|Classification and external resources|
Generalized 3 Hz spike and wave discharges in EEG
|ICD-10||G40, P90, R56|
Epileptic seizures (colloquially a fit) are brief episodes of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can vary from uncontrolled jerking movement (tonic-clonic seizure) to as subtle as a momentary loss of awareness (absence seizure). The syndrome of recurrent, unprovoked seizures is termed epilepsy, but seizures can also occur in people who do not have epilepsy. Additionally, there are a number of conditions that look like seizures but are not.
About 5–10% of all people will have an unprovoked seizure by the age of 80 and the chance of experiencing a second seizure is between 40% and 50%. Epilepsy affects about 1% of the population currently and affects about 4% of the population at some point in time. Most of those affected—nearly 80%—live in developing countries.
- 1 Signs and symptoms
- 2 Causes
- 3 Mechanism
- 4 Diagnosis
- 5 Prevention
- 6 Management
- 7 Prognosis
- 8 Epidemiology
- 9 History
- 10 Society and culture
- 11 Research
- 12 References
- 13 External links
Signs and symptoms
The signs and symptoms of seizures vary depending on the type. The most common type of seizures are convulsive (60%). Two-thirds of these begin as focal seizures and become generalized while one third begin as generalized seizures. The remaining 40% of seizures are non-convulsive, an example of which is absence seizures.
Jerking activity may start in a specific muscle group and spread to surrounding muscle groups in which case it is known as a Jacksonian march. Unusual activities that are not consciously created may occur. These are known as automatisms and include simple activities like smacking of the lips or more complex activities such as attempts to pick something up.
There are six main types of generalized seizures: tonic-clonic, tonic, clonic, myoclonic, absence, and atonic seizures. They all involve a loss of consciousness and typically happen without warning.
- Tonic-clonic seizures present with a contraction of the limbs followed by their extension along with arching of the back which lasts 10–30 seconds. A cry may be heard due to contraction of the chest muscles. The limbs then begin to shake in unison. After the shaking has stopped it may take 10–30 minutes for the person to return to normal.
- Tonic seizures produce constant contractions of the muscles. The person may turn blue if breathing is impaired.
- Clonic seizures involve shaking of the limbs in unison.
- Myoclonic seizures involve spasms of muscles in either a few areas or generalized through the body.
- Absence seizures can be subtle, with only a slight turn of the head or eye blinking. The person often does not fall over and may return to normal right after the seizure ends, though there may also be a period of post-ictal disorientation.
- Atonic seizures involve the loss of muscle activity for greater than one second. This typically occurs bilaterally (on both sides of the body).
A seizure can last from a few seconds to more than five minutes at which point it is known as status epilepticus. Most tonic-clonic seizures last less than two or three minutes. Absence seizures are usually around 10 seconds in duration.
After the active portion of a seizure, there is typically a period of confusion referred to as the postictal period before a normal level of consciousness returns. This usually lasts 3 to 15 minutes but may last for hours. Other common symptoms include: feeling tired, headache, difficulty speaking, and abnormal behavior. Psychosis after a seizure is relatively common, occurring in between 6 and 10% of people. Often people do not remember what occurred during this time.
Seizures have a number of causes. Of those with seizure about 25% have epilepsy. A number of conditions are associated with seizures but are not epilepsy including: most febrile seizures and those that occur around an acute infection, stroke, or toxicity. These seizures are known as "acute symptomatic" or "provoked" seizures and are part of the seizure-related disorders. In many the cause is unknown.
Different causes of seizures are common in certain age groups.
- During the neonatal period and early infancy the most common causes include hypoxic ischemic encephalopathy, central nervous system (CNS) infections, trauma, congenital CNS abnormalities, and metabolic disorders.
- The most frequent cause of seizures in children is febrile seizures which happen in 2–5% of those between the ages of six months and five years.
- During childhood, well-defined epilepsy syndromes are generally seen.
- During adulthood, the likely causes are alcohol related, strokes, trauma, CNS infections, and brain tumors.
- In older adults, cerebrovascular disease is a very common cause. Other causes are CNS tumors, head trauma, and other degenerative diseases that are common in the older age group, such as dementia.
