Febrile seizure

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What is a febrile seizure

What is a febrile seizure

Febrile seizures are febrile convulsions that can happen during a fever (febrile means “feverish”). They affect kids 3 months to 6 years old, and are most common in toddlers 12–18 months old. Febrile seizures are the most common type of convulsions in infants and young children and occur in 2 to 5 percent of American children before age 5. Febrile seizures usually last for a few minutes and are accompanied by a fever above 100.4°F (38°C). The fever may accompany common childhood illnesses such as a cold, the flu, or an ear infection. In some cases, a child may not have a fever at the time of the seizure but will develop one a few hours later. Febrile seizures can be scary to witness, but remember that they’re fairly common and brief febrile seizures (less than 15 minutes) do not cause any long-term health problems and are not usually a symptom of serious illness. In most cases, they don’t lead to any health or developmental problems. If you have questions or concerns, talk with your doctor.

Febrile seizures are not considered epilepsy (seizure disorder), and kids who’ve had one have only a slightly increased risk for developing epilepsy. Having a febrile seizure does not mean a child has epilepsy, since epilepsy is characterized by reoccurring seizures that are not triggered by fever. Even prolonged febrile seizures (lasting more 15 minutes) generally have a good outcome but carry an increased risk of developing epilepsy.

While they can be frightening, febrile seizures usually end without treatment and don’t cause other health problems. Having one doesn’t mean that a child will have epilepsy or brain damage.

Approximately 40 percent of children who experience one febrile seizure will have a recurrence. Children at highest risk for recurrence are those who have:

their first febrile seizure at a young age (younger than 18 months)
a family history of febrile seizures
a febrile seizure as the first sign of an illness
a relatively low temperature increases with their first febrile seizure.

A prolonged initial febrile seizure does not substantially boost the risk of reoccurring febrile seizures. However, if another does occur, it is more likely to be prolonged.

There are two types of febrile seizures:

Simple febrile seizures are usually over in a few minutes, but in rare cases they can last up to 15 minutes. During this type of seizure, a child’s whole body may convulse, shake, and twitch; his or her eyes may roll; and he or she may moan or become unconscious. Children can sometimes vomit or urinate (pee) on themselves during the convulsions.
Complex febrile seizures can last more than 15 minutes or happen more than once in 24 hours. They may also involve movement or twitching of just one part of the body.

The vast majority of febrile seizures are convulsions. Most often during a febrile seizure, a child will lose consciousness and both arms and legs will shake uncontrollably. Less common symptoms include eye rolling, rigid (stiff) limbs, or twitching on only one side or a portion of the body, such as an arm or a leg. Sometimes during a febrile seizure, a child may lose consciousness but will not noticeably shake or move.

Febrile seizures stop on their own and last only a few minutes, while the fever may continue for some time. Some kids might feel sleepy afterward; others feel no lasting effects.

No one knows why febrile seizures happen, although evidence suggests that they’re linked to certain viruses and the way that some children’s developing brains react to high fevers.

Kids with a family history of febrile seizures are more likely to have one, and about 1 in every 3 kids who have had one seizure will have another (usually within the first 1–2 years of the first). Kids who are younger (under 15 months) when they have their first febrile seizure are also at higher risk for a future febrile seizure. Most children outgrow having febrile seizures by the time they are 5 years old.

What to do during a febrile seizure

If your child is having a febrile seizure, stay calm and:

Make sure your child is on a safe surface, such as the floor, and cannot fall down or hit something hard.
Lay your child on his or her side to prevent choking (the recovery position see Figure 1 and video below). This is especially important if your child has a lot of saliva coming out of the mouth.
Watch for breathing problems, including any color change in your child’s face.
Stay with your child and try to make a note of how long the seizure lasts. If the seizure lasts more than 5 minutes, or your child turns blue, it may be a more serious type of seizure — call your local emergency number for an ambulance right away.

Don’t put anything into your child’s mouth during a seizure – including medication – as there’s a slight chance they might bite their tongue.

It’s also important to know what you should NOT do during a febrile seizure:

DON’T try to hold or restrain your child.
DON’T put anything in your child’s mouth.
DON’T try to give your child fever-reducing medicine.
DON’T try to put your child into cool or lukewarm water to cool off.

Take your child to the nearest hospital or dial your local emergency number for an ambulance if:

your child is having a fit for the first time
the seizure lasts longer than five minutes and shows no signs of stopping
you suspect the seizure is being caused by another serious illness – for example, meningitis
your child is having breathing difficulties
your child looks sluggish and is not responding normally
your child doesn’t go back to normal behavior for an hour or more after the seizure
your child looks dehydrated
another seizure happens within 24 hours
the seizure involved only certain parts of the body instead of the whole body

While it’s unlikely that there’s anything seriously wrong, it’s important to get your child checked.

If your child has had febrile seizures before and the seizure lasts for less than five minutes, see your doctor for advice.

A child who hasn’t gotten certain vaccines and has a febrile seizure could be at greater risk for meningitis, a disease that affects the membranes covering the brain and spinal cord. Get immediate medical care if your child has any signs of meningitis, such as a stiff neck, a lot of vomiting, or, in infants, a bulging soft spot on the head.

