Abstract Number ‐ 89: Left M1 occlusion rescued by the Recurrent artery of Huebner: a spectrum of MCA collaterals
Authors: Blanden Adam R , Raveendran Laxshika , Titoff Victoria , Swarnkar Amar S , Masoud Hesham 
Published: April 2023

Introduction
Proximal MCA occlusion has variable presentation and clinical course, ranging from MCA syndrome with completed infarct at presentation to asymptomatic, discovered incidentally on imaging. This variability is likely dictated by variable collateral circulation that ultimately fails on variable time courses. For discussion we can divide these into (1) rapid progressors, (2) standard, (3) slow progressors, (4) situationally symptomatic, and (5) asymptomatic. There is clear evidence for the role of endovascular therapy for those who are significantly symptomatic and progress along an acute timeline when combined with imaging criteria (1 and 2), but there is no clear guidance for those patients who progress slowly or are minimally symptomatic (3‐5).

Methods
We present selected cases of patients with left MCA occlusion from groups 3–5 along with their presentation and collateral flow as assessed by non‐invasive imaging and DSA.

Results
Case 1. Slow Progressor. A 63‐year‐old woman with past occipital lobe strokes presented with progressive aphasia of insidious onset that began at some point the previous day. NIHSS 4 for aphasia and LOC questions. Initial CTA revealed a left M1 occlusion with ASPECTS 9. Despite low NIHSS and extended time to LKW, she was brought to the angiography suite. Initial angiogram confirmed M1 occlusion with extensive collateralization via the left ACA and anterior temporal artery, but no reconstitution of the MCA proper. Thrombectomy was completed with TICI2B recanalization. Followup MRI revealed minimal infarct in the left insula. The patient was discharged with an NIHSS of 1 for a baseline hemianopia not appreciated on initial exam. Case 2. Situationally Symptomatic. A 55‐year‐old man with symptomatic epilepsy from bilateral subdural hygromas was admitted for video EEG monitoring of episodic dizziness and word‐finding difficulty. Initial exam revealed only orthostatic light‐headedness. Further history revealed these events often happed at night upon standing. No epileptiform events were captured. MRA revealed a complete occlusion of the proximal M1 with reconstitution at the M2 bifurcation in the sylvian fissure. Given lack of persistent clinical deficit and absence of infarct on MRI, DSA was deferred. The patient is followed outpatient without further symptom progression. Case 3. Asymptomatic. A 38 year‐old‐man with TBI presented to the emergency department with thunderclap headache. Initial exam was without deficits. CTA and MRA revealed complete occlusion of the left MCA. We proceeded to the angiography suite where DSA revealed complete left M1 occlusion with distal reconstitution at the M2 bifurcation primarily via the Recurrent Artery of Huebner in addition to ACA collaterals. Lumbar puncture was benign and his headache responded completely to typical migraine treatment. The patient was discharged to outpatient follow up without further sequalae.

Conclusions
We present a series of illustrative cases of patients with MCA occlusion of variable collateral supply and clinical course, none of whom met conventional criteria for endovascular intervention. More research is needed to establish clinical and imaging criteria to separate patients who would benefit from endovascular intervention from those who are best managed medically in these scenarios.