A number of disorders including: low blood sugar, low blood sodium, hyperosmolar nonketotic hyperglycemia, high blood sodium, low blood calcium and high blood urea levels may cause seizures. As may hepatic encephalopathy and the genetic disorder porphyria.
- cavernoma or cavernous malformation is a treatable medical condition that can cause seizures, headaches, and brain hemorrhages.
- arteriovenous malformation (AVM) is a treatable medical condition that can cause seizures, headaches, and brain hemorrhages.
- space-occupying lesions in the brain (abscesses, tumours). In people with brain tumours, the frequency of epilepsy depends on the location of the tumor in the cortical region.
Both medication and drug overdoses can result in seizures, as may certain medication and drug withdrawal. Common drugs involved include: antidepressants, antipsychotics, cocaine, insulin, and the local anaesthetic lidocaine. Difficulties with withdrawal seizures commonly occurs after prolonged alcohol or sedative use.
- Infection with the pork tapeworm, which can result in neurocysticercosis, is the cause of up to half of epilepsy cases in areas of the world where the parasite is common.
- parasitic infections such as cerebral malaria
- infection, such as encephalitis or meningitis
Seizures may occur as a result of high blood pressure, known as hypertensive encephalopathy, or in pregnancy as eclampsia when accompanied by either seizures or a decreased level of consciousness. Very high body temperatures may also be a cause. Typically this requires a temperature greater than 42 °C (107.6 °F).
- head injury may cause non-epileptic post-traumatic seizures or post-traumatic epilepsy
- seizures in a person with a shunt may indicated failure
- haemorrhagic stroke can occasionally present with seizures, embolic strokes generally do not (though epilepsy is a common later complication); cerebral venous sinus thrombosis, a rare type of stroke, is more likely to be accompanied by seizures than other types of stroke
- multiple sclerosis may cause seizures
Electroconvulsive therapy (ECT) deliberately sets out to induce a seizure for the treatment of major depression.
Normally brain electrical activity is non synchronous. In epileptic seizures, due to problems within the brain, a group of neurons begin firing in an abnormal, excessive, and synchronized manner. This results in a wave of depolarization known as a paroxysmal depolarizing shift.
Normally after an excitatory neuron fires it becomes more resistant to firing for a period of time. This is due in part from the effect of inhibitory neurons, electrical changes within the excitatory neuron, and the negative effects of adenosine. In epilepsy the resistance of excitatory neurons to fire during this period is decreased. This may occur due to changes in ion channels or inhibitory neurons not functioning properly. This then results in a specific area from which seizures may develop, known as a "seizure focus". Another cause of epilepsy may be the up regulation of excitatory circuits or down regulation of inhibitory circuits follow an injury to the brain. These secondary epilepsies, occur through processes known as epileptogenesis. Failure of the blood–brain barrier may also be a causal mechanism.
Focal seizures begin in one hemisphere of the brain while generalized seizures begin in both hemispheres. Some types of seizures may change brain structure, while others appear to have little effect. Gliosis, neuronal loss, and atrophy of specific areas of the brain are linked to epilepsy but it is unclear if epilepsy causes these changes or if these changes result in epilepsy.
It is important to distinguish primary seizures from secondary causes. Depending on the presumed cause blood tests and/or lumbar puncture may be useful. Hypoglycemia may cause seizures and should be ruled out. An electroencephalogram and brain imaging with CT scan or MRI scan is recommended in the work-up of seizures not associated with a fever.
Seizure are organized according to whether the source of the seizure within the brain is localized to one side of the brain (focal seizures) or begins in both sides (generalized seizures).
Generalized seizures are divided according to the effect on the body and include: tonic-clonic (grand mal), absence (petit mal), myoclonic, clonic, tonic, and atonic seizures. Some seizures are of an unknown type such as epileptic spasms.
Most people are in a postictal state following a seizure (drowsy or confused). There may be signs of other injuries. A small study found that a bite to the side of the tongue was very helpful when present: while only a quarter of those with seizures had such a bite, most with such a bite had seizures.
