Epilepsy is a disorder marked by recurring seizures due to abnormal activity of nerve cells, called neurons, in the brain.
In North America, about 2 million people have this condition and as many as 150,000 more people develop epilepsy each year, about a third of them children.
Epilepsy may have many possible causes such as an imbalance of nerve-signaling chemicals called neurotransmitters or because of the brain's attempt to repair itself after a head injury or stroke that may inadvertently generate abnormal nerve connections. Other types of epilepsy run in families and have been tied to specific genes.
Seizures or convulsions are a symptom of epilepsy, but not everyone who has seizures has epilepsy. Most patients with epilepsy have more than one type of seizure. To understand epilepsy, it's useful first to understand the types of seizures that may occur.
The two categories of seizures are generalized and partial. Partial seizures also are known as local or focal seizures. Generalized seizures result from electrical impulses arising from the entire brain.
Epilepsy is usually treated with medication. Often, anticonvulsant medication treatment will be lifelong and can have major effects on quality of life. In some cases the implantation of a stimulator of the vagus nerve, or a special diet can be helpful. Neurosurgical operations for epilepsy can be palliative, reducing the frequency or severity of seizures. In some patients, an operation can be curative.
If a seizure lasts longer than 5 minutes, or if more than one seizure occurs without regaining consciousness, emergency medical services should be contacted.
Generalized seizures typically occur with no warning. There are six types of generalized seizures.
Tonic-clonic ("grand-mal" seizure) -- You lose consciousness and often collapse. Your body becomes stiff and then begins jerking. Finally, you fall into a deep sleep. During grand-mal seizures, injuries such as tongue-biting can occur, or you can lose bladder control.
The proper initial response to a tonic-clonic seizure is to prevent the person from self-injury by placing something soft beneath the head, moving them away from sharp edges, and rolling the person into the recovery position. Should the person regurgitate, this should be allowed to drip out the side of the person's mouth.
Absence seizure ("petit mal" seizure) -- You lose awareness and stare blankly for a few seconds. Usually, there are no other symptoms. These seizures may occur several times a day.
Myoclonic seizure -- Your body may jerk, as if being shocked by electricity. The jerks can range from a single muscle jerking to involvement of the entire body.
Clonic seizure -- Both sides of your body jerk rhythmically at the same time.
Tonic seizure -- Your muscles suddenly become very stiff.
Atonic or akinetic seizure -- This causes your muscles to relax, particularly in the arms and legs, which can cause you to suddenly fall. It frequently causes injuries, such as facial cuts.
Partial seizures begin from activity in a smaller part of the brain. The part of the brain where a seizure is triggered is called the seizure focus.
Partial seizures are divided into simple, complex and those seizures that evolve from partial-onset into generalized tonic-clonic seizures. The difference between simple and complex seizures is that during simple partial seizures, you retain awareness. During complex partial seizures, you lose awareness.
Simple partial seizure -- You may experience movements such as jerking or stiffening, various sensations, peculiar memories such as a feeling of "deja-vu" or various emotions. Full consciousness is retained.
Complex partial seizure -- Same as above except that your awareness is impaired and you may appear to be "out of touch" or "spaced out." You also may involuntarily chew, walk, fidget, or perform other repetitive movements or simple actions.
Secondarily generalized seizure -- If a partial seizure evolves into a tonic-clonic seizure, it's known as a secondarily generalized seizure.