Laboratory and non-laboratory tests are used to diagnose and monitor epilepsy, to determine what kind(s) of seizures a person is having, to identify underlying conditions such as toxins, infections, drug or alcohol withdrawal, fever (in a child), or diabetes that may be causing seizures, and to distinguish epilepsy from conditions such as fainting or a stroke that may cause some of the same symptoms.
A medical history, input from the patient, and input from family members who have witnessed the seizures are important parts of the diagnostic process. Someone with epilepsy may remember a strange smell, an aura, and/or sensations that precede a seizure but may not remember what has happened during the seizure itself. Depending upon the signs and frequency of a person's seizures, it may take some time to determine the proper diagnosis.
- Electroencephalogram (EEG) – the primary diagnostic tool for epilepsy; it is used to evaluate the brain's electrical activity and identify changes in brain wave patterns.
- Computed tomography (CT) – identify brain structure abnormalities and tumors
- Magnetic resonance imaging (MRI) – also identify brain abnormalities
- Positron emission tomography (PET) – radioactive material is used to look at active areas of the brain.
- Single-photon emission computed tomography (SPECT) – radioactive material is used to identify the region of the brain where seizures originate when it is not clear on other scans.
Laboratory tests are primarily used to monitor anti-epileptic medications and to search for conditions that may cause seizures, such as diabetes, infection, meningitis or encephalitis.
Periodic therapeutic drug monitoring is performed when a patient is taking a specific medication to ensure that therapeutic levels are achieved. Epileptic medications that are monitored include:
Other testing is done to identify possible causes for seizures, including:
- CBC (Complete Blood Count) – to evaluate blood cells to check for a variety of conditions, including infection
- Glucose – to check for the possibility of diabetes
- CSF analysis – to check for infection and help diagnose meningitis and encephalitis
- Blood culture – to check for septicemia, infection in the blood