Abstract Number ‐ 122: Minimally symptomatic left M1 occlusion from carotid web
Authors: Eskian Mahsa , Hoffman Haydn , Blanden Adam R , Gould Grahame C , Masoud Hesham 
Published: April 2023

Introduction
Minimally symptomatic large vessel occlusion (LVO) is an area of prognostic and management uncertainty. Current guidelines recommend thrombectomy only for patients with NIHSS of 6 or greater when additional timeline and imaging criteria are met. However, patients with initial mild or rapidly improving symptoms with LVO can eventually deteriorate, raising the question of whether all patient with acute LVO should be offered thrombectomy.

Methods
We present a case of minimally symptomatic M1 occlusion due to ipsilateral carotid web managed without thrombectomy.

Results
A 42‐year‐old woman with Systemic Lupus Erythematosus (SLE) and hypertension presented to an outside hospital with sudden transient left monocular vision loss, aphasia, right‐side weakness, and dizziness. At the time of presentation (1h from LKW) exam revealed only mild aphasia (NIHSS 1) with normal blood pressure. CTA demonstrated left M1 occlusion with reconstitution of flow at the M2 bifurcation. She was given IV Alteplase and transferred to our center. On 7 h from LKW repeat imaging demonstrated persistence of the left M1 occlusion with an ipsilateral near‐occlusion suspicious for carotid web at the ICA origin, but exam was without deficit. She was monitored closely for neurological deterioration, but remained without significant symptoms. MRA taken the next day demonstrated complete recanalization of the left M1. She was taken to the angiography suite on an outpatient basis for stenting of the carotid web at the origin of the internal carotid artery. Initial diagnostic angiogram revealed near occlusion of the ICA at the origin with post‐stenotic dilation, which was treated with angioplasty and stenting with distal embolic protection. She has remained stable to 8‐month follow‐up with no recurrent stroke.

Conclusions
Minimally symptomatic LVO presents significant endovascular management uncertainty. While clinical trials support the use of mechanical thrombectomy for significantly symptomatic patients, there is no consensus to guide treatment decisions for patients with minimal symptoms. This uncertainty is driven at least in part by an inability to reliably distinguish between patients who are likely to progress and would benefit from intervention before their collateral circulation fails, and those who will recanalize or develop a compensated chronic occlusion. In this case, our patient received tPA and saw symptom improvement, but this did not remove her M1 occlusion. Angiographic investigation was limited as the patient was asymptomatic, however non‐invasive imaging revealed robust collateralization including reconstitution of MCA flow and left ICA injection failed to opacify the ipsilateral ACA despite patency in recent CT angiography, indicating a right to left flow dominance in circle of Willis collaterals. We opted for close monitoring with follow‐up imaging and outpatient correction of the carotid web, which resulted in a positive outcome. More work is needed to establish criteria to predict which patients with minimally symptomatic LVO are likely to progress.