Danger Signs for Headaches Requiring Immediate Medical Attention
The most critical danger signs for headaches requiring immediate medical attention include sudden onset "thunderclap" headache (worst headache of life), headache with focal neurological deficits, altered consciousness, neck stiffness, fever, or headache following trauma, as these may indicate life-threatening conditions such as subarachnoid hemorrhage, stroke, or meningitis. 1
Red Flag Signs and Symptoms
Immediate Emergency Evaluation Required
- Thunderclap headache - sudden, severe headache reaching maximal intensity within seconds to minutes, described as "worst headache of life" 1
- Focal neurological deficits - including weakness, numbness, visual changes, speech difficulties 1, 2
- Altered mental status - confusion, decreased level of consciousness 1
- Neck stiffness/meningismus - may indicate subarachnoid hemorrhage or meningitis 1
- Headache following head trauma - especially with loss of consciousness 1, 3
- Headache worsened by Valsalva maneuver (coughing, straining) 4
- Headache causing awakening from sleep 4
- Headache with rapidly increasing frequency or severity 4, 2
High-Risk Patient Populations
- Age >50 years with new-onset headache 2
- Immunocompromised patients 2
- History of cancer 2
- Pregnancy or postpartum period 4
Concerning Associated Symptoms
- Visual disturbances - blurred vision, double vision 1
- Photophobia (sensitivity to light) with other concerning features 1
- Nausea/vomiting - particularly when severe or persistent 1
- Fever - may indicate infection 1
- Papilledema - swelling of the optic disc, indicating increased intracranial pressure 2
- Personality changes - new onset behavioral changes 2
Potential Life-Threatening Causes
Subarachnoid Hemorrhage (SAH)
- Classic presentation: thunderclap headache ("worst headache of life")
- Often accompanied by nausea, vomiting, neck stiffness, brief loss of consciousness
- Misdiagnosis associated with 4-fold higher likelihood of death or disability 1
- Warning/sentinel headaches may occur 2-8 weeks before major rupture in 10-43% of patients 1
Stroke/Vascular Events
- Sudden severe unilateral headache may indicate carotid or vertebral artery dissection
- May be accompanied by Horner syndrome or other focal neurological deficits 1
- Venous sinus thrombosis - particularly in children with mastoiditis or girls using oral contraceptives 1
Meningitis/Encephalitis
- Headache with fever, neck stiffness, photophobia
- May have altered mental status 1
Increased Intracranial Pressure
- Headache worse when lying down or in the morning
- Associated with papilledema, nausea, vomiting 4
Diagnostic Approach Algorithm
For thunderclap headache or suspected SAH:
For suspected stroke or vascular abnormality:
- MRI with MRA/MRV preferred when available 1
- CT/CTA if MRI unavailable or contraindicated
For suspected infection:
- MRI brain with contrast preferred 1
- Consider lumbar puncture if meningitis suspected
Common Pitfalls to Avoid
- Failure to obtain neuroimaging for patients with red flag symptoms - most common diagnostic error in SAH 1
- Dismissing sentinel headaches - may precede catastrophic rupture by 2-8 weeks 1
- Relying solely on clinical features to distinguish benign from serious causes - SAH cannot be reliably distinguished from non-SAH thunderclap headache on clinical grounds alone 5
- Missing post-traumatic intracranial hemorrhage - headache may be the only symptom 3
- Overlooking medication overuse headache - can complicate diagnosis and management 4
Remember that while headache is a common complaint (accounting for only 1% of all headaches evaluated in emergency departments), recognizing these danger signs is crucial as timely diagnosis and intervention for conditions like SAH can be lifesaving 1.