Exams and Tests

Making the correct diagnosis is vital to identifying the appropriate treatment to control seizures.

Diagnosing epilepsy can be quite difficult. When you consult a doctor after you or your child has had unexplained seizures, you and the doctor will work together to answer three questions:

• Was the event a seizure, or was it something that looked like a seizure? Several conditions can appear to be seizures but are not in fact seizures. (These might include breath-holding spells, migraine headaches, muscle twitches or tics, sleep disorders, or psychogenic seizures.) Taking antiepileptic medicines to treat nonepileptic seizures can expose you or your child to unnecessary risks.
• If you are having seizures, are the seizures caused by epilepsy? Not everyone who has a seizure has epilepsy. The seizure may have been caused by something else (such as fever, certain medicines, an electrolyte imbalance, or inhaling fumes). Taking antiepileptic medicines when you do not have epilepsy may put you at unnecessary risk from possible side effects.
• If you have or may have epilepsy, what types of seizures are you having? The different types of epileptic seizures (partial and generalized) are not treated in the same way or with the same medicines. For example, some medicines that control complex partial seizures may make absence seizures worse.

A physical exam and detailed medical history often provide the best clues as to whether you have epilepsy and what type of epilepsy and seizures you have. Discussing what happens to you just before, during, and right after a seizure can help the doctor make a diagnosis.

Your doctor may want to rule out other possible causes for the seizures with other laboratory tests, which may include:

• Complete blood count (CBC) to check for infection, and blood chemistry tests to check for abnormal electrolyte levels (such as magnesium, sodium, and calcium), signs of kidney or liver malfunction, and other common problems.
• Lumbar puncture (sometimes called a spinal tap), which is an analysis of spinal fluid evaluated to rule out infections, such as meningitis and encephalitis.
• Toxicology screen, which examines blood, urine, or hair to look for poisons, illegal drugs, or other toxins.

Electroencephalogram (EEG)

The most useful test in support of a diagnosis of epilepsy is an electroencephalogram (EEG). A computer records your brain's electrical patterns as wavy lines. If you have epilepsy, the EEG may show abnormal spikes or waves in your brain's electrical activity patterns. Different types of epilepsy cause different patterns. But an EEG is limited in its ability to diagnose epilepsy. And many people with epilepsy have normal EEGs in between seizures.

Imaging tests (MRI and CT)

Magnetic resonance imaging (MRI) and computed tomography (CT) are imaging tests that allow a doctor to view the brain and evaluate the cause and location of a possible source of epilepsy within the brain. The scans can reveal scar tissue, tumors, or structural problems in the brain that may be the cause of seizures or epilepsy. MRI is the more helpful test in most cases. Imaging tests may not be done after a first seizure, but they are recommended in many situations (such as after a first seizure in adults or after a head injury).

See an MRI image of a seizure.