Acute Intracranial Mechanical Thrombectomy for Complicated Lesions

Mechanical thrombectomy (MT) for emergent large vessel occlusion (ELVO) of the internal carotid artery and the M1 segment of the middle cerebral artery can improve patient prognosis compared to medical therapy alone. Although a high recanalization rate of approximately 90% has been reported for MT using a stent retriever (SR) or aspiration catheter (AC), in actual clinical practice, we sometimes encounter complex cases that require recanalization using conventional MT techniques due to anatomical factors and the complexity of the lesion. This article presents several complex cases of MT, describing the following six typical conditions that are likely to be encountered clinically and discussing the therapeutic strategies and techniques for these complicated lesions in the literature: (1) difficulty accessing the lesion due to tortuous vessel anatomy, (2) carotid artery and intracranial tandem lesion, (3) distal lesions beyond the M2 segment of the middle cerebral artery, (4) vertebra-basilar artery occlusion, (5) intracranial atherosclerotic stenosis (ICAS), and (6) cerebral artery dissection.We generally adopted a combined technique with SR and AC as the first choice for these procedures. The advantages of this combined technique are as follows: (1) embolization in a new territory (ENT) is reduced by tightly catching the thrombus with both the SR and AC; (2) because the axis of the AC is aligned with the axis of the parent artery due to the distally placed stent, there is less vascular damage due to branch vessel withdrawal during SR retraction; and (3) distal advancement of the AC is facilitated by anchoring the SR distally. To improve patient outcomes, surgeons should aim to achieve complete recanalization at one pass (FPE: first-pass effect) using various treatment strategies and techniques adapted to the situation.