Teaching Case: Nonaneurysmal Perimesencephalic Subarachnoid Hemorrhage

Teaching case on nonaneurysmal perimesencephalic subarachnoid hemorrhage, a benign SAH variant with characteristic prepontine cistern blood and negative CTA/DSA. Conservative management; excellent prognosis.

• Eurorad teaching case illustrating imaging features of perimesencephalic SAH, a subtype with very low risk of underlying aneurysm.
• Classic distribution: blood centered anterior to the brainstem, often with extension into adjacent cisterns, and no aneurysm on angiography.
• Relevant for radiology trainees and general radiologists interpreting emergency head CTs—recognizing this pattern can avoid unnecessary repeated angiography.

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