• Also Known As:
  • Seizure Disorder
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What is epilepsy?

Epilepsy is a condition characterized by recurrent seizures. Most seizures do not have a lasting affect on the brain or body, but a loss of consciousness may lead to falls and injuries, especially if the affected person is driving, bathing, cooking, or doing other potentially hazardous activities. Seizures that last longer than 5-10 minutes are called status epilepticus and require prompt medical attention. Prolonged seizures, longer than 30 minutes, can increase the risk of permanent damage and can, in some cases, be fatal.

Not every seizure is considered epilepsy. Those that are due to temporary conditions such as a high fever in an infant, acute meningitis or encephalitis, or alcohol or drug withdrawal are not considered unprovoked seizures. Likewise, not every set of symptoms that looks like a seizure is actually caused by changes in brain electrical activity. Fainting, migraine headaches, narcolepsy, drug use, mental illness, and a variety of other conditions that temporarily alter consciousness or perception may produce some of the same symptoms.

Epilepsy is diagnosed when someone has 2 or more unprovoked seizures at least 24 hours apart. According to the National Institute of Neurological Disorders and Stroke (NINDS), 2.3 million adults and 500,000 children in the U.S. live with epilepsy. While epilepsy can affect anyone, children under the age of 2 and adults over 65 are most likely to be affected. The majority of people with epilepsy will respond to treatment, but about 30% to 40% will continue to have seizures despite treatment.

Any condition that affects the brain has the potential to cause epilepsy. This includes head trauma, abnormal brain development, lack of oxygen during birth, brain tumors, strokes, cerebrovascular disease, toxins such as lead poisoning, infections, neurologic diseases like Alzheimer disease, and metabolic disorders. Some forms of epilepsy run in families and are related to genetic defects. The causes of many cases of epilepsy are unknown; the Centers for Disease Control and Prevention (CDC) states that nearly two-thirds of cases of epilepsy have no underlying cause identified.

Epileptic seizures can be classified as either focal or generalized. Focal seizures originate from a single location in the brain, while generalized seizures involve both sides of the brain. A few seizures may start as focal seizures and then become secondarily generalized. About 60% of people with epilepsy have focal seizures. For more information about types of seizures, visit the NINDS web page Seizures and Epilepsy: Hope Through Research.


About Epilepsy

Signs and Symptoms

Seizures are abnormal electrical discharges in the brain that temporarily disrupt the normal transmission of messages to the body. They can produce alterations in consciousness, cause odd rhythmic or repetitive movements, jerking or twitching of limbs, and/or can lead to convulsions that contract muscles throughout the body.

Sometimes epileptic auras precede seizures. Auras are the heightened sensitivity or unusual perception of sight, sound, smell, taste, or touch that warn people of an imminent seizure. They may involve sensations, for example, of a cool breeze or a bright light and may include feelings of numbness or nausea. What happens during a seizure episode depends on which part(s) of the brain are affected. Many people with epilepsy experience similar symptoms with each seizure, but some may have a wide variety of symptoms.

Most seizures last a few seconds to a few minutes. If a person’s consciousness is altered or lost, the person will frequently not remember what has happened. Those affected may have no after-effects, may have a brief period of confusion, and/or may experience weakness and fatigue that can last for several days.


Laboratory and non-laboratory tests are used to diagnose and monitor epilepsy, to determine what kind(s) of seizures a person is having, to identify underlying conditions such as toxins, infections, drug or alcohol withdrawal, fever (in a child), or diabetes that may be causing seizures, and to distinguish epilepsy from conditions such as fainting or a stroke that may cause some of the same symptoms.

A medical history, input from the patient, and input from family members who have witnessed the seizures are important parts of the diagnostic process. Someone with epilepsy may remember a strange smell, an aura, and/or sensations that precede a seizure but may not remember what has happened during the seizure itself. Depending upon the signs and frequency of a person’s seizures, it may take some time to determine the proper diagnosis.

Non-laboratory Tests

  • Electroencephalogram (EEG) – the primary diagnostic tool for epilepsy; it is used to evaluate the brain’s electrical activity and identify changes in brain wave patterns.

