A 45-year old woman who had an injury from a motor vehicle crash 9 months prior to being admitted to the hospital reported experiencing 3 months of nausea and vomiting, progressive dysphagia to solids and liquids, and a 15-pound weight loss. The motor vehicle crash had resulted in skull fractures and a subarachnoid hemorrhage. On examination, she was found to be dysarthric with monotonal hypophonia and mild left-arm ataxia. Because she had an elevated creatinine level, noncontrasted magnetic resonance imaging of the brain was performed. The results showed an increased fluid-attenuated inversion recovery signal within the pontomedullary region and the left cerebellar hemisphere (Figure, A-C). Because of this finding, together with the woman's weight loss and progressive clinical course, there was concern for a neoplastic process. However, the results of magnetic resonance spectroscopy indicated brainstem edema, and the results of noncontrasted magnetic resonance imaging of the cervical spine suggested a vascular malformation (Figure, D). To further evaluate the vascular malformation, a cerebral angiogram was performed, the results of which demonstrated a direct carotid cavernous fistula (CCF) as a rare cause of the brainstem edema (Figure, E).1- 2 Ten days after endovascular coiling of the CCF, the patient regained her ability to swallow and was discharged from the hospital. At home, she tolerated a regular diet and was ambulatory and self-sufficient.