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Updated: Nov 9, 2025
Permanent Cerebral Vessel Occlusion via Double Ligature and Transection
Published on: July 21, 2013
Differences between proximal and distal M1 occlusions after mechanical thrombectomy
Seung Hwan Kim1, Seong Won Kim2, Hyungon Lee3
1Department of Neurosurgery, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Republic of Korea.
Purpose:
Whether M1 occlusions proximal (pM1) and distal (dM1) to the lenticulostriate perforators result in different clinical outcomes after mechanical thrombectomy (MT) is unknown. We retrospectively compared the clinical outcomes and baseline characteristics of patients with these two types of occlusions.
Methods:
From March 2010 to May 2019, we performed MT for 141 M1 occlusions, including pM1 occlusions (n = 58) and dM1 occlusions (n = 83).
Results:
Good clinical outcomes (modified Rankin Scale score 0 to 2) were achieved in 28 out of 58 (48.3%) patients with pM1 occlusions and 46 out of 83 (55.4%) patients with dM1 occlusions without significance (p = 0.493). Cardioembolic occlusions represented 19 out of 58 (32.6%) pM1 occlusions and 53 out of 83 (63.9%) dM1 occlusions, and atherosclerotic occlusions represented 37 out of 58 (63.8%) pM1 occlusions and 27 out of 83 (32.5%) dM1 occlusions, with significance (p = 0.001). Rescue treatments, such as balloon angioplasty or stenting, were needed more for pM1 occlusions than dM1 occlusions (21 out of 58 (36.2%) vs. 8 out of 83 (9.8%), p < 0.001). The multivariable logistic regression analysis demonstrated that the need for rescue treatment was associated with pM1 occlusions (adjusted odds ratio; 3.804, 95% confidence interval; 1.306-11.082, p = 0.014).
Conclusions:
In our series, pM1 and dM1 occlusions did not significantly differ in good clinical outcomes. Our study also showed that pM1 occlusions were more strongly associated with atherosclerotic occlusions, while dM1 occlusions were more strongly associated with cardioembolic occlusions, and rescue treatments were needed more often for pM1 occlusions than dM1 occlusions.
Insights
Proximal M1 and distal M1 occlusions showed similar clinical outcomes after mechanical thrombectomy. However, proximal M1 occlusions were linked to atherosclerosis and required more rescue treatments.
Area of Science:
- Neurology
- Interventional Neuroradiology
- Vascular Neurology
Background:
- Mechanical thrombectomy (MT) is a key treatment for acute ischemic stroke.
- Understanding the impact of occlusion location within the M1 segment is crucial for optimizing treatment strategies.
Purpose of the Study:
- To compare clinical outcomes and baseline characteristics between proximal M1 (pM1) and distal M1 (dM1) occlusions treated with MT.
- To investigate the etiological differences and procedural requirements for pM1 versus dM1 occlusions.
Main Methods:
- Retrospective analysis of 141 patients undergoing MT for M1 occlusions from March 2010 to May 2019.
- Categorization into pM1 (n=58) and dM1 (n=83) groups.
- Comparison of clinical outcomes (modified Rankin Scale), occlusion etiology, and need for rescue treatments.
Main Results:
- No significant difference in good clinical outcomes (mRS 0-2) between pM1 (48.3%) and dM1 (55.4%) occlusions (p=0.493).
- pM1 occlusions were more frequently atherosclerotic (63.8%) compared to dM1 (32.5%) (p=0.001).
- dM1 occlusions were more frequently cardioembolic (63.9%) compared to pM1 (32.6%) (p=0.001).
- Rescue treatments were significantly more common in pM1 occlusions (36.2%) than dM1 occlusions (9.8%) (p<0.001).
- pM1 occlusions were independently associated with the need for rescue treatment (aOR=3.804).
Conclusions:
- Proximal and distal M1 occlusions do not significantly impact good clinical outcomes post-mechanical thrombectomy.
- Etiology differs, with pM1 occlusions more associated with atherosclerosis and dM1 with cardioembolism.
- Proximal M1 occlusions necessitate more frequent rescue interventions during mechanical thrombectomy.