Imaging scans:

  • Computed tomography (CT) – identifies brain structure abnormalities and tumors
  • Magnetic resonance imaging (MRI) – also identifies brain abnormalities
  • Positron emission tomography (PET) – radioactive material is used to look at active areas of the brain
  • Single-photon emission computed tomography (SPECT) – radioactive material is used to identify the region of the brain where seizures originate when it is not clear on other scans

Laboratory Tests
Laboratory tests are primarily used to monitor anti-epileptic medications and to search for conditions that may cause seizures, such as diabetes, infection, meningitis or encephalitis.

Periodic therapeutic drug monitoring is performed when a patient is taking a specific medication to ensure that therapeutic levels are achieved. Epileptic medications that are monitored include:

There are some newer second-generation antiepileptic drugs, such as levetiracetam, that usually do not require routine monitoring but may be tested in order to evaluate and adjust dosage as necessary.

Other testing is done to identify possible causes for seizures, including:

  • Complete blood count (CBC) – to evaluate blood cells to check for a variety of conditions, including infection
  • Glucose – to check for the possibility of diabetes
  • CSF analysis – to check for infection and help diagnose meningitis and encephalitis
  • Blood culture – to check for septicemia, infection in the blood
  • Drug abuse testing—to detect drugs and/or alcohol (ethanol)


Many cases of epilepsy can be prevented by taking precautions. These include safety measures to avoid head injury, such as wearing a helmet while riding a bicycle or motorcycle and wearing a seat belt while in a car. Prenatal care can help to avoid infections and other causes of fetal brain damage. Immunizations reduce the probability of contracting infections that could lead to this condition. Treating medical conditions such as hypertension and cardiovascular disease during adulthood can also help to prevent epilepsy.

Effective treatment depends on accurate diagnosis of the type of epilepsy someone has. For 70-80% of those diagnosed with the disorder, seizures can be controlled with available treatments, such as medication and surgery.

In people who have epilepsy, seizures can often be prevented or decreased in frequency by consistently taking the appropriate anti-epileptic medication. Commonly prescribed drugs include:

  • Carbamazepine
  • Phenytoin
  • Phenobarbital
  • Valproic acid

There are several newer second-generation antiepileptic drugs, such as levetiracetam, that may be prescribed as an adjunctive (secondary) treatment in combination with other antiepileptic drugs.

The choice of drug depends on the person and on the type of seizure. Patients should work with their healthcare provider to find the right medication(s) and dose. In cases where medication is not effective or produces severe side effects, a special diet that is high in fat and low in carbohydrate may help to control seizures. For some types of epilepsy, surgery is the best option to reduce or eliminate seizures.

The number of seizures can also be decreased by avoiding triggers such as sleep deprivation, excessive stress, visual stimuli such as bright, flashing lights, alcohol consumption, and use of illicit drugs (e.g., cocaine). Treating underlying conditions can also lessen the frequency of seizures. An implanted device called a vagus nerve stimulator is another possibility for those who have seizures that are not well controlled by medication. More devices are being researched, including an implantable, pacemaker-type instrument that is designed to prevent epileptic seizures. For more on treatment options, visit the NINDS page Seizures and Epilepsy: Hope Through Research.

View Sources

Sources Used in Current Review

Sept. 4, 2015. A definition and classification of status epilepticus – Report of the ILAE Task Force on Classification of Status Epilepticus. Epilepsia. Available online at http://onlinelibrary.wiley.com/doi/10.1111/epi.13121/abstract. Accessed November 2016.

(July 6, 2016) Medscape. First Adult Seizure. Available online at http://emedicine.medscape.com/article/1186214-overview. Accessed November 2016.

National Institute of Neurological Disorders and Stroke. Curing the Epilepsies: The Promise of Research. Available online at http://www.ninds.nih.gov/disorders/epilepsy/epilepsy_research.htm#introduction. Accessed November 2016.

National Institute of Neurological Disorders and Stroke. The Epilepsies and Seizures: Hope Through Research. Available online at http://www.ninds.nih.gov/disorders/epilepsy/detail_epilepsy.htm#3109_2. Accessed November 2016.

Centers for Disease Control and Prevention. Epilepsy FAQs. Available online at http://www.cdc.gov/epilepsy/basics/faq.htm#What%20causes%20epilepsy. Accessed November 2016.

Centers for Disease Control and Prevention. Preventing Epilepsy. Available online at http://www.cdc.gov/epilepsy/preventing-epilepsy.htm. Accessed November 2016.

