A Wada test is used for pre-operative surgical planning in epilepsy. Patients who have epilepsy that is refractory to medications, and who are selected as candidates for surgical resection of a region of abnormal brain tissue, may undergo a Wada test. The test is performed in the angiography suite, similar to all other neurointerventional procedures. Electroencephalogram (EEG) leads are placed on the head to measure brain wave recordings and a diagnostic catheter cerebral angiogram is performed to evaluate the intracranial blood supply. A medication (sodium amytal) is then injected into a blood vessel to temporarily put half of the brain to sleep. The patient is then engaged in a series of memory and language tests. The medication wears off in a few minutes and the procedure is then repeated for the other half of the brain. This test is intended to determine which side of the brain controls language function and identify the role that each hemisphere plays in memory.