Intermittent symptoms of obstructive hydrocephalus in a young woman with Chiari-I malformation are reported from the Neuro-Ophthalmology Service, Wills Eye Hospital, Philadelphia, PA. A previously healthy 26 year old woman experienced episodes of intermittent pressure headaches, dizziness, tingling in the right arm, and right anterior chest pressure for two months. These episodes lasted 5-15 minutes and occurred up to 15 times a day. They were followed by blurred vision with the appearance a “green patch” inferiorly before the left eye. Bilateral optic disc elevation was identified with indirect ophthalmoscopy. Lumbar puncture showed an opening pressure of 190 mm H₂O. Intravenous fluorescein angiography demonstrated venous stasis, diffuse retinal hemorrhages, and disc edema interpreted as consistent with papillophlebitis. An MRI using multiple thin sagittal sections directed at the posterior fossa revealed the Chiari I malformation, and an intraventricular catheter confirmed that the malformation was causing an intermittent obstruction and increased intracranial pressure. In one attack in which the patient experienced several typical episodes of right hand and right chest paresthesias, headache, and blurred vision the simultaneous intracranial pressure readings were elevated to a maximum of 580 mm H₂O. The pressure was sustained for approximately 2 minutes; as it decreased the patient’s symptoms abated. Following posterior fossa decompression and a C1 to C3 laminectomy the pressure was relieved and the patient was asymptomatic. [1]