What are the red flags for headaches that require immediate medical evaluation?

From the Guidelines

Headaches that present with certain concerning features, such as sudden onset of the worst headache of your life (thunderclap headache), require immediate medical evaluation to rule out potentially life-threatening conditions like subarachnoid hemorrhage (SAH) or other serious causes. According to the Ottawa SAH Rule, as outlined in the 2023 guideline for the management of patients with aneurysmal subarachnoid hemorrhage 1, red flags for headaches that necessitate immediate medical attention include:

• Age ≥40 years
• Neck pain or stiffness
• Witnessed loss of consciousness
• Onset during exertion
• Thunderclap headache (instantly peaking pain)
• Limited neck flexion on examination These criteria are designed to identify patients who may have a SAH, which is a medical emergency. The guideline emphasizes the importance of a thorough evaluation, including imaging studies like noncontrast head CT, which can detect SAH with high sensitivity, especially when interpreted by fellowship-trained, board-certified neuroradiologists 1. Key points to consider in the evaluation of headaches include:
• Sudden onset of severe headache
• Headaches accompanied by fever, stiff neck, confusion, seizures, double vision, weakness, or numbness
• Headaches that wake the patient from sleep, occur with exertion, or worsen when changing positions
• New headaches in people over 50 or those with cancer, HIV, or pregnancy
• Headaches following head trauma, especially with vomiting or altered consciousness
• Progressive headaches that worsen over days or weeks rather than improving These warning signs may indicate serious conditions like meningitis, brain hemorrhage, stroke, tumor, or increased intracranial pressure, and delaying medical care in these situations could lead to permanent neurological damage or be life-threatening 1.

From the Research

Headache Red Flags

Headache red flags are warning signs that indicate a headache may be a symptom of a more serious underlying condition. The following are some of the red flags that require immediate medical evaluation:

• Sudden or abrupt onset of headache 2, 3
• New neurological deficit, such as decreased consciousness or confusion 2, 3
• History of neoplasm or cancer 2, 3
• Older age, typically over 50 years 2
• Recent head trauma, typically within 2-7 days prior to headache onset 2
• Pregnancy or puerperium 2, 3
• Immune suppression, such as HIV/AIDS 3
• Painful eye with autonomic features, such as tearing or redness 4, 3
• Posttraumatic onset of headache 3
• Pathology of the immune system, such as HIV/AIDS 3
• Systemic symptoms, such as fever or weight loss 3
• Pattern change or recent onset of new headache 3
• Positional headache, which worsens with certain positions or activities 3
• Precipitated by sneezing, coughing, or exercise 3
• Papilledema, or swelling of the optic disc 3
• Progressive headache or atypical presentations 3

Clinical Evaluation

A thorough clinical evaluation is essential to identify headache red flags and determine the underlying cause of the headache. This includes:

• Obtaining a complete headache and medical history 5
• Performing a thorough neurologic examination 5
• Identifying trigger factors and associated symptoms 5
• Evaluating for analgesic rebound headache 5

Diagnostic Approach

The diagnostic approach to headache evaluation involves:

• Classifying headaches as primary or secondary 5
• Identifying red flags and orange flags for secondary headaches 3
• Using the SNNOOP10 list to screen for secondary causes 3
• Ordering specific tests based on a working diagnosis, rather than an exhaustive battery of tests 6