Wednesday, May 22, 2019

Blog #106: LEARN ABOUT THE FEBRILE SEIZURE



            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.