Makindo Medical Notes

Related Subjects: |Hypertension |Subarachnoid Haemorrhage |Perimesencephalic Subarachnoid haemorrhage |Haemorrhagic stroke |Acute Stroke Assessment (ROSIER&NIHSS)

💥 The main cause of subarachnoid haemorrhage (SAH) is rupture of a berry aneurysm. Any sudden "thunderclap headache" should be considered SAH until proven otherwise. See the SAH management topic for full details.

🧠 Introduction

• Berry (saccular) aneurysms are developmental vascular abnormalities of the Circle of Willis and its branches.
• Causes include inherited connective tissue weakness, anatomical defects, and abnormal haemodynamic flow.
• Not present at birth but may appear in early adulthood, enlarge, and rupture later in life.
• Account for ~5% of all strokes but with high mortality and morbidity.
• Most remain asymptomatic lifelong; a minority rupture, causing subarachnoid haemorrhage (SAH).

🖼️ Images

⚠️ Presentation

• 💥 Sudden “thunderclap” headache or collapse due to SAH → emergency referral to neurosurgery.
• 70–80% of non-traumatic SAH cases are from aneurysmal rupture.
• 🔍 Sentinel bleeds: up to 50% report a sudden severe headache days/weeks before rupture.
• Pressure effects from large aneurysms may cause cranial nerve palsies (e.g. IIIrd nerve palsy with PCoA aneurysm).
• Asymptomatic aneurysms may be detected incidentally or through family screening.

📌 Anatomy

• Aneurysms have a neck and dome. Rupture usually occurs from the dome.
• Typically form at arterial bifurcations where the media and internal elastic lamina are deficient.
• Often develop mural thrombus and become irregular with growth.

📊 Risk Factors

• Smoking 🚬 and Hypertension.
• Age >40, female sex, family history of aneurysms.
• Larger aneurysm size and location (posterior circulation, basilar apex, PCoA) increase rupture risk.

🤝 Associations

• ADPKD (Autosomal Dominant Polycystic Kidney Disease).
• Ehlers-Danlos type IV, Marfan syndrome.
• Coarctation of the aorta, bicuspid aortic valve.
• NF1, hereditary haemorrhagic telangiectasia, α1-antitrypsin deficiency.

📍 Common Sites

🩻 Imaging

• Non-contrast CT: Detects SAH acutely; CTA follows if aneurysm suspected.
• CT Angiography (CTA): First-line in most UK centres; quick and widely available.
• MRI/MRA: Shows aneurysms as flow voids; good for follow-up.
• Digital Subtraction Angiography (DSA): Gold standard for small/complex aneurysms and planning intervention.

🩺 Treatment & Prognosis

All ruptured aneurysms require urgent treatment (usually within 24h). Small, incidental aneurysms <7mm are often observed unless symptomatic or high-risk. Mortality after aneurysmal SAH is ~30–40% at 1 month.

🛠️ Treatment Options

• Endovascular Coiling 🌀: Minimally invasive, avoids craniotomy. Preferred if anatomy is suitable. ISAT trial showed better 1-year outcomes than clipping.
• Surgical Clipping ✂️: Craniotomy and aneurysm clipping. Effective but carries procedural risk and higher vasospasm rates.
• Supportive: Nimodipine for vasospasm prophylaxis, neurocritical care, BP control.

Other Aneurysms

• Fusiform: Elongated spindle-shaped aneurysms, often basilar artery. Rarely rupture, mainly compressive symptoms.
• Mycotic: Infective emboli (endocarditis). Risk of infarcts/abscess; treat underlying infection.

📚 References

• ISUIA: International Study of Unruptured Intracranial Aneurysms.
• ISAT Trial: Lancet 2002 – better outcomes with coiling.
• NICE Guidance: Stroke and TIA (NG128, 2019); SAH management pathways.