They are doing the MRI to make sure there's nothing blocking the flow of cerebrospinal fluid out of the brain. If that's clear, it's likely they will want to do a spinal tap. After that, there are treatments to keep CSF pressure down (repeat lumbar punctures, shunts, and various procedures to take the pressure off the optic nerve). There are some drugs to both lower the pressure and to manage the headaches. The most widely-used treatment is weight loss, as Pseudotumor cerebrei is most common in obese women of childbearing age, particularly among those who have gained weight recently.