Febrile seizure: Symptoms, Pathogenesis, Diagnosis & Treatments
Symptoms
Fever seizures are defined as seizures occurring in children between 6 months and 60 months with a febrile disease of greater than 38 degrees, but not due to central nervous system infection or metabolic abnormalities. A simple febrile seizure is defined as a febrile seizure that starts with a generalized tonic-clonic pattern and lasts only within 15 minutes and does not recur within 24 hours. If it does not, it is classified as a complex febrile seizure . On the other hand, if seizures continue for more than 30 minutes, they are defined as Status Epilepticus because they can cause permanent damage to the central nervous system.
Pathophysiology
More than 2% to 5% of all children experience febrile seizures at any one time and most suffer from simple febrile seizures. In simple febrile convulsions, the mortality rate does not increase without leaving any sequelae of abnormal behavior or dysfunction, whereas combined febrile seizure increases the risk of death by more than two times compared with that of normal children. More than 50% of the cases come from the pre-1-year-old age. About 30% of the cases come to the hospital with the first illustrations, and about 50% have been shown more than twice. 15% of epileptic children have experienced febrile seizures. Among the causative factors involved, genetic factors play an important role. In some cases, a single gene inherited as an autosomal dominant pattern has been identified, but in most cases it is influenced by a multifactorial genetic approach. Currently known single genes are FEB 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, among which FEB 2 is a protein that functions as an Na channel.
Risk factors for febrile convulsions include recurrent febrile convulsions, combined febrile seizures lasting more than 15 minutes or relapsing within 24 hours, febrile convulsions characterized by localized convulsions, fever duration within 1 hour , There is an abnormality in nerve development. The epilepsy syndrome is characterized by the presence of multiple epilepsy syndromes, including generalized epilepsy with febrile seizure plus (GEFS +), severe myoclonic epilepsy of infancy (Dravet syndrome), temporal lobe epilepsy secondary to mesial Temporal sclerosis.
Generalized Epilepsy with Febrile Seizure Plus is usually autosomal dominant and has a variety of seizure phenotypes. The age at onset is pediatric in the first place, and most cases are natural remission in middle childhood. At the beginning of the procedure, several febrile seizures appear at first, and an increasingly diverse form and degree of anorexietic systemic seizures appear. Focal Febrile seizures plus epilepsy is an atypical variant of this syndrome that occurs mainly in focal seizures.
Dravet Syndrome is phenotypically the most severe febrile seizure spectrum of epilepsy. Initially, febrile or febrile unilateral Clonic seizure appears to recur almost every week. Heat-induced resemblance is similar to febrile seizure, but it is more localized, clustery, has a long duration and frequent recurrence. As the progression progresses, the seizures that appear with the fever also occur in the mild fever and the symptoms appear without the fever. The seizure pattern is mainly Myoclonus, seizures, partial seizures, and may be accompanied by long-term developmental delay and impairment. There is a loss of function mutation in the SCN1A gene, one of the causes, in GEFS +. Some cases of Vaccine encephalopathy, known as febrile seizures after vaccination, have been identified as Dravet syndrome, and controversy over the concept of Vaccine Encephalopathy is growing.
Diagnosis
For diagnosis and evaluation, it is essential to listen to the history of the preceding infection and perform neurological examination. Information on the causes of otitis media, human herpesvirus types 6 and 7 may be useful. In order to rule out metabolic imbalance from the cause, it is necessary to perform basic general chemistry tests on the blood to confirm the electrolyte and glucose concentration, and CSF examination can be carefully performed to exclude central nervous system infections such as meningitis. CSF testing is necessary in children who have not received a bacterial vaccine between 6 months and 12 months. Because febrile convulsions should not be due to central nervous system infections, the normal range of test pressure, glucose, protein, and white blood cell counts should be included.
The diagnosis of febrile seizures is needed to assess the risk of recurrence after a few hours. If the age is before 1 year, if the fever is within 24 hours, if the fever is between 38 and 39 degrees, if febrile convulsions and epilepsy are present, if the fever is febrile, epileptic, mixed febrile, All of these are risk factors and the probability of recurrence can be estimated based on how many are included. If there are three or more, the probability of recurrence is 73 ~ 100%.
When the risk factors are similar, the probability of transition to epilepsy increases. In this case, evaluation through EEG is necessary. On the other hand, there is little need to perform EEG in the first case of simple febrile convulsions. However, if the recovery is too late after the seizure is over, EEG can be performed to determine whether the seizure is continuing or not. EEG waves can be seen when the state is asleep, but this does not suggest the possibility of transition to epilepsy. The EEG should be performed only under strictly indicated indications, usually after 2 weeks of seizure, because it is often seen within 2 weeks of nonspecific findings. Electroencephalography (EEG) You should measure your awake time and sleep time over 20 minutes. If epilepsy is suspected, brain imaging can be performed. Hippocampal sclerosis is found in 11% of patients with status epilepticus.
Treatments
The use of antiepileptics in a single febrile seizure is rare and should be considered carefully only under thorough risk assessment. If seizures persist for more than 5 minutes, use benzodiazepine drugs such as diazepam, lorazepam, and midazolam for first-aid treatment, considering the possibility of status epilepticus. If this is not the case, try to administer Benzodiazepine, followed by Phenobarbital, Phenytoin and Valproate. Long-term prophylactic anti-epileptic treatment is rarely used, but should be used only when there is clear evidence of a long term benefit and is not used for mere preventive purposes. Symptoms can be relieved with fever, such as NSAIDs, when fever occurs, but it does not reduce subsequent recurrences of febrile convulsions.