In adults testing electrolytes, blood glucose and calcium levels is important to rules these out as causes. As is an electrocardiogram. A lumbar puncture may be useful to diagnose a central nervous system infection but is not routinely needed. Routine antiseizure medical levels in the blood are not required in adults or children. In children additional tests may be required.
A high blood prolactin level within the first 20 minutes following a seizure may be useful to confirm an epileptic seizure as opposed to psychogenic non-epileptic seizure. Serum prolactin level is less useful for detecting partial seizures. If it is normal an epileptic seizure is still possible and a serum prolactin does not separate epileptic seizures from syncope. It is not recommended as a routine part of diagnosis epilepsy.
An electroencephalography is only recommended in those who likely had an epileptic seizure and may help determine the type of seizure or syndrome present. In children it is typically only needed after a second seizure. It cannot be used to rule out the diagnosis and may be falsely positive in those without the disease. It certain situations it may be useful to prefer the EEG while sleeping or sleep deprived.
Diagnostic imaging by CT scan and MRI is recommended after a first non-febrile seizure to detect structural problems inside the brain. MRI is generally a better imaging test except when intracranial bleeding is suspected. Imaging may be done at a later point in time in those who return to their normal selves while in the emergency room. If a person has a previous diagnosis of epilepsy with previous imaging repeat imaging is not usually needed with subsequent seizures.
Differentiating an epileptic seizure from other conditions such as syncope can be difficult. Other possible conditions that can mimic a seizure include: decerebrate posturing, psychogenic seizures, dystonia, migraine headaches, and strychnine poisoning. In addition, 5% of people with a positive tilt table test may have seizure-like activity that seems to be due to cerebral hypoxia. Convulsions may occur do to psychological reasons and this is known as a psychogenic non-epileptic seizure. Non-epileptic seizures may also occur due to a number of other reasons.
In those with a history of febrile seizures medications (both antipyretics and anticonvulsants) have not been found effective for prevention; however, some appear to be associated with harm. In those without a history of seizures and a subdural hematoma the evidence is unclear regarding a benefit versus harm from using anticonvulsants. This is also true following a craniotomy as well as after stroke, intracranial venous thrombosis, and subarachnoid haemorrhage both in those who have and have not had seizures.
Potentially sharp or dangerous objects should also be moved from the vicinity, so that the individual is not hurt. After the seizure if the person is not fully conscious and alert, they should be placed in the recovery position. A seizure longer than five minutes is a medical emergency known as status epilepticus. Contrary to a common misconception, bystanders should not attempt to force objects into the mouth of the person suffering a seizure, as doing so may cause injury to the teeth and gums.
The first line treatment of choice for someone who is actively seizing is a benzodiazepine, most guidelines recommend lorazepam. This may be repeated if there is no effect after 10 minutes. If there is no effect after two doses, barbiturates or propofol may be used.
Ongoing medication is not typically needed after a first seizure and is generally only recommended after a second one has occurred or in those with structural lesions in the brain. After a second seizure anti-epileptic medications are recommended. Approximately 70% of the people are able to get full control with continuous use of medication. Typically one type of anticonvulsant is preferred.
Following a first seizure the risk of more seizures in the next two years is 40–50%. The greatest predictors of more seizures is problems on either the electroencephalogram or on imaging of the brain. In adults, after 6 months seizure free, after a first seizure the risk of a subsequent seizure in the next year is less than 20% regardless of treatment. Up to 7% of seizure that present to the emergency are in status epilepticus. In those with a status epilepticus mortality is between 10 and 40%. Those who have a seizure that is provoked (occurring right around an acute brain event or toxic exposure) have a low risk of re-occurrence; however, have a higher risk of death compared to those with epilepsy.
Rates are highest in those less than a year of age and greater than 55. About 1% or 50 million people currently have epilepsy worldwide. About 4% of people develop epilepsy at some point in time.
Following standardization proposals devised by Henri Gastaut and published in 1970, terms such as "petit mal", "grand mal", "Jacksonian", "psychomotor", and "temporal-lobe seizure" have fallen into disuse.
Society and culture
Seizures result in direct economic costs of about one billion dollars in the United States. Epilepsy results in economic costs in Europe of around 15.5 billion Euros in 2004. In India epilepsy is estimated to result in costs of 1.7 billion USD or 0.5% of the GDP. They make up about 1% of emergency department visits (2% for emergency departments for children) in the United States.
