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Summary: Rationale: Few studies have looked at long-term epileptic and cognitive outcome of frontal lobe epilepsy (FLE) in children. Most are limited by inclusion of lesional and nonlesional patients.
Goal: To define the epileptic and functional outcome of children with nonlesional FLE.
Methods: We reviewed medical records and neuropsychological evaluations of patients with nonlesional FLE diagnosed between 1994 and 2004. We included children with either focal or regional frontal EEG and/or functional imaging abnormalities. We reviewed their charts for seizure and neuropsychological outcome.
Results: We included 21 children. Twelve (57.1%) presented with daily seizures. Seizures were nocturnal in 8 of 21, secondarily generalized in 6 of 21, adversive in 5 of 21, and focal motor in 6 of 21. Although, initial seizure control was poor in 14 of 21, long-term control was achieved in 10 of 21 after 14.6 ± 22.3 months. Early development was normal in 12 of 21 but at later formal neuropsychological evaluation only 3 of 12 still had a normal profile. The majority of children had learning difficulties requiring special education prior to seizure onset (6 of 10). A clearly defined regression after seizure onset was observed in three children. The majority exhibited attention deficit and hyperactivity or impulsivity (14 of 21), behavioral problems (8 of 21), and cognitive impairments (10 of 21). Early seizure control was associated with a better cognitive outcome.
Conclusion: Nonlesional FLE is associated with poor seizure and behavioral outcomes. Whether this is secondary to MRI-silent developmental lesions or to the progressive repercussion of seizures on frontal lobe functions remains uncertain. A prospective study with early neuropsychological assessment could help confirm the latter.
Frontal lobe epilepsy (FLE) has a significant impact on the children's behavior, learning, and development (1–5). Executive function, attention, and fine motor deficits are some of the disabilities described with frontal lobe dysfunction. These have been previously reported in adult patients with lesional FLE as well as in children with frontal lobe injury (2,3). Our group previously compared 16 children with FLE, eight with temporal lobe epilepsy, and eight with generalized absence on different neuropsychological tests (2). We demonstrated that children with FLE are more impaired in attention, impulse control, and working memory than the two other groups. But little data is available on the epileptic and neuropsychological outcome of children with nonlesional FLE (4).
The aim of our study was to define these outcomes in children with nonlesional FLE. We wanted to evaluate the impact of FLE on school performance and neuropsychological profile and correlate these changes with the long-term epileptic outcome in the absence of a structural lesion.
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The principal finding of this study is that in children with nonlesional FLE, seizure control does not guarantee the absence of severe comorbidity in this population. Our data suggest that the comorbidity often precedes seizure onset. We hypothesize that subtle-MRI silent lesions involving the frontal lobes might be the underlying etiology in a number of these children. Development of new MRI techniques might help us with the diagnosis of an underlying lesional etiology (6).
However, early age of onset and persistent seizures appear to lead to additional difficulties as previously reported (1). In children, epilepsy can interfere with normal brain development (2). We know that epilepsy can disrupt learning and even brain development (7). The impact of seizures during development might be even more important in children with FLE as frontal lobes continue to develop after birth and until late adolescence (2,3). For example, 10 of our 11 patients with seizure-onset before age six had an unfavorable epileptic and neuropsychological outcome. The majority of children with nonlesional FLE require special educational support and sometime specialized schools. The reason of their educational failure seems multiple but involving behavioral more than cognitive problems.