Febrile Seizures

Definition

A febrile seizure is a convulsion (shaking, twitching, muscle tightness) or fainting associated with a fever. It occurs in infants or small children. This seizure is not associated with any other illness or medical condition except the fever.

There are two types of febrile seizures called simple and complex. They are determined by the length of seizure, how often they recur and recovery characteristics:

• Simple febrile seizures:
  • Convulsions last between a few seconds to 15 minutes
  • Seizures are followed by a period of confusion and sleepiness which slowly goes away
• Complex febrile seizures:
  • Last longer than 15 minutes
  • Occur more than once within 24 hours
  • Convulsions which affect only part the body

Febrile seizures can be alarming. Fortunately children tend to outgrow these seizures. There is also a very low risk for long term physical or mental disorders.

Causes

High body temperature due to a fever is believed to trigger the seizure. The fever is most often caused by common viral infections. Some febrile seizures may be caused by fever after routine immunizations.

Risk Factors

Age is the greatest risk factor. Febrile seizures occur between the ages of three months to five years. Most febrile seizures occur in children between 6 months to 3 years of age. In general, the younger the age that the first febrile seizure occurs, the more likely it is that a child will have another seizure.

There is some evidence that a tendency for febrile seizures may run in families.

Symptoms

Signs of a febrile seizure include:

• A fever, usually above 102°F (38.9ºC)
• Convulsion (jerking or stiffening muscles)
• Abnormal eye movements
• Coarse breathing sounds during the convulsion
• Loss of consciousness
• Loss of bladder or bowel control
• Vomiting
• Brief period of drowsiness or confusion following a seizure

The seizure typically lasts anywhere from a few seconds to a few minutes.If you suspect your child is having a febrile seizure, stay calm and follow these steps:

• Unless the doctor has told you otherwise, call 911.
• Protect from physical injury. Place your child on the floor or bed away from any hard or sharp objects.
• Protect the airway. Do not place anything in the mouth during the convulsion. Turn the child’s head or body to the side. This will allow saliva or vomit to drain from the mouth.
• Watch the time. The length of the convulsions should be less than five minutes.

Diagnosis

Your doctor will diagnose febrile seizure based on information of the seizure and your child’s health. The doctor will also look for other medical conditions that can cause a seizure and fever. They include meningitis, encephalitis, or any other intracranial disease. Your doctor will rule these out before diagnosing a febrile seizure.

To determine the source of the fever or rule out other conditions your doctor may order:

• Blood tests
• Urine tests
• Lumbar puncture —procedure to remove a sample of spinal fluid to look for meningitis or encephalitis

Additional evaluations of the brain may be needed after complex febrile seizures. This is done to look for any injuries due to prolonged or severe seizures. Tests may include:

• CT scan —a type of x-ray that uses a computer to make pictures of structures inside the head
• MRI scan —a test that uses magnetic waves to make pictures of structures inside the head
• Electroencephalogram (EEG)—a test used to evaluate brain function or disorders