Febrile convulsions or febrile seizures can be frightening for parents. Their beautiful, otherwise healthy young child suddenly loses consciousness and involuntary muscular contractions (convulsions). While febrile convulsions may look violent, they are rarely serious and actually quite common. The best way for parents of infants and young children to prepare for febrile convulsions is to learn about the condition before it occurs.

Incidence of febrile convulsions

Febrile seizures are a common occurrence in young children. Febrile convulsions can occur at any time between the ages of six months and six years, but the highest likelihood that they will occur is between the ages of 12 and 18 months. A child above the age of six seizures are more likely to be epilepsy than febrile convulsions.

Genetics seems to play a role in the onset of the condition. Febrile seizures are more likely to occur in close relatives of those who have experienced febrile seizures in the past. If one child has febrile seizures, there is a 10 to 20% chance of other children in that family will have febrile seizures as well. If at least one of the parents also had febrile seizures when they were young, the chance of their children having febrile seizures may be as high as 50%.

Causes and prevention

As the name implies, febrile seizures occur when the child experiences a fever. That said, it is unclear why certain children develop convulsions when they experience a fever.

It is possible that factors released in the blood during a fever, such as cytokines, increase the likelihood that a seizure may occur.

Children also tend to hyperventilate during a fever, which may change blood chemistries and predispose to seizure.

Febrile convulsions can occur in children who have either viral or bacterial infections—no particular virus or bacterium has been specifically linked to febrile seizures. 

The chance of a febrile seizure increases soon after a child receives certain vaccines, including the diphtheria, tetanus toxoid, and whole-cell pertussis (DTP) and the measles, mumps, and rubella (MMR) vaccine. The period of increased risk is between 1 to 2 weeks after the vaccine was administered, and there is a 3- to 6- fold increased risk during this time. Unfortunately, it is difficult to predict the first febrile convulsion in any given child.

Preventative therapies

Two possible preventative therapies are antiepileptic drugs or fever reducing drugs, such as paracetamol. The former option is not very safe and neither is terribly effective. In order to prevent febrile seizures, the child must be given seizure medications on a daily basis. When children were given antiepileptic medications from six months to two years, this slightly reduced the risk of having febrile seizures but the risk of having adverse effects occurred in 30% of children. On the other hand, paracetamol is considered safe for children but there is no evidence that reducing fever can reliably protect against febrile seizures.

Neither antiepileptic drugs nor fever reducing drugs are recommended for the prevention of febrile seizures.

What occurs during febrile convulsions?

Febrile convulsions can be simple or complex; simple febrile seizures are most common. During a febrile seizure, the child's body will convulse or shake and the child's eyes may roll back. Simple febrile seizures last less than 15 minutes and occur once in a 24-hour period. Simple febrile seizures are generalised, meaning they affect the entire body equally and the child loses consciousness immediately (i.e. is unresponsive and cannot be roused). Complex febrile seizures last longer than 15 minutes and may occur more than once in a day. A complex febrile seizure may affect only one limb or one side of the body and the child may or may not lose consciousness.

Warning signs for febrile convulsions

Unfortunately, there are few warning signs of febrile convulsions.

Since they occur during the first day of a fever, a parent’s suspicion may be raised when a child develops an elevated temperature. It also appears that febrile seizures may occur more often when body temperature increases rapidly. Sadly, these warning signs are not always reliable. Febrile seizures may occur when body temperature is going down or on the second or third day of a fever.

What you should do during febrile convulsions?

First of all, don't panic. Febrile convulsions usually look much worse than they actually are. Additionally, most febrile seizures will stop within a matter of minutes. That said, if this is your child's first febrile seizure you should seek expert medical advice as soon as possible. Most parents will call emergency medical services, and that is perfectly reasonable. In fact, if this seizure does not resolve in a matter of minutes then calling emergency medical services is advised. In any case, the child should be seen by a pediatrician as soon as possible for an evaluation.

If the child also vomits, has a stiff neck, or has difficulty breathing, then call for an ambulance immediately.

While waiting for emergency personnel to arrive, make sure the child is in a safe, soft environment. You can place pillows around the child so that, during their convulsions, they do not strike hard objects. Do not try to place anything in the child's mouth, because it may become a choking hazard. After a complex febrile seizure, the child may still be groggy and unresponsive. This is normal and is called a post-ictal phase. If this occurs, inform your pediatrician or pediatric neurologist.

Short-term consequences of febrile convulsions

Children who experience simple febrile seizures have few short-term consequences, if any. Likewise, the prognosis is highly favorable. In fact, most patients with simple febrile seizures do not require any additional diagnostic testing of the history and a physical examination.

Children who experience a complex febrile seizure will usually undergo a lumbar puncture, also known as the spinal tap. This is to rule out infection in the brain and meninges (i.e. meningitis) and other serious causes of seizure. They may also have blood tests.

Most children with complex febrile seizures will experience few short-term consequences, if any.

Long-term consequences of febrile convulsions

Intellectual disabilities, neurologic problems, and behavioral problems are rare following febrile convulsions. In fact, several reports indicate that there may be no solid link between febrile convulsions and later cognitive problems. It is possible, however, for recurrent febrile seizures to develop. Approximately one in three children who have had one febrile seizure will have another.

Four factors increase the risk that a child will have recurrent febrile seizures:

• The first seizure occurred before the age of one
• A close relative had febrile seizures
• The body temperature at which the seizure occurred was relatively low (38 degrees C)
• The time between the fever starting in the seizure occurring was relatively short.

The risk of developing epilepsy later in life after having febrile seizures is relatively low. In a healthy child who has had simple febrile seizures, the risk of epilepsy is essentially the same as it is in the general population. Children who had one or more complex febrile seizures are at increased risk for developing epilepsy later in life. Focal seizures (i.e. seizures affecting one part of the body rather than the entire body), seizures lasting greater than 15 min., and multiple seizures within 24 hours increase the risk of developing epilepsy by up to 50%. The more risk factors the child experienced during the complex seizure, the greater risk of later having epilepsy. A child with other developmental abnormalities and complex febrile seizures is a greatly increased risk of developing epilepsy.

Febrile status epilepticus

Febrile status epilepticus is defined as a febrile seizure that last longer than 30 minutes.

While simple febrile seizures are considered relatively harmless and complex seizures in otherwise healthy children are considered minor, a condition called febrile status epilepticus is always a serious condition and medical emergency.

Febrile status epilepticus is defined as a febrile seizure that last longer than 30 minutes.

Febrile status epilepticus is unlikely to stop on its own and should be treated with one or more antiepileptic drugs. Children who experience febrile status epilepticus should undergo a full clinical workup.

Perhaps surprisingly, the chance of long-term epilepsy after febrile status epilepticus does not appear to be higher than in other forms of febrile seizures. The long-term consequences of febrile status epilepticus are not currently known, but are under investigation.

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