Tests and diagnosisBy Mayo Clinic staff
Your doctor may use a number of tests to diagnose epilepsy, from neurological exams to imaging techniques like MRI scans.
- Neurological and behavioral exam. Your doctor may want to test your motor abilities, behavior and intellectual capacity to see how the seizures are affecting you.
- Blood tests. Your doctor may take a blood sample to check for signs of infections, electrolyte imbalance, anemia or diabetes, which can be associated with seizures.
Your doctor may also suggest tests to detect abnormalities within the brain. These include:
- Electroencephalogram (EEG). This is the most common test to help diagnose epilepsy. An EEG records the electrical activity of your brain via electrodes temporarily attached to your scalp with a paste-like substance. If you have epilepsy, it's common to have changes in your normal pattern of brain waves, even when you're not having a seizure. Your doctor may want to monitor you on video while conducting an EEG of you awake or asleep in hopes of recording the seizure to see what kind of seizures you're having. Sometimes your doctor will have to do something to provoke a seizure while you're being tested, such as asking you to sleep very little the night before.
- Computerized tomography (CT). You might be given a CT scan if you go to an emergency room for an initial seizure, because it's generally a readily available test. CT machines use a type of X-ray equipment to obtain cross-sectional images of your brain and skull. CT scans can reveal abnormalities in the brain that might be causing your seizures, including tumors, bleeding and cysts.
- Magnetic resonance imaging (MRI). An MRI provides much the same type of information as a CT scan, but in far greater detail. MRIs use radio waves and a strong magnetic field to produce detailed images of your brain. MRIs can reveal brain abnormalities that could be causing your seizures.
- Functional MRI (fMRI). A functional MRI measures the changes in blood flow that occur when specific parts of your brain are working. Doctors generally use an fMRI before surgery to identify the exact locations of critical functions, like speech, so that surgeons can avoid injuring those places while operating.
- Positron emission tomography (PET). PET scans use a small amount of low-dose radioactive material that's injected into a vein to help visualize active areas of the brain and detect abnormalities.
- Single-photon emission computerized tomography (SPECT). This type of test is used primarily if you've had an MRI and EEG that didn't pinpoint the location in your brain where the seizures are originating. A SPECT test uses a small amount of low-dose radioactive material that's injected into a vein to create a detailed, 3-D map of the blood flow activity in your brain during seizures.
- Neuropsychological tests. This group of tests includes IQ, memory and speech assessments, which help doctors pinpoint where the seizures are originating. This type of testing is routinely done before epilepsy surgery.
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