Carotid rete mirabile associated with subarachnoid hemorrhage

A 47-year-old man presented with carotid rete mirabile manifesting as subarachnoid hemorrhage (SAH). Computed tomography showed SAH, and angiography disclosed an abnormal vascular network around the petrous and cavernous portions of the internal carotid artery. Single photon emission computed tomography (SPECT) with technetium-99m methyl cysteinate dimer revealed reduced regional cerebral blood flow (CBF). Twelve months later, he was leading a normal life without neurological problems, hemorrhage, or ischemic manifestations. SPECT with iodine-123 N-isopropyl-p-iodoamphetamine and the acetazolamide challenge test showed the CBF had normalized.