Fulminant bilateral cerebral infarction caused by paradoxical embolism in a patient with protein S Ala525Val substitution

We report a 42‐year‐old woman who developed sudden fulminant cerebral infarction in the bilateral middle cerebral artery territories, causing status epilepticus and a decreased level of consciousness. Investigation showed thrombus in the right soleus vein and a patent foramen ovale, but no obvious embolic source, such as atrial fibrillation or a carotid or cerebral artery atherosclerotic lesion. Blood coagulation tests showed decreased levels of free protein S (25%) and total protein S (52%), and decreased protein S activity (15%). The patient was diagnosed with cerebral infarction as a result of paradoxical embolism, and type I protein S deficiency. DNA sequencing identified a novel point mutation in the PROS 1 gene, leading to the amino acid substitution, Ala525Val. It should be noted that this protein S mutation can cause thrombophilia and cerebral infarction.