The Wada test, also known as the Intracarotid Amobarbital Procedure (IAP), was named after Dr. Juhn Wada. He developed the combination of neuro-imaging and neuropsychological testing methods to examine independent functions of the brain such as memory and language. It is useful in determining which hemisphere is “dominant” for speech and if memory is functional on one or both sides of the brain.

The Wada test is part of the pre-surgical evaluation for people being considered for epilepsy surgery. It helps to determine what might be the best type of surgery for an individual. It is important to know where speech and memory are located in the brain so that surgery does not affect these functions.

Before for the Test

• On the day before the test, you must schedule an appointment for your child to see a specialist. The specialist will gather information about your child’s speech, cognitive and memory functions.
• Remove any jewellery or other metal objects your child may be wearing during the test.

During the Test

Part 1: Angiography

• Your child will lie on his/her back on the X-ray table.
• A local anaesthetic will be injected into the groin.
  • This injection may cause a slight pressure and burning sensation. Inform your child that s/he may feel some mild discomfort when the needle is inserted. Otherwise this procedure is painless.
  • A small incision allows a small tube (catheter) to enter through your child’s skin into the artery. The catheter will move into the vessels.
• A fluoroscopy will show the internal structure of your body by means of X-rays. This will be visible on a monitor.
• Dye will be injected through the catheter as the X-rays are taken.
  • Inform your child that s/he may experience a feeling of heat, pressure and sometimes pain for approximately 10 to 20 seconds.
  • Your child may get a metallic taste in his/her mouth, but this taste will subside.
  • Inform your child that s/he may hear noises from the X-ray machine as it takes images of the dye passing through the blood vessels.
• Your child must remain still through the entire procedure.
• This part of the test takes approximately one to two hours depending on the number of blood vessels that need to be examined.

Part 2: Wada Test

• Sodium amobarbital will be injected into the catheter. This will cause one side of the brain to “sleep” while the other side continues to function as usual.
  • Your child will not be able to move the side of the body opposite the injection immediately after the injection.
  • Your child may not be able to speak immediately after the injection.
  • Your child may feel some temporary weakness. This is the time to assess his/her speech and memory.
• The neurologist will ask your child to identify pictures, words, objects, shapes and numbers. Your child will have to answer questions and remember what is shown.
• The effects of the drug will wear off in about five to 10 minutes.
• This process is repeated with the other side of the brain.

After the Testthe Test

• The catheter will be removed.
  • Pressure and a bandage will be applied to the puncture site to prevent bleeding. No stitches will be required.
  • The nurse will ensure that your child keep his/her leg straight or elevated to prevent the puncture site from bleeding.
• The X-ray dye will cause your child to urinate more than usual. It is important for your child to drink plenty of fluids.
• Your child will remain in the hospital four to five hours after the test before you can take him/her home.
• You will get written information for your child’s home care after leaving the hospital.

Personnel

• physicians (neurologists and neuroradiologists)
• neuroradiology technologists
• nurses
• physician assistants
• neuropsychologists
• EEG technicians

Payment

The test is covered by the Ontario Health Insurance Plan (OHIP).

Important Considerations

• Notify the doctor if your child has any allergies, or sensitivity to drugs such as local anaesthetics, barbiturates, X-ray dyes, etc.
• After the procedure, your child may feel some tenderness and bruising at the injection site. Ice packs may be applied to this area to ease the pain.
• Let your child know that if s/he feels any discomfort such as nausea, coldness, headache, numbness in the foot, a warm wet feeling or swelling in the groin, s/he should tell the nurse immediately.

Click here to learn about other types of diagnostic tests.

Single Photon Emission Computed Tomography is a functional imaging technique that creates three-dimensional images of the brain on computer. This allows physicians to visualize blood flow through different areas of the brain.

Individuals with epilepsy often have changes in blood flow to specific areas of the brain when a seizure begins. SPECT measures blood flow between and during seizures. Physicians compare these scans to identify the blood flow changes in specific areas of the brain to identify where seizures originate.

Measuring the relative cerebral blood flow demonstrates how well the various regions of the brain are functioning . This information helps physicians to more accurately diagnose the type of seizure, locate the site where a seizure originates and evaluate a potential candidate for surgery.

