A new study has found that a subgroup of children who suffer from convulsive status epilepticus – an epileptic seizure that lasts 30 minutes or longer, or clusters of prolonged seizures – may experience long-term brain damage years after. This is according to research presented at the American Epilepsy Society’s 67th Annual Meeting.
The researchers, led by Suresh Pujar of the Institute of Child Health at Imperial College London in the UK, say it has long been believed that the most common form of childhood convulsive status epilepticus (CSE) – called prolonged febrile (fever-induced) seizures (PFS) – is a cause of mesial temporal sclerosis (MTS).
MTS is defined as a scarring of the hippocampus in the brain and loss of neurons.
But the investigators note that it has been unclear as to whether CSE can cause long-term MTS or prolonged damage to the hippocampus.
To investigate whether this is the case, the researchers conducted 3D magnetic resonance imaging (MRI) on 144 children aged between 6.3 and 10 years, in order to measure their hippocampal volume. Of these, 70 were healthy children with no symptoms of epilepsy.
The other 74 children had CSE and were divided into four patient groups based on the classifications of their epileptic episodes. These were prolonged febrile seizure, acute symptomatic (CSE triggered by an event, such as head injury), remote symptomatic (CSE triggered months after an event), and idiopathic/unclassified.
The children were followed-up for an average of 8.5 years after their prolonged seizures.
Remote symptomatic CSE linked to reduced hippocampal growth
To reach their findings, the researchers compared volumes of the left and right hippocampus of each child before calculating their asymmetry. These measures were then compared across all groups.
The findings revealed that children who had remote symptomatic CSE had lower hippocampal volume, compared with the group of healthy children. Furthermore, children with remote symptomatic CSE also had escalated asymmetry of the hippocampal structure, compared with all other groups.
There was no difference in volume or asymmetry between any of the other groups with CSE and children without the condition.
Explaining the results further, Pujar says:
“On group analysis, hippocampal growth in children who had prolonged febrile seizures, acute symptomatic, and idiopathic or unclassified CSE was not impaired at a mean follow-up of 8.5 years post convulsive status epilepticus.
But children with remote symptomatic convulsive status epilepticus have a significant reduction in hippocampal volume and increased asymmetry compared to all the other groups in our study.”
The researchers say that their findings partly oppose previous beliefs and suggest that if children are neurologically normal prior to development of CSE, prolonged seizures – regardless of whether they are febrile or not – may not have long-term effects on hippocampal growth.