Many areas of the world require there to be a minimum of six months from the last seizure before people can return to driving.
Scientific work into the prediction of epileptic seizures began in the 1970s. Several techniques and methods have been proposed, but evidence regarding their usefulness is still lacking.
- Fisher R, van Emde Boas W, Blume W, Elger C, Genton P, Lee P, Engel J (2005). "Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE)". Epilepsia 46 (4): 470–2. doi:10.1111/j.0013-9580.2005.66104.x. PMID 15816939.
- Wilden, JA; Cohen-Gadol, AA (Aug 15, 2012). "Evaluation of first nonfebrile seizures.". American family physician 86 (4): 334–40. PMID 22963022.
- Longo, Dan L. (2012). "369". Harrison's principles of internal medicine. (18th ed. ed.). New York: McGraw-Hill. ISBN 978-0071748896.
- Berg, AT (2008). "Risk of recurrence after a first unprovoked seizure". Epilepsia. 49 Suppl 1: 13–8. doi:10.1111/j.1528-1167.2008.01444.x. PMID 18184149.
- "Epilepsy". Fact Sheets. World Health Organization. October 2012. Retrieved January 24, 2013.
- Shearer, Peter. "Seizures and Status Epilepticus: Diagnosis and Management in the Emergency Department". Emergency Medicine Practice.
- National Institute for Health and Clinical Excellence (January 2012). "Chapter 1: Introduction". The Epilepsies: The diagnosis and management of the epilepsies in adults and children in primary and secondary care. National Clinical Guideline Centre. pp. 21–28.
- Hughes, JR (August 2009). "Absence seizures: a review of recent reports with new concepts.". Epilepsy & behavior : E&B 15 (4): 404–12. doi:10.1016/j.yebeh.2009.06.007. PMID 19632158.
- Hammer, edited by Stephen J. McPhee, Gary D. (2010). "7". Pathophysiology of disease : an introduction to clinical medicine (6th ed. ed.). New York: McGraw-Hill Medical. ISBN 9780071621670.
- Bradley, Walter G. (2012). "67". Bradley's neurology in clinical practice. (6th ed. ed.). Philadelphia, PA: Elsevier/Saunders. ISBN 978-1437704341.
- National Institute for Health and Clinical Excellence (January 2012). "9". The Epilepsies: The diagnosis and management of the epilepsies in adults and children in primary and secondary care. National Clinical Guideline Centre. pp. 119–129.
- Simon, David A. Greenberg, Michael J. Aminoff, Roger P. (2012). "12". Clinical neurology (8th ed. ed.). New York: McGraw-Hill Medical. ISBN 978-0071759052.
- Trinka, E; Höfler, J; Zerbs, A (September 2012). "Causes of status epilepticus.". Epilepsia. 53 Suppl 4: 127–38. doi:10.1111/j.1528-1167.2012.03622.x. PMID 22946730.
- Holmes, Thomas R. (2008). Handbook of epilepsy (4th ed. ed.). Philadelphia: Lippincott Williams & Wilkins. p. 34. ISBN 9780781773973.
- Panayiotopoulos, CP (2010). A clinical guide to epileptic syndromes and their treatment based on the ILAE classifications and practice parameter guidelines (Rev. 2nd ed. ed.). [London]: Springer. p. 445. ISBN 9781846286445.
- James W. Wheless, ed. (2009). Advanced therapy in epilepsy. Shelton, Conn.: People's Medical Pub. House. p. 443. ISBN 9781607950042.
- Stasiukyniene, V.; Pilvinis, V.; Reingardiene, D.; Janauskaite, L. (2009). "[Epileptic seizures in critically ill patients]". Medicina (Kaunas) 45 (6): 501–7. PMID 19605972.
