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.
Conditions that cause similar symptoms to epilepsy include:
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 or a recording during sleep. 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. Repeated EEGs are often needed to confirm a diagnosis, particularly for certain partial seizures that often produce an initially normal EEG reading.
Video Electroencephalography (Video EEG). For this task, patients are admitted to a special part of the hospital where they are monitored both by EEG and are also watched by a video camera. Patients may need this for a variety of reasons including withdrawal or addition of medications in a patient with difficult-to treat-epilepsy, before epilepsy surgery for some patients, and also when psychogenic nonepileptic seizures are suspected.
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.
Magnetic Resonance Imaging (MRI). Doctors strongly recommend MRIs for children with first seizures in certain cases, such as children under 1 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 are emerging as important tools for epilepsy researchers. By detecting abnormalities, such as changes in brain activity, positron emission tomography (PET) may help locate damaged or scarred locations in the brain where partial seizures are triggered. These findings may help determine which patients with severe epilepsy are good candidates for surgery. Single-photon emission computer tomography (SPECT) may also be used to decide if the surgery should be performed and what part of the brain needs to be removed. Both of these imaging techniques are generally only needed when an MRI of the brain has not been helpful.
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