Epileptic seizure

Epileptic seizure
SynonymEpileptic fit,[1] seizure, fit, convulsions[2]
Generalized 3 Hz spike and wave discharges in EEG
SpecialtyNeurology, emergency medicine
DurationTypically < 2 minutes[4]
TypesProvoked, unprovoked[5]
CausesProvoked: Low blood sugar, alcohol withdrawal, low blood sodium, fever, brain infection, concussion[3][5]
Unprovoked: Unknown, brain injury, brain tumor, previous stroke[4][3][5][6]
Diagnostic methodBased on symptoms, blood tests, medical imaging, electroencephalography[6]
Differential diagnosisSyncope, nonepileptic psychogenic event, tremor, migraine, transient ischemic attack[3][4]
TreatmentLess than 5 min: Place person on their side, remove nearby dangerous objects[7]
More than 5 min: Treat as per status epilepticus[7]
Frequency~10% of people (at one point in time)[4][8]

A seizure, technically known as an epileptic seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain.[5] Outward effects vary from uncontrolled shaking movements involving much of the body with loss of consciousness (tonic-clonic seizure), to shaking movements involving only part of the body with variable levels of consciousness (focal seizure), to a subtle momentary loss of awareness (absence seizure).[3] Most of the time these episodes last less than 2 minutes and it takes some time to return to normal.[4][7] Loss of bladder control may occur.[3]

Seizures may be provoked and unprovoked.[5] Provoked seizures are due to a temporary event such as low blood sugar, alcohol withdrawal, low blood sodium, fever, brain infection, or concussion.[3][5] Unprovoked seizures occur without a known or fixable cause such that ongoing seizures are likely.[4][3][5][6] Unprovoked seizures may be triggered by stress or sleep deprivation.[3] Diseases of the brain, where there has been at least one seizure and a long term risk of further seizures, are collectively known as epilepsy.[5] Conditions that look like epileptic seizures but are not include fainting, nonepileptic psychogenic event, and tremor.[3]

A seizure that lasts for more than a brief period of time is a medical emergency.[9] Any seizure lasting longer than 5 minutes should be treated as status epilepticus.[7] A first seizure generally does not require long term treatment with anti-seizure medications unless a specific problem is found on electroencephalogram (EEG) or brain imaging.[6] Typically it is safe to complete the work-up following a single seizure as an outpatient.[3] In many, with what appears to be a first seizure, other minor seizures have previously occurred.[10]

Up to 10% of people have at least one epileptic seizure.[4][8] Provoked seizures occur in about 3.5 per 10,000 people a year while unprovoked seizures occur in about 4.2 per 10,000 people a year.[4] After one seizure, the chance of experiencing a second is about 50%.[11] Epilepsy affects about 1% of the population at any given time[8] with about 4% of the population affected at some point in time.[6] Nearly 80% of those with epilepsy live in developing countries.[8] Many places require people to stop driving until they have not had a seizure for a specific period of time.[4]

Signs and symptoms

The signs and symptoms of seizures vary depending on the type.[12] The most common type of seizure is convulsive (60%).[13] Two-thirds of these begin as focal seizures and become generalized while one third begin as generalized seizures.[13] The remaining 40% of seizures are non-convulsive, an example of which is absence seizure.[14]

Focal seizures

Focal seizures are often preceded by certain experiences, known as an aura.[12] These may include sensory, visual, psychic, autonomic, olfactory or motor phenomena.[15]

In a complex partial seizure a person may appear confused or dazed and can not respond to questions or direction. Focal seizure may become generalized.[15]

Jerking activity may start in a specific muscle group and spread to surrounding muscle groups—known as a Jacksonian march.[16] Unusual activities that are not consciously created may occur.[16] 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.[16]

Generalized seizures

There are six main types of generalized seizures: tonic-clonic, tonic, clonic, myoclonic, absence, and atonic seizures.[17] They all involve a loss of consciousness and typically happen without warning.[18]

  • Tonic-clonic seizures present with a contraction of the limbs followed by their extension, along with arching of the back for 10–30 seconds.[18] A cry may be heard due to contraction of the chest muscles.[18] The limbs then begin to shake in unison.[18] After the shaking has stopped it may take 10–30 minutes for the person to return to normal.[18]
  • Tonic seizures produce constant contractions of the muscles.[18] The person may turn blue if breathing is impaired.[18]
  • Clonic seizures involve shaking of the limbs in unison.[18]
  • Myoclonic seizures involve spasms of muscles in either a few areas or generalized through the body.[18]
  • Absence seizures can be subtle, with only a slight turn of the head or eye blinking.[15] 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.[15]
  • Atonic seizures involve the loss of muscle activity for greater than one second.[16] This typically occurs bilaterally (on both sides of the body).[16]


A seizure can last from a few seconds to more than five minutes, at which point it is known as status epilepticus.[19] Most tonic-clonic seizures last less than two or three minutes.[19] Absence seizures are usually around 10 seconds in duration.[14]


After the active portion of a seizure, there is typically a period of confusion called the postictal period before a normal level of consciousness returns.[12] This usually lasts 3 to 15 minutes[20] but may last for hours.[21] Other common symptoms include: feeling tired, headache, difficulty speaking, and abnormal behavior.[21] Psychosis after a seizure is relatively common, occurring in between 6 and 10% of people.[22] Often people do not remember what occurred during this time.[21]

Other Languages
العربية: نوبة (طب)
Deutsch: Krampfanfall
한국어: 뇌전증 발작
Nederlands: Insult
português: Crise epiléptica
slovenščina: Epileptični napad
српски / srpski: Епилептички напад
srpskohrvatski / српскохрватски: Epileptički napad
中文: 癲癇發作