In addition to blood-work and a full neurological exam, including a detailed health history, your doctor will order further diagnostic tests if he or she suspects epilepsy. Below are some of the tests that they use to help with diagnosing epilepsy.
An EEG is a primary diagnostic test that records brain waves. Brain cells communicate by transmitting small electric signals. Abnormal brain waves caused by excessive electric signals indicate seizure activity. EEGs record this electrical activity in the brain and detect abnormalities that indicate possible seizures.
Computed Tomographic Scan
A CT or CAT scan is a series of detailed x-rays, taken at different angles in the brain. They indicate structural abnormalities in the brain or skull that may relate to seizures.
Magnetic Resonance Imaging
MRI uses magnetic fields instead of x-rays, to produce two- and three-dimensional images of the brain. It detects brain tumours and other brain abnormalities.
Functional Magnetic Resonance Imaging – A functional MRI provides information about active brain tissue function and blood delivery. It can find the exact location of a seizure area. Doctors use it to measure small metabolic changes in the active part of the brain. It also maps the areas used for thought, speech, movement and sensation.
Video EEG Monitoring
This test records brain waves on an EEG while the patient is also monitored by video. The purpose of the test is to capture a seizure event on video and observe by EEG what is happening in the brain. In this way, doctors can tell if the event is epileptic (caused by unusual electrical activity in the brain). This test also helps to pinpoint the location of the seizure activity. As such, it is part of the pre-surgical examination for a patient who may undergo surgery.
The practices above are the primary preferred tests in Canada. What follows is a brief description of tests that may be used in other areas.The following tests are not performed in British Columbia.
Positron Emission Tomography
A PET scan shows brain function, metabolism and how glucose is used in the brain through colour computer images.
Single Photon Emission Computed Tomography
SPECT uses three-dimensional images to show blood flow in different parts of the brain (People with epilepsy often have changes in blood flow when a seizure begins).
Magnetoencephalography/Magnetic Source Imaging – (not currently done in BC for epilepsy)
MEG/MSI records magnetic brain waves to assess brain function and structure.