You should also contact your doctor if your child shows signs and symptoms of dehydration, a lack of fluid in the body.

This includes:

a dry mouth
sunken eyes
a lack of tears when crying
a sunken fontanelle – the soft spot usually found at the top of a young child’s head.

Figure 1. Recovery position

Are febrile seizures harmful?

The vast majority of febrile seizures are short and do not cause any long-term damage. During a seizure, there is a small chance that the child may be injured by falling or may choke on food or saliva in the mouth. Using proper first aid for seizures can help avoid these hazards.

There is no evidence that short febrile seizures cause brain damage. Large studies have found that even children with prolonged febrile seizures have normal school achievement and perform as well on intellectual tests as their siblings who do not have seizures. Even when the seizures last a long time, most children recover completely.

Multiple or prolonged seizures are a risk factor for epilepsy, but most children who experience febrile seizures do not go on to develop the reoccurring seizures that are characteristic of epilepsy. Some children, including those with cerebral palsy, delayed development, or other neurological abnormalities as well as those with a family history of epilepsy are at increased risk of developing epilepsy whether or not they have febrile seizures. Febrile seizures may be more common in these children but do not contribute much to the overall risk of developing epilepsy.

Children who experience a brief, full body febrile seizure are slightly more likely to develop epilepsy than the general population. Children who have a febrile seizure that lasts longer than 10 minutes; a focal seizure (a seizure that starts on one side of the brain); or seizures that reoccur within 24 hours, have a moderately increased risk (about 10 percent) of developing epilepsy as compared to children who do not have febrile seizures.

Of greatest concern is the small group of children with very prolonged febrile seizures lasting longer than 30 minutes. In these children, the risk of epilepsy is as high as 30 to 40 percent though the condition may not occur for many years. Recent studies suggest that prolonged febrile seizures can injure the hippocampus, a brain structure involved with temporal lobe epilepsy (TLE).

Febrile seizure complications

Most febrile seizures produce no lasting effects. Simple febrile seizures don’t cause brain damage, mental retardation or learning disabilities, and they don’t mean your child has a more serious underlying disorder.

Febrile seizures don’t indicate epilepsy, a tendency to have recurrent seizures caused by abnormal electrical signals in the brain.

Recurrent febrile seizures

The most common complication is the possibility of more febrile seizures. The risk of recurrence is higher if:

Your child’s first seizure resulted from a low fever.
The period between the start of the fever and the seizure was short.
An immediate family member has a history of febrile seizures.
Your child was younger than 15 months at the time of the first febrile seizure.

Febrile seizure causes

A high body temperature causes most febrile seizures.

Infection

Usually the fevers that trigger febrile seizures are caused by a viral infection, less commonly by a bacterial infection. Viral infections such as the flu and roseola, which often are accompanied by high fever, appear to be most associated with febrile seizure.

Post-immunization seizures

The risk of febrile seizures may increase after some childhood immunizations, such as the diphtheria, tetanus and pertussis or measles-mumps-rubella vaccinations. A child can develop a low-grade fever after a vaccination. The fever, not the vaccination, causes the seizure.

Risk factors for febrile seizure

Factors that increase the risk of having a febrile seizure include:

Young age. Most febrile seizures occur in children between 6 months and 5 years of age. It’s unusual for children younger than 6 months to have a febrile seizure, and it’s rare for these seizures to occur after 3 years of age.
Family history. Some children inherit a family’s tendency to have seizures with a fever. Additionally, researchers have linked several genes to a susceptibility to febrile seizures.

Febrile seizures prevention

Experts recommend that children who have experienced a febrile seizure not take any anti-seizure medication to prevent future seizures, as the side effects of these daily medications outweigh any benefits. This is especially true since most febrile seizures are brief and harmless.

Most febrile seizures occur in the first few hours of a fever, during the initial rise in body temperature. Giving your child infants’ or children’s acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) at the beginning of fever may make your child more comfortable. However, available studies show this does not reduce the risk of having another febrile seizure.

Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye’s syndrome, a rare but potentially life-threatening condition, in such children.

Prescription prevention medications

Rarely, prescription anticonvulsant medications are used to try to prevent febrile seizures. However, these medications can have serious side effects that may outweigh any possible benefit.

Although the majority of children with febrile seizures do not need medication, children especially prone to febrile seizures may be treated with medication, such as oral diazepam (Valium), lorazepam intensol, clonazepam (Klonopin) or rectal diazepam (Diastat) may be prescribed for children who are prone to febrile seizures. These medications are typically used to treat seizures that last longer than 10 minutes or if the child has more than one seizure within 24 hours. They are not typically used to prevent febrile seizures. These medications may lower the risk of having another febrile seizure. It is usually well tolerated, although it occasionally can cause drowsiness, a lack of coordination, or hyperactivity. Children vary widely in their susceptibility to such side effects.

