PhD defence M.H.C. (Martijne) Bansraj-Duvekot

Below is a brief summary about the dissertation:

Ischemic stroke can be effectively treated with acute reperfusion treatments: intravenous thrombolytics (IVT) and endovascular thrombectomy (EVT). However, the effects of both IVT and EVT strongly decline over time. Early recognition of stroke and rapid initiation of these treatments are essential to maximize chances of recovery. This thesis addresses three ways to shorten the time from stroke onset to the start of reperfusion therapy are: 1) preventing patient delay after stroke onset, 2) transportation of suspected stroke patients to the right destination, and 3) improving diagnosis of EVT-eligible stroke with vessel imaging.

A large part of delay in the prehospital setting consists of the time from symptom onset to the first medical contact. Direct notification of emergency medical services (EMS) by patient or bystanders after onset of stroke symptoms helps to facilitate rapid arrival at the hospital and subsequent treatment. Public stroke campaigns instruct people to alert EMS as soon as possible after noticing stroke symptoms, but still several patients with suspected stroke call their general practitioner (GP) first.

Endovascular thrombectomy in patients with an intracranial proximal large vessel occlusion (LVO) can only be performed in specialized intervention centers capable of EVT. IVT can be administered in all stroke centers. Several strategies are proposed for the ambulance transportation of suspected stroke patients. With the drip-and-ship strategy, a patient is presented to the closest hospital for rapid IVT. In case of EVT-eligibility, a subsequent interhospital transfer to an intervention center is arranged. Prehospital stroke scales can be used for prehospital triage to distinguish between patients with a high and a low LVO likelihood for direct transportation to an intervention center or the closest hospital. Using these scales, a more personalized approach is proposed: with the use of a personalized prehospital decision tool, multiple factors can be taken into account to determine the optimal transportation strategy.

Crucial in the treatment of LVO patients is the rapid and accurate detection of LVOs on vessel imaging. However, the accuracy of CTA evaluations in daily clinical practice has never been investigated. In addition, to aid fast CTA evaluation and LVO detection, diagnostic tools with artificial intelligence algorithms have been developed, but their clinical utility has not been evaluated yet.

The overall aim of this thesis was to improve the prehospital triage and diagnostic work-up of patients with suspected stroke. The specific research questions were:

1. Which factors influence the direct notification of emergency medical services by patients with suspected stroke?  
2. How sensitive are prehospital stroke scales for the detection of different intracranial large vessel occlusion locations?
3. What is the in-field performance of prehospital stroke scales?
4. What is the impact of prehospital transportation strategies on patient flows and treatment times?
5. What is the diagnostic performance of CTA evaluations in daily clinical practice and of an automated LVO detection algorithm in patients with suspected stroke?