Introduction: MCA variants include, duplication, fenestrations, early branching and accessory MCA1. In 1977 Manelfe et al divided the accessory MCA into 3 types. Type 1, arises from the ICA slightly proximal to its bifurcation, type 2 arises from the proximal A1 ACA segment and type 3 arises from the distal A1 segment near Acom artery2. Case Report. 48 year old previously healthy female found down by her daughter. CT/CTA showed subarachnoid hemorrhage, Hunt Hess 4, fisher grade 4 and a left ICA aneurysm. An EVD was placed and subsequently underwent successful coil embolization of a ruptured left carotid ophthalmic aneurysm. Post bleed day 7, she developed severe vasospasm. She underwent transluminal balloon angioplasty of left middle cerebral artery. 7 days after angioplasty Head CT showed Infarction in the left frontal and parietal lobes.

Methods: Technical note. Diagnostic angiogram showed severe vasospasm. Both the main MCA as well as the accessory MCA suffered vasospasm. Angioplasty was only performed along the main MCA (M1) trunk. Approaching the accessory MCA trunk is not recommended. As it originates from the distal A1 segment, accessing it with a hyperglide balloon can be challenging therefore increasing the risk of dissection and/or worsening vasospasm.

Results: Discussion The accessory MCA artery is considered a rare MCA variant, its embryological origin is still unknown and its incidence has been described to be around 0.31% in angiographic series3. The accessory MCA’s cortical blood supply may vary and it mainly supplies the orbitofrontal territory2. Komiyama et al described the role of the accessory MCA as collateral blood supply in the case of ICA/MCA occlusion and concluded that the accessory MCA can provide collateral blood supply but usually not enough to supply the whole MCA territory4.

Conclusions: Knowing congenital variants is essential to understanding collateral blood supply and planning surgical management of intracranial pathology.

Patient Care: Provides guidance on how to approach treatment of vasospasm in patients with normal anatomical variants of intacranial circulation.

Learning Objectives: By the conclusion of this session, participants should be able to know the importance of anatomical variations in the cerebral vasculature and identifye an efective treatment for vasospasm in these cases

References: 1- Makowicz G, Poniatowska R, Lusawa M, Variants of cerebral arteries – anterior circulation. Pol J Radiol. 2013 Jul-Sep; 78(3): 42–47. 2- Komiyama M, Nakajima H, Nishikawa M et al: Middle cerebral artery variations: duplicated and accessory arteries. Am J Neuroradiol, 1998; 19: 45–49 3- Abanou A, Lasjaunias P, Manelfe C, Lopez-Ibor L. The accessory middle cerebral artery (AMCA): diagnostic and therapeutic consequences. Anat Clin 1984;6:305–309 4- Komiyama M, Nishikawa M, Yasui T. The role of the accessory middle cerebral artery as a collateral blood supply. AJNR Am J Neuroradiol 1997;18:587–590