How is epilepsy diagnosed?

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See a doctor if you have had a 'possible seizure' or similar event. Sometimes it is difficult for a doctor to confirm that you have had a seizure. The most important part of confirming the diagnosis is the description of what happened. Other conditions can look like seizures. For example, faints, panic attacks, collapses due to heart problems, breath-holding attacks in children, and other problems.
Therefore, it is important that a doctor has a clear description of what happened during the 'event'. Preferably this is from the person affected, and also from an eyewitness. The description may be typical of a seizure. However, sometimes it is difficult for a doctor to definitely confirm the diagnosis. Tests such as brain scans, EEG, and blood tests may help.

A brain scan (usually an MRI or CT scan) can show the structure of different parts of the brain. A brain scan is not always necessary.
EEG (ElectroEncephaloGram). This test records the electrical activity of the brain. Special stickers are placed on various parts of the scalp. They are connected to the EEG machine. This amplifies the tiny electrical messages given off by the brain, and records their pattern on paper or computer. The test is painless. Some types of seizure produce typical EEG patterns. However, a normal recording does not rule out epilepsy, and not all EEG abnormalities are related to epilepsy.
Blood tests and other tests may be advised to check on your general well being. They may also look for other possible causes of the 'event'.

Although helpful, tests are not foolproof. It is possible to have epilepsy with normal test results. Also, if an abnormality is found on a brain scan, it does not prove that it causes seizures. However, tests may help to decide if the 'event' was a seizure, or caused by something else. It is unusual for a diagnosis of epilepsy to be made after one seizure, as the definition of epilepsy is 'recurrent seizures'. For this reason a doctor may suggest to 'wait and see' if it happens again before making a firm diagnosis of epilepsy.