What are the warning signs that a headache may be life-threatening?

Warning Signs of Life-Threatening Headache

The most critical warning signs that a headache may be life-threatening include sudden onset "thunderclap" headache (worst headache of life), altered mental status, focal neurological deficits, fever with neck stiffness, headache worsening with position changes, and new-onset headache in patients over 50 years or with cancer/immunosuppression history.

Red Flag Symptoms and Signs

Immediate Medical Emergency Signs

• Thunderclap headache: Sudden, severe headache reaching maximum intensity within seconds to minutes 1
• Altered mental status: Confusion, drowsiness, or loss of consciousness (occurs in up to 53% of subarachnoid hemorrhage cases) 1
• Focal neurological deficits: Any weakness, numbness, vision changes, or speech disturbance 2
• Neck stiffness/rigidity: Especially when accompanied by fever (present in 35% of subarachnoid hemorrhage cases) 1, 3
• Seizures: Particularly in the context of a new severe headache (occur in up to 20% of subarachnoid hemorrhage patients) 1

Additional Concerning Features

• Headache triggered by exertion, coughing, or sexual activity 4
• Positional headache: Pain that worsens with changes in position or lying down 2
• Occipital location: Headache primarily in the back of the head (statistically associated with serious underlying disease in children) 5
• New-onset headache in patients >50 years 2, 6
• Headache in immunocompromised patients or those with cancer 6
• Headache that awakens from sleep 2
• Progressive worsening over days/weeks 2
• Inability to describe headache quality (particularly concerning in children) 5

Life-Threatening Causes of Headache

Vascular Causes

1. Subarachnoid Hemorrhage (SAH)

   • Classic presentation: Sudden "worst headache of life" 1
   • Warning/sentinel bleeds occur in 15-37% of cases, typically 2-8 weeks before catastrophic rupture 1
   • Rebleeding risk is highest in first 24 hours (15%) with 70% mortality rate 1

2. Cerebral Venous Sinus Thrombosis

   • May present with severe headache that can be difficult to diagnose due to nonspecific manifestations 7
   • Associated with conditions like hyperthyroidism, dehydration, or hypercoagulable states 7

3. Intracranial Hemorrhage

   • May present with headache, focal neurological deficits, and altered mental status 2

Infectious Causes

1. Meningitis

   • Presents with headache, fever, neck stiffness, photophobia 3
   • Headache may be severe, bilateral, and of abrupt onset in aseptic meningitis 3
   • Requires immediate lumbar puncture if suspected 2

2. Encephalitis

   • Headache with altered mental status, seizures, and focal neurological deficits 2
   • MRI with contrast is indicated for suspected cases 2

Space-Occupying Lesions

1. Brain Tumor

   • Presents with progressively worsening headache, often worse in morning or with position changes 5
   • May be accompanied by vomiting, seizures, or focal neurological deficits 5

2. Brain Abscess

   • Headache with fever, focal neurological deficits 2

Diagnostic Approach for Suspected Life-Threatening Headache

Immediate Evaluation

1. Non-contrast CT scan: First-line imaging for suspected subarachnoid hemorrhage (sensitivity approaching 100% in first 3 days) 1

2. Lumbar puncture: If CT negative but clinical suspicion remains high for SAH or meningitis 1, 3

3. MRI with contrast: For suspected brain tumor, abscess, or encephalitis 2

4. CT angiography or MR angiography: For suspected vascular abnormalities 1

Clinical Pitfalls to Avoid

• Dismissing a severe headache without thorough evaluation in patients with risk factors
• Failing to recognize sentinel bleeds before catastrophic aneurysm rupture 1
• Not performing lumbar puncture when CT is negative but clinical suspicion for SAH or meningitis remains high 1
• Relying solely on clinical features to distinguish between life-threatening and benign causes (clinical features alone cannot reliably distinguish SAH from non-SAH thunderclap headaches) 4

Special Populations

Children and Adolescents

• Most acute severe headaches in children are due to upper respiratory infections (57%), followed by migraine (18%) and viral meningitis (9%) 5
• Serious causes like brain tumors (2.6%) and intracranial hemorrhage (1.3%) are less common but require vigilance 5
• Occipital location and inability to describe pain quality are statistically associated with serious disease in children 5

Elderly Patients

• New-onset headache in patients over 50 years warrants thorough investigation 2, 6
• Higher risk of secondary causes including temporal arteritis, intracranial masses, and vascular events 6

Remember that while most headaches are benign, recognition of these warning signs allows for timely intervention in potentially life-threatening conditions.