Introduction/Purpose Occlusion rates and morbidity associated with endovascular treatment of middle cerebral artery (MCA) aneurysms is widely varied in the literature. Complete or near-complete occlusion rates range from 53.5%–84.2%, and perioperative morbidity ranges from 6.0%–19.6%, with thromboembolic complications representing the majority. Some authors have argued against the use of assist devices such as balloons or stents, suggesting that they increase the risk of thromboembolic complications. We present our single center experience of endovascular treatment for MCA aneurysms, with a focus on thromboembolic complications.
Materials and Methods The cases of 92 MCA aneurysms that were treated with endovascular intervention between 2003–2015 were retrospectively reviewed. Mycotic and giant aneurysms treated with parent vessel occlusion were excluded, leaving 78 cases. Demographic, clinical, and radiographic variables were recorded and analyzed.
Results 36 (46%) were ruptured, 59 (75%) were MCA bifurcation, 9 (11%) were anterior temporal, 7 (9%) were M1, and 4 (5%) were M2. Average size was 5.9 mm with an average neck size of 3.2 mm, and an average dome/neck ratio of 1.9. 52 (67%) of the aneurysms had a vessel arising from the neck. 32 (41%) of cases utilized an assist device (23 (29%) balloon, 9 (12%) stent). Complete or near-complete occlusion (Raymond 1 or 2) was achieved in 68 (87%), and only partial occlusion in 10 (13%).
53 (68%) of cases had follow up of at least 6 months. Of these, 36 (68%) had complete occlusion (Raymond 1), while 16 (30%) had residual or recurrent neck and 1 (2%) had residual dome filling (Raymond 2 and 3, respectively). 6 (11%) of these required retreatment while the other 11 (21%) were managed conservatively with serial imaging demonstrating stable residual neck. 43 (90%) of patients with available follow up records had good functional outcome (MRS 0–2).
There were 15 (19%) thromboembolic events, 1 intraoperative rupture requiring craniotomy, 1 iatrogenic arterial dissection, and 2 instances of coil migration. Of the thromboembolic events, 12 (15%) resolved with intervention, 2 (3%) were delayed requiring take back which then resolved, and only 1 (1%) could not be resolved which resulted in permanent neurologic deficit. 13 (17%) utilized intra-arterial thrombolysis and 2 (3%) mechanical thrombectomy. Thus, while there was an overall 19% thromboembolic event rate, only 1% resulted in permanent thrombotic occlusion or neurologic deficit.
The use of an assist device, bifurcation aneurysm, and the presence of a vessel arising from the neck of the aneurysm trended toward higher risk of transient thromboembolic event, although this did not reach statistical significance. However, no cases utilizing an assist device resulted in permanent neurologic deficit.
Conclusion In the endovascular treatment of MCA aneurysms, the use of balloons or stents and aneurysm complexity such as bifurcation origin or vessel arising from the neck can carry a high risk of thromboembolic complication. If surgeons are aware of this risk, utilize delayed angiograms at the end of the case to ensure that no thrombus has formed, and have thrombolytic drugs or mechanical thrombectomy devices readily available, permanent complications can be safely avoided.
Disclosures T. Link: None. S. Boddu: None. N. Lin: None. P. Gobin: None. J. Knopman: None. A. Patsalides: None.
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