View source for Seizure

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  DiseasesDB     = 19011 |
  ICD10          = {{ICD10|G|40||g|40}}, {{ICD10|I|64||i|64}}, {{ICD10|P|90||p|90}}, {{ICD10|R|56||r|56}}|
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  MeshID         = D012640 |
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A '''seizure''' is a temporary abnormal electro-physiologic phenomenon of the [[brain]], resulting in abnormal synchronization of electrical [[neuron]]al activity. It can manifest as an alteration in [[mental state]], [[tonic (physiology)|tonic]] or [[clonic]] movements, convulsions, and various other psychic symptoms (such as [[déjà vu]] or [[jamais vu]]). It is caused by a temporary abnormal electrical activity of a group of [[brain]] cells.  The medical syndrome of recurrent, unprovoked seizures is termed [[epilepsy]], but some seizures may occur in people who do not have epilepsy. 

The treatment of epilepsy is a subspecialty of [[neurology]]; the study of seizures is part of [[neuroscience]].

==Differential Diagnosis==

* Partial seizure (involves only part of the brain)
*:* Simple or complex
* Generalized seizure (involves both hemispheres)
*:* Tonic-clonic
*:* Atonic
*:* Myoclonic
*:* Absence
* Epilepsy
* Secondary seizure
*:* [[Hypoxia]]
*:* Metabolic abnormalities
*:* Infection
*:* Cerebrovascular etiologies
*:* Drug effects, withdrawal, intoxication
*:* Hypoxic-ischemic encephalopathy
*:* Febrile seizures in children
*:* Structural lesions 
* Nonepileptic seizure
* Inborn errors of metabolism
*:* Disorders of sugar metabolism
*:* Organic acidemias
*:* [[Glycogen storage disease|Glycogen storage diseases]]
*:* Disorders of amino acid metabolism
*:* Urea cycle disorders
*:* Peroxisomal disorders
*:* Mitochondrial disorders
* [[Rasmussen's encephalitis]]

==Signs and symptoms==

Seizures can cause involuntary changes in body movement or function, sensation, awareness, or behavior. A seizure can last from a few seconds to [[status epilepticus]], a continuous seizure that will not stop without intervention. Seizure is often associated with a sudden and involuntary contraction of a group of muscles. However, a seizure can also be as subtle as marching numbness of a part of the body, a brief loss of [[memory]], sparkling or flashes, sensing an unpleasant odor, a strange [[epigastric]] sensation or a sensation of fear. Therefore seizures are typically classified  as [[motoneuron|motor]], [[sensory neuron|sensory]], [[Autonomic nervous system|autonomic]], [[emotion|emotional]] or [[cognitive]]. 

In some cases, the full onset of a seizure event is preceded by some of the sensations described above. These sensations can serve as a warning to the sufferer that a full [[tonic-clonic seizure]] is about to occur. These "warning sensations" are cumulatively called an ''aura''.[http://www.epilepsy.com/epilepsy/auras.html]

Symptoms experienced by a person during a seizure depend on where in the brain the disturbance in electrical activity occurs. Recent studies show that seizures happen in sleep more often than was thought. A person having a tonic-clonic seizure may cry out, lose consciousness and fall to the ground, and convulse, often violently. A person having a [[complex partial seizure]] may appear confused or dazed and will not be able to respond to questions or direction. Some people have seizures that are not noticeable to others. Sometimes, the only clue that a person is having an [[absence seizure]] is rapid blinking or a few seconds of staring into space.

It is commonly thought among healthcare providers that many seizures, especially in children, are preceded by [[tachycardia]] that frequently persists throughout the seizure. This early increase in heart rate may supplement an aura as a physiological warning sign of an imminent seizure.

==Types==
{{Main|Seizure types}}

Seizure types are organized according to whether the source of the seizure within the brain is localized (''partial'' or ''focal'' onset seizures) or distributed (''generalized'' seizures). Partial seizures are further divided on the extent to which consciousness is affected ([[simple partial seizures]] and [[complex partial seizures]]). If it is unaffected, then it is a ''simple partial'' seizure; otherwise it is a ''complex partial'' seizure. A partial seizure may spread within the brain - a process known as ''secondary generalisation''. Generalized seizures are divided according to the effect on the body but all involve loss of consciousness. These include [[Absence seizure|absence]], [[Myoclonus|myoclonic]], [[Clonic seizure|clonic]], tonic, [[tonic-clonic seizure|tonic-clonic]], and [[Atonic seizure|atonic]] seizures.

Following standardization proposal published in 1970, out-dated terms such as "petit mal", "grand mal", "Jacksonian", "psychomotor", and "temporal-lobe seizure" have fallen into disuse.

