Cerebral vein thrombosis shown by MRI. A 46 year old man with a short history of left facial pain and numbness, and subsequently headaches, had a normal physical examination and a normal CT scan of head. Lumbar puncture yielded normal CSF under increased pressure. MRI showed thrombosis of the superior sagittal sinus, subsequently confirmed by angiography. MRI is a sensitive test for detecting intracranial venous thrombosis, and may be the investigation of choice when this disorder is suspected. 