The radiation exposure from a brain scan is small. It is in the range of one to three times your annual exposure to natural background radiation.

Before a SPECT Exam

• No special diet or medication is required. Your child may eat and drink as usual.
• Your child should wear comfortable clothing during the examination.
• Remove all metal objects (jewellery, keys, coins, pens, etc.) before the examination. These can cause defects in the scan.
• Inform your child that a needle will be injected into his/her arm or hand. Reassure your child that s/he will feel only a small prick from the needle.
• Let your child know that the technologist will be in the examination area at all times if s/he needs anything.

During a SPECT Exam

• A technician will ask you about your child’s medical history (e.g. head injury, seizures, stroke).
• Your child will lie on his/her back while the technician injects and a small amount of radioactive substance into a vein in his/her arm or hand. This radioactive agent will localize in an area of the brain and will be imaged with a camera.
  • This radioactive agent will localize in an area of the brain for the camera to capture.
  • Adverse reactions to this substance are very rare. Even then, it is only a mild skin reaction such as a rash.
• Your child will remain lying down for another 10 to 20 minutes.
• The technician will move a large camera near your child’s head.
  • It will take several pictures that show how well blood flows through various areas of your child’s brain.
  • The camera will remain close to your child’s head throughout the exam. It rotates once around his/her head and lightly brushes your child’s shoulders. It will not touch any other part of the body.
• The only sounds you will hear are the slight noise of the camera rotation and the cooling fans in the equipment.
  • There are no loud noises during the examination.
• Your child will be instructed to remain still and breath normally. Any movement will blur the images. Your child may have to repeat the scan if there is movement of the head.
  • If your child is too young to keep his/her head still, s/he may require sedation.
• Your child will be able to communicate with the technologist throughout the procedure.
• Preparation for the examination takes 30 minutes. The imaging takes another 30 minutes.

After a SPECT Exam

• When scanning is complete, the technologist will return to assist your child off the table. You child may go home and resume normal activities.
• A radiologist or physician will interpret the images and send a report to your child’s doctor.

Personnel

• Nuclear Medicine Technologists (NMTs)
  • work under the supervision of physicians to perform the SPECT exam
  • prepare, measure and give radioactive tracers to patients orally or by injection
• Doctors
  • interpret results

Payment

A SPECT exam is covered by the Ontario Health Insurance Plan (OHIP).

Important Considerations

• Pregnant women should not undergo a SPECT scan because of the radioactive isotopes used.
• Inform your doctor if your child is or may be pregnant, before proceeding with a nuclear medicine scan.

Click here to learn about other types of diagnostic tests.

Neuropsychological testing (also known as neuropsychometric testing) assesses a variety of brain functions including:

• memory,
• reading,
• comprehension,
• judgment,
• motor abilities,
• spatial perception and
• ability to process and interpret information.

The tests quantitatively measure these functions to demonstrate possible abnormalities of the brain. This may help to identify the type of epilepsy an individual has and locate the origin of the patient’s seizures.

Individuals with epilepsy occasionally report difficulties with memory, concentration or other cognitive areas. Neuropsychological tests assess these abilities and provide information about a person’s strengths and weaknesses. This offers doctors some insight into the cause and severity of seizures. They may also aid in the patient’s evaluation for surgical treatment.

Before the Exam

• Prepare a snack for your child to bring to the test as the procedures are lengthy.
• If your child wear eye glasses or hearing aids, please ensure s/he wears them on the day of the test.

During the Exam

• The neuropsychologist will ask your child to do the following tasks one at a time:
  • answer questions
  • solve puzzles
  • work with objects
  • remember words and sounds
• The tests usually last three to four hours for a child but may take longer.

After the Exam

• A neuropsychologist will interpret the results of the test and send the report to your child’s physician.
• The physician will then make an appointment with you to discuss the results.

Personnel

• Neuropscyhologists
  • administer the test and interprets the results
• Psychology Assistants
  • assist the neuropsychologist (HSC)
• Doctors
  • receive reports from neuropsychologists
  • discuss the results with the patient

Payment

This test is covered by the Ontario Health Insurance Plan (OHIP).

Click here to learn about other types of diagnostic tests.