[Case report: cerebral ischemia--a routine emergency case?].

We report the case of a 77-year-old man, who presented with seemingly clear cerebral ischemia. During transport a short-term inexplicable decline of oxygen saturation occurred. In-hospital diagnosis showed not only a thrombosis of A. basilaris but also pulmonary embolism with a venous thrombosis of the lower leg. The thrombosis of A. basilaris itself represents a form of paradoxical embolism with persistent patent foramen ovale. Even with a seemingly obvious diagnosis less obvious diagnoses also have to be considered.