Signs of an Aneurysm
The clinical presentation of an aneurysm depends critically on its location and whether it has ruptured, with ruptured intracranial aneurysms presenting as "the worst headache of my life" (thunderclap headache) and abdominal aortic aneurysms typically remaining asymptomatic until rupture or presenting as a pulsatile abdominal mass.
Intracranial (Brain) Aneurysms
Ruptured Aneurysm (Subarachnoid Hemorrhage)
The hallmark presentation is distinctive and life-threatening 1:
- Thunderclap headache: Sudden onset, reaching maximal intensity immediately—described by 80% of alert patients as "the worst headache of my life"
- Associated symptoms (in order of frequency):
- Nausea/vomiting (77%)
- Headache (74%)
- Loss of consciousness (53%)
- Nuchal rigidity/stiff neck (35%)
- Photophobia
- Seizures (up to 20%, especially in first 24 hours)
- Focal neurological deficits
- Cranial nerve palsies
Critical warning sign: 10-43% of patients report a "sentinel headache" (warning leak) occurring 2-8 weeks before major rupture 1. This sentinel headache is usually milder but may last several days. Recognizing this warning leak is lifesaving, as it precedes catastrophic rupture and increases the odds of early rebleeding 10-fold 1.
Unruptured Aneurysm
Most remain asymptomatic until rupture 2, 3. When symptomatic:
Acute presentations (37% of symptomatic cases):
Chronic presentations (32% of symptomatic cases):
- Persistent headache (51%)
- Visual deficits (29%)—from compression of optic pathways 4
- Weakness (11%)
- Facial pain (9%)
Important caveat: Larger aneurysms (>2 cm) are more likely to cause symptoms through mass effect 3.
Abdominal Aortic Aneurysm (AAA)
Unruptured AAA
Most AAAs are asymptomatic and discovered incidentally 5, 6:
- Pulsatile abdominal mass (when large enough to palpate)
- Vague abdominal or back discomfort
- No symptoms in majority of cases
Screening context: AAA screening is cost-effective for men >65 years who have ever smoked 6. Risk factors include hypertension, smoking, three-vessel coronary disease, and first-degree male relative with AAA 5.
Ruptured or Symptomatic AAA
This is a surgical emergency with high mortality:
- Severe, sudden abdominal or back pain
- Hypotension/shock
- Pulsatile abdominal mass with tenderness
- 12% die before reaching medical attention 7, 1
Radiological signs of rupture include retroperitoneal hematoma, contrast extravasation, high crescent sign, and paraortic fat stranding 8.
Thoracic Aortic Aneurysm (TAA)
Most patients are asymptomatic, diagnosed incidentally during imaging for other reasons 8:
When Symptomatic:
- Chest or back pain (suggests rapid expansion or impending rupture) 9
- Aortic regurgitation (with aortic root involvement)
- Compression symptoms:
- Hoarseness (recurrent laryngeal nerve)
- Dysphagia (esophageal compression)
- Dyspnea (tracheal/bronchial compression)
High-risk features beyond diameter include saccular morphology, uncontrolled hypertension, rapid growth rate (≥3 mm/year for ascending, ≥10 mm/year for descending), and relation to patient's height 8.
Common Diagnostic Pitfalls
Misdiagnosis of ruptured intracranial aneurysm: Historically occurred in 12-64% of cases 1. The most common error is failure to obtain noncontrast head CT. Misdiagnosis increases likelihood of death or disability 4-fold 1.
Dismissing sentinel headache: Since headache is common (1% of ED headaches are from SAH), a high index of suspicion is essential for sudden, severe headaches 7, 1.
Variable presentations: Individual findings occur inconsistently—not all patients have the classic presentation 1.
Asymptomatic nature of most aneurysms: Both AAA and intracranial aneurysms typically remain silent until complications occur, emphasizing the importance of appropriate screening in high-risk populations 5, 2, 6.