Benign neonatal convulsions (BNC) is a relatively uncommon type of epilepsy that happens in babies and very young infants. The seizures, or convulsions, start in the neonatal period – between birth and 28 days after the baby has been born. Most seizures occur between 3 and 14 days after the baby has been born. Because many start on the fifth day of life, they used to be called ‘fifth day fits’. The seizures affect girls and boys equally.
There are 2 types of BNC:
• Benign familial neonatal convulsions
• Benign non-familial (also called sporadic) neonatal convulsions
In the first type, benign familial neonatal convulsions, someone else in the family must have had similar convulsions and this is usually one of the baby’s parents. It may be hard for the parents to know whether they had convulsions as a baby, because they won’t remember themselves! Therefore, if possible, the baby’s grandparents should be asked if they can remember whether the baby’s parents had convulsions or ‘fits’ at the same age. A genetic fault that causes benign familial neonatal convulsions has been found in some genes, which are part of chromosome number 8 and also chromosome number 20.
In the second type, benign non-familial (also called ‘sporadic’) neonatal convulsions, there is no history of convulsions at a similar age in other members of the family.
The seizures can appear in different forms:
- The head turns to one side and then jerks a few times. This can be followed by a clonic seizure affecting either the right or left side of the body
- The arms or legs stiffen and then jerk rhythmically for some seconds or up to a minute (called a clonic seizure)
- There may be brief periods of apnoea – when the baby may stop breathing. The baby’s face may also go red and jerk and the eyes may water
- There are repeated ‘cycling’ or ‘punching' movements of the legs or arms
- Rarely, the whole body goes stiff and then all four limbs jerk (called a ‘tonic-clonic’ seizure). This type of seizure usually only occurs towards the end of the first month of life
Most seizures last less than 2 minutes. The seizures are more likely to happen when the baby or infant is sleepy or has just woken from sleep. The babies are otherwise normal and will have been feeding and behaving normally before the seizures started. Their birth will usually have been normal.
BNC is diagnosed when the doctor takes a careful history of when the seizures started and also a careful family history. Seizures that start on the fifth to fourteenth day after birth in otherwise normal babies are important clues as to the correct diagnosis. Results of tests such as blood tests and brains scans such as computed tomography (CT) or magnetic resonance imaging (MRI) are usually normal. The EEG may be normal or show only minor abnormalities.
There are many other causes for seizures, and other epilepsy syndromes that might also start at the same age. Causes can include low levels of glucose, calcium or magnesium in the blood, serious infections such as meningitis or encephalitis or abnormalities in the brain. Because of this, it is often important for the doctor to rule out these other causes first. This may include a lumbar puncture test to look for meningitis or encephalitis, and a more detailed brain scan, the MRI scan. There are also other epilepsy syndromes that can start in the neonatal period; these are much more severe syndromes and include:
- Migrating partial seizures (epilepsy) in infancy
- Early mycolonic encephalopathy (EMEE)
- Early infantile epileptic encephalopathy (EIEE – Ohtahara syndrome)
Blood tests can also be done to look for the genetic fault called a ‘mutation’. This mutation is found in children with benign familial neonatal convulsions. This is called a mutation in the KCNQ2 and KCNQ3 genes. No genetic fault has yet been found in benign non-familial (also called sporadic) neonatal convulsions.
Epilepsy Action has more information about diagnosis.
Treatment is not always necessary because the seizures may only happen for a few weeks. However, sometimes epilepsy medicine is prescribed, particularly if the seizures continue to happen. Commonly used epilepsy medicines include carbamazepine (Tegretol), sodium valproate (Epilim) or much less commonly, phenobarbital or phenytoin. The newer drugs such as levetiracetam (Keppra) or lamotrigine (Lamictal) may also be effective. The medicine is usually given for 6 or occasionally 12 months and then slowly discontinued.
There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.
Information about treatments for children can be found on the Medicines for Children website.
In most babies or infants, the seizures usually stop after a few days or weeks. More rarely, the seizures may continue for a few months. About one in 12 children who have benign familial neonatal convulsions may start having other types of seizures in late childhood or, more commonly, in adulthood. However, the risk seems to be much lower in benign non-familial (also called sporadic) neonatal convulsions. In this group, only one or two children in every 100 will develop epilepsy in adulthood. If this happens, the seizures are usually controlled with epilepsy medicines.
Babies feed normally, behave normally and develop normally. They usually don’t have learning disabilities or need extra care/support in the future.
Babies who have benign familial neonatal convulsions or benign non-familial (sporadic) neonatal convulsions can be given the full range of immunisations, including mumps, measles and rubella.
What is a syndrome?
A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an EEG are also used to help identify epilepsy syndromes.
If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.
Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.