Epilepsy Foundation. Who Gets Epilepsy? Available online at http://www.epilepsy.com/learn/epilepsy-101/who-gets-epilepsy. Accessed November 2016.

Epilepsy Foundation. Adding vs substituting AEDs. Available online at http://www.epilepsy.com/information/professionals/refractory-seizures/actions-take/aed-changes. Accessed November 2016.

(March-April 2012) An initial experience with therapeutic drug monitoring of levetiracetam as reported from a pediatric clinical setting in India. Neurology India. Available online at http://www.ncbi.nlm.nih.gov/pubmed/22626693. Accessed November 2016.

Preventing Epilepsy Seizures. Everyday Health. Available online at http://www.everydayhealth.com/epilepsy/preventing-epilepsy-seizures.aspx. Accessed November 2016.

Mayo Clinic. Epilepsy treatment. Available online at http://www.mayoclinic.org/diseases-conditions/epilepsy/diagnosis-treatment/treatment/txc-20117241. Accessed November 2016.

Scheffer, I. E., Berkovic, S., Capovilla, G., Connolly, M. B., French, J., Guilhoto, L., Hirsch, E., Jain, S., Mathern, G. W., Moshé, S. L., Nordli, D. R., Perucca, E., Tomson, T., Wiebe, S., Zhang, Y.-H. and Zuberi, S. M. (2017). ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology. Epilepsia. doi:10.1111/epi.13709. Available online at http://onlinelibrary.wiley.com/doi/10.1111/epi.13709/full. Accessed March 2017.

Sources Used in Previous Reviews

(2008 September 11, Updated). Seizures and Epilepsy: Hope Through Research. National Institute of Neurological Disorders and Stroke [On-line information]. Available online at http://www.ninds.nih.gov/disorders/epilepsy/detail_epilepsy.htm. Accessed on 9/17/08.

Adamolekun, B. (2008 March, Revision). Seizure Disorders. The Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec16/ch214/ch214a.html?qt=epilepsy&alt=sh. Accessed on 9/7/08.

(2008 January). One of the Nation’s Most Common Disabling Neurological Conditions. CDC at a Glance [On-line information]. Available online at http://www.cdc.gov/nccdphp/publications/AAG/epilepsy.htm. Accessed on 9/14/08.

Mayo Clinic Staff (2007 April 27). Epilepsy. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/print/epilepsy/DS00342/DSECTION=all&METHOD=print. Accessed on 9/17/08.

Cavazos, J. and Lum, F. (2007 November 30). Seizures and Epilepsy: Overview and Classification. EMedicine [On-line information]. Available online at http://www.emedicine.com/neuro/TOPIC415.HTM. Accessed on 9/17/08.

About Epilepsy. Epilepsy Foundation [On-line information]. Available online at http://www.epilepsyfoundation.org/about/ and http://www.epilepsyfoundation.org/aboutus/pressroom/pr20050720.cfm. Accessed on 9/7/08.

Epilepsy, Frequently Asked Questions. Epilepsy Foundation [On-line information]. Available online at http://www.epilepsyfoundation.org/answerplace/faq.cfm. Accessed on 9/17/08.

Lehman, C. and McMillin, G. (2008 March, Reviewed). Seizure Disorders – Epilepsy. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/NeurologicDz/SeizureDis.html#. Accessed on 9/19/08.

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition]. Pp 657-658.

Centers for Disease Control and Prevention. Epilepsy – Basics – FAQs. Available online at http://www.cdc.gov/epilepsy/basics/faqs.htm. Accessed September 2012.

National Institute of Neurological Disorders and Stroke. Epilepsy Information. Available online at http://www.ninds.nih.gov/disorders/epilepsy/epilepsy.htm. Accessed September 2012.

National Institute of Neurological Disorders and Stroke. Seizures and Epilepsy: Hope Through Research. Available online at http://www.ninds.nih.gov/disorders/epilepsy/detail_epilepsy.htm. Accessed September 2012.

MedlinePlus Medical Encyclopedia. Epilepsy. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000694.htm. Accessed September 2012.

MayoClinic.com. Epilepsy. Available online at http://www.mayoclinic.com/health/epilepsy/DS00342. Accessed September 2012.

Scheffer, Ingrid E. Genetic Testing in Epilepsy: What Should You Be Doing? Epilepsy Curr. 2011 Jul-Aug; 11(4): 107–111. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3152152/. Accessed September 2012.