Ophthalmic Artery Variant Affecting the Treatment of Olfactory Groove Meningioma

A 58-year-old lady with no known prior comorbidities presented with an indolent frontal headache that worsened over the last month. It was worse at night, causing her sleep disturbances without any postural relationship. There were no history or examination findings suggesting seizures, focal neurodeficits, or trauma. Bilateral visual acuity was preserved with normal and equally reacting pupils. Contrast-enhanced MRI of the brain revealed a large midline extra-axial lesion in the anterior skull base, suggestive of olfactory groove meningioma (OGM) elevating the frontal lobes and displacing the vascular flow voids with intense, homogeneous enhancement [Figure 1]. Preoperative digital subtraction angiography (DSA) showed the right ophthalmic artery (OphA) originating from the right middle meningeal artery (MMA), just proximal to its frontal branch origin, instead of the Internal Carotid Artery (ICA) [Figure 2]. Abnormal tumor blush was seen from the dural branches of the bilateral ophthalmic arteries. As the patient did not consent to the risk of vision loss, surgery was done without preoperative embolization.Figure 1: Contrast-enhanced MRI of olfactory grove meningioma with axial flair (a), T2 (b), T1 pre- (d) and post-contrast (e), sagittal T1 pre- (c) and post-contrast (f) images showing a midline homogeneously enhancing tumor with peri-focal edema aroundFigure 2: Diagnostic cerebral angiograms of the right ICA (a) showing absence of ophthalmic artery origin (open arrowhead), right ECA run (b) showing choroidal blush (arrowheads) and ophthalmic artery origin from the middle meningeal artery (thin black arrow) and selective microcatheter canulation of the variant ophthalmic artery through it (c) showing both tumor blush (thick arrows) as well as choroidal blush (arrowheads)OGMs are a part of the hypervascular skull-base meningiomas, comprising approximately 44% of all skull-base tumors.[1] They are usually supplied by the hypertrophied external carotid artery branches such as the sphenopalatine artery or MMA, which offer safe and effective embolization before surgery.[2] The replaced origin of the OphA from MMA has been reported in up to 16% of cadaveric dissections.[3] Inadvertent embolization of MMA without noticing the variant OphA can cause irreversible on-table blindness. Embolization of the tumors fed by the OphA is possible by canulating it distal to the bend demarcating the ocular end-arteries and avoiding proximal reflux.[4] OGM excision without preoperative embolization may be incomplete with >1 L preoperative blood loss, as in our case. Detailed analysis of vascular anatomy by DSA and selective angiograms is sine-qua-non for the safe and effective treatment of OGMs. The patient has provided informed consent for the publication of the case. Abbreviations DSA = Digital Subtraction Angiography OGM = Olfactory Groove Meningioma. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.