==Diagnosis==

It can be difficult to distinguish a seizure from other conditions causing a collapse, abnormal movements or other seizure manifestations. A 2007 [[Evidence based medicine|evidence-based]] review from the [[American Academy of Neurology]] and the American Epilepsy Society recommends an [[electroencephalogram]] (EEG, brain wave activity) and brain imaging with [[CT scan]] or [[MRI scan]] in the work-up of adults presenting with a first apparently unprovoked seizure. [[Blood tests]], [[lumbar puncture]] or toxicology screening can be helpful in specific circumstances suggestive of an underlying cause like [[meningitis]] or [[drug overdose]], but there is insufficient evidence to support their routine use in the work-up of an adult with an apparently unprovoked first seizure.<ref name="AAS2007">Krumholz A, Wiebe S, Gronseth G, Shinnar S, Levisohn P, Ting T, Hopp J, Shafer P, Morris H, Seiden L, Barkley G, French J; Quality Standards Subcommittee of the American Academy of Neurology; American Epilepsy Society. Practice Parameter: evaluating an apparent unprovoked first seizure in adults (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology and the American Epilepsy Society. ''Neurology'' 2007; '''69(21)''': 1996-2007. PMID 18025394</ref>

===Determining whether a seizure occurred===

Differentiating a seizure from other conditions such as [[Fainting|syncope]] can be difficult. In addition, 5% of patients with a positive [[tilt table test]] may have seizure-like activity that seems to be due to [[cerebral hypoxia]].<ref name="pmid12963568">{{cite journal |author=Passman R, Horvath G, Thomas J, ''et al'' |title=Clinical spectrum and prevalence of neurologic events provoked by tilt table testing |journal=Arch. Intern. Med. |volume=163 |issue=16 |pages=1945-8 |year=2003 |pmid=12963568 |doi=10.1001/archinte.163.16.1945}}</ref>

====Physical examination====

A small study found that finding a bite to the side of the tongue was very helpful when present<ref name="pmid7487261">{{cite journal |author=Benbadis SR, Wolgamuth BR, Goren H, Brener S, Fouad-Tarazi F |title=Value of tongue biting in the diagnosis of seizures |journal=Arch. Intern. Med. |volume=155 |issue=21 |pages=2346-9 |year=1995 |pmid=7487261 |doi=}}</ref>"
* [[sensitivity (tests)|sensitivity]] of  24%
* [[specificity (tests)|specificity]] of 99%

====Serum prolactin level====

Two [[meta-analysis|meta-analyses]] have quantified the role of an elevated serum prolactin.
The first meta-analysis found that<ref name="pmid14988379">{{cite journal |author=Ahmad S, Beckett MW |title=Value of serum prolactin in the management of syncope |journal=Emergency medicine journal : EMJ |volume=21 |issue=2 |pages=e3 |year=2004 |pmid=14988379 |doi=}}</ref>:
"If a serum prolactin concentration is greater than  three times the baseline when taken within one hour of syncope, then in the  absence of test "modifiers":
# the patient is nine times more likely to have  suffered a GTCS as compared with a pseudoseizure positive LR = 8.92 (95% CI  (1.31 to 60.91)), SN = 0.62 (95% CI (0.40 to 0.83)), SP = 0.89 (95% CI (0.60 to  0.98))
# five times more likely to have suffered a GTCS as compared with  non-convulsive syncope positive LR 4.60 (95% CI (1.25 to 16.90)), SN = 0.71 (95% CI (0.49 to 0.87)), SP = 0.85 (95%  CI (0.55 to 0.98)). " 

The second meta-analysis found:<ref name="pmid16157897">{{cite journal |author=Chen DK, So YT, Fisher RS |title=Use of serum prolactin in diagnosing epileptic seizures: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology |journal=Neurology |volume=65 |issue=5 |pages=668-75 |year=2005 |pmid=16157897 |doi=10.1212/01.wnl.0000178391.96957.d0}}</ref>
#"Elevated serum prolactin assay, when measured in the  appropriate clinical setting at 10 to 20 minutes after a suspected event, is a  useful adjunct for the differentiation of generalized tonic-clonic or complex  partial seizure from psychogenic nonepileptic seizure among adults and older  children (Level B)."
#"Serum prolactin assay does not distinguish  epileptic seizures from syncope (Level B). 
#"The  use of serum PRL assay has not been established in the evaluation of status"  epilepticus, repetitive seizures, and neonatal seizures (Level U)."

The serum prolactin level is less [[sensitivity (tests)|sensitive]] for detecting partial seizures.<ref name="pmid15256189">{{cite journal |author=Shukla G, Bhatia M, Vivekanandhan S, ''et al'' |title=Serum prolactin levels for differentiation of nonepileptic versus true seizures: limited utility |journal=Epilepsy & behavior : E&B |volume=5 |issue=4 |pages=517-21 |year=2004 |pmid=15256189 |doi=10.1016/j.yebeh.2004.03.004}}</ref>

====EEG====

An isolated abnormal electrical activity recorded by an [[electroencephalography]] examination without a clinical presentation is called subclinical seizure. They may identify background epileptogenic activity, as well as help identify particular causes of seizures.

===Investigation of underlying cause===

Additional diagnostic methods include [[CT Scan]]ning and [[MRI]] imaging or angiography.  These may show structural lesions within the brain, but the majority of those with epilepsy show nothing unusual.  

