Author Archives: eCreative Studios

Electroencephalogram (EEG)

August 8, 2011

Electro refers to electricity; encephalo refers to the brain; gram refers to record.

A doctor may order an EEG test to determine whether you have epilepsy and in what form. The EEG allows the doctor see if there are any irregularities electrical activities occurring in the brain that may produce seizures.

An electroencephalogram is a non-invasive diagnostic test. It records electrical activity on the surface of the brain to identify the location of the abnormally firing neurons that cause seizures. An electroencephalograph is the instrument used to register this activity and record it on graph paper. A neurologist uses these recordings to help identify the location, severity and type of seizure disorder. This safe and painless procedure will not affect you in any way.

It is important to remember that an abnormal EEG does not diagnose epilepsy nor does a normal EEG reading exclude epilepsy. An EEG can only measure abnormal electrical activity that occurs during the test period. Sometimes, the brain of the person with epilepsy functions perfectly normal during the test.

Tests that have been done on people with epilepsy commonly show uneven activity or large changes in the voltage of brain waves (spikes). Different patterns of activity from different spots on the scalp point to different kinds of epilepsy.

Before an EEGExpand Before an EEG Section

  • If the doctor has ordered a sleep test, adjust your sleeping schedule (reduce sleep) according to the doctor’s instructions and avoid caffeine drinks.
  • Wash your hair thoroughly. Your scalp should be clean and oil-free for the test so that electrodes can stay on your head and work effectively. No conditioners or any hair products should be used.
  • Remove any hair accessories before going to the test centre.
  • It is important to eat before being tested in order to help stabilize your blood sugar level.
  • Continue to take your medication(s) unless instructed otherwise by your doctor.

During an EEGExpand During an EEG Section

  • Before the test, you may be asked to provide information about your medical history and any medications being taken.
  • The test may be given in a small room separated from the EEG machine and the technologist. This allows you to take the test in a quiet, relaxing environment.
  • Some clinics may have small TV cameras set up in the test area to videotape your movement during the test. Analyzing this recorded movement along with the EEG recording may help the doctor identify your type of seizure.
  • The technician will ask you to lie on a stretcher. S/he will then measure your head and mark where the metal discs will be placed. These small metal discs, called electrodes, will be applied to various places on the scalp with a special cream. This painless process takes 15 to 20 minutes.
  • You will be instructed to keep your eyes closed and to remain still and relaxed throughout the examination.
    • Inaccurate results can be caused by an irregular heartbeat, sweating, eye movement, eye blinking, muscle tension, sucking movements, chewing or any movement. Therefore, to help ensure accurate results, you must relax and breath normally, stay quiet and still, and carefully follow the technician’s instructions.
  • Various procedures may be used during the test to stimulate the brain or to trigger certain brain waves and produce clearer wave patterns.
    • You may be asked to open and close your eyes several times.
    • You may be instructed to breathe deeply through your mouth for short time. This may cause a slight dizzy feeling or numbness in the hands or feet. These are natural reactions and will subside once the deep breathing is over.
    • A bright, flashing light may be placed in front of your eyes which may cause you to see different geometric designs and patterns of light.
    • If your doctor ordered a sleep test, you will be given a mild sedative to help you fall asleep during the examination.
    • These different procedures are done in order to compare brain activity under a wide variety of conditions.
  • The entire EEG test takes 60 to 90 minutes.

After an EEGExpand After an EEG Section

  • The electrodes will be removed from your head. There may be some stickiness from the cream used to place the electrodes. Wash your hair when you get home.
  • You should be able to resume normal activities, unless told otherwise by the doctor or technician.

PersonnelExpand Personnel Section

EEG Technologists and Technicians

  • help physicians diagnose epilepsy
  • take your medical history
  • prepare the EEG test
  • operate the EEG machine to record electrical impulses transmitted by the brain and nervous system
  • apply electrodes to designated spots on your head
  • prepare data for doctors to interpret

Physicians who specialize in EEGs

  • read and interpret the results of the EEGs
  • supervise the EEG technicians

Payment: An EEG test is fully covered by the Ontario Health Insurance Plan (OHIP).

Click here to learn about other types of diagnostic tests.

Magnetoencephalography (MEG) or Magnetic Source Imaging (MSI)

August 8, 2011

Magnetoencephalography (MEG), also known as Magnetic Source Imaging (MSI), is a non-invasive scanning technique that provides information about the structure and function of the brain. It is a safe and painless procedure.

