Febrile seizure
Encyclopedia
A febrile seizure, also known as a fever fit or febrile convulsion, is a convulsion
associated with a significant rise in body temperature. They most commonly occur in children between the ages of 6 months and 6 years and are twice as common in boys as in girls.
. A febrile seizure is the effect of a sudden rise in temperature (>39°C/102°F) rather than a fever that has been present for a prolonged length of time. As well as this, parents caring for children who may be febrile, wrap them up in warm blankets in an attempt to comfort the child, unknowingly increasing their fever and therefore the problem.
Febrile seizures occurring in children between the ages of 6 months and about 6 years can be due to a hypersensitive hypothalamus
in the brain. The hypothalamus
is responsible for homeostatic core temperature regulation, (amongst other factors) and in younger children it is still a developing portion of the brain, meaning it is susceptible to hypersensitive reactions to slight raises in body temperature.
Febrile seizures represent the meeting point between a low seizure threshold (genetically and age-determined; some children have a greater tendency to have seizures under certain circumstances) and a trigger, which is fever. The genetic causes of febrile seizures are still being researched. Some mutations that cause a neuron
al hyperexcitability (and could be responsible for febrile seizures) have already been discovered.
Several genetic associations have been identified. These include:
Certain forms are considered channelopathies.
is one that must be arrived at by eliminating
more serious causes of seizure
and fever: in particular, meningitis
and encephalitis
must be considered. However, in locales in which children are immunized for pneumococcal and Haemophilus influenzae
, the prevalence of bacterial meningitis is low. If a child has recovered and is acting normally, bacterial meningitis is very unlikely. The diagnosis of a febrile seizure should not prevent evaluation of the child for source of fever, although this is usually limited to evaluation of the urine in the younger age groups.
The simple seizure represents the majority of cases and is considered to be less of a cause for concern than the complex.
Simple febrile seizures do not cause permanent brain injury
; do not tend to recur frequently (children tend to outgrow them); and do not make the development of adult epilepsy
significantly more likely (about 3–5%), compared with the general public (1%). Children with febrile convulsions are more likely to suffer from a febrile epileptic attacks in the future if they have a complex febrile seizure, a family history
of a febrile convulsions in first-degree relatives (a parent or sibling), or a preconvulsion history of abnormal neurological signs or developmental delay. There is an 80% chance that children who have complex febrile seizures will have seizures later on in life. Similarly, the prognosis
after a simple febrile seizure is excellent, whereas an increased risk of death
has been shown for complex febrile seizures, partly related to underlying conditions.
or clonazepam
are active against febrile seizures, with sodium valproate showing superiority over clonazepam.
Convulsion
A convulsion is a medical condition where body muscles contract and relax rapidly and repeatedly, resulting in an uncontrolled shaking of the body. Because a convulsion is often a symptom of an epileptic seizure, the term convulsion is sometimes used as a synonym for seizure...
associated with a significant rise in body temperature. They most commonly occur in children between the ages of 6 months and 6 years and are twice as common in boys as in girls.
Causes
The direct cause of a febrile seizure is not known; however, it is normally precipitated by a recent upper respiratory infection or gastroenteritisGastroenteritis
Gastroenteritis is marked by severe inflammation of the gastrointestinal tract involving both the stomach and small intestine resulting in acute diarrhea and vomiting. It can be transferred by contact with contaminated food and water...
. A febrile seizure is the effect of a sudden rise in temperature (>39°C/102°F) rather than a fever that has been present for a prolonged length of time. As well as this, parents caring for children who may be febrile, wrap them up in warm blankets in an attempt to comfort the child, unknowingly increasing their fever and therefore the problem.
Febrile seizures occurring in children between the ages of 6 months and about 6 years can be due to a hypersensitive hypothalamus
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
in the brain. The hypothalamus
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
is responsible for homeostatic core temperature regulation, (amongst other factors) and in younger children it is still a developing portion of the brain, meaning it is susceptible to hypersensitive reactions to slight raises in body temperature.
Febrile seizures represent the meeting point between a low seizure threshold (genetically and age-determined; some children have a greater tendency to have seizures under certain circumstances) and a trigger, which is fever. The genetic causes of febrile seizures are still being researched. Some mutations that cause a neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
al hyperexcitability (and could be responsible for febrile seizures) have already been discovered.
