Can aneurysms present with simple headache?

Can Aneurysms Present with Simple Headache?

Yes, cerebral aneurysms can present with headache alone, though the characteristics typically distinguish them from "simple" benign headaches—and recognizing these warning features is critical to preventing catastrophic rupture.

Clinical Presentation Patterns

Ruptured Aneurysms

The classic presentation of aneurysmal rupture is unmistakable and should never be confused with a simple headache:

• The "thunderclap" headache occurs in 80% of patients with ruptured aneurysms, described as "the worst headache of my life" with sudden onset reaching maximal intensity within 1 hour or immediately 1, 2, 3
• Associated symptoms include nausea/vomiting (77%), nuchal rigidity (35%), brief loss of consciousness (53%), photophobia, and focal neurological deficits 2
• Hunt and Hess Grade 1 specifically describes "asymptomatic or mild headache" as a presentation of subarachnoid hemorrhage, indicating even ruptured aneurysms can occasionally present with less dramatic symptoms 4

Unruptured Aneurysms: The Critical Warning Signs

Sentinel or warning headaches occur in 10-43% of patients with aneurysmal SAH within 2-8 weeks before major rupture, representing minor bleeding episodes that are frequently misdiagnosed 3, 5. These are not "simple" headaches:

• The onset is sudden and unusual in severity and location, unlike any headache the patient has previously experienced 5
• Frequently accompanied by transient nausea, vomiting, visual disturbances, or meningism 5
• Dismissing these warning headaches increases the odds of early rebleeding 10-fold 3

Unruptured aneurysms without hemorrhage can also cause headache through acute expansion or mass effect:

• Thunderclap headache without subarachnoid hemorrhage has been documented with unruptured aneurysms showing very thin aneurysm domes, indicating high rupture risk 6
• Cluster-like headache patterns have been reported with carotid artery aneurysms, resolving after surgical clipping 7
• Headache is common in patients with unruptured aneurysms (65% in one series), particularly with aneurysms of the ophthalmic segment (C6) of the internal carotid artery and sphenoidal segment (M1) of the middle cerebral artery 8
• These headaches are typically deep pain occurring more than 15 days per month, with severity greater than 5/10 in 85% of cases 8

Incidental Aneurysms

Guidelines explicitly distinguish between aneurysm-related headaches and incidental findings during workup for clearly unrelated headaches (migraine, tension-type headache) 4. The causality between unruptured aneurysms and chronic headache patterns remains unclear, and most headaches in patients with unruptured aneurysms are thought to be incidental 9.

Critical Red Flags That Distinguish Aneurysmal Headache

Never dismiss a headache as "simple" if any of these features are present:

• Sudden onset reaching peak intensity within seconds to minutes 2
• "Worst headache of my life" description 1, 2, 3
• Progressive worsening over weeks with personality or cognitive changes 3
• Associated focal neurological deficits or cranial nerve palsies 4, 2
• Brief loss of consciousness 2
• Nuchal rigidity or meningeal signs 2, 5

Common Diagnostic Pitfalls

Misdiagnosis of aneurysmal SAH occurs in up to 12% of cases, with failure to obtain neuroimaging being the most common error 3. Warning headaches are frequently misinterpreted as migraine, tension headache, influenza, sinusitis, or neck strain 5.

The most critical mistake is dismissing headache without recognizing red flags, as misdiagnosis carries a nearly 4-fold higher likelihood of death or disability 3.

Immediate Diagnostic Approach for Suspected Aneurysmal Headache

• Obtain urgent non-contrast head CT immediately for any thunderclap or severe sudden-onset headache 3
• CT sensitivity is 98.7% within 6 hours when interpreted by fellowship-trained neuroradiologists, and remains close to 100% in the first 3 days 2
• If CT is negative but clinical suspicion remains high, perform lumbar puncture to evaluate for xanthochromia (sensitivity 100%, specificity 95.2% when performed >6-12 hours after symptom onset) 2, 3
• If warning headache is suspected, lumbar puncture is the examination of choice once CT has ruled out mass lesion 5

Bottom Line for Clinical Practice

While unruptured aneurysms can be associated with various headache patterns, the term "simple headache" should never apply to aneurysmal presentations. The key is recognizing that aneurysm-related headaches have distinctive warning features—sudden onset, unusual severity, atypical location, or associated neurological symptoms—that demand immediate neuroimaging. A more vigilant attention to warning headaches offers the greatest opportunity for altering the otherwise serious natural history of aneurysmal subarachnoid hemorrhage 5.