How is Epilepsy Diagnosed?
Reviewed by: HU Medical Review Board | Last reviewed: November 2021 | Last updated: June 2022
Epilepsy is a neurological (brain) disease that causes people to have seizures. But people may have seizures for many reasons, not just epilepsy. Migraine, stroke, low blood sugar, and narcolepsy may all cause symptoms that may look like epilepsy seizures.
To diagnose epilepsy, your doctor will order many tests and conduct a physical exam. The tests may include:1,2
- EEG (electroencephalogram)
- Blood work
- Brain imaging tests
- Neurological exam
- Hospital monitoring
- Genetic testing
The doctor will also want to talk about the seizure event, either with you or someone who saw the seizure. All of this information helps the doctor understand what type of seizure you had and how seizures may affect your brain.
Generally, a person is diagnosed with epilepsy if they have at least 2 unprovoked seizures more than 24 hours apart. Unprovoked means the seizures are not caused by a medical condition other than epilepsy.1,2
Physical exam and medical history
During a basic physical exam, a doctor checks your weight, height, heart rate, and blood pressure. They also look at your eyes and ears, listen to your heart and lungs, and press on your belly.
Your doctor will also take a medical history. This means they will ask you about your overall health and about your seizures. You will also be asked about whether people in your family have seizures or epilepsy. Be ready to answer questions about:2
- Any drugs or supplements you take
- Past surgeries, accidents, and illnesses
- Vaccine history
- Illegal drug and alcohol use
- Whether you have been tested for epilepsy before
A neurological exam is a detailed, specialized exam done by a neurologist. A neurological exam tests how your brain and the rest of your nervous system are working. These tests look at a range of things controlled by the brain. This includes:1
- Balance, walking, and coordination
- Concentration and memory
- Senses like sight, hearing, touch, and taste
Your doctor may run several blood tests. These will check your overall health and to rule out other conditions. A complete blood count (CBC) is a common test that measures red blood cells, white blood cells, platelets, and hemoglobin. It is also common to have a blood glucose test after a first seizure.1,2
Blood chemistry, or chemistry panel, measures different aspects of health. This test looks at things like liver and kidney function, electrolytes, glucose, calcium, and magnesium. The test can be tailored to what your doctor wants to know.1,2
A urinalysis tests urine. This test may be used to check for infections, kidney health and evidence of diabetes.1,2
An EEG (electroencephalogram) is a test that measures electrical activity in the brain. An EEG shows brain wave patterns that can tell your doctor what type of seizures you are having. Some EEGs include a video recording, too.1,2
Brain imaging tests
The most common imaging tests ordered for epilepsy are computed tomography (CT scan) and magnetic resonance imaging (MRI). Both take pictures of the brain. These pictures help your doctor know if seizures are caused by changes to the structure of the brain.1,2
Some people with seizures may need to spend time in the hospital. This is often done in an epilepsy monitoring unit, where EEG tests may last for days or even weeks. This is known as long-term monitoring. There are 2 main reasons for this:1,2
- Someone had their first seizure and has not returned to normal behavior, had a serious seizure-related injury, or continues to have more seizures.
- Doctors need to give or change medicines quickly while they monitor the person and try to trigger and record more seizures.
- Doctors need more detailed test results to understand a person’s seizure disorder type or to help with epilepsy surgical planning.
Genetic tests look at whether changes in someone’s genes are causing their epilepsy. Genetic tests are usually not among the first tests done if epilepsy is suspected. But these tests can be helpful in people with hard-to-control seizures, signs of an epilepsy syndrome, or a family history of epilepsy.3