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|LETTER TO EDITOR
|Year : 2015 | Volume
| Issue : 5 | Page : 797-799
Infraoptic course of the anterior cerebral artery associated with anterior communicating artery and distal anterior cerebral artery aneurysms
Arun Sadashiva Rao1, Narayanam Anantha Sai Kiran1, Zarina Abdul Assis2, Alangar S Hegde1
1 Department of Neurosurgery, Sri Sathya Sai Institute of Higher Medical Sciences, Bengaluru, Karnataka, India
2 Department of Neuroradiology, Sri Sathya Sai Institute of Higher Medical Sciences, Bengaluru, Karnataka, India
|Date of Web Publication||6-Oct-2015|
Narayanam Anantha Sai Kiran
Department of Neurosurgery, Sri Sathya Sai Institute of Higher Medical Sciences, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Rao AS, Kiran NA, Assis ZA, Hegde AS. Infraoptic course of the anterior cerebral artery associated with anterior communicating artery and distal anterior cerebral artery aneurysms. Neurol India 2015;63:797-9
|How to cite this URL:|
Rao AS, Kiran NA, Assis ZA, Hegde AS. Infraoptic course of the anterior cerebral artery associated with anterior communicating artery and distal anterior cerebral artery aneurysms. Neurol India [serial online] 2015 [cited 2019 Oct 22];63:797-9. Available from: http://www.neurologyindia.com/text.asp?2015/63/5/797/166563
An infraoptic course of the anterior cerebral artery (IO-ACA) is extremely uncommon.,,, We describe a case of IO-ACA associated with anterior communicating artery (ACOM) and distal ACA (DACA) aneurysms.
A 64-year-old lady presented to the emergency department in an altered sensorium (Glasgow Coma Scale score - E2V1M5). Computed tomography brain showed a diffuse subarachnoid hemorrhage. Her digital subtraction angiography (DSA) demonstrated a saccular ACOM aneurysm and another saccular aneurysm arising from the left DACA [Figure 1]a,[Figure 1]b,[Figure 1]c. The right ACA had an unusually early origin at the level of the ophthalmic artery, and an initial horizontal medial course from its origin, before turning superiorly to join the ACOM artery [Figure 1]a and [Figure 1]b. The left A1 segment of ACA was aplastic and the right vertebral artery was hypoplastic [Figure 1]d,[Figure 1]f. At surgery, a single A1 was seen on the right side arising from the proximal intradural internal carotid artery (ICA) at the level of ophthalmic artery and coursing medially below the optic nerve [Figure 1]g and [Figure 1]h. After an initial IO course, the ACA was seen ascending between the optic nerves anterior to the optic chiasm and had a long vertical superior course until it reached the ACOM artery. The ACOM and DACA aneurysms were clipped. The patient's neurological status remained the same until the time of discharge.
|Figure 1: (a-c) Digital subtraction angiogram revealing early bifurcation of the right internal carotid artery at the level of the ophthalmic artery with an initial unusual horizontal medial course from its origin (broken arrow in a) and the coexisting distal anterior cerebral artery aneurysm and anterior communicating artery aneurysm; (d) digital subtraction angiographic showing the aplastic right A1; (e and f) digital subtraction angiogram (e) and computed tomography angiogram (f) showing the hypoplastic right vertebral artery; (g and h) intraoperative images showing an early origin of the right anterior cerebral artery and its infraoptic course (RA1 - right A1 segment of anterior cerebral artery, RO - right optic nerve, LO - left optic nerve)|
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An IO course of the A1 segment was first described by Robinson in 1959. The IO course may be unilateral or bilateral. Unilateral IO-ACA is more commonly reported on the right side. Some authors term this anomalous vessel as “carotid - anterior cerebral artery anastomosis.” This is because an associated ipsilateral hypoplastic normally positioned supraoptic A1 ACA is reported in a few cases. The characteristic angiographic findings of IO-ACA, as also noted in the present case, include an early origin of ACA at the level of ophthalmic artery, and its initial horizontal - medial course before turning superiorly toward the ACOM artery. IO-ACA usually ascends anterior to the chiasm after the initial IO course, as has also been described in the present case. Rarely, the IO-ACA may pierce the optic nerve or chiasma. The various associations described in literature are aneurysm(s) in the circle of Willis, contralateral ICA agenesis, common origin with an ophthalmic artery, azygos ACA, ACA originating from extradural ICA, plexiform ACOM, fused pericallosal artery, duplication of superior cerebellar artery, moyamoya disease, coarctation of aorta, bicuspid aortic valve, abnormal gyrus segmentation, suprasellar craniopharyngioma, and hypoplastic vertebral artery.,,,
Recognition of IO-ACA associated with ACOM aneurysm in the preoperative imaging is important for planning the surgical approach for gaining proximal control of the aneurysm. Proximal A1 segment aneurysms associated with IO-ACA may be difficult to treat surgically as the aneurysm may extend below the optic nerve requiring retraction of the optic nerve. A part of the aneurysm may even be extending into the cavernous sinus in more proximally located aneurysms. IO-ACA makes coiling of the associated ACOM aneurysm easier to perform because of a straighter configuration and a larger size of IO A1 when compared to the supraoptic A1 artery. Considering the much higher incidence of associated aneurysms associated with this anomaly, all patients with IO-ACA should be on regular follow-up.
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