Clipping for a Partially Thrombosed Anterior Communicating Artery (AcomA) Aneurysm Presenting with Delayed Visual Loss after Pipeline Embolization Device (PED) Treatment – Case Report

Aim: Aneurysm surgery after endovascular treatment has several constraints. We present the case of clipping of a thrombosed enlarging aneurysm presenting with visual loss after a stenting procedure.

Methods: A 70 years old woman, during investigations for migraine, was diagnosed to have an aneurysm of the AcomA at the left A1-A2 junction, pointing antero-inferiorly, with intraluminal thrombus. Our multidisciplinary team proposed either surgically or endovascular treatment, the latter was preferred by the patient. After antiplatelet therapy, a PED was positioned at the left A1-A2 with immediate contrast stasis within the sac.

AngioMR at 1 month showed no intraaneurysmal flow and the neurological examination was normal. After 3 months the patient developed progressive complete visual loss in the left eye. Visual field and optical coherence tomography (OCT) suggested a lesion of the retrobulbar, prechiasmatic left optic nerve.

MRI/DSA showed normal flow in the parent vessel, exclusion of the aneurysm and paradoxical aneurysmal growth, related to intrasaccular thrombosis, worsening the mass effect on the optic nerve,. After discussion in the neurovascular board we decided to operate. The optic nerve was compressed by turgid thrombosed aneurysm with mixed components. The sac was dissected away from the nerve and excised and the aneurismal neck was clipped.

Results: Vision recovered on the first postop day which was confirmed with tests of visual acuity, fields and OCT.

PED for AcomA aneurysm has a rate of immediate procedural success of 96% and complete exclusion in 86% at mean follow-up of 10.4 months1. The procedure has a 5% worsening of previous visual deficit, due to ophthalmic artery hypoperfusion 2. Certain aneurysms continue to show filling after PED, but the ideal time frame for other alternatives is under debate 3. Also, some aneurysms seems to never close even after discontinuation of the 3 months dual antiplatelet therapy. The rate of failure increases in case of big size, complicated morphology or previous endovascular treatment.3

Conclusion: We describe an unusual complication of a new and delayed neurological deficit after a successful endovascular treatment, which was then reversed by surgery. The stent renders the artery rigid and makes the clipping of the neck more difficult. This case illustrates the need to be judicious while proposing PED treatment for freshly thrombosed aneurysms exerting mass effect on critical structures such as the optic nerve.

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