Introduction: Carotid-Ophthalmic aneurysms are a subgroup of vascular lesions, accounting for 11% of all intracranial aneurysms and requiring technically challenging treatment strategies with a relatively high morbidity. The objective of this study was to characterize the feasibility of superficial temporal artery (STA) to intraorbital ophthalmic artery (OpA) bypass for the effective management of such lesions.
Methods: A total of ten cadaveric specimens were dissected. An orbitopterional craniotomy was performed with prior isolation of the frontal branch of STA. Microsurgical exposure of OpA was achieved using a superomedial transorbital approach. The calibers of frontal STA and OpA proximal to central retinal artery (CRA) were measured. An end-to-end anastomosis was performed from STA to OpA and the required length of donor artery was recorded.
Results: The intraorbital OpA was found to be related inferolaterally (90%) and inferomedially (10%) to the optic nerve. The distance from intraorbital entrance of OpA to CRA was 7.3±1.5mm. The distance from the superficial periorbita to proximal segment of OpA was 33.4±3.2mm and superficial transposition of OpA reduced it by an average of 9.2mm, decreasing the depth of the surgical corridor. The mean calibers of frontal branch of STA and OpA at the anastomotic site were 1.5±0.1mm and 1.5±0.1mm, respectively. The required STA graft length for a tension-free bypass construct was 130.8±14mm. The mean surgical area for the bypass was 1.2±0.3cm2.
Conclusions: This study confirmed the feasibility of STA-OpA bypass with good caliber match and graft length. This bypass could offer prophylactic or therapeutic neuroprotection, potentially salvaging vascular supply to intraorbital OpA in the management of complex ophthalmic aneurysms, which fail endovascular management or require complete trapping with an intradural OpA sacrifice. This technique could also be used in cases of intracanalicular/intraorbital ophthalmic aneurysms and iatrogenic injury to the OpA. Clinical translation will be required to determine its applicability in neurosurgical practice.
Patient Care: Microvascular reconstruction using the STA-OpA bypass can prevent ischemic injury to the central retinal artery thus, preserving visual function. Additionally, to aid the surgical management of complex ophthalmic aneuryms, the intradural segment of the ophthalmic artery can be ligated or sacrificed after completing the bypass.
Learning Objectives: 1. To understand the anatomy of ophthalmic artery, in particular the origin of the central retinal artery and the intraorbital branches.
2. To understand the technique for an EC-IC bypass from STA to proximal extradural ophthalmic artery via a superomedial transorbital approach