- Thurman, DJ; Beghi, E; Begley, CE; Berg, AT; Buchhalter, JR; Ding, D; Hesdorffer, DC; Hauser, WA; Kazis, L; Kobau, R; Kroner, B; Labiner, D; Liow, K; Logroscino, G; Medina, MT; Newton, CR; Parko, K; Paschal, A; Preux, PM; Sander, JW; Selassie, A; Theodore, W; Tomson, T; Wiebe, S; ILAE Commission on, Epidemiology (September 2011). "Standards for epidemiologic studies and surveillance of epilepsy.". Epilepsia. 52 Suppl 7: 2–26. doi:10.1111/j.1528-1167.2011.03121.x. PMID 21899536.
- Graves, RC; Oehler, K; Tingle, LE (Jan 15, 2012). "Febrile seizures: risks, evaluation, and prognosis.". American family physician 85 (2): 149–53. PMID 22335215.
- Martindale, JL; Goldstein, JN; Pallin, DJ (February 2011). "Emergency department seizure epidemiology.". Emergency medicine clinics of North America 29 (1): 15–27. doi:10.1016/j.emc.2010.08.002. PMID 21109099.
- Harrison's Principles of Medicine. 15th edition
- Hildebrand, J (July 2004). "Management of epileptic seizures". Curr Opin Oncol 16 (4): 314–7. doi:10.1097/01.cco.0000127720.17558.38. PMID 15187884.
- Bhalla, D.; Godet, B.; Druet-Cabanac, M.; Preux, PM. (Jun 2011). "Etiologies of epilepsy: a comprehensive review.". Expert Rev Neurother 11 (6): 861–76. doi:10.1586/ern.11.51. PMID 21651333.
- "Epilepsy". Fact Sheets. World Health Organization. October 2012. Retrieved January 24, 2013.
- Somjen, George G. (2004). Ions in the Brain Normal Function, Seizures, and Stroke.. New York: Oxford University Press. p. 167. ISBN 9780198034599.
- Goldberg, EM; Coulter, DA (May 2013). "Mechanisms of epileptogenesis: a convergence on neural circuit dysfunction.". Nature reviews. Neuroscience 14 (5): 337–49. doi:10.1038/nrn3482. PMID 23595016.
- Oby, E; Janigro, D (Nov 2006). "The blood-brain barrier and epilepsy.". Epilepsia 47 (11): 1761–74. doi:10.1111/j.1528-1167.2006.00817.x. PMID 17116015.
- Jerome Engel, Jr., Timothy A. Pedley, ed. (2008). Epilepsy : a comprehensive textbook (2nd ed. ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 483. ISBN 9780781757775.
- "Current Guidelines For Management Of Seizures In The Emergency Department" (PDF).
- Simon D. Shorvon (2004). The treatment of epilepsy (2nd ed.). Malden, Mass.: Blackwell Pub. ISBN 978-0-632-06046-7.
- Benbadis SR, Wolgamuth BR, Goren H, Brener S, Fouad-Tarazi F (1995). "Value of tongue biting in the diagnosis of seizures". Arch. Intern. Med. 155 (21): 2346–9. doi:10.1001/archinte.155.21.2346. PMID 7487261.
- National Institute for Health and Clinical Excellence (January 2012). "4". The Epilepsies: The diagnosis and management of the epilepsies in adults and children in primary and secondary care. National Clinical Guideline Centre. pp. 57–83.
- Luef, G (October 2010). "Hormonal alterations following seizures.". Epilepsy & behavior : E&B 19 (2): 131–3. doi:10.1016/j.yebeh.2010.06.026. PMID 20696621.
- Ahmad S, Beckett MW (2004). "Value of serum prolactin in the management of syncope". Emergency medicine journal : EMJ 21 (2): e3. doi:10.1136/emj.2003.008870. PMC 1726305. PMID 14988379.
- Shukla G, Bhatia M, Vivekanandhan S, et al. (2004). "Serum prolactin levels for differentiation of nonepileptic versus true seizures: limited utility". Epilepsy & behavior : E&B 5 (4): 517–21. doi:10.1016/j.yebeh.2004.03.004. PMID 15256189.
- Chen DK, So YT, Fisher RS (2005). "Use of serum prolactin in diagnosing epileptic seizures: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology". Neurology 65 (5): 668–75. doi:10.1212/01.wnl.0000178391.96957.d0. PMID 16157897.
