A partial seizure is a sudden change in consciousness, muscle control or behavior caused by abnormal activity in an isolated part of the brain. A partial seizure is different from a generalized seizure, which usually involves the entire brain.

Seizures occur when the neurons in the brain suddenly increase activity, causing an electrical storm that can overwhelm the brain. This can result in a variety of symptoms, depending on the area of the brain affected. Anything that disrupts the normal function of the brain can cause seizures. Although roughly half of all seizures have no known cause, there are certain factors that may trigger seizures, such as head injury, genetic abnormalities, alcohol withdrawal and brain tumors.

Partial seizures are generally categorized as being either complex or simple. Complex seizures usually originate in the temporal lobe of the brain. During a complex partial seizure, the person may stare into space and perform seemingly conscious tasks, which are known as automatisms. When the seizure is over, the person rarely has any recollection of the seizure. During a simple partial seizure, people are awake and aware, although they have no control over their actions. Simple seizures are usually further categorized according to the area of the brain affected.

Many partial seizures occur only once and require no treatment. However, people with recurring partial seizures may be treated with seizure medications. People who are unable to control seizures with medication may be candidates for brain surgery to remove the affected area of the brain responsible for the seizures.