How does it work?

MEG detects small biomagnetic signals that the brain produces and records magnetic fields over the surface of the head. These signals show which areas of the brain are active, allowing us to see how different areas of the brain interact with one another.

MEG can help identify the areas of the brain emitting abnormal electric currents that cause seizures. Patients often perform cognitive tasks during the MEG to help localize the learning and memory areas of the brain. The MEG produces a high resolution image of the brain that relates the functioning of the brain with behaviour.

One advantage MEG has over PET and fMRI, which depend on changes in blood flow in the brain, is speed. Unlike PET and fMRI, MEG is fast enough to provide information about the changes in neuronal firing to the millisecond. MEG records magnetic signals produced by the responding neurons, which enables us to see rapid brain potentials.

Before an MEG/MSI

  • No special diet is required. You can eat and drink as usual.
  • Dress in comfortable clothing on the day of the test.
  • Wash your hair and refrain from using hairspray, gel or other hair products.
  • Do not wear any metal objects (jewellery, piercings, belts, etc.).

During an MEG/MSI

  • The test will take place in a shielded room away from fan motors, elevators and other sources of magnetic “noise.”
  • You will either lie down on a bed or sit in a chair.
  • An electrical device, known as a neuromagnetometer, will be placed near your head. This instrument acts as an antenna to pick up the magnetic fields emerging from the brain. It takes a snapshot every millisecond.

Payment

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

Click here to learn about other types of diagnostic tests.

Single Photon Emission Computed Tomography (SPECT)

August 8, 2011

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.
  • Dress in comfortable clothing.
  • Remove all metal objects (jewellery, keys, coins, pens, etc.) to prevent defects in the scan.

During a SPECT Exam

  • A technician will ask you about your past medical history (e.g. head injury, seizures, stroke).
  • You will lie on your back while the technician injects and a small amount of radioactive substance into a vein in your arm or hand.
    • 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.
  • You will remain lying down for another 10 to 20 minutes.
  • The technician will move a large camera near your head.
    • It will take several pictures that show how well blood flows through various areas of your brain.
    • The camera will remain close to your head throughout the exam. It rotates once around your head and lightly brushes your shoulders. It will not touch any other part of your 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.
  • Remain still and breath normally.
    • Any movement will blur the images. You may have to repeat the scan if you move your head.
  • You 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, you may resume your normal activities.
  • A radiologist or physician will interpret the images and send a report to your 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. Be sure to inform your doctor if you are or suspect you may be pregnant before proceeding with a nuclear medicine scan.

Click here to learn about other types of diagnostic tests.

Wada Test

August 8, 2011

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 the Test

  • A specialist will schedule an appointment with you to gather information about your speech, cognitive and memory functions.
  • Do not wear jewellery or other metal objects during the test.
  • You must arrange someone to pick you up after the test as you will not be able to drive home after the procedure

During the Test

Part 1: Angiography

  • You will lie on your 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.You 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 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.
    • You may experience a feeling of heat, pressure and sometimes pain for approximately 10 to 20 seconds.
    • You may have a metallic taste in your mouth, but this taste will subside.
    • You may hear noises from the X-ray machine as it takes images of the dye passing through the blood vessels.
  • It is important that you remain still throughout 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.
    • Immediately following the injection, you will not be able to move the side of the body opposite the injection.
    • You may not be able to speak immediately after the injection.
    • You may feel some temporary weakness. This is the time to assess your speech and memory.
  • The neurologist will ask you to identify pictures, words, objects, shapes and numbers. You 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 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 you keep your leg straight or elevated to prevent the puncture site from bleeding.
  • The X-ray dye will cause you to urinate more than usual. It is important to drink plenty of fluids.
  • You will remain in the hospital four to five hours after the test before you are able to go home with accompaniment.
    • You will not be able to drive. Arrange with someone to pick you up after the test.
  • You will get written information for 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 you have any allergies or sensitivities to drugs (local anaesthetics, barbiturates, X-ray dyes, etc.).
  • After the procedure, you may feel some tenderness and bruising at the injection site. You may apply ice packs to this area to ease the pain.
  • You should inform the nurse if you feel any discomfort such as nausea, coldness, headache, numbness in the foot or a warm wet feeling or swelling in the groin.

Click here to learn about other types of diagnostic tests.