Ruptured anterior cerebral artery aneurysm at the origin of the accessory middle cerebral artery.

A 36-year-old female patient was admitted to our hospital with a rare case of aneurysm at the origin of the accessory middle cerebral artery (MCA) manifesting as severe headache and vomiting. Neurological examination did not detect any abnormalities or consciousness disturbance. Computed tomography demonstrated diffuse subarachnoid hemorrhage. Magnetic resonance angiography showed an aneurysm in the horizontal portion of the left anterior cerebral artery (A(1)). Digital subtraction angiography and three-dimensional digital subtraction angiography demonstrated a saccular aneurysm originating at the junction of the left A(1) and accessory MCA. Another accessory MCA originated at the proximal portion of the left A(2) without an aneurysm. Two accessory MCAs were found on the left. Neck clipping was performed via a left pterional approach. One month after admission, she was discharged without neurological deficits.