The 27th webinar of the European Stroke Organization’s educational series was hosted by Dr. Marieta Peycheva and Dr. Ellis van Etten. With the title “Intravenous thrombolysis in patients with relative and absolute contraindications: how far should we go?”, it features Dr. Thomas Meinel (Inselspital, Bern University Hospital, Switzerland) and Dr. Odysseas Kargiotis (University of Patras, Greece) discussing the boundaries of intravenous thrombolysis (IVT) in some complex situations.

The first part of the discussion regarded patients on direct oral anticoagulants (DOACs), highlighting a case where a patient with high rivaroxaban levels was treated with IVT without complications. Although 2021 ESO guidelines are restrictive regarding DOACs, recent observational data and the 2026 American guidelines suggest that high plasma levels might not always preclude treatment with an individualized risk-benefit analysis. While idarucizumab is a common and safe reversal agent for dabigatran, the use of andexanet alfa as reversal of rivaroxaban/apixaban is not recommended before IVT primarily due to a documented increase in thrombotic events. Ongoing RCTs will clarify the safety and efficacy of IVT in this scenario and results are expected 2028.

The dilemma of minor strokes is another key topic, exemplified by a case where IVT treatment for a mild disabling deficit (left hemiparesis with impaired gait, NIHSS 4) resulted in a fatal brainstem hematoma. Although underpowered and yielding non-statistically significant results, the PRISMS trial demonstrated a trend that alteplase may not benefit minor non-disabling strokes, suggesting that IVT should be avoided in these particular cases. The definition of “disabling” remains inherently subjective and requires careful clinical judgment. However, in patients with large vessel occlusions (LVO) and mild symptoms, some evidence suggests IVT may still be beneficial.

Regarding post-operative patients, guidelines generally suggest waiting 14 days after major surgery, yet the experts emphasize that individual circumstances, such as a non-traumatic spinal puncture, might allow for earlier intervention and communication with the surgeon might be helpful for decision-making.

Patients with a history of stroke were also addressed. Non-randomized data and meta-analyses indicate that previous ischemic strokes generally do not significantly increase haemorrhage risk, though clinical outcomes are often poorer due to pre-existing disabilities. However, strokes occurring within the prior two weeks signal a higher risk for symptomatic haemorrhage, requiring careful consideration of timing and lesion size. In patients with a history of haemorrhagic stroke, the underlying cause is the primary risk predictor. In this context, the two speakers challenge the strict use of microbleed counts: to contraindicate IVT, physicians should rather look for the presence of potential Cerebral Amyloid Angiopathy (CAA)-related symptoms than simply consider exceeding a threshold of ten microbleeds.

For patients with unknown stroke onset times, the consensus is that advanced imaging such as CT perfusion or MRI is mandatory to identify salvageable tissue, as treating without such data beyond standard windows is risky.

In other special scenarios, IVT is considered reasonably safe during pregnancy for disabling deficits but requires caution in cases of recent large myocardial infarctions or long-bone fractures due to systemic bleeding risks. Finally, the presenters stress the importance of individualized care and involving patients and families in decision-making for borderline cases, noting that legal requirements for informed consent vary significantly across different countries.

The 26th webinar of the European Stroke Organisation’s educational series focused on the critical topic, “When the weather strikes: understanding stroke risk in the era of climate extremes”. Moderated by Dr Marieta Peycheva and Dr Vojtech Novotny, the session was delivered by two expert neurologists.

The first speaker, Dr. Vasileios Tentolouris Piperas (from the National and Kapodistrian University of Athens, Greece), presented evidence linking air pollution and wildfires to increased stroke risk. Climate change, defined as a long-term shift in average weather patterns, is contributing to an increase in intense and destructive wildfires. In Europe alone, approximately 1 million hectares were burned in 2025 up to October 28th, an area equivalent to Montenegro. Wildfires are significant sources of pollution, as well as the energy production industry and the urban traffic. One of the main air pollutants is the Particulate Matter (PM) 2.5, extremely small particles associated with cerebrovascular risk. The talk highlighted that outdoor air pollution is now recognised as the second most important modifiable risk factor globally for stroke-related disability, according to the 2025 World Stroke Organisation fact sheet. Epidemiological data confirms that exposure to wildfires or high PM 2.5 concentrations leads to a short-term rise in cerebrovascular events, especially within the first few days and among adults over 65. Long-term exposure also increases stroke incidence and mortality. The mechanisms involve the activation of sensory receptors in the respiratory system, leading to a sympathetic response (vasospasm/arrhythmias); an inflammatory response causing oxidative stress and hypercoagulable states; and the potential translocation of particles that contribute to platelet aggregation and atherosclerotic plaque formation. It was suggested that future interventions should focus on reducing pollution in high-risk areas globally, such as South Asia and Northern Africa, but also monitor susceptible areas in Europe, like the Mediterranean and the Balkans.

The second speaker, Professor Anita Arsovska (from the University Clinic of Neurology, University Ss Cyril and Methodius in Skopje, North Macedonia), discussed how ambient temperature extremes and rapid fluctuations affect stroke occurrence, defining climate change as a fundamental threat to human health. Research consistently links both high and low temperatures to increased stroke events, though the pattern differs by stroke subtype. Ischemic stroke risk peaks during warmer months and is associated with heat extremes and heat waves, with effects often immediate, occurring within the first four days. In contrast, intracerebral hemorrhage shows a stronger association with cold temperatures. The effects of cold often exhibit a longer lag, extending up to 30 days, reflecting delayed consequences of cold-induced blood pressure changes. Rapid temperature fluctuations (e.g., changes between 5 and 8 degrees Celsius) also increase stroke risk. Pathophysiologically, extreme cold triggers vasoconstriction and hypertension, increasing hemorrhagic risk, while extreme heat leads to dehydration and hypercoagulable states, increasing ischemic risk. The elderly and those with comorbidities like heart failure are highly vulnerable. It was proposed that public health strategies should include early warning systems using machine learning models combined with weather data to forecast high-risk days and enhance hospital preparedness. Furthermore, incorporating temperature risk into discharge planning and patient counseling is crucial.

Finally, during the Q&A session, the speakers agreed that incorporating climate-related risk factors into professional education and national registries is an essential next step for the stroke community.

Learn more about our Educational Webinars: ESO Educational Webinars -European Stroke Organisatoin