Prevously healthy 2-month-old infant with macrocephaly had a seizure. Physical exam and routine blood work were unremarkable. A head CT demonstrated no acute findings. A skeletal survey and ophthalmologic exam were normal.  A head MR done 7 hours after the CT confirmed subdural, subarachnoid and intraventricular hemorrhage thought to be due to cortical venous thrombosis. 

MRI scanning may not always be available for acutely ill infants. This case demonstrates the importance of obtaining urgent MRI studies if possible.