WADA Testing (Phase II)

Yale-New Haven Hospital,
20 York Street,
New Haven, CT

Go to the first floor of the East Pavilion and sign in at the Admitting Desk.


WADA testing is a procedure performed during angiography that assesses which side of your brain has your language and memory functions. During the test, one side of the brain is put to sleep (anesthetized) by injecting a medication into the carotid artery. There are 4 to 8 minutes during which the activities of one side of the brain are suspended, so the abilities of the other side of the brain can be tested in isolation. Typical uses of the test include the lateralization of language abilities (the surgeon wants to know if the side of the brain being operated on is the speech side or not), and a determination that the patient will not lose memory after surgery.

Patient Instructions

  • You will be admitted to the hospital for one night following the procedure.
  • You will have pre-study blood drawn.
  • You must inform the doctor of any allergies to medications.
  • Drink only clear liquids after midnight (e.g. tea, clear broth, apple juice, water).
  • Take your daily medications as usual (unless your physician gives you other instructions). If you are diabetic and require daily insulin injections, ask your primary care physician when you should take your insulin and inform us.
  • You will be given local anesthetic into the groin prior to the passage of a catheter (a small, flexible tube) through the skin into the artery.
  • You will notice a warm feeling lasting approximately ten to twenty seconds after the catheter is positioned within the carotid artery, and x-rays are taken while x-ray dye is injected through the catheter.
  • You will hear noise as the x-ray machine takes pictures.
  • You must remain motionless while the dye is injected and the x-rays are taken.
  • You will be lying on the x-ray table for one to two hours.
  • You will be asked to read words, identify objects, pictures, shapes and numbers, and answer questions about what you are shown.
  • The catheter will be removed at the end of the test.
  • Pressure will be applied to the site of the catheter insertion for ten to fifteen minutes until clotting forms and bleeding stops. A small dressing will be applied to the site. Stitches are not required.
  • You will be able to eat and drink after the procedure is completed.
  • You will need to lie flat for several hours to prevent bleeding at the injection site.

Intracranial Monitoring (Phase III)

In addition to the previously described MRI, SPECT and PET scans, neuropsychological assessment and EEG monitoring, some patients will require a more invasive evaluation. Approximately 40-60% of the patients considered for surgical treatment will need intracranial monitoring with implanted electrodes to localize the epileptogenic area responsible for seizure onset.

Intracranial monitoring consists of depth electrodes (thin wires placed deep in the brain to detect seizure activity that cannot be detected by electrodes placed on the surface of the head) or subdural or epidural strips or grids (small plastic strips or sheets containing electrodes placed on the surface of the brain underneath the skull).

During intracranial monitoring a team of research neuropsychologists may also perform brain mapping through electrical stimulation of the implanted intracranial electrodes. They are able to pinpoint the functional areas of the brain which are then safeguarded during surgery.

You will have a pre-operative visit prior to the scheduled surgery date. At this time you will meet with an Anesthesiologist who will be with you during surgery. Instructions regarding surgery will also be provided at this appointment. You will have a visit with the neurosurgeon for any additional questions you may have prior to surgery, history and physical exam, and to provide permission to perform the surgery.

What to expect

  • The morning of the procedure you will arrive from home.
  • You will be taken to the operating room where you will have anesthesia, then the neurosurgeon will place the electrodes.
  • Once the surgery is completed (approximately 6-8 hours) you will go to the Neurological Intensive Care Unit. Pediatric patients will be taken to the Pediatric Intensive Care Unit. You will spend the first night in the intensive care unit.
  • The day after surgery, you will have an MRI, a CT scan, and a SPECT Cerebral Blood Flow study.
  • After the above scans have been completed you will be taken to a specialized room that has audio-visual monitoring. Your electrodes will be connected to a specialized machine that will record your brain wave activity, and your behavior will be recorded with a camera in the room. This phase is similar to Phase I.
  • You will have a large, bulky tight dressing on your head. Your face and eyes may be slightly swollen.
  • After sufficient seizure activity is recorded, the electrodes will be removed. You will return to the operating room for the removal of the electrodes.
  • You will be discharged to home a few days after the second operation.