PMC3130469_01
Preoperative (a) axial T1 post-contrast and (b) T2 images demonstrating a large suprasellar mass with a heterogeneously enhancing nodular component and enhancing cystic component. Marked ventriculomegaly of the temporal horns is evident, reflecting obstructive hydrocephalus secondary to the large tumor. The bilateral A1s are not well visualized due to the presence of the mass lesion
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F1
Magnetic resonance imaging (MRI) demonstrated a 4-cm mass with solid and cystic components filling the suprasellar region and causing considerable compression of the optic apparatus [Figure 1a, b].
(a) View of the left-sided (LIA1) and right-sided (RIA1) infraoptic A1s coursing posteriorly in the pre-chiasmatic cistern and over the optic chiasm. The origin of the right infraoptic A1 and right ophthalmic artery (ROph) from the proximal right ICA are also visible. LOn and ROn signify left and right optic nerves, respectively. (b) A Rhoton dissector is utilized to elevate the left infraoptic A1 (LIA1) and reveal the right-sided infraoptic A1 (RIA1) in the pre-chiasmatic cistern. Calcified tumor (*) can be seen filling the optico-carotid cistern between the left internal carotid artery (LICA) and left optic nerve (LOn). (c) Lower magnification view of the left infraoptic A1 (LIA1) taking its origin from the proximal left ICA (LICA) and passing underneath the left optic nerve (LOn). The hypoplastic, supraoptic A1 (LA1) is also seen taking its origin from the left ICA in the more customary location before coursing above the optic apparatus toward the AComm complex (not pictured)
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F2
Initial microdissection revealed two large-caliber vessels ascending between the optic nerves and coursing posteriorly over the chiasm[Figure 2a] Further investigation demonstrated the vessels to be bilateral infraoptic A1 segments. Care was taken to preserve these vessels, as well as the left-sided hypoplastic A1 branch that was found coursing over the chiasm [Figure 2b]. Following gross total resection of the lesion, the infraoptic course of the A1s could be easily visualized [Figure 2c].
Illustration of the operative field after resection of the tumor demonstrating the course of the bilateral infraoptic A1 arteries
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F3
The anatomy of the region is illustrated in Figure 3.
Postoperative (a) axial T1 post-contrast image demonstrating gross total resection of the tumor and (b) axial T2 image illustrating the bilateral infraoptic A1s (arrow) arising from the proximal ICA bilaterally
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F4
In the absence of the large mass, the A1 segments could be seen clearly taking their origin near the level of the OphA and passing beneath the optic nerves bilaterally  [Figure 4a, b].
(a) Lateral and (b) A-P reconstruction of a 3D time-of-flight MR angiogram obtained postoperatively, revealing the hallmark appearance of the infraoptic A1s (arrow) taking a very proximal origin off the bilateral ICAs just distal to the cavernous segment
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F5
Because of the relatively strong association of cerebral aneurysms with an infraoptic A1 anomaly, an MR angiogram was obtained [Figure 5a, b].