Thrombectomy for Distal, Medium Vessel Occlusions

Abstract

Endovascular thrombectomy (EVT) is well established as a highly effective treatment for acute ischemic stroke (AIS) due to proximal, large vessel occlusions (PLVOs). With iterative further advances in catheter technology, distal, medium vessel occlusions (DMVOs) are now emerging as a promising next potential EVT frontier. This consensus statement integrates recent epidemiological, anatomic, clinical, imaging, and therapeutic research on DMVO-AIS and provides a framework for further studies. DMVOs cause 25% to 40% of AISs, arising as primary thromboemboli and as unintended consequences of EVT performed for PLVOs, including emboli to new territories (ENTs) and emboli to distal territories (EDTs) within the initially compromised arterial field. The 6 distal medium arterial arbors (anterior cerebral artery [ACA], M2–M4 middle cerebral artery [MCA], posterior cerebral artery [PCA], posterior inferior cerebellar artery [PICA], anterior inferior cerebellar artery [AICA], and superior cerebellar artery [SCA]) typically have 25 anatomic segments and give rise to 34 distinct arterial branches nourishing highly differentiated, largely superficial cerebral neuroanatomical regions. DMVOs produce clinical syndromes that are highly heterogenous but frequently disabling. While intravenous fibrinolytics are more effective for distal than proximal occlusions, they fail to recanalize one-half to two-thirds of DMVOs. Early clinical series using recently available, smaller, more navigable stent retriever and thromboaspiration devices suggest EVT for DMVOs is safe, technically efficacious, and potentially clinically beneficial. Collaborative investigations are desirable to enhance imaging recognition of DMVOs; advance device design and technical efficacy; conduct large registry studies using harmonized, common data elements; and complete formal randomized trials, improving treatment of this frequent mechanism of stroke.

Effectiveness of very low profile thrombectomy device in primary distal medium vessel occlusion, as rescue therapy after incomplete proximal recanalization or following iatrogenic thromboembolic events

“…This retrospective study was performed at a single tertiary neurointerventional center in all consecutive AIS and elective patients treated with the Tigertriever 13 device between December 2018 and September 2020 (21 months). Patients were classified into three groups 1 : primary isolated DMVO, secondary DMVO after MT in proximal PLVO, 3 and DMVO related to thromboembolic complications during aneurysm or AVM embolization.…”

“…1 2 It is estimated that DMVO accounts for 25-40% of all brain vessel occlusions. 3 While IVT remains the primary therapy of choice, many contraindications limit its use in clinical practice. Moreover, IVT fails to recanalize one-half to two-thirds of DMVOs.…”

“…6 Considering the impact of rapid and full or near-complete recanalization on clinical outcome, 7 exploring the benefit of MT for primary or secondary DMVO is warranted. 3 Moreover, thromboembolic complications during embolization of brain aneurysms or arteriovenous malformation may also benefit from DMVO thrombectomy, 8 especially in patients receiving dual antiplatelet medication, where thrombolysis may result in or worsen hemorrhagic complications.…”

A review of endovascular treatment for medium vessel occlusion stroke

“…Treatment decision-making is further complicated by the variety of clinical symptoms MeVO patients can present with, which are dependent on the eloquence of the affected area. 3 A patient with a right-sided small branch anterior M2 occlusion, for example, may barely suffer from any deficits, but another patient suffering from a similar sized left-sided M2 occlusion may present with severe aphasia. Furthermore, new thrombolytic agents such as Tenecteplase, 33 and neuroprotectants such as Nerinetide 17 could improve the prognosis of MeVO stroke with conservative management and thereby also influence treatment decisionmaking in MeVO EVT.…”

Acute reperfusion therapies for acute ischemic stroke patients with unknown time of symptom onset or in extended time windows: an individualized approach

“…A recently published comprehensive review on EVT for distal, medium vessel occlusions (DMVOs) proposed the term LVO to be reserved for ICA, MCA M1 segment, basilar and vertebral artery, all vessels with diameters usually > 2mm, whereas DMVOs refer to more-distal arterial segments of diameter 0.75–2 mm. 113 Detection of DMVOs with CTA in the acute phase may be challenging even for experienced neuroradiologists; CTP has been shown to increase the yield of CTA for DMVO detection by revealing brain ischemia and directing attention of the examiner to a small part of the arterial tree. 114 , 115 Despite the paucity of evidence for the role of EVT for DMVOs in extended time windows, the possibility for treatment should be considered, especially for cases with severe clinical deficit as these occlusions are associated with a high risk of long-term disability.…”