Which site is more common for sah
SAH (subarachnoid hemorrhage) most commonly arises from rupture of a saccular (berry) aneurysm. The most frequent site is the anterior communicating artery (ACoA), followed by the posterior communicating artery (PCoA) and the middle cerebral artery (MCA) bifurcation.
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The textbooks give a clear, consistent answer. Here is a complete summary:
Most Common Site for SAH (Subarachnoid Hemorrhage)
About 80% of spontaneous SAH cases are caused by rupture of a saccular (berry) aneurysm. These aneurysms form at arterial branch points, and their distribution by frequency is:
| Rank | Location | Approximate Frequency |
|---|---|---|
| 1st | Anterior communicating artery (AComA) | ~30% |
| 2nd | Posterior communicating artery (PComA) | ~25% |
| 3rd | Middle cerebral artery (MCA) bifurcation | ~20% |
| Other | Remaining vessels (basilar, vertebral, etc.) | ~25% |
Key points:
- Over 85% of aneurysms arise from the anterior (carotid) circulation; only ~10% come from the vertebrobasilar system.
- Berry aneurysms are most often found at bifurcation points of the middle cerebral, anterior cerebral/AComA, and posterior communicating arteries.
- They are least common at the vertebral artery.
- Certain conditions increase risk: autosomal dominant polycystic kidney disease and Ehlers-Danlos syndrome type IV.
So, in short: the anterior communicating artery is the single most common site for a ruptured aneurysm causing SAH (~30% of cases).
- Neuroanatomy through Clinical Cases, 3rd Ed.
- Goldman-Cecil Medicine, International Ed.
- Essentials of Forensic Medicine and Toxicology, 36th Ed.
- Grainger & Allison's Diagnostic Radiology
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