Fever
Febrile seizures are seizures associated with fever. They are not
the result of brain disorders or other factors. Febrile seizures are
by far the most common kind of seizure in early childhood, affecting
2% to 4% of young children in the United States and Western Europe.
The fever is usually substantial (38.3 C, or 101 F or higher). It is
often associated with upper respiratory, ear, or other infection.
Rapid elevation of temperature in particular may trigger febrile
seizures.
Genetic studies suggest that having certain genes may predispose
children to develop these seizures. This can mean that children with
a family history of febrile seizures are especially vulnerable.
Febrile seizures have a variety of symptoms, and typically include
loss of consciousness and tonic-clonic (tonic=rigid;
clonic=jerking) movements.
Although most children who have febrile seizures do not later
develop epilepsy, they do have an increased risk compared to children
with no history of febrile seizure. Children at particular risk for
later epilepsy include those who have:
- A family history of epilepsy.
- Developmental delay or neurological problems.
- Unusually severe febrile seizures.
Most children who have had febrile seizures develop and behave
normally. Some research, however, suggests that children who have had
particularly long (more than 20 minutes) febrile seizures show
deficits in nonverbal skills later in childhood.
Treatment of febrile seizures consists of lowering the fever and
managing any underlying infection. Other therapies such as
anticonvulsant medications, high-dose acetaminophen therapy, and
Valium suppositories have not been found to be particularly effective
in preventing febrile seizures.
Brain Injury Before or During Birth
The fetal brain is vulnerable to several factors that can disrupt
its development and predispose a child to seizures.
Maternal infections during pregnancy--such as cytomegalovirus,
toxoplasmosis, and syphilis--can cross the placenta to infect the
fetus. These viruses slow fetal brain growth by killing brain cells
and inducing the formation of small calcium deposits throughout the
brain. Children with these congenital infections are usually
developmentally delayed, and are at high risk for seizure disorders.
Fetal brain tissue also may bleed or die from lack of oxygen or other
vital nutrients at various times during pregnancy and delivery. Among
the factors associated with this type of injury are:
- A placenta that looks unusual or is torn.
- Rapid or prolonged labor.
- Significantly pre-term or post-term delivery.
- Chronic maternal illness such as severe hypertension.
Such complications increase the infant's risk for development of
epilepsy and also for developmental delay and cerebral palsy. From
35% to 45% of children with cerebral palsy also have epilepsy; there
is a strong correlation between these disorders.
Brain Injury After Birth
The blood vessels supplying the brain of a premature infant are
more fragile and prone to rupture than those of a full-term infant.
Very premature infants (less than 28 weeks gestation) are at
increased risk for postnatal brain injury. They may develop seizures
as well as other neurologic problems. Hemorrhaging (bleeding) may
occur, with damage to one or both sides of the brain.
Early childhood head trauma also contributes to brain injury, and
therefore to epilepsy. Survivors of shaken-baby syndrome are at
particular risk.
Accidental trauma also plays an important role. Age- and
weight-appropriate car restraint systems (car seats and seat belts)
should be used. Babies should not be placed in infant walkers.
Children should wear bicycle helmets.
Postnatal infection also can injure the young brain and predispose
a child to epilepsy. Both encephalitis (infection of the brain) and
meningitis (infection of the membranes covering the brain and spine)
are relatively common in infants and toddlers. Although most children
recover without problems, some will experience developmental delay,
vision and hearing deficits, and seizures.
Congenital Malformations
A wide spectrum of congenital brain malformations exist -- from
incidental, minor anomalies to major structural abnormalities. The
more severe the abnormality, the more likely it is to be associated
with epilepsy, cerebral palsy, severe mental retardation, and vision
disorders. These conditions are typically diagnosed by head CT
(computerized tomography) or MRI (magnetic resonance imaging) scan.
Under normal circumstances, the growing outer layer, or cerebral
cortex, of the fetal brain will develop folds called gyri. Some of
the most severe brain malformations involve abnormal gyri formation.
A child with abnormal gyri--gyri that are too small or
large, for example--will be at high risk for seizure
disorders. Epilepsy in such children can be especially challenging to
control.
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