Diagnosis

After a seizure, your doctor will thoroughly review your symptoms and medical history. Your doctor may order several tests to determine the cause of your seizure and evaluate how likely it is that you'll have another one.

Tests may include:

• A neurological exam. Your doctor may evaluate your behavior, motor abilities and mental function to determine if you have a problem with your brain and nervous system.
• Blood tests. Your doctor may take a blood sample to check your blood sugar levels and look for signs of infections, genetic conditions or electrolyte imbalances.
• Lumbar puncture. If your doctor suspects an infection as the cause of a seizure, you may need to have a sample of cerebrospinal fluid removed for testing.
• An electroencephalogram (EEG). In this test, doctors attach electrodes to your scalp with a paste-like substance. The electrodes record the electrical activity of your brain, which shows up as wavy lines on an EEG recording. The EEG may reveal a pattern that tells doctors whether a seizure is likely to occur again. EEG testing may also help your doctor exclude other conditions that mimic epilepsy as a reason for your seizure. Depending on the details of your seizures, this test may be done at an outpatient visit in the clinic, overnight at home with an ambulatory device or over a few nights in the hospital.

Imaging tests may include:

• Magnetic resonance imaging (MRI). An MRI scan uses powerful magnets and radio waves to create a detailed view of your brain. Your doctor may be able to detect lesions or abnormalities in your brain that could lead to seizures.
• Computerized tomography (CT). A CT scan uses X-rays to obtain cross-sectional images of your brain. CT scans can reveal abnormalities in your brain that might cause a seizure, such as tumors, bleeding and cysts.
• Positron emission tomography (PET). A PET scan uses 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). A SPECT test uses a small amount of low-dose radioactive material that's injected into a vein to create a detailed, 3D map of the blood flow activity in your brain that happens during a seizure. Doctors may also conduct a type of SPECT test called subtraction ictal SPECT coregistered with MRI (SISCOM), which may provide even more-detailed results. This test is usually done in a hospital with overnight EEG recording.