Several genetic associations have been identified. These include:
| Type | OMIM | Gene |
|---|---|---|
| FEB3A | SCN1A | |
| FEB3B | SCN9A | |
| FEB4 | GPR98 GPR98 G protein-coupled receptor 98, also known as GPR98, is a human protein and gene.-External Links:* -Further reading:... |
|
| FEB8 | GABRG2 GABRG2 Gamma-aminobutyric acid receptor subunit gamma-2 is a protein that in humans is encoded by the GABRG2 gene.-Interactions:GABRG2 has been shown to interact with GABARAP and Dopamine receptor D5.-Further reading:... |
Certain forms are considered channelopathies.
Diagnosis
The diagnosisMedical diagnosis
Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...
is one that must be arrived at by eliminating
Diagnosis of exclusion
A diagnosis of exclusion is a medical condition reached by a process of elimination, which may be necessary if presence cannot be established with complete confidence from examination or testing...
more serious causes of seizure
Seizure
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 or as mild as a brief loss of awareness...
and fever: in particular, meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
and encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
must be considered. However, in locales in which children are immunized for pneumococcal and Haemophilus influenzae
Haemophilus influenzae
Haemophilus influenzae, formerly called Pfeiffer's bacillus or Bacillus influenzae, Gram-negative, rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe. H...
, the prevalence of bacterial meningitis is low. If a child has recovered and is acting normally, bacterial meningitis is very unlikely. The diagnosis of a febrile seizure should not prevent evaluation of the child for source of fever, although this is usually limited to evaluation of the urine in the younger age groups.
Types
There are two types of febrile seizures.- A simple febrile seizure is one in which the seizure lasts less than 15 minutes (usually much less than this), does not recur in 24 hours, and involves the entire body (classically a generalized tonic-clonic seizureTonic-clonic seizureTonic–clonic seizures are a type of generalized seizure that affects the entire brain...
). - A complex febrile seizure is characterized by longer duration, recurrence, or focus on only part of the body.
The simple seizure represents the majority of cases and is considered to be less of a cause for concern than the complex.
Simple febrile seizures do not cause permanent brain injury
Brain damage
"Brain damage" or "brain injury" is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors...
; do not tend to recur frequently (children tend to outgrow them); and do not make the development of adult epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
significantly more likely (about 3–5%), compared with the general public (1%). Children with febrile convulsions are more likely to suffer from a febrile epileptic attacks in the future if they have a complex febrile seizure, a family history
Family history (medicine)
In medicine, a family history consists of information about disorders from which the direct blood relatives of the patient have suffered. Genealogy typically includes very little of the medical history of the family, but the medical history could be considered a specific subset of the total history...
of a febrile convulsions in first-degree relatives (a parent or sibling), or a preconvulsion history of abnormal neurological signs or developmental delay. There is an 80% chance that children who have complex febrile seizures will have seizures later on in life. Similarly, the prognosis
Prognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
after a simple febrile seizure is excellent, whereas an increased risk of death
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...
has been shown for complex febrile seizures, partly related to underlying conditions.
Symptoms
During simple febrile seizures, the body will become stiff and the arms and legs will begin twitching. The patient loses consciousness, although their eyes remain open. Breathing can be irregular. They may become incontinent (wet or soil themselves); they may also vomit or have increased secretions (foam at the mouth). The seizure normally lasts for less than five minutes.Treatment
The vast majority of patients do not require treatment for either their acute presentation with a seizure or for recurrences. The best way to manage is to control the temperature with acetaminophen (Paracetamol) or by sponging. When anticonvulsant therapy is judged by a doctor to be indicated, anticonvulsants can be prescribed. Sodium valproateSodium valproate
Sodium valproate or valproate sodium is the sodium salt of valproic acid and is an anticonvulsant used in the treatment of epilepsy, anorexia nervosa, panic attack, anxiety disorder, posttraumatic stress disorder, migraine and bipolar disorder, as well as other psychiatric conditions requiring...
or clonazepam
Clonazepam
Clonazepamis a benzodiazepine drug having anxiolytic, anticonvulsant, muscle relaxant, and hypnotic properties. It is marketed by Roche under the trade name Klonopin in the United States and Rivotril in Australia, Brazil, Canada and Europe...
are active against febrile seizures, with sodium valproate showing superiority over clonazepam.