The accessory middle cerebral artery (AMCA). Diagnostic and therapeutic consequences.

The existence of the accessory middle cerebral artery (AMCA) is a rare anatomical variation with an estimated incidence of 0.31%. The embryological development of this artery is unknown. Three anatomical subtypes are described: in the type 1 variety the AMCA arises from the internal carotid artery; in the type 2, the AMCA originates from the proximal part of the anterior cerebral artery; in type 3, the AMCA arises from the distal part of the anterior cerebral artery. The use of endovascular techniques to treat cerebral vascular malformations requires knowledge of the anatomical subtype of AMCA and the brain regions it supplies (cortex, basal ganglia).