[A case of multiple cerebral arterial thrombosis due to congenital protein C deficiency].

We report a 49-year-old man who had right hemiparesis and motor aphasia. A computed tomography revealed hypodense areas in the left frontal subcortex. A cerebral angiography demonstrated occlusion of the left distal internal carotid artery and both anterior cerebral arteries, as well as stenosis of the left internal carotid artery at the cervical portion. The second angiogram obtained a month later showed no changes. The diagnosis of atherothrombotic cerebral infarction was established on the basis of clinical profile and angiographic findings. Protein C activity and antigen levels were reduced to approximately one half of the normal level in the patient and his brother. The patient had no other risk factors for stroke. Protein C deficiency has been considered one of the risk factors for thrombotic diseases. Venous thrombosis is the most common clinical manifestation, whereas arterial thrombosis is relatively rare. It is generally believed that arterial ischemic stroke associated with protein C deficiency occurs with embolic mechanism, and atherothrombotic infarction is extremely rare. This is the first report suggesting the possibility that protein C deficiency can cause cerebral thrombosis.