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Determining child’s risk for epilepsy after febrile seizure via diagnostic procedures

New study reveals brain imaging and brain activity recordings could determine children at high risk

Seizures that occur during a childhood fever are usually harmless, but when the fever continues they can indicate a higher risk for epilepsy later on in life.

In a study funded by the National Institutes of Health reveal that MRI and EEG can help determine which children are at higher risk for epilepsy. The study finds that within days of a prolonged fever-related seizure some children have signs of acute brain injury, abnormal brain anatomy, altered brain activity, or both.

View slideshow: Generalized seizures

Dr. Shlomo Shinnar, MD, PhD, FANN, Professor of Neurology, Pediatrics and Epidemiology and Population Health, Hyman Climenko Professor of Neuroscience Research at Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York, and study investigator stated in a release "Our goal has been to develop biomarkers that will tell us whether or not a particular child is at risk for epilepsy. This could in turn help us develop strategies to prevent the disorder.”

Febrile seizures are seizures that occur during the course of a high fever, the majority of children with febrile seizures have rectal temperatures greater than 102 degrees Fahrenheit. Approximately one in every 25 children will have at least one febrile seizure, and more than one-third of these children will have additional febrile seizures before they outgrow the tendency to have them. Most children recover quickly and do not endure long term health effects. But a child having one or more prolonged febrile seizures during childhood is known to be at higher risk epilepsy later on in life. Some experts estimate that the risk of later epilepsy is 30-40 percent following febrile status epilepticus (FSE). A seizure or series of seizures can last from thirty minutes to several hours.

"While the majority of children fully recover from febrile status epilepticus, some will go on to develop epilepsy. We have no way of knowing yet who they will be," says Dr. Shinnar.

The Consequences of Prolonged Febrile Seizures in Childhood (FEBSTAT) study is focused specifically on FSE and the risk of temporal lobe epilepsy. This is one of the most common forms of epilepsy and is characterized by seizures in the temporal lobe, a brain region important for memory.

The study included children aged one month to five years with a febrile seizure lasting longer than 30 minutes; namely, febrile status epilepticus (febrile SE). Children with severe preexisting neurological abnormality were excluded from the study.

Within days of FSE the children underwent an MRI (magnetic resonance imaging which are painless. usually children five years or older do fine without any sedation, and an EEG (electroencephalography) a painless, non-invasive test which monitors electrical activity in the brain and is often used to diagnose and monitor epilepsy.

The MRI findings were reported in July 2012, and the EEG findings were reported today. Both papers were published in Neurology.

The MRI scans revealed that FSE is sometimes associated with abnormalities in the hippocampus, The hippocampus is the part of the brain that is involved in memory forming, organizing, and storing. The hippocampus is a horseshoe shaped paired structure, with one hippocampus located in the left brain hemisphere and the other in the right hemisphere

All MRIs were reviewed by 2 neuroradiologists blinded to clinical details. A group of 96 children with first simple FS who were imaged using a similar protocol served as controls.

Among the 191 with FSE 22 had signs of hippocampal injury on MRI, and 20 had developmental abnormalities of the hippocampus. Abnormal MRI results were rare among children with simple febrile seizures, defined as lasting 10 minutes or less. Out of the 96 children that had simple febrile seizures only two children had developmental abnormalities of the hippocampus and none had signs of brain injury.

Almost half the children with FSE had abnormal EEG findings. There was also a correlation between the MRI and EEG findings. Children with evidence of acute brain injury after FSE were more than twice as likely to have abnormal EEG findings.

The researchers wrote in their conclusion in the MRI study “This prospective study demonstrates that children with FSE are at risk for acute hippocampal injury and that a substantial number also have abnormalities in hippocampal development. Follow-up studies are in progress to determine the long-term outcomes in these children.”

Dr. Vicky Holets Whittemore, PhD, Program Director, Epilepsy at the National Institute of Neurological Disorders and Stroke stated "This study may give us insights into how epilepsy develops.” He further stated "If MRI and EEG findings associated with FSE ultimately do correlate with epilepsy, they could be used to identify kids who are at risk and who might benefit from research on preventative therapies for epilepsy.” "EEG could be especially useful since it is low cost, non-invasive, and readily available at most hospitals.” "EEG could be especially useful since it is low cost, non-invasive, and readily available at most hospitals."

The study is funded by the National Institute of Neurological Disorders and Stroke. This study began almost ten years ago. The recruiting sites in the study were Montefiore Medical Center and Jacobi Hospital in the New York City; Lurie Children's Hospital in Chicago; Duke University Medical Center in Durham, N.C.; Virginia Commonwealth University Hospital in Richmond; and Eastern Virginia Medical School in Norfolk.

Dr. Shinnar is the senior editor of the book Childhood Seizures and co-editor of the book Febrile Seizures. He has published over 150 original papers and over 100 reviews and chapters. He is the recipient of the prestigious Research Recognition Award of the American Epilepsy Society.

Information on febrile seizures can be viewed online at Healthy Children.org