Fever seizures are defined as seizures occurring in children between 6 months and 60 months with a febrile disease of greater than 38 degrees, but not due to central nervous system infection or metabolic abnormalities. A simple febrile seizure is defined as a febrile seizure that starts with a generalized tonic-clonic pattern and lasts only within 15 minutes and does not recur within 24 hours. If it does not, it is classified as a complex febrile seizure . On the other hand, if seizures continue for more than 30 minutes, they are defined as Status Epilepticus because they can cause permanent damage to the central nervous system.
Pathophysiology
More than 2% to 5% of all children experience febrile seizures at any one time and most suffer from simple febrile seizures. In simple febrile convulsions, the mortality rate does not increase without leaving any sequelae of abnormal behavior or dysfunction, whereas combined febrile seizure increases the risk of death by more than two times compared with that of normal children. More than 50% of the cases come from the pre-1-year-old age. About 30% of the cases come to the hospital with the first illustrations, and about 50% have been shown more than twice. 15% of epileptic children have experienced febrile seizures. Among the causative factors involved, genetic factors play an important role. In some cases, a single gene inherited as an autosomal dominant pattern has been identified, but in most cases it is influenced by a multifactorial genetic approach. Currently known single genes are FEB 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, among which FEB 2 is a protein that functions as an Na channel.
Risk factors for febrile convulsions include recurrent febrile convulsions, combined febrile seizures lasting more than 15 minutes or relapsing within 24 hours, febrile convulsions characterized by localized convulsions, fever duration within 1 hour , There is an abnormality in nerve development. The epilepsy syndrome is characterized by the presence of multiple epilepsy syndromes, including generalized epilepsy with febrile seizure plus (GEFS +), severe myoclonic epilepsy of infancy (Dravet syndrome), temporal lobe epilepsy secondary to mesial Temporal sclerosis.
Generalized Epilepsy with Febrile Seizure Plus is usually autosomal dominant and has a variety of seizure phenotypes. The age at onset is pediatric in the first place, and most cases are natural remission in middle childhood. At the beginning of the procedure, several febrile seizures appear at first, and an increasingly diverse form and degree of anorexietic systemic seizures appear. Focal Febrile seizures plus epilepsy is an atypical variant of this syndrome that occurs mainly in focal seizures.
Dravet Syndrome is phenotypically the most severe febrile seizure spectrum of epilepsy. Initially, febrile or febrile unilateral Clonic seizure appears to recur almost every week. Heat-induced resemblance is similar to febrile seizure, but it is more localized, clustery, has a long duration and frequent recurrence. As the progression progresses, the seizures that appear with the fever also occur in the mild fever and the symptoms appear without the fever. The seizure pattern is mainly Myoclonus, seizures, partial seizures, and may be accompanied by long-term developmental delay and impairment. There is a loss of function mutation in the SCN1A gene, one of the causes, in GEFS +. Some cases of Vaccine encephalopathy, known as febrile seizures after vaccination, have been identified as Dravet syndrome, and controversy over the concept of Vaccine Encephalopathy is growing.
Diagnosis
For diagnosis and evaluation, it is essential to listen to the history of the preceding infection and perform neurological examination. Information on the causes of otitis media, human herpesvirus types 6 and 7 may be useful. In order to rule out metabolic imbalance from the cause, it is necessary to perform basic general chemistry tests on the blood to confirm the electrolyte and glucose concentration, and CSF examination can be carefully performed to exclude central nervous system infections such as meningitis. CSF testing is necessary in children who have not received a bacterial vaccine between 6 months and 12 months. Because febrile convulsions should not be due to central nervous system infections, the normal range of test pressure, glucose, protein, and white blood cell counts should be included.
The diagnosis of febrile seizures is needed to assess the risk of recurrence after a few hours. If the age is before 1 year, if the fever is within 24 hours, if the fever is between 38 and 39 degrees, if febrile convulsions and epilepsy are present, if the fever is febrile, epileptic, mixed febrile, All of these are risk factors and the probability of recurrence can be estimated based on how many are included. If there are three or more, the probability of recurrence is 73 ~ 100%.
When the risk factors are similar, the probability of transition to epilepsy increases. In this case, evaluation through EEG is necessary. On the other hand, there is little need to perform EEG in the first case of simple febrile convulsions. However, if the recovery is too late after the seizure is over, EEG can be performed to determine whether the seizure is continuing or not. EEG waves can be seen when the state is asleep, but this does not suggest the possibility of transition to epilepsy. The EEG should be performed only under strictly indicated indications, usually after 2 weeks of seizure, because it is often seen within 2 weeks of nonspecific findings. Electroencephalography (EEG) You should measure your awake time and sleep time over 20 minutes. If epilepsy is suspected, brain imaging can be performed. Hippocampal sclerosis is found in 11% of patients with status epilepticus.
Treatments
The use of antiepileptics in a single febrile seizure is rare and should be considered carefully only under thorough risk assessment. If seizures persist for more than 5 minutes, use benzodiazepine drugs such as diazepam, lorazepam, and midazolam for first-aid treatment, considering the possibility of status epilepticus. If this is not the case, try to administer Benzodiazepine, followed by Phenobarbital, Phenytoin and Valproate. Long-term prophylactic anti-epileptic treatment is rarely used, but should be used only when there is clear evidence of a long term benefit and is not used for mere preventive purposes. Symptoms can be relieved with fever, such as NSAIDs, when fever occurs, but it does not reduce subsequent recurrences of febrile convulsions.
