Topic Overview

After you have had a seizure, it can be difficult to predict whether you will have more seizures. This makes it hard to decide whether to begin treatment for epilepsy. The first seizure you report may not actually be the first seizure you’ve had. You may have had seizures in the past, such as brief absence seizures or auras, without knowing they were seizures.

Doing an electroencephalogram (EEG), especially after sleep deprivation, may reveal abnormalities in the brain’s electrical activity that may help confirm the diagnosis of epilepsy.

CT and MRI scans can be helpful in detecting changes in the brain that could be related to epilepsy. These tests may be done immediately if the person who has had the seizure also has a decreased level of consciousness or new motor or sensory problems that do not improve shortly after the seizure ends. Scans may also be done if the person has ongoing headache or fever, AIDS, recent trauma (especially to the head), or a history of cancer or anticoagulant therapy. These things increase the likelihood that the seizure may have been related to a serious problem in the brain. The nature of the seizure and the person’s age can also help determine whether an imaging test is needed and how soon it is needed.

When deciding to start treatment, you and your doctor can consider how likely you are to have a second seizure. Risk factors for having a second seizure include:

• Evidence of a structural lesion in the brain as seen on a CT or MRI scan.
• Abnormal EEG results.
• History of an injury to your brain, such as a stroke or trauma.
• A seizure that occurred at night.

There is some evidence to support the use of antiepileptic medicines after a first seizure to reduce the risk of more seizures. But medicine is usually not prescribed if you do not have any of the above risk factors and are thought to be unlikely to have more seizures. Taking antiepileptic medicines when you are not at risk for more seizures exposes you to side effects and potential harm from the medicine.