When a Seizure Lasts a Long Time

Prolonged seizures in children linked to developmental problems

April 7, 2013 / Author:  / Reviewed by: Robert Carlson, M.D

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(dailyRx News) Most children's seizures do not last very long, but some can last over 30 minutes. These are more likely in a child's first three years of life if the child is prone to seizures.

A recent study found that children who experienced these prolonged seizures also showed developmental difficulties, though the seizure may not have caused those issues.

The developmental problems and seizure could be related to an underlying condition, such as epilepsy. Also, the developmental problems were primarily associated with seizures that occurred without a fever.

Children with a fever-caused seizure did not show the same below-average development.  

"Tell a pediatrician if your child has seizures."

The study, led by Marina M. Martinos, of the Developmental Cognitive Neurosciences Unit at UCL Institute of Child Health in London, looked at the possible developmental effects of long-lasting seizures.

A seizure that lasts longer than 30 minutes is called convulsive status epilepticus (CSE). Children may or may not have convulsions or a fever while experiencing one of these.

The researchers recruited 54 children between the ages of 1 month and 3 and a half years old who had experienced one of these long-term seizures within the past six weeks.

Half the children had had a seizure caused by a fever of at least 100.4 degrees Fahrenheit (febrile seizure), and half had a non-febrile CSE.

These children and 17 healthy children who had not experienced any CSE all received neurological and developmental assessments.

The assessments involved evaluation of the children's cognitive, language and motor skill sets on a scale where 100 describes the "average" child. A score of 15 points higher or lower or more is considered one significant measurement outside of the normal or typical range.

The children who had a non-febrile seizure had worse scores on their developmental growth than children whose seizures had been caused by fevers. They averaged approximately around 65 to 80 on the scales while the children with febrile seizures averaged approximately 85 to 100.

Other than the presence of a fever, there were no differences between the characteristics of the seizures themselves.

However, 19 of the 27 children with non-febrile seizures had already received a diagnosis of epilepsy, and 20 of the children with non-febrile had had previous seizures of any kind.

None of the children with febrile seizures were diagnosed with epilepsy, and only 9 of them had had previous seizures of any kind. Also, only one of the children with a febrile seizure had had a previous prolonged seizure (CSE), compared to 11 of the children with non-febrile CSE who had had previous extended seizures.

The children who had a prolonged febrile seizure scored in the normal range for developmental outcomes but did not score as well as the healthy children who had not had a prolonged seizure. The healthy children averaged from around 95 to 120 on the scales.

The children also received brain scans with magnetic resonance imaging (MRI) to see if they had any abnormalities.

Among the children who had prolonged febrile seizures, none showed minor or major abnormalities in their MRI scans. Among the children who had non-febrile CSE, 8 had a major abnormality and 4 had a minor abnormality in their brains.

When 38 of the children who had seizures were assessed one year after the initial assessment, they did not show any changes in their development.

In other words, whatever developmental problems the children with seizures showed did not appear to get better or worse for these children a year later.

This finding does not mean that the seizure itself caused the developmental problems or caused them to last long-term. It could be that children who have one of these long-lasting seizures already have underlying issues that relate to both the seizure and the developmental problems.

In other words, there could be another condition that caused both the seizure and difficulties with developmental abilities. The seizure did not necessarily cause or worsen developmental problems.

In fact, the parents of 12 children with non-febrile seizures and the parents of six children with febrile seizures had reported developmental problems before the child experience the CSE.

Also, four of the children with febrile CSE and six of the children with non-febrile CSE had been born premature.

Other than the presence or absence of a fever, the researchers did not find any other characteristics of the seizures that predicted whether a child would have a better or worse developmental outcome.

The study was published April 8 in the journal Epilepsia. The research was funded by the Wellcome Trust, the Department of Health's NIHR Biomedical Research Centre and Great Ormond Street Hospital Children's Charity. The authors declared no conflicts of interest.