Millions of tiny electrical signals are generated by the nerve cells in the brain. They regulate movement, emotions and consciousness, among other things. Normally, these electrical signals discharge in an orderly manner. There is a balance between the "on" and "off" firing of these electrical impulses. But if something goes wrong with this process - a surge of impulses, too much "on" and not enough "off" - a seizure can occur.

A seizure is a brief, temporary disturbance of the brain's electrical system. It can occur in just one region of the brain (partial) or it can affect all regions (generalized). Seizures can look very different. It depends on which part and how much of the brain is involved, A seizure can last a few seconds to a few minutes.

Types of seizures
Seizures are categorized as generalized or partial.

• Partial seizure. About 60 percent of people with epilepsy have one of the different types of partial seizures. In a simple partial seizure, the person remains conscious but may have unusual feelings or sensations. In a complex partial seizure, the person may have a change in or loss of consciousness. The change in consciousness may be an altered or dreamlike state.
• Generalized seizure. Generalized seizures cause loss of consciousness, falls or massive muscle spasms. There are different types of generalized seizures. In absence or petit mal seizures, the person may appear to be staring into space. With tonic seizures the muscles of the body stiffen, generally those in the back, legs, and arms. Clonic seizures cause repeated jerking movements of muscles on both sides of the body. Tonic-clonic or grand mal seizures are a mixture of symptoms. These include stiffening of the body and repeated jerks of the arms and/or legs, as well as loss of consciousness.

When does a seizure mean epilepsy?
Watching someone have a seizure can be scary. An isolated seizure does not automatically mean a person has epilepsy. One in 10 adults will have a seizure sometime during their life. All people who have seizures don't automatically need treatment. Doctors will often wait to see if a person has a second or third seizure before starting treatment.

Epilepsy is diagnosed when a person has recurrent seizures. Treatment depends on the cause of the seizure, and whether a cause can be found. Doctors may be able to treat an underlying condition, such as an infection or metabolic problem, to stop seizures. When an underlying cause can't be identified or treated, medications that act directly on the brain's electrical system are used to control seizure activity.