As seizures have a [[differential diagnosis]], it is common for patients to be simultaneously investigated for cardiac and endocrine causes. Checking [[glucose]] levels, for example, is a mandatory action in the management of seizures as [[hypoglycemia]] may cause seizures, and failure to administer glucose would be harmful to the patient. Other causes typically considered are [[Fainting|syncope]] and [[cardiac arrhythmia]]s, and occasionally [[panic attack]]s and [[cataplexy]]. For more information, see [[non-epileptic seizures]].

==Management==

The first aid for a seizure depends on the type of seizure occurring. Generalized seizures will cause the person to fall, which may result in injury. A tonic-clonic seizure results in violent movements that cannot and should not be suppressed. The person should never be restrained, nor should there be any attempt to put something in the mouth. 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]].

It is not necessary to call an ambulance if the person is known to have epilepsy, if the seizure is shorter than five minutes and is typical for them, if it is not immediately followed by another seizure, and if the person is uninjured. Otherwise, or if in any doubt, medical assistance should be sought. 

A seizure longer than five minutes is a medical emergency. Relatives and other caregivers of those known to have epilepsy often carry medicine such as rectal [[diazepam]] or [[buccal mucosa|buccal]] [[midazolam]] in order to rapidly end the seizure.

===Safety===

A sudden fall can lead to broken bones and other injuries. Children who are affected by frequent drop seizures may wear helmets to protect the head during a fall.

The unusual behavior resulting from the chaotic brain activity of a seizure can be misinterpreted as an aggressive act. This may invoke a hostile response or police involvement, where there was no intention to cause harm or trouble. During a prolonged seizure, the person is defenseless and may become a victim of theft.

A [[seizure response dog]] can be trained to summon help or ensure personal safety when a seizure occurs. These are not suitable for everybody. Rarely, a dog may develop the ability to sense a seizure before it occurs.<ref name=Dalziel_2003>{{cite journal |author=Dalziel D, Uthman B, Mcgorray S, Reep R |title=Seizure-alert dogs: a review and preliminary study |journal=Seizure |volume=12 |issue=2 |pages=115-20 |year=2003 |pmid=12566236}}</ref>

==Seizures without epilepsy==

Unprovoked seizures are often associated with epilepsy and related [[seizure disorder]]s.

Causes of ''provoked'' seizures include:
*[[Arteriovenous malformation]] (AVM) is a treatable medical condition that can cause seizures, headaches, and brain hemorrhages.  An MRI can quickly confirm or reject this as a cause.  
*[[head injury]]
*[[intoxication]] with drugs
*drug toxicity, for example [[aminophylline]] or [[local anesthetics]]
*normal doses of certain drugs that lower the seizure threshold, such as [[tricyclic antidepressant]]s
*[[infection]], such as [[encephalitis]] or [[meningitis]]
*[[fever]] leading to [[febrile convulsions]] (but see above)
*[[metabolism|metabolic]] disturbances, such as [[hypoglycaemia]], [[hyponatremia]] or [[Hypoxia (medical)|hypoxia]]
*[[withdrawal]] from drugs ([[anticonvulsant]]s and [[sedative]]s such as [[ethanol|alcohol]], [[barbiturates]], and [[benzodiazepines]])
*space-occupying lesions in the brain ([[abscess]]es, [[tumor]]s)
*seizures during (or shortly after) pregnancy can be a sign of [[eclampsia]].
*binaural beat brainwave entrainment may trigger seizures in both epileptics and non-epileptics
*[[stroke]] may cause seizures, with [[embolism|embolic]] strokes more likely to present with seizures; [[cerebral venous sinus thrombosis]], a rare type of stroke, is more likely to be accompanied by seizures than other types of stroke
*[[multiple sclerosis]] sufferers may rarely experience seizures

Some medications produce an increased risk of seizures and [[electroconvulsive therapy]] (ECT) deliberately sets out to induce a seizure for the treatment of major depression. Many seizures have unknown causes.

Seizures which are provoked are not associated with epilepsy, and people who experience such seizures are normally not diagnosed with epilepsy. However, the seizures described above resemble those of epilepsy both outwardly, and on [[EEG]] testing.

Seizures can occur after a subject witnesses a traumatic event. This type of seizure is known as a psychogenic non-epileptic seizure and is related to posttraumatic stress disorder.

==See also==

*[[Epilepsy]]
*[[Photosensitive epilepsy]]
*[[Psychogenic non-epileptic seizures]]
*[[EPUNA]]

==References==
{{Reflist|2}}

==External links==
* [http://www.nlm.nih.gov/medlineplus/seizures.html MEDLINEplus: Seizures]
* [http://www.epilepsy.com Epilepsy and seizure information for patients and health professionals : Epilepsy.com]

{{SIB}}

[[es:Convulsión]]
[[fr:Convulsion]]
[[it:Convulsione]]
[[nl:Epileptisch insult]]
[[scn:Cummursioni]]
[[tr:Havale (tıp)]]

[[Category:Neurology]]
[[Category:Epilepsy|*]]
[[Category:Signs and symptoms]]
[[Category:Emergency medicine]]


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