Impact of severe epilepsy on development: Recovery potential after successful early epilepsy surgery

Abstract

SUMMARYPurpose: Epilepsy surgery in young children with focal lesions offers a unique opportunity to study the impact of severe seizures on cognitive development during a period of maximal brain plasticity, if immediate control can be obtained. We studied 11 children with early refractory epilepsy (median onset, 7.5 months) due to focal lesion who were rendered seizure-free after surgery performed before the age of 6 years. Methods: The children were followed prospectively for a median of 5 years with serial neuropsychological assessments correlated with electroencephalography (EEG) and surgery-related variables. Results: Short-term follow-up revealed rapid cognitive gains corresponding to cessation of intense and propagated epileptic activity [two with early catastrophic epilepsy; two with regression and continuous spike-waves during sleep (CSWS) or frontal seizures]; unchanged or slowed velocity of progress in six children (five with complex partial seizures and frontal or temporal cortical malformations). Longer-term follow-up showed stabilization of cognitive levels in the impaired range in most children and slow progress up to borderline level in two with initial gains. Discussion: Cessation of epileptic activity after early surgery can be followed by substantial cognitive gains, but not in all children. In the short term, lack of catch-up may be explained by loss of retained function in the removed epileptogenic area; in the longer term, by decreased intellectual potential of genetic origin, irreversible epileptic damage to neural networks supporting cognitive functions, or reorganization plasticity after early focal lesions. Cognitive recovery has to be considered as a ''bonus,'' which can be predicted in some specific circumstances. KEY WORDS: Epilepsy, Epilepsy surgery, Development, Neuropsychology, Child.Epilepsy surgery in young children with focal lesions offers a unique opportunity to study the impact of severe seizures on development if immediate seizure control can be obtained and pre-and postoperative development can be compared in subjects with maximal neural plasticity (Deonna & Roulet-Perez, 2005). The literature on outcome after surgical treatment in young children has focused primarily on seizure control related to different variables, such as type of procedures and pathologies. Until recently, studies did not provide comparative pre-and postoperative cognitive levels based on tests (Asarnow et al., 1997). Loddenkemper et al. (2007) were the first to use objective assessments in infants operated before 3 years of age to study their developmental outcomes. Their patients presented with catastrophic epilepsy, including infantile spasms due to hemispheric or more focalized lesions; a first developmental level was obtained before and a second 6 months after surgery. A modest improvement was found in the majority of patients, with the best results in the younger children who also happened to be those who had infantile spasms and the lowest initial developmental levels. However, individual results...

Impact of epilepsy surgery on development of preschool children: identification of a cohort likely to benefit from early intervention

“…First, because we chose a developmental group that excluded infants and toddlers, our group did not include patients in the first year of life, who are likely to have more severe disease. 28 Second, resection was undertaken prior to potential cognitive decline and involved only limited focal resections. In addition, patients who needed more extensive resections, such as multilobar surgeries or hemispherectomies, and patients who were already functioning below average prior to referral for presurgical workup, were not included in this study.…”

“…19,23,33 However, literature evaluating cognitive outcome in young children to date has yielded contradictory and confusing results, perhaps stemming from methodological confounds. Outcome studies have yielded such varied results as 1) improved cognitive outcomes; 3,8,19,34 2) slight improvement in cognition being more likely than decline, with significant declines in some children; 37 3) reversible decline in at least some children, especially following left temporal lobectomy; 7 4) lack of improved outcome, with some cognitive recovery being a "bonus"; 28 5) "stabilized developmental velocity"; 6 6) no improvement in outcome postsurgery, 2,30 with this lack of improvement theorized to be associated with an abnormal neural substrate versus seizures per se; 30 and 7) no improvement, with the possibility of decline in some cases. 1 Although methodological issues are beginning to be addressed in adolescents and adults, 4 they have not been addressed to the same extent in children, particularly very young children.…”

“…Generally, the pediatric surgical outcome literature has been muddied by heterogeneous samples, combining many factors, including 1) markedly different surgical therapies, from focal resections to hemispherectomies; 3,26,28 2) broad age inclusion criteria, at different developmental levels, from 6 to 17 or 18 years 30,37 or 1 to 15 years 1 or "all children"; 2 3) variable levels of functioning prior to resection; 30 4) wide ranges of presurgical seizure duration; 28 and 5) variable pathologies. 2,28 Because many pediatric studies have focused on different age ranges, some studies have attempted to narrow the developmental scope, but their methods have still varied from each other, making them difficult to compare. Age range samples include patients less than 6 or 7 years at surgery, 19,28 3 to 7 years, 6 8 to 159 months, 34 less than 3 years, 20,26 or 3 to 36 months.…”

“…2,28 Because many pediatric studies have focused on different age ranges, some studies have attempted to narrow the developmental scope, but their methods have still varied from each other, making them difficult to compare. Age range samples include patients less than 6 or 7 years at surgery, 19,28 3 to 7 years, 6 8 to 159 months, 34 less than 3 years, 20,26 or 3 to 36 months. 3 A number of studies 7,21,22,29,32,37 have focused on temporal lobectomies and have provided important information regarding outcome following this procedure, with some variable findings.…”

“…There is a clear need to better define and study more homogeneous groups of children despite the challenges of power inherent in narrowing groups. In addition, because resection can be undertaken too late to avoid irreversible disability 4 and because early cessation of epileptogenic spread from a focal onset can be crucial for the return to normal developmental trajectories, 28 it is essential to identify well-defined patient groups who may particularly benefit from early surgical therapy. We sought to narrow the scope of our evaluation to 1) focal resections; 2) a specific and narrow age range and developmental level, 2-6 years, similar to at least 1 prior study 6 and corresponding with a specific developmental period previously identified by Piaget (preoperational stage, 2-6 or 7 years); and 3) patients who were not yet showing clear global cognitive deficits at the time of resection.…”