Diagnosis

An epilepsy diagnosis is often made during an emergency visit for a seizure. If a person seeks medical help for a previous or suspected seizure, the doctor will ask about the patient's medical history, including seizure events.

One interesting study suggested that a doctor might be able to identify the location in the brain where the seizure is originating by watching the patient wipe his or her nose. A runny nose is common after a temporal lobe seizure, but not after seizures in other locations. Furthermore, the hand with which the patient wipes the nose coincides with the side of the brain in which the seizure occurs.

Ruling Out Serious Causes & Similar Conditions

Health- or life-threatening causes of seizures should first be ruled out. (See Causes in this report.)

The doctor will also rule out conditions that cause similar symptoms, including:

• Syncope. Syncope, a brief lapse of consciousness in which blood flow is reduced to the brain, can mimic epilepsy. It often misdiagnosed as epilepsy. Research continues to suggest that taking the patient's history and giving a physical exam, rather than administering an assortment of cardiac tests, is the most effective way to diagnose syncope.
• Migraines. Migraine headaches, particularly migraine with auras, may sometimes be confused with epilepsy. With epileptic seizure, the preceding aura is often seen as multiple, brightly colored, circular spots, while migraine sufferers tend to see black, white, or colorless lined or zigzag flickering patterns. Typically the migraine pain expands gradually over minutes toward one side.
• Panic Attacks. One study found that, in some patients, partial seizures resembled a panic disorder. Symptoms of panic disorder include palpitations, sweating, trembling, sensation of breathlessness, chest pain, feeling of choking, nausea, faintness, chills or flushes, fear of losing control, and fear of dying.
• Narcolepsy. Narcolepsy, a sleep disorder that causes a sudden loss of muscle tone and excessive daytime sleepiness, can be confused with epilepsy.

Diagnostic Tools

Electroencephalogram (EEG). The most important diagnostic tool for epilepsy is an EEG, which measures brain waves. Ideally, it should be performed within 24 hours of a seizure. An EEG recording session may last for less than an hour, but in some cases the doctor will want a day-long recording. Long-term monitoring may be necessary in some cases when patients do not respond to medications. Portable EEG units are available in some places, which can be used to monitor patients throughout normal activities. EEGs are not foolproof; in one study half of people who had experienced an epileptic seizure showed a normal EEG reading. Repeated EEGs are often needed to confirm a diagnosis, particularly for certain partial seizures that often produce an initially normal EEG reading.

Computerized Tomography (CT) Scans. Usually, the first brain imaging test ordered for most adults and children with first-time seizures is a CT scan. This imaging technique is sensitive enough for most purposes. In children, even if the scan is normal, the doctor will follow up to be sure other problems are not present.

A CT or CAT scan (computed tomography) is a much more sensitive imaging technique than X-ray, allowing high definition not only of the bony structures, but of the soft tissues. Clear images of organs such as the brain, muscles, joint structures, veins and arteries, as well as anomalies like tumors and hemorrhages may be obtained with or without the injection of contrasting dye.

Magnetic Resonance Imaging (MRI). Experts now strongly recommend MRIs for children with first seizures in certain cases, such as children under one year old and those with seizures that are associated with any unexplained significant mental or motor problems. These images may help to determine if the disorder can be treated with surgery, and may be used as a guide for surgeons.

Other Advanced Imaging Techniques. More advanced scanning techniques, particularly magnetic resonance spectroscopy (MRS), magnetoencephalography (MEG), positron emission tomography (PET), and single-photon emission computer tomography (SPECT), are emerging as important tools for epilepsy researchers. They are useful for detecting abnormalities, such as changes in brain activity, damaged or scarred locations in the brain where partial seizures are triggered, or tumors and other abnormalities that may be causing seizures. Some, such as MEG, may help determine which patients with severe epilepsy are good candidates for surgery.

Polysomnography

Some researchers recommend polysomnography for certain patients. This test is used to detect sleep disorders, such as obstructive sleep apnea, that are can be associated with epilepsy.

Investigative Diagnostic Procedures

Low brain levels of the neurotransmitter gamma aminobutyric acid (GABA) are associated with an increased risk of seizure recurrence. Some researchers suggest that measuring GABA levels, along with EEG recordings, could help better assess the risk of recurring seizures, and may identify which patients might benefit from GABA-stimulating drugs.