Arvo building, auditorium F115, address: Arvo Ylpön katu 34.
Doctoral defence of Lic.Med. Sara Protto
The field of science of the dissertation is Radiology.
The opponent is professor Klaus Hausegger (University of Klagenfurt, Austria). Professor Antti Paakkala acts as the custos.
The language of the dissertation defence is English.
Mechanical thrombectomy in acute anterior circulation stroke
Stroke is one of the most common causes of morbidity and mortality worldwide. Stroke entails cessation of blood flow to the brain parenchyma which leads to cell death. Stroke therapy has seen a huge improvement in the past few years with the introduction of new techniques as mechanical thrombectomy (MT) with improved stent retrievers. Stent retriever is a retrievable metal mesh which allows rapid restoration of brain perfusion following the delivery and retrieval of the device. We investigated the outcomes of patients treated with MT in a stroke population treated in our institution for anterior circulation ischemic stroke between January 2013 and December 2014. Even though the superiority of MT over medical treatment such as intravenous thrombolysis (IVT) has been demonstrated in recent randomized trials, it is still unclear which patients benefit most from this treatment. In order to address this issue, we evaluated the influence of different clinical and imaging parameters on clinical and technical outcomes. Among these parameters were the location of the clot in computed tomography angiography (CTA) and the device used to perform the intervention. We examined the prognostic value of data derived from perfusion CT studies (CTP) and finally compared the outcome of patients who underwent MT to those who received only IVT to clarify the patient subgroups in which MT outperforms IVT.
We could not demonstrate any difference in outcome between different clot locations. The use of different newer generation stent retrievers was not consistently related to a difference in clinical nor technical outcomes implying that the choice between the two devices studied could be left to the operator. Nevertheless, we demonstrated that perfusion CT and especially cerebral blood volume maps (CBV) can be used to identify patients who do not benefit from MT. Low CBV assessed with the Alberta Stroke Program Early CT score (ASPECTS) at admission was associated with a large infarct in the follow-up imaging studies and was a significant predictor of poor three month clinical outcome, especially in the setting of poor collateral circulation and/or moderate or severe stroke. Having no visible collateral circulation in the admission CTA was closely related to poor clinical outcome.
We demonstrated the superiority of MT over IVT in the treatment of proximal large vessel occlusions in the anterior circulation (ICA, M1 segment of the middle cerebral artery), whereas neither therapy outperformed the other in more distal occlusions. Our results showed that surviving a proximal large vessel occlusion without any disability essentially required MT.
The dissertation is published in the publication series of Acta Universitatis Tamperensis; 2303, Tampere University Press, Tampere 2017. The dissertation is also published in the e-series Acta Electronica Universitatis Tamperensis; 1807, Tampere University Press 2017.