Objective:

To compare how procedural strategies and patient selection influence outcomes of mechanical endovascular reperfusion (MER) for medium and distal intracranial occlusions relative to large vessel occlusions (LVO) and medically managed controls across a multi-hospital academic system.

Background:

MER is highly effective for proximal LVO, including the MCA M1 segment. However, recent trials have not demonstrated superiority over medical management for medium and distal occlusions, with ongoing equipoise regarding ACA and PCA occlusions. These studies largely mandated stent retriever use, raising questions about whether aspiration thrombectomy offers advantages in distal vessels or specific subgroups.

Design/Methods:

We retrospectively reviewed 911 thrombectomy cases performed between 2018 and 2025 across three hospitals within a major academic health system in New York City. Patients were stratified by occluded vessel (MCA [M1, M2, M3/M4], PCA [P1, P2], ACA [A1, A2]) and analyzed by hemisphere, age, and stroke severity. Procedures were performed by five experienced neuro-interventionalists who preferentially used aspiration thrombectomy for medium and distal occlusions. Medically managed occlusions served as controls.

Results:

Among 214 MCA occlusion patients, mean presenting NIHSS by segment was M1 = 14 (n = 96), M2 = 9 (n = 99), and M3 = 7 (n = 19), with mean NIHSS improvement of 6, 5, and 0, respectively. Improvement in the primary disabling deficit (aphasia or motor weakness) occurred in 81% of M1 and 82% of M2 occlusions and TICI 2c-3 reperfusion was achieved in >90% of both. Favorable 90-day mRS 0–2 was seen in 31% of M1 and 42% of M2 cases. Logistic regression adjusting for stroke severity demonstrated comparable outcomes for M1 and M2 MER (OR 1.31, 95% CI 0.70–2.44).

Conclusions:

M1 and M2 occlusions demonstrated similarly favorable outcomes and high recanalization rates using a predominantly first-pass aspiration approach. A small subgroup of M3/M4 occlusions showed no significant neurological improvement following MER.