Ruptured distal anterior cerebral artery aneurysm presenting with acute subdural hematoma without subarachnoid hemorrhage

We report a case of distal anterior cerebral artery (DACA) aneurysm presenting with subdural hematoma (SDH) without subarachnoid hemorrhage (SAH). A patient in his fifties presented with headache. Fluid-attenuated inversion recovery magnetic resonance imaging revealed SDH in the interhemispheric fissure and left frontotemporal region. SAH was not detected. Computed tomographic angiography revealed aneurysms in the left internal carotid artery (ICA) and DACA. The patient underwent frontotemporal craniotomy, which confirmed an unruptured ICA aneurysm, followed by bilateral frontal craniotomy for clipping of DACA aneurysm. The left DACA aneurysm was identified as the source of the SDH. Intraoperative findings showed adhesion between the aneurysm body and falx cerebri, explaining the SDH formation. Literature review identified only six reported cases of SDH without SAH due to DACA aneurysm. Evidence suggests that DACA aneurysms have a relatively higher propensity to cause SDH without SAH, likely due to the anatomical characteristics of the parent vessel and aneurysm projection.