An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement (tonic-clonic seizure) or as mild as a brief loss of awareness. It can manifest as an alteration in mental state, tonic or clonic movements, convulsions, and various other psychic symptoms (such as déjà vu or jamais vu). Sometimes it is not accompanied by convulsions but a full body "slump", where the person simply will lose control of their body and slump to the ground. The medical syndrome of recurrent, unprovoked seizures is termed epilepsy, but seizures can occur in people who do not have epilepsy.
About 4% of people will have an unprovoked seizure by the age of 80 and the chance of experiencing a second seizure is between 30% and 50%. Treatment may reduce the chance of a second one by as much as half.
Following standardization proposals published in 1970, out-dated terms such as "petit mal", "grand mal", "Jacksonian", "psychomotor", and "temporal-lobe seizure" have fallen into disuse.
Signs and symptoms
Seizures may cause involuntary changes in body movement or function, sensation, awareness, or behavior. Seizures are often associated with a sudden and involuntary contraction of a group of muscles and loss of consciousness. However, a seizure can also be as subtle as a fleeting numbness of a part of the body, a brief or long term loss of
memory, visual changes, sensing/discharging of an unpleasant odor, a strange
epigastric sensation, or a sensation of fear and total state of confusion. A seizure can last from a few seconds to
status epilepticus, a continuous group of seizures that is often life-threatening without immediate intervention. Therefore seizures are typically classified as
motor,
sensory,
autonomic,
emotional or
cognitive. After a seizure, while the brain is recovering, there can be a transient loss of memory; usually the short term memory.
In some cases, the full onset of a seizure event is preceded by some of the sensations described above, called Vertiginous epilepsy. These sensations can serve as a warning to the sufferer that a generalized tonic–clonic seizure is about to occur. These "warning sensations" are cumulatively called an aura. Also, it is commonly believed among healthcare providers that many seizures, especially those 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.
Some patients are able to tell when a seizure is about to happen. Some symptoms experienced by the person before a seizure may include dizziness, lightheadedness, tightening of the chest, and some experience things in slow-motion just prior to the seizure. Symptoms experienced by a person during a seizure depend on where in the brain the disturbance in electrical activity occurs. Partial and frontal seizures and focal epileptic discharges tend to happen more during sleep than during wakefulness. In contrast, psychogenic nonepileptic seizures are rare between midnight and 6 a m. and never occur during sleep. Generalized epilepsy but not focal epilepsy is higher in the morning probably reflecting a diurnal variation in cortical excitability. 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, extreme confusion for a few seconds or sometimes into hours.
Causes
Unprovoked seizures are often associated with epilepsy and related
seizure disorders.
Causes of provoked seizures include:
sleep deprivation
cavernoma or cavernous malformation is a treatable medical condition that can cause seizures, headaches, and brain hemorrhages. An MRI can quickly confirm or reject this as a cause.
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 may cause non-epileptic post-traumatic seizures or post-traumatic epilepsy, in which the seizures chronically recur.
intoxication with drugs, for example aminophylline or local anaesthetics
normal doses of certain drugs that lower the seizure threshold, such as tricyclic antidepressants
infection, such as encephalitis or meningitis
fever leading to febrile convulsions (but see above)
metabolic disturbances, such as hypoglycaemia, hyponatremia or hypoxia
withdrawal from drugs (anticonvulsants, antidepressants, and sedatives such as alcohol, barbiturates, and benzodiazepines,)
space-occupying lesions in the brain (abscesses, tumors)
seizures during (or shortly after) pregnancy can be a sign of eclampsia.
seizures in a person with hydrocephalus may indicate severe shunt failure.
binaural beat brainwave entrainment may trigger seizures in both epileptics and non-epileptics
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 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.
Diagnosis
Only about 25 percent of people who have a seizure or develop status epilepticus have
epilepsy. It is important to distinguish primary epileptic seizures from secondary causes.
Blood tests,
lumbar puncture or
toxicology screening can be helpful in specific circumstances suggestive of an underlying cause like alcohol or benzodiazepine withdrawal,
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. A 2007
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. MRI is more sensitive in a first apparently unprovoked seizure.
Differentiating an epileptic seizure from other conditions such as syncope can be difficult. A reliable description of a witnessed seizure is the most important factor in determining whether a seizure has occurred.
Physical examination
Most patients are in a
postictal state following a seizure. In this state they are drowsy and often confused. There may be signs of other injuries. A small study found that finding 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 (
sensitivity of 24%), the finding was very specific for seizures, with only 1% due to other causes (
specificity of 99%).
Serum prolactin level
Two
meta-analyses have quantified the role of an elevated
serum prolactin.
The first meta-analysis found that:
"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:
#"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 sensitive for detecting partial seizures.
EEG
An isolated abnormal electrical activity recorded by an
electroencephalography examination without a clinical presentation is called subclinical seizure. They can identify background epileptogenic activity, as well as help identify causes of seizures.
Investigation of underlying cause
Additional diagnostic methods include
CT Scanning and
MRI imaging or
angiography. These may show structural lesions within the brain and heart, 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 syncope and cardiac arrhythmias, and occasionally panic attacks and cataplexy. In addition, 5% of patients with a positive tilt table test may have seizure-like activity that seems to be due to cerebral hypoxia. 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. Bystanders should remain calm and avoid crowding the person.
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 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.
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.
See also
Epilepsy
Epileptogenesis
Photosensitive epilepsy
Psychogenic non-epileptic seizures
EPUNA or episode of unusual neurological activity
Postictal state
Seizure trigger
Seizure prediction
References
External links
Seizure First Aid
MEDLINEplus: Seizures
Epilepsy and seizure information, news and support for people with epilepsy and their friends, families, doctors and caregivers: Epilepsy Foundation
Epilepsy and seizure information for patients and health professionals : Epilepsy.com
Category:Symptoms and signs: General
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