SEATTLE — Magnetic resonance imaging seldom changes the acute management of children with new-onset afebrile seizures who have a normal computed tomography scan, according to a study of more than 1,000 children.
In the retrospective study reported at the annual meeting of the American Epilepsy Society, Dr. Dewi Depositario-Cabacar, a neurologist with the Children's National Medical Center in Washington, and her colleagues assessed imaging findings and management among children seen at the center for new-onset afebrile seizure-like events that occurred during an 86-month period from October 2000 through December 2007.
All of the children were evaluated according to a standardized protocol that included a head CT scan. Some also underwent MRI on a 1.5-Tesla scanner at their treating physician's discretion.
Results showed that 1,278 children with new-onset afebrile seizures had a noncontrast head CT, and 710 of them also had an MRI.
Of the 489 children with a normal CT scan who underwent MRI, 165 (34%) had abnormal MRI findings.
The most common finding was an incidental abnormality (seen in 23% of this subgroup). The most common nonincidental findings were dysplasia (13%), focal signal hypodensities or hyperdensities (13%), vascular abnormalities (7%), atrophy/encephalomalacia (6%), and mesial temporal sclerosis (6%).
The MRI findings altered acute management in only eight (5%) of the children who had a normal CT scan but an abnormal MRI scan. These children had final diagnoses of meningoencephalitis, new arterial strokes, toxoplasmosis, low-grade gliomas, and sinus thrombosis.
“However, all of the children had focal abnormalities by history or by examination,” Dr. Depositario-Cabacar noted. In addition, two children had known contributing medical factors: acute mye-loid leukemia in one child and cardiac surgery in another.
In an additional analysis of the 30 children with nonspecific CT findings who underwent MRI, 10 (33%) had new findings on MRI. These findings were vascular abnormalities, infection, dysplasia, and delayed myelination.
“This study confirms that MRI is superior to CT in identifying and delineating abnormalities,” Dr. Depositario-Cabacar said of the findings.
However, she concluded, among children having a first afebrile seizure and a normal CT scan, there is a low probability that MRI findings will alter management acutely.
Dr. Depositario-Cabacar reported that she had no conflicts of interest to report in association with the study.
MRI altered acute management in only 5% of the children with a normal CT scan but abnormal MRI. DR. DEPOSITARIO-CABACAR