Young, healthy children can have
seizures when they get high fevers such as with ear and upper respiratory
infections. These seizures are more likely if family members have had them. Four
percent of young children in the United States experience febrile seizures.
The
typical age range is 3 months to 5 or 6 years. The peak incidence of febrile
seizures is between 18-22 months of age. They occur during the rising phase
of fever and during the first day of the illness. Only one febrile seizure
that day is typical. Seizures that occur later in the febrile illness suggest
some other condition. Only 2 percent of youngsters who have had a febrile
seizure go on to develop epilepsy by age 7 years.1 The possibility of developing epilepsy
later in life is increased if there is a prior neurologic developmental abnormality;
if the convulsion lasts longer than 3-5 minutes; if convulsive jerking involves
just one part of the body (focal) rather than a generalized convulsion; and if
the EEG (electroencephalogram) is abnormal.
Convulsions that occur with fevers
after age 5 or 6 years should not be considered benign febrile seizures. These
children should receive a thorough evaluation to search for some causative
condition and if none is found, then epilepsy is likely. Children who have
benign febrile convulsions are not considered to have epilepsy (epilepsy is
defined as more than one seizure often due to no identifiable cause).
Among children who experience their
first febrile seizure before their first birthday, half will have at least one
more. Among children who are older than 1 year when the first febrile seizure
occurs, about 1 in 4 will have more. The overall prognosis, however, is
excellent.
Febrile convulsions are diagnosed
when no other condition is present that can cause high fevers and the seizures occur
before age six years. Meningitis and encephalitis must be considered. Clinical
judgment determines if the spinal fluid is to be examined by a lumbar puncture.
Serious causes of a convulsion associated with fever are considered if the
convulsion occurs after the initial fever-peak or if there are
multiple convulsions. Convulsions associated with a vaccination-induced
fever are typically benign febrile seizures unless confused with a rare encephalopathic
reaction to the immunization.2
Acute treatment of the convulsion is
usually not necessary unless it lasts 3-5 minutes. Diazepam (Valium) can be
administered intravenously, intramuscularly or per rectum. Treatment should be given
if it is a prolonged seizure.
Prophylactic treatment (i.e. daily
antiepileptic medications), can be used if the child under 6 years old
experiences frequent convulsions during the rising phase of fevers.
Daily administration may be indicated because seizures can occur before the
fever is detected and then administration of the drug is too late. If
prophylaxis is chosen it’s usually continued 1-2 years after the last febrile
convulsion and then tapered off over 1-2 months. The problem with prophylactic
treatment is that only one-third of the population of young children will
experience another seizure with a subsequent febrile illness. There is no
evidence that prophylaxis reduces the risk of future epilepsy.
Risk factors for future epilepsy
diagnosis in children who experience febrile seizures includes a family history
of non-febrile epileptic seizures, pre-existing neurological conditions or
developmental delay, seizures lasting longer than 3-5 minutes, focal localized
seizures and multiple seizures in one day.
1.
Nelson KB, Ellenberg JH: Predictors of epilepsy in children who have
experienced febrile seizures. N Engl J Med 295:1029, 1976.
2.
Engel, Jr J: Seizures and Epilepsy. Philadelphia, PA: F.A.Davis Co. 1989, p
181-183.
Lance
Fogan, M.D. is Clinical Professor of Neurology at
the David Geffen School of Medicine at UCLA.
“DINGS” is his first novel. It is a
mother’s dramatic story that teaches
epilepsy, now available in eBook, audiobook and soft cover editions.
