Sudden onset hemiplegia at high altitude.

Travel to high altitude and the incumbent exposure to hypobaric hypoxia leads to a prothrombotic state. This may increase the likelihood of thromboembolic events, including stroke, in otherwise healthy individuals. While there have been sporadic anecdotal reports of 'stroke-like' syndromes at high altitude for over 100 years, there are surprisingly few detailed reports supported by imaging.This report describes a case of posterior circulation infarct thought to be due to a paradoxical embolus through a patent foramen ovale. The relationship between high-altitude physiology, increased incidence of thromboembolism and the significance of patent foramen are discussed in the report. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.