A young woman's unexplained stroke traced to a lung vascular malformation

A woman in her 40s with no known medical conditions presented with right-sided weakness. Diffusion-weighted MRI showed an infarct in the left thalamus, and no obvious cause was apparent at first.

Detailed investigation uncovered a pulmonary arteriovenous malformation and hereditary haemorrhagic telangiectasia. In this condition, an abnormal link between pulmonary arteries and veins lets blood bypass the lung circulation (a right-to-left shunt). Clots can then travel to the brain, a route known as paradoxical embolism.

She was treated with transcatheter embolisation and kept on a single antiplatelet drug. The authors report no further strokes since then. This is a single case report, so it illustrates a rare mechanism of stroke rather than showing how often it occurs or how well the treatment works.