Wada Testing

The Wada test, also known as the intra-carotid sodium amobarbital procedure (ISAP), establishes cerebral language and memory representation of each hemisphere. Neuro Interventional Radiologists conduct the test while the patient is awake. Essentially, the physician introduces a barbiturate into one of the internal carotid arteries via a catheter from the femoral artery. They inject the drug into one cerebral hemisphere at a time via the right or left internal carotid artery. If the right carotid is injected, the right side of the brain is inhibited and cannot communicate with the left side. The effect shuts down any language and or memory function in that hemisphere in order to evaluate the other hemisphere ("half of the brain"). An EEG, recording concurrently, confirms that the injected side of the brain is inactive. The Neuro Interventional Radiologist engages the patient in a series of language and memory related tests. They evaluate the memory by showing a series of items or pictures to the patient and within a few minutes and as soon as the effect of the medication dissipates, test the patient's ability to recall. Correlation with formal neuropsychological testing has some predictive power regarding seizure outcome following anterior temporal lobectomy. Currently, there is great variability in the processes used to administer this test, and therefore difficult to compare results from one patient to another.