- Passman R, Horvath G, Thomas J, et al. (2003). "Clinical spectrum and prevalence of neurologic events provoked by tilt table testing". Arch. Intern. Med. 163 (16): 1945–8. doi:10.1001/archinte.163.16.1945. PMID 12963568.
- Schierhout, G; Roberts, I (2001). "Anti-epileptic drugs for preventing seizures following acute traumatic brain injury.". The Cochrane database of systematic reviews (4): CD000173. doi:10.1002/14651858.CD000173. PMID 11687070.
- Offringa, M; Newton, R (Apr 18, 2012). "Prophylactic drug management for febrile seizures in children.". The Cochrane database of systematic reviews 4: CD003031. doi:10.1002/14651858.CD003031.pub2. PMID 22513908.
- Ratilal, BO; Pappamikail, L; Costa, J; Sampaio, C (Jun 6, 2013). "Anticonvulsants for preventing seizures in patients with chronic subdural haematoma.". The Cochrane database of systematic reviews 6: CD004893. doi:10.1002/14651858.CD004893.pub3. PMID 23744552.
- Pulman, J; Greenhalgh, J; Marson, AG (Feb 28, 2013). "Antiepileptic drugs as prophylaxis for post-craniotomy seizures.". The Cochrane database of systematic reviews 2: CD007286. doi:10.1002/14651858.CD007286.pub2. PMID 23450575.
- Kwan, J; Wood, E (Jan 20, 2010). "Antiepileptic drugs for the primary and secondary prevention of seizures after stroke.". The Cochrane database of systematic reviews (1): CD005398. doi:10.1002/14651858.CD005398.pub2. PMID 20091574.
- Kwan, J; Guenther, A (Jul 19, 2006). "Antiepileptic drugs for the primary and secondary prevention of seizures after intracranial venous thrombosis.". The Cochrane database of systematic reviews (3): CD005501. doi:10.1002/14651858.CD005501.pub2. PMID 16856099.
- Marigold, R; Günther, A; Tiwari, D; Kwan, J (Jun 5, 2013). "Antiepileptic drugs for the primary and secondary prevention of seizures after subarachnoid haemorrhage.". The Cochrane database of systematic reviews 6: CD008710. doi:10.1002/14651858.CD008710.pub2. PMID 23740537.
- Sharma, AN; Hoffman, RJ (Feb 2011). "Toxin-related seizures.". Emergency medicine clinics of North America 29 (1): 125–39. doi:10.1016/j.emc.2010.08.011. PMID 21109109.
- Doherty, MJ; Haltiner, AM (Jan 23, 2007). "Wag the dog: skepticism on seizure alert canines.". Neurology 68 (4): 309. doi:10.1212/01.wnl.0000252369.82956.a3. PMID 17242343.
- Bonnett, LJ; Tudur-Smith, C; Williamson, PR; Marson, AG (2010-12-07). "Risk of recurrence after a first seizure and implications for driving: further analysis of the Multicentre study of early Epilepsy and Single Seizures". BMJ (Clinical research ed.) 341: c6477. doi:10.1136/bmj.c6477. PMC 2998675. PMID 21147743.
- Neligan, A; Hauser, WA; Sander, JW (2012). "The epidemiology of the epilepsies.". Handbook of clinical neurology 107: 113–33. doi:10.1016/B978-0-444-52898-8.00006-9. PMID 22938966.
- "Epilepsy (Seizure Disorder)". Retrieved 30 March 2012.
- Perucca, P; Gilliam, FG (September 2012). "Adverse effects of antiepileptic drugs.". Lancet neurology 11 (9): 792–802. doi:10.1016/S1474-4422(12)70153-9. PMID 22832500.
- Gastaut H (1970). "Clinical and electroencephalographical classification of epileptic seizures.". Epilepsia 11 (1): 102–13. doi:10.1111/j.1528-1157.1970.tb03871.x. PMID 5268244.
- Litt B, Echauz J (May 2002). "Prediction of epileptic seizures". Lancet Neurol 1 (1): 22–30. doi:10.1016/S1474-4422(02)00003-0. PMID 12849542.
|Look up epileptic seizure in Wiktionary, the free dictionary.|