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1492. Infraoptic ACA or Carotid – ACA Anastomosis: A Very Rare Embryological Variation
Authors * Denotes Presenting Author
  1. Einat Slonimsky *; Hershey Medical Center
  2. Sangam Kanekar; Hershey Medical Center
Objective:
An infraoptic course of the ACA is a rare cerebrovascular variation that can be associated with anterior communicating artery aneurysm. The purpose of this study is: 1. Describe infraoptic ACA or Carotid-ACA anastomosis, a very rare vascular anatomic variation. 2. Discuss the embryology of this variant. 3. Demonstrate this rare embryological variation on CT and MR angiography. 4. Discuss its clinical significance. 5. Understand the anatomy for appropriate management of associated vascular pathology (Anterior communicating aneurysm).

Materials and Methods:
Variations of the anterior cerebral artery–anterior communicating artery complex are common, however of little clinical significance. An infraoptic course of the ACA is a very rare variation. The magnetic resonance angiographic prevalence has been reported to be 0.086%.About 44% of patients with an infraoptic course of the ACA are associated with Anterior communicating artery aneurysm. This makes it a clinically important vascular variation for endovascular treatment planning. We describe the CT and MR angiographic findings of this rare vascular variation along with review of its embryology.

Results:
Generally, ACA arises from the internal carotid artery (ICA) terminus and runs medially superior to the optic nerves (supraoptic course) and communicates with contralateral ACA through the anterior communicating artery. An infraoptic course of the A1 segment of the ACA is associated with a low ICA bifurcation. The bifurcation is usually located intradurally at or just above the level of the origin of the ophthalmic artery. Rarely, infraoptic origins of A1 are proximal or at the level of origin of the ophthalmic arteries and arise below the optic strut possibly extradurally. Abberant ACA course has been shown to be associated with aneurysms. This needs its prompt recognition, to allow optimum treatment planning (surgical / endovascular). Understanding and reporting of this variant is clinically important for management, either surgical or endovascular.

Conclusion:
Abberant ACA course has been shown to be associated with aneurysms. This needs its prompt recognition, to allow optimum treatment planning (surgical / endovascular). Understanding and reporting of this variant is clinically important for management, either surgical or endovascular.