An unusual cause of cerebral venous thrombosis in a four-year-old child.

BACKGROUND AND PURPOSE Inherited protein S deficiency has been associated with an increased risk of thromboembolic disease. It is possible that such a coagulopathy could predispose children to the development of strokes by permitting clot formation in response to stimuli that ordinarily would be insufficient to cause thrombus formation. CASE DESCRIPTION We evaluated a previously well 4-year-old boy who developed cerebral venous thrombosis after suffering minor head trauma. Crossed-immunoelectrophoresis of his plasma showed a marked decrease of the free, active form of protein S. Family studies revealed that the patient's father and other paternal relatives had a similar abnormality of protein S. CONCLUSIONS We suggest that the cerebral venous thrombosis in this child was initially precipitated by minor head trauma and pathological thrombus formation was then potentiated by inherited protein S deficiency. This case extends the clinical spectrum for protein S deficiency and emphasizes the importance of evaluating family members to establish a specific diagnosis and therapeutic intervention.