Ruptured intracranial aneurysms typically produce basal cisternal subarachnoid hemorrhage, yet anterior communicating artery (ACoA) aneurysms may generate atypical hemorrhage distributions that can delay recognition of an aneurysmal etiology. We conducted a focused review of the adult literature describing hemorrhage involving the cavum septi pellucidi (CSP) and related septal compartments, with emphasis on aneurysmal sources, imaging pitfalls, anatomical substrates, and management implications. We integrate the review with an illustrative case: a 45-year-old man presented with thunderclap headache persisting for 5 days and no neurological deficits (WFNS I). MRI demonstrated a fluid–blood level strictly confined to the CSP, and CTA revealed a bilobed ACoA aneurysm abutting the lamina rostralis; microsurgical clipping was performed uneventfully with full recovery. The reviewed literature supports that true intraseptal/CSP hemorrhage is rare, may be mistaken for interhemispheric fissure clot on CT, and can occasionally arise from ACoA/distal anterior cerebral artery aneurysm rupture through a preferential septal route when local midline anatomy permits. Recognition of isolated CSP hemorrhage in adults with acute severe headache should prompt urgent vascular imaging, and post-occlusion care should remain aligned with aneurysmal subarachnoid hemorrhage neurocritical pathways, including consideration of vasospasm prophylaxis and surveillance.
Zavatto et al. (Sun,) studied this question.
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