Perimesencephalic Hemorrhage: Illustrative Case Report Involving “Spot Sign”

Nonaneurysmal perimesencephalic hemorrhage (PMSAH) is a form of subarachnoid hemorrhage with a generally favorable prognosis. The majority of PMSAH cases present with normal cerebral angiography with an unknown exact source of bleeding. However, it is classically thought to be venous in origin. We present a rare case of active or recent venous prepontine “spot sign” extravasation of a 59-year-old man, identified on admission computed tomography angiography but negative on catheter-based angiography and follow-up imaging, strongly suggesting an evident venous cause.