Experts answer 7 frequently asked questions about epilepsy.
More than 2 million people in the United States have some form of epilepsy, a group of related disorders marked by recurrent seizures. WebMD asked epilepsy experts your most frequently asked questions.
How do people develop epilepsy?
In most cases -- about seven in 10 people -- the cause of epilepsy is unknown. In other cases, epilepsy can have a symptomatic cause, such as birth injuries, head injuries, and infectious diseases including meningitis and encephalitis. It can also be caused by genetic conditions and stroke.
"Whatever the cause, epilepsy causes too many nerve cells to fire in the brain at the same time," says Donald Olson, MD, director of the Epilepsy Program at Lucile Packard Children's Hospital at Stanford University Medical Center. "Depending on which part of the brain the cells are firing in, the symptoms could vary from a strange feeling, to one side of the body jerking, to a whole-body convulsion."
How is epilepsy diagnosed?
A doctor will start by taking a medical history, followed by a physical and neurological examination of muscle strength, reflexes, eyesight, hearing, and ability to detect various sensations. Other tests include an electroencephalogram (EEG) test, which measures electrical impulses in the brain; imaging studies of the brain, often with magnetic resonance imaging (MRI); and blood tests to measure red and white blood cell counts, blood sugar, blood calcium and electrolyte levels; and to evaluate liver and kidney function.
What are the types of seizures?
Seizures are divided into two broad categories: partial and generalized.
Partial seizures affect only a specific part of the brain and are further grouped into two types: In simple partial seizures, a person may have jerking movement and abnormal sensations, such as extreme emotion or changes in taste, depending on what part of the brain the seizure affects. In complex partial seizures, a person loses awareness and may have unconscious movements such as lip smacking and fidgeting. Partial seizures that spread and become generalized are called partial seizures secondarily generalized.
Generalized seizures affect the entire brain from the beginning of the seizure and are broken down into several types: In generalized tonic-clonic seizures, the entire body stiffens and jerks and a person loses consciousness. This is also known as a grand mal seizure. Myoclonic seizures are lightning jerks of the muscle, usually on both sides of the body. In absence seizures, a person loses awareness and has a blank stare, as if he or she is looking through you. This is also known as a petit mal seizure. Atonic seizures cause the body to lose muscle tone with no warning and fall over.