Tests and diagnosis

By Mayo Clinic Staff

Medical history

Your doctor will ask for a detailed description of the seizure, which is crucial for diagnosis. Because people who have grand mal seizures lose consciousness and don't remember their seizures, the description needs to come from people who have witnessed the seizures. Your doctor may try to determine whether a particular trigger, such as intense exercise, loud music or lack of sleep, preceded your seizure. However, most people have no identifiable or consistent trigger.

Neurological exam

If you've had a seizure, your doctor usually will perform a neurological exam that tests:

  • Reflexes
  • Muscle tone
  • Muscle strength
  • Sensory function
  • Gait
  • Posture
  • Coordination
  • Balance

He or she may also ask questions to assess your thinking, judgment and memory.

Blood tests and scans

Blood tests may be ordered as appropriate to check for problems that could be causing or triggering the seizures.

Your doctor may also suggest scans or tests designed to detect abnormalities within the brain.

  • Electroencephalogram (EEG). An EEG displays the electrical activity of your brain via electrodes affixed to your scalp. People with epilepsy often have changes in their normal pattern of brain waves, even when they're not having a seizure.

    In some cases, your doctor may recommend video-EEG monitoring, which may require a hospital stay. This allows your doctor to compare — second by second — the behaviors observed during a seizure with your EEG pattern from exactly that same time. This comparison can help your doctor pinpoint the type of seizure disorder you have, which helps to identify the most appropriate treatment options, and it can help make sure that the diagnosis of seizures is correct.

  • Magnetic resonance imaging (MRI). An MRI machine produces detailed images of your brain. Although many people with seizures and epilepsy have normal MRIs, certain MRI abnormalities may provide a clue as to the cause of seizures in some cases.

    During the test, you will lie on a padded table that slides into the MRI machine. Your head will be immobilized in a brace, to improve precision. The test is painless, but some people experience claustrophobia inside the MRI machine's close quarters. If you think you may have this problem, inform your doctor.

Jun. 23, 2011