Self Limited Familial and Non-Familial Neonatal Infantile Seizures
What Is Self-Limited Neonatal-Infantile Seizures?
The epilepsy syndrome of self-limited neonatal-infantile seizures used to be known as benign familial or non-familial neonatal-infantile seizures. Seizures begin in the first several months of life in an otherwise healthy infant. Typical seizure onset is between 2 days and 7 months of life.
- There is no difference in the electrical patterns on EEG or the features of neonatal-infantile seizures that have a familial or non-familial pattern.
- The only difference is the presence of family history of seizures. If no family history is present, it is thought the genetic change causing this condition occurred for the first time in the child (termed de novo).
Males and females are equally affected by this condition.
How Common Is This Condition
How often this syndrome occurs in not know. This may be due in part to the overlap between this condition and self-limited neonatal and infantile seizures.
Diagnosis Of Seizures
- Self-limited neonatal-infantile seizures are diagnosed based on key clinical and EEG features.
- The required clinical features include seizures starting with the first several months of life in an otherwise healthy infant.
- This means that there were no health concerns during the pregnancy or delivery.
- The child also has a normal neurological exam and is meeting developmental milestones.
- Neuroimaging studies, including either a head ultrasound or brain MRI, are normal.
- An EEG is typically normal when the child is not having seizures, although rarely seizure discharges in the back of the brain can be seen.
What Do Seizures Look Like?
The typical seizures have repetitive jerking on one side of the face or body, such as the arm, leg, or both, and often. The jerking often spreads to jerking movements on both sides of the body. The seizures sometimes cluster together when they occur.
What Investigations Might Be Performed?
- EEG: The EEG will show abnormal electrical activity during a seizure. Between seizures, the EEG will typically be normal.
- MRI: This should be normal.
- Lumbar puncture (spinal tap): This is often done to evaluate for a serious bacterial infection, unless there is already a known family history of this condition and patient is healthy and does not have a fever.
- Genetic testing: Genetic testing is recommended in infants with a family history of similar seizures in the newborn and infant period.
What Is The Cause?
Changes in several different genes has been seen in children with self-limited familial and non-familial neonatal-infantile seizures.
- An autosomal dominant expression pattern has been seen - this means that a change in only one copy of the gene is needed to cause the condition.
- The two genes most commonly identified include KCNQ2 and SCN2A.
- Children with an identified SCN2A mutation are more likely to have seizure begin after six months of age.
This type of epilepsy can affect infants in different ways. Some infants may have changes in thinking or cognitive problems as well as seizures. They may also have problems with balance and coordination.
- Seizures typically stop by 1-2 years of age. They sometimes can last into early childhood.
- However, there can be an increased risk of febrile seizures and afebrile seizures later in life.
- Historically, it is thought that development is normal and there is no long-term learning or cognitive effects.
- More recently, it has been suggested that mild learning difficulties may be present in some children.
- Wolff M, Johannesen KM, Hedrich UBS, et al. Genetic and phenotypic heterogeneity suggest therapeutic implications in SCN2A-related disorders. Brain. 2017: 140; 1316-1336.
- Grinton BE, Heron SE, Pelekanos JT. Familial neonatal seizures in 36 families: Clinic and genetic features correlate with outcome. Epilepsia. 2015; 56(7): 1071-1080.
- Learn more at http://www.epilepsydiagnosis.org.
- More about Benign Familian Neonatal Infantile Seizure from the National Institutes of Health.
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