The purpose of this study is to use a wire with a Doppler tip to measure blood flow in vessels in the brain and determine hemodynamic factors associated with treatment success or failure. Many neurological diseases cause abnormal blood flow in the brain in specific vessels. The special wire used in this study is place into brain blood vessels during standard of care procedure to treat such diseases, and blood flow parameters (such as velocity and pressure) are measured to gain better understanding of these neurological diseases.