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Objective: We describe a multicenter experience with vagus nerve stimulator implantation in pediatric patients with drug-resistant epilepsy. Our goal was to assess vagus nerve stimulation efficacy and identify potential predictors of favorable outcome. Methods: This is a retrospective study. Inclusion criteria: ≤18 years at time of vagus nerve stimulator implantation, at least 1 year of follow-up. All patients were previously found to be unsuitable for an excisional procedure. Favorable clinical outcome and effective vagus nerve stimulation therapy were defined as seizure reduction >50%. Outcome data were reviewed at 1, 2, 3, and 5 years after vagus nerve stimulator implantation. Fisher exact test and multiple logistic regression analysis were employed. Results: Eighty-nine patients met inclusion criteria. Responder rate (seizure frequency reduction >50%) at 1-year follow-up was 25.8% (4.5% seizure-free). At last follow-up, 31.5% had a favorable outcome and 5.2% were seizure free. The only factor significantly predicting favorable outcome was time to vagus nerve stimulator implantation, with the best outcome achieved when vagus nerve stimulator implantation was performed within 3 years of seizure onset. Implantation between 3 and 5 years after epilepsy onset correlated with better long-term seizure freedom (13.3% at T5). Overall, 65.2% of patients evidenced improved quality of life at last follow-up. However, 12.4% had adverse events, but most were mild and disappeared after 3-4 months. Conclusions: Early vagus nerve stimulator implantation within 5 years of seizure onset was the only predictor of favorable clinical outcome in pediatric patients. Improved quality of life and a low incidence of significant adverse events were observed.

Disorders of cortical development form a spectrum of lesions produced by insults to the developing neocortex. These conditions typically first manifest in childhood with epilepsy, developmental delay, and focal neurologic signs. Although the clinical and electrophysiologic findings are often nonspecific, high-resolution magnetic resonance imaging facilitates diagnosis during life, and assists in delineating specific clinical syndromes. While many patients are dysmorphic and severely affected by mental retardation and epilepsy, some have normal or near-normal cognitive function and no seizures. Molecular studies of dysplastic cortex are providing new insights into the basic mechanisms of brain function and development, while pathologic analysis of tissue removed at surgery is helping to define epileptic circuitry. Treatment of the epilepsy associated with cortical dysplasia is often frustrating, but surgical approaches based on accurately defining epileptogenic regions are proving increasingly successful. Genetic diagnosis is important for accurate counseling of families. (J Child Neurol 1999;14:759-771).

Although certain clinical, electroencephalographic (EEG), magnetic resonance imaging (MRI), and pathologic findings in adults with intractable temporal lobe epilepsy predict seizure outcome following temporal lobectomy, predictors of seizure outcome have not been studied systematically in pediatric temporal lobectomy series. We retrospectively analyzed preoperative clinical, EEG, and neuroimaging findings with reference to seizure outcome (seizure free or non-seizure free) in 33 children (mean age, 9.3 years) who underwent tailored temporal lobe resections for intractable temporal lobe epilepsy. Trends were apparent with (1) younger age at seizure onset, younger age at surgery, shorter duration of epilepsy, localized unilateral temporal lesions on MRI, and right-sided surgery more frequently associated with a seizure-free outcome, and (2) significant prior history, daily preoperative seizures, generalized motor seizures, mental retardation, and localized unilateral temporal epileptiform EEG activity more frequently associated with a non-seizure-free outcome. However, none of these findings, alone or in combination, correlated with postoperative seizure status at a statistically significant level. Submitting the four variables generally considered to be most predictive of favorable outcome (ie, normal intelligence, unilateral ictal and interictal EEG discharges, and focal temporal MRI lesion) to a multiple-cutoff procedure did not predict seizure freedom. Our data indicate that predictors of outcome of temporal lobectomy in adults may not apply in children, perhaps due to inherent neurobiologic differences in the etiology and expression of temporal lobe epilepsy, and should therefore not be used as sole determinants of surgical candidacy in children. (J Child Neurol 1996;11:445-450).

Partial seizures, the most frequent type of epilepsy at all ages, remain a distinct yet relatively understudied disorder in early life. Their true incidence has not been defined, despite an extremely unfavorable long-term prognosis. They differ from partial seizures presenting later in life in several important aspects and are prone to misdiagnosis because of the difficulties inherent in recognizing subtle seizure manifestations and in assessing level of consciousness in very young patients. Most seizures are symptomatic of assorted prenatally acquired hemispheric insults; perinatal damage and tumors are less common. Video-electroencephalographic studies indicate that the majority of ictal events consist of behavioral arrest, stereotyped automatisms, and motor phenomena. Oroalimentary and gross motor automatisms are frequent, whereas highly organized gestural and behavioral sequences are extremely rare. Lateralized or asymmetric tonic, clonic, and occasional myoclonic motor manifestations characterize the majority of episodes. Pure behavioral arrest is much less common. These seizure patterns imply immaturity of systems responsible for inhibiting access to motor pathways and for organizing motor expression. Ictal and interictal epileptiform discharges are often focal or lateralized but lack age-specific features. Although as a rule partial seizures persist, some individuals display generalized or mixed seizure disorders in later life. ( J Child Neurol 1992;7:66-69).

Children with well-localized medically resistant seizures are often referred for surgical therapy. In young children, at least three maturational issues playa significant role in the selection process and long-term outcome. First, the early years are a time of exceptionally rapid brain development leading to dynamic changes in the electroencephalogram and the clinical expression of seizures. Many early-onset seizure presentations are also associated with catastrophic outcomes, developmental arrest, or regression. Second, the immature limbic system may be vulnerable to stresses operating in early life, although the consequences may not become apparent for many years. Third, in comparison to the adult, the child's nervous system typically exhibits superior functional recovery after lesioning, but the process of sparing and recovery is often incomplete. An understanding of how these neurobiologic factors influence developmental outcome will ultimately lead to greater selectivity of candidates for early surgery and to improved long-term prognosis. (J Child Neurol 1994;9(Suppl):2S42-2S49).

Noninvasive assessment of children with chronic epilepsy is often imprecise and localization of seizure foci requires intracranial electroencephalographic monitoring. Subdural electrodes provide coverage of large areas of neocortex and are ideally suited for evaluating children with intractable epilepsy and to functionally map critical cortex. This report discusses the role of subdural electroencephalography in the evaluation of childhood epilepsy. (J Child Neurol 1994; 9(Suppl):2S61-2S66).