformation, particularly when occipital headache is worsened by Valsalva maneuver 4

Vascular Imaging

• CTA head and neck is indicated when arterial dissection is strongly suspected; if MRA is inconclusive, CTA provides further evaluation 4
• MRA is indicated for children with sickle cell anemia presenting with headache, and plays an important role in stroke imaging 4
• MRV (in conjunction with MRI) is the imaging study of choice for suspected venous sinus thrombosis or pseudotumor cerebri syndrome; 52% of patients with pseudotumor cerebri show venous obstruction on the dominant side 4
• CTV is an alternative to MRV for venous sinus thrombosis with high sensitivity and specificity, though MRV remains preferred in children 4

Special Population Considerations

Children with Sickle Cell Anemia

• Lower threshold for imaging is warranted because acute headache in these children is more frequently associated with acute CNS events than in the general pediatric population 4
• These patients are at risk for posterior reversible encephalopathy syndrome (especially post-bone marrow transplant) and subarachnoid hemorrhage (especially with arterial aneurysm) 4
• History of stroke, TIA, seizures, neurologic symptoms, focal examination findings, or elevated platelet counts warrants confirmatory imaging 4
• MRI is the modality of choice due to superior sensitivity for infarction and parenchymal abnormalities 4
• MRA is indicated in the setting of headache 4

Suspected Pseudotumor Cerebri Syndrome (PTCS)

• MRI with MRV is indicated; look for dilatation of optic nerve sheaths on fat-suppressed sequences 4
• Venous outflow obstruction may be reversible after lumbar puncture, suggesting it could be secondary to increased intracranial pressure itself 4
• When cerebellar tonsillar ectopia >5 mm is identified, consider PTCS as well 4

Suspected Giant Cell Arteritis

• Obtain ESR and CRP, recognizing that ESR can be normal in 10-36% of giant cell arteritis cases 2, 3
• Refer to rheumatology for temporal artery biopsy and management 3

When Neuroimaging is NOT Indicated

• Typical migraine with completely normal neurological examination has extremely low probability of serious intracranial pathology (≈0.2%, comparable to 0.4% in asymptomatic volunteers) 1, 3
• Ordering imaging solely for patient reassurance or anxiety, without red-flag findings, exposes patients to unnecessary radiation, cost, and risk of incidental findings leading to further unwarranted testing 1

Common Pitfalls to Avoid

• Do not rely solely on neuroimaging without considering the complete clinical picture—history and examination findings must guide the diagnostic approach 1
• Do not dismiss new-onset headaches in patients >50 years—this age group has substantially higher risk of secondary causes 1, 2, 3
• Do not overlook the need for neuroimaging when red flags are present—failure to investigate can significantly worsen morbidity and mortality 2, 5
• Do not assume a preexisting primary headache disorder excludes secondary headache—patients with primary headaches can acquire secondary conditions that present as a change in baseline pattern 5, 6
• Do not order CT when MRI is more appropriate—except for acute hemorrhage or when MRI is unavailable, MRI provides superior resolution without radiation exposure 1, 2
• Do not delay CT if MRI is not available or feasible when acute stroke is suspected 4

Management Based on Etiology

Life-Threatening Conditions Requiring Emergency Admission

• Subarachnoid hemorrhage: Immediate neurosurgical consultation 1, 3
• Meningitis: Immediate infectious disease consultation, empiric antibiotics before imaging if bacterial meningitis suspected 1, 2, 3
• Acute stroke: Immediate stroke team activation 4
• Arterial dissection: Immediate vascular neurology or neurosurgery consultation 4

Urgent Referral (Within 48 Hours to 1 Month)

• Suspected spontaneous intracranial hypotension (orthostatic headache): Urgent neurology referral within 48 hours 3
• Suspected giant cell arteritis: Urgent rheumatology referral, start high-dose corticosteroids pending biopsy 3
• Diagnosis in doubt or first-line treatments fail: Routine neurology referral within 2-4 weeks 3
• Rapid clinical deterioration or serious complications: Urgent specialist referral within 1 month 3

Outpatient Management

• Confirmed primary headache disorder without red flags can be managed with appropriate acute and preventive therapies 3, 7
• Medication-overuse headache (≥15 headache days/month with overuse of non-opioid analgesics ≥15 days/month or other acute medications ≥10 days/month for >3 months) requires withdrawal of overused medications and preventive therapy 2, 3, 7