Girl Thinking

About Epilepsy


How epilepsy is diagnosed

Finding What Caused a Seizure

After a person’s first seizure, they should see their doctor. The doctor will try to determine what might have caused the seizure, as well what types of treatment(s) might be appropriate. They will check for signs that the person may have additional seizures or a tendency towards seizures. The doctor will also check for signs of any illness or injuries that could be causing the seizures. Some seizures are very easy to see because they cause convulsions or unusual behavior. Other seizures may be harder to recognize. Finding out what type of seizures a person is having is the first step in finding a treatment to control them.

Some questions the physician will try to answer include:

  • Was the seizure caused by a short-term illness (fever, infection)?
  • Was the seizure a result of a malfunction in the brain’s electrical system?
  • Was it due to something that can be prevented from happening again?
  • Was the seizure caused by something within the brain structure?
  • Was the seizure a one-time event, or does the person have a pattern of seizures?

While every diagnostic process will vary, the major steps in the process should include: a detailed and complete medical history, a detailed account of the seizure, and various medical tests.

Medical History

A person’s medical history will be some of the most important information the doctor needs in reaching a diagnosis of epilepsy. In particular, the doctor will want to know as much as possible about a person’s seizures from beginning to end, including:

If a person does not know what happens during their seizures, they should try to bring someone with them who does, or bring a written description.

Medical Tests

Several kinds of medical test can be helpful in determining the diagnosis and treatment.

Physiological Tests

These tests are to assess how the functions of the body are performing. This could be a typical physical exam, including cardiac, neurological, and mental status, as well as common things such as blood pressure, weight, listening to the heart, etc. Your physician might also want to perform a blood test to help identify potential causes of a seizure and/or to identify other significant illnesses. Blood tests can also be used to detect if there is an infection or exposure to any poisons that may have caused the seizure.

Electroencephalogram (EEG)

An EEG shows brain wave activity to see if there is any unusual activity in the brain that may produce seizures. During this test, which is safe and painless, a technician pastes electrodes onto a person’s scalp over the hair. The electrodes are small, metal discs with thin wires that send the brain’s electrical impulses to a computer, which prints out the activity as a series of wavy or spiked lines. Patterns on the print-out will help the doctor to diagnose the type of seizure(s), likelihood of seizure recurrence, where in the brain the seizure activity is starting, and what treatment(s) might work best.

The EEG test, which can last anywhere from a half-hour to an overnight stay, usually takes place in a hospital or epilepsy clinic. Often, the test is video recorded. Looking at the recording may help the doctor to make a diagnosis if a person happens to have a seizure while being monitored.

The technician may ask a person to do simple tasks while wearing the electrodes, such as taking deep breaths through the mouth, blinking your eyes rapidly, or looking at a flashing light.

Children should be prepared in advance of an EEG test so as to make the experience as stress-free as possible. Children can “practice” on a doll or stuffed animal.

Sometimes the history indicates that a person is having seizures, but the EEG results indicate normal brain electrical activity. If this is the case, the doctor may order a longer EEG test or one that uses special, ultra-sensitive electrodes that can pick up on fainter electrical impulses from the brain.

Brain Imaging

The doctor may order several different types of tests that show images of the brain. These tests help a doctor to tell if there are any physical changes in the structure of the brain that may be causing the seizures (such as blood clots, malformations, tumors, or scar tissue). These tests are performed by a machine that looks a little like a front-loading washing machine. A person lies on an examination table in front of the machine, and the table is slowly moved forward until their head is inside the imaging chamber. The machine will make loud clunking and humming noises.

As with the EEG test, an MRI or CT scan is safe and painless, and children should be prepared in advance so that they know what to expect.

  • Magnetic Resonance Imaging (MRI) is a common test where detailed pictures of the brain are produced using powerful magnets and radio waves. Earplugs or music are usually provided to help block the noise during this procedure.
  • Computerized Axial Tomography (CAT or CT) Scan is a series of x-ray images taken from different angles and then combined by a computer to create cross-section images of the bones, blood vessels, and soft tissues of the head.

CT scans are quicker than MRI scans of the brain, but CT scans do expose you to small amounts of radiation. Although generally safe, there is a small increased lifetime risk of cancer from CT scan x-ray exposure. The risk is greater the earlier in life the exposure occurs, and it becomes greater with multiple CT scan exposures.

Genetic Testing

Genetic testing may be used to help identify any genetic factors that contributed to the seizure. This information could help provide the person with more specific information about a possible epilepsy syndrome.

Lumbar Puncture or Spinal Tap

This test helps to diagnose serious infections and is used predominantly when a person presents in the emergency room with prolonged seizures and a fever. A needle is inserted between two vertebrae in the lower back (lumbar region) to remove a sample of cerebrospinal fluid, which is the fluid that surrounds the brain and spinal cord to protect them from injury. The fluid will be screened for color, blood cell count, protein, glucose, and other substances.

The doctor will try to determine whether the seizures are being caused by epilepsy or another condition. It may not always be possible to make a definite diagnosis of epilepsy. If a diagnosis cannot be clearly established, consider a referral to an epilepsy specialist.

If you are diagnosed with epilepsy, find out the specific types of seizures you are having. This information will determine the types of treatment and first aid procedures, and will help you to explain more about your epilepsy to others.