A child whose first febrile seizure is a prolonged one does not necessarily have a higher risk of having reoccurring prolonged seizures. But if the child has another seizure, it is likely to be prolonged. Because very long febrile seizures are associated with the potential for injury and an increased risk of developing epilepsy, some doctors may prescribe medication to these children to prevent prolonged seizures. The parents of children who have experienced a long febrile may wish to talk to their doctor about this treatment option.

Febrile seizure symptoms

Febrile seizure symptoms can range from mild — staring — to more severe shaking or tightening of the muscles.

A child having a febrile seizure may:

Have a fever higher than 100.4 °F (38.0 °C)
Lose consciousness
Shake or jerk arms and legs

Febrile seizures are classified as simple or complex:

Simple febrile seizures. This more common type lasts from a few seconds to 15 minutes. Simple febrile seizures do not recur within a 24-hour period and are generalized, not specific to one part of the body.
Complex febrile seizures. This type lasts longer than 15 minutes, occurs more than once within 24 hours or is confined to one side of your child’s body.

Febrile seizures most often occur within 24 hours of the onset of a fever and can be the first sign that a child is ill.

How to take your baby’s temperature

A normal temperature in babies and children is about 97.5 °F (36.4 °C), but this can vary slightly. A fever is usually considered to be a temperature of 100.4 °F (38 °C) or above.

Your baby may have a fever if they:

feel hotter than usual to the touch – on their forehead, back or stomach
feel sweaty or clammy
have flushed cheeks

If you think your baby has a fever, it’s best to check their temperature with a thermometer. This will help you work out whether you need to get medical advice.

Ideally, you need a digital thermometer to get a fast, accurate reading. You can buy these online or from pharmacies and most large supermarkets.

To take your child’s temperature:

put the thermometer in your baby’s armpit – always use the thermometer in the armpit with children under five
gently but firmly, hold their arm against their body to keep the thermometer in place for however long it says in the manufacturer’s instructions – usually about 15 seconds; some digital thermometers beep when they’re ready
the display on the thermometer will then show your child’s temperature

Figure 2. How to take your baby’s temperature

How can I make sure the reading is accurate?

If you use a digital thermometer under your child’s armpit and follow the manufacturer’s instructions carefully, you should get an accurate reading.

There are a few things that can slightly alter the reading – for example, if your child has been:

wrapped up tightly in a blanket
in a very warm room
very active
cuddling a hot water bottle
wearing a lot of clothes
having a bath

If this is the case, allow your baby to cool down for a few minutes, but don’t let your baby get cold or shivery, then take his/her temperature again to see if there’s any change.

Other types of thermometer

You can buy other types of thermometer, but they may not be as accurate as a digital thermometer for taking a baby or small child’s temperature:

ear (tympanic) thermometers – these allow you to take a temperature reading from the ear, and are quick but expensive; they can give misleading readings if you don’t put them in the ear correctly, which is more likely to happen with babies because their ear holes are so small
strip-type thermometers – these are held against the forehead and aren’t an accurate way of taking a temperature: they show the temperature of the skin, rather than the body

You should never use an old-fashioned glass thermometer containing mercury. These can break, releasing small splinters of glass and highly poisonous mercury. They’re no longer used in hospitals and you can’t buy them in shops. If your child is exposed to mercury, get medical advice immediately.

Febrile seizure diagnosis

Identifying the cause of your child’s fever is the first step after a febrile seizure.

Simple febrile seizures

To determine the cause of infection, your doctor may recommend:

A blood test
A urine test
A spinal tap (lumbar puncture), to find out if your child has a central nervous system infection, such as meningitis

Complex febrile seizures

For complex febrile seizures, your doctor also may recommend an electroencephalogram (EEG), a test that measures brain activity.

If the seizure involved just one side of the child’s body, your doctor may also recommend an MRI to check your child’s brain.

Before diagnosing febrile seizures in infants and children, doctors sometimes perform tests to be sure that the seizures are not caused by an underlying or more serious health condition. For example, meningitis, an infection of the membranes surrounding the brain, can cause both fever and seizures that can look like febrile seizures but are much more serious. If a doctor suspects a child has meningitis a spinal tap may be needed to check for signs of the infection in the cerebrospinal fluid (fluid surrounding the brain and spinal cord). If there has been severe diarrhea or vomiting, dehydration could be responsible for seizures. Also, doctors often perform other tests such as examining the blood and urine to pinpoint the cause of the child’s fever.

If the seizure is either very prolonged or is accompanied by a serious infection, or if the child is younger than 6 months of age, the clinician may recommend hospitalization. In most cases, however, a child who has a febrile seizure usually will not need to be hospitalized.

Febrile seizure treatment

Most febrile seizures stop on their own within a couple of minutes. If your child has a febrile seizure that lasts more than 10 minutes — or if your child has repeated seizures — call for emergency medical attention.

More-serious episodes

If the seizure lasts longer than 15 minutes, a doctor may order medication to stop the seizure.

If the seizure is prolonged or accompanied by a serious infection or if the source of the infection can’t be determined, then your doctor may want your child to stay in the hospital for further observation. But a hospital stay isn’t usually necessary for simple febrile seizures.