Seizures (SEE-zhers) occur when the electrical patterns of the brain are interrupted by powerful rapid bursts of electrical energy. A seizure may cause a person to lose consciousness, fall down, jerk or convulse, or simply blank out for a few seconds. Infection, injury, or medical problems can cause a seizure. Epilepsy * is a disease of the nervous system characterized by recurring seizures.
As part of his sixth grade study of self-awareness, Eric was assigned to draw the frames of a film that would show the world as he saw it. Teachers were puzzled by what Eric drew. One frame showed him pouring milk, the next frame was completely black, and the next frame showed spilled milk. In another sequence, Eric drew a teacher calling on him to answer a math problem, followed by another black frame, and then a picture of the teacher complaining that Eric was not paying attention. The teachers realized that Eric's project did show the world as he saw it. The mysterious black frames were blackouts. Doctors determined that Eric had absence seizures, a type of seizure that causes a brief loss of consciousness. Medication successfully controlled Eric's seizures.
Whether a person is sleeping or awake, millions of tiny electrical charges pass between neurons * in the brain and to all parts of body. These cells “fire,” or transmit electrical impulses, in an orderly and controlled manner. Seizures occur when overactive nerve cells send out powerful rapid electrical charges that disrupt the brain's normal function. The disruption can temporarily affect how a person behaves, moves, thinks, or feels.
Symptoms of a seizure can include combinations of the following:
There are two kinds of seizure disorders: an isolated seizure that occurs only once, and epilepsy (EP-i-lep-see). Epileptic seizures occur more than once and over a period of time. In both epilepsy and isolated seizures, the seizure may have different symptoms or characteristics depending on where it begins in the brain and how the electrical discharge spreads across the brain. Seizures can be generalized or partial.
Generalized seizures affect nerve cells throughout the cerebral cortex * (the cauliflower-like outer portion of the brain) or the entire brain. Generalized seizures often are hereditary, which means they run in families. They may also be caused by imbalances in a person's kidney or liver function or in their blood sugar.
The most common generalized seizures are:
An electroencephalogram (e-LEK-tro-en-SEF-a-lo-gram), commonly known as an EEG, records electric currents in the brain and can track abnormal electrical activity. Doctors may also look for structural brain abnormalities using other types of scans, including computed tomography (CT) * and magnetic resonance imaging (MRI) * . In some research centers, positron emission tomography (PET) * is used to identify areas of the brain that are producing seizures.
A lumbar puncture, sometimes called a spinal tap, can detect infection. The procedure requires that a physician carefully insert a thin needle between two vertebrae (bones) in the patient's spine and draw out a small amount of cerebrospinal fluid * (CSF). The fluid is analyzed for the presence of bacterial or viral infections, tumors, or blood disorders that might provide a clue to the cause of the seizure.
Seizures are associated with the following diseases and conditions:
It is important to remain calm and not panic when someone has a seizure. An adult usually asks if the person has epilepsy. If the person is unable to communicate, an adult checks for a medical identification bracelet or tag that carries information about the underlying cause of the seizure. Treatment for seizures depends on the cause; febrile seizures may require no additional treatment once the fever is resolved. Patients who suffer from epileptic seizures are treated with antiseizure medications.
See also Brain Injuries • Brain Tumor • Diabetes • Encephalitis • Epilepsy • Fever • Hypoglycemia • Infection • Kidney Disease • Lead Poisoning • Meningitis • Poisoning • Preeclampsia/Eclampsia • Stroke • Substance Abuse
Devinsky, Orrin, Erin Conway, and Courtney Schnabel Glick. Epilepsy in Children. New York: Demos, 2015.
Wyllie, Elaine. Wyllie's Treatment of Epilepsy: Principles and Practice, 6th ed. New York: Lippincott Williams & Wilkins, 2015.
MedlinePlus “Seizures.” U.S. National Library of Medicine. https://www.nlm.nih.gov/medlineplus/ency/article/003200.htm (accessed July 6, 2016).
Epilepsy Foundation. 8301 Professional Pl. East, Suite 200, Landover, MD 20785-2353. Toll-free: 800-332-1000. Website: http://www.epilepsyfoundation.org (accessed November 4, 2015).
* epilepsy (EP-i-lep-see) is a condition of the nervous system characterized by recurrent seizures that temporarily affect a person's awareness, movements, or sensations. Seizures occur when powerful rapid bursts of electrical energy interrupt the normal electrical patterns of the brain.
* neurons are nerve cells. Most neurons have extensions called axons and dendrites through which they send and receive signals from other neurons.
* cerebral cortex (suh-REE-brul KOR-teks) is the part of the brain that controls functions such as conscious thought, listening, and speaking.
* aura is a warning sensation that precedes a seizure or other neurological event.
* computed tomography (kom-PYOO-ted toe-MAH-gruhfee), or CT, a technique in which a machine takes many x-rays of the body to create a threedimensional picture. Formerly called computerized axial tomography (CAT).
* magnetic resonance imaging (or MRI) uses magnetic waves, instead of x-rays, to scan the body and produce detailed pictures of the body's structures.
* positron emission tomography (POZ-i-tron i-MISH-en toe-MAH-gruh-fee) uses a radiotracer that accumulates in an area of the body and emits gamma rays that are detected as diagnostic images. Also called PET imaging or PET scanning.
* cerebrospinal fluid (seh-ree-bro-SPY-nuhl) is the fluid that surrounds the brain and spinal cord.