A 25-year-old obese woman developed headaches and visual blurring. Examination showed papilledema and cranial MRI showed a large Chiari I malformation. Acetazolamide was initiated and a repeat cranial MRI surprisingly showed resolution of the Chiari I malformation. Chiari I malformation associated with papilledema has never been shown to resolve with acetazolamide therapy. Copyright © Informa Healthcare.