The catheter will be guided painlessly into the vessels to be examined. At this time, the patient will notice a very warm feeling lasting approximately ten to twenty seconds. At the same time the patient experiences the warm feeling, the patient will also hear noise as the x-ray machine takes pictures of the dye's passage through the blood vessels. It is very important that the patient remain motionless while the dye is injected and the x-rays are taken. Although the length of the picture-taking process can be as brief as fifteen minutes, the actual time it takes will depend on the number of blood vessels that need to be examined.
Most patients can anticipate lying on the x-ray table for one to two hours.
Next, the neuroradiologist will inject sodium amobarbital into the catheter. When the drug reaches the side of the brain under study, the patient will lose all strength on the side of the body opposite to the injection. This weakness is temporary, typically lasting five to fifteen minutes. It is during these few moments that the critical assessments of the patient's speech and memory will be made. To test the patient's speech, the patient will be asked to read words, identify objects, pictures, shapes and numbers and answer questions about what they are shown.