Effectiveness of Endovascular Recanalization Treatment for M2 Segment Occlusion: Comparison Between Intracranial ICA, M1, and M2 Segment Thrombectomy

Rationale and objectives: Mechanical thrombectomy is common practice in proximal anterior vessel occlusion. However, it remains unclear whether peripheral artery occlusions should be treated as well. This retrospective study aimed to prove the effectiveness of endovascular recanalization treatment for the M2 segment by comparison of intracranial internal carotid artery (ICA), M1 segment, and M2 segment thrombectomy.

Materials and methods: All patients who received endovascular treatment for distal ICA, M1, or M2 segment occlusions between January 2010 and July 2017 at our center were re-analyzed with respect to reperfusion success, interventional and clinical parameters. Statistical analysis was performed by Mann Whitney test, Chi square test, and Spearman correlation analysis.

Results: A total of 261 patients (median age, 72 years), 100 with ICA, 137 with M1, and 24 with M2 segment occlusion, were included. Duration of endovascular treatment was significantly longer in ICA occlusions (median, 83 minutes, p < 0.001) compared to M1 (56 minutes) or M2 segment occlusions (49 minutes). Recanalization and reperfusion success and rate of endovascular complications did not differ between occlusion sites (AOL, p = 0.071; mTICI, p = 0.540; complications, p = 0.064). No significant difference in revascularization success was found between the different thrombectomy devices (direct thrombus aspiration, stent retrieving, or a sequential combined approach; p = 0.112). Successful M2 recanalization (mTICI 2b-3) correlated significantly with stronger posttherapeutic NIHSS reduction (r = 0.691, p < 0.001).

Conclusion: We found endovascular treatment of M2 segment occlusions as safe and successful as endovascular therapy of the ICA or M1 segment, with stronger posttherapeutic NIHSS reduction after successful compared to insufficient M2 recanalization.