Factors associated with treatment delays in pediatric refractory convulsive status epilepticus

OBJECTIVE

To identify factors associated with treatment delays in pediatric patients with convulsive refractory status epilepticus (rSE).

METHODS

This prospective, observational study was performed from June 2011 to March 2017 on pediatric patients (1 month to 21 years of age) with rSE. We evaluated potential factors associated with increased treatment delays in a Cox proportional hazards model.

RESULTS

We studied 219 patients (53% males) with a median (25th-75th percentiles [p₂₅-p₇₅]) age of 3.9 (1.2-9.5) years in whom rSE started out of hospital (141 [64.4%]) or in hospital (78 [35.6%]). The median (p₂₅-p₇₅) time from seizure onset to treatment was 16 (5-45) minutes to first benzodiazepine (BZD), 63 (33-146) minutes to first non-BZD antiepileptic drug (AED), and 170 (107-539) minutes to first continuous infusion. Factors associated with more delays to administration of the first BZD were intermittent rSE (hazard ratio [HR] 1.54, 95% confidence interval [CI] 1.14-2.09; p = 0.0467) and out-of-hospital rSE onset (HR 1.5, 95% CI 1.11-2.04; p = 0.0467). Factors associated with more delays to administration of the first non-BZD AED were intermittent rSE (HR 1.78, 95% CI 1.32-2.4; p = 0.001) and out-of-hospital rSE onset (HR 2.25, 95% CI 1.67-3.02; p < 0.0001). None of the studied factors were associated with a delayed administration of continuous infusion.

CONCLUSION

Intermittent rSE and out-of-hospital rSE onset are independently associated with longer delays to administration of the first BZD and the first non-BZD AED in pediatric rSE. These factors identify potential targets for intervention to reduce time to treatment.

Adherence to the 2007 cystic fibrosis pulmonary guidelines: a national survey of CF care centers

OBJECTIVE

To examine cystic fibrosis (CF) physician adherence to the 2007 CF Foundation (CFF) Pulmonary Guidelines for Chronic Medications. Specifically adherence and barriers to prescribing level A medication recommendations (i.e., inhaled tobramycin and dornase alfa) and level B medication recommendations (i.e., macrolide antibiotics and hypertonic saline) were studied.

METHODS

During Spring 2010, the CFF emailed survey invitations to directors of 136 accredited CF care centers treating 50+ CF patients. Directors were asked to forward the invitations to their physician colleagues. One hundred thirty-three surveys were included in the analyses, representing 92 centers. Barriers were conceptualized based on Cabana et al.'s framework for adherence to guidelines. Adherence was assessed via a case vignette.

RESULTS

Logistic regression analysis revealed that higher outcome expectancy (OR = 1.099, CI 1.010-1.196) and fewer environmental/system barriers (OR = 1.484, CI 1.158-1.902) were significantly associated with Vignette Adherence. A trend for an association between Familiarity and Vignette Adherence (OR = 1.642, CI 0.953-2.828) was evident, while no demographic variables were significantly associated with Vignette Adherence.

CONCLUSION

Targeting outcome expectancy and external barriers with multifaceted, ongoing interventions may improve guideline adherence. Pulmonologists are clearly looking for empirical evidence that these medications benefit their patients over the long-term and offset patient treatment burden with improved health.

Communication gaps between physicians and patients with postherpetic neuralgia: results from a national study on practice patterns

Background

The purpose of this study was to identify differences in perceptions of care regarding postherpetic neuralgia, including communication patterns between patients and physicians and levels of satisfaction with therapies and care.

Methods

A survey was developed for physicians (neurologists, internists, and family physicians) and patients with postherpetic neuralgia in order to determine their perspectives on its management.

Results

A total of 142 eligible patient respondents were included in the study, and responses were compared with those of 150 primary care physicians and 76 neurologist respondents. Few patients and physicians indicated satisfaction with the currently available treatments for postherpetic neuralgia. While nearly all physicians responded that they discuss the cause of postherpetic neuralgia with a patient, one in four patients indicated that their physician did not discuss the cause. Similarly, one in four patients were not aware of the duration of postherpetic neuralgia, the treatment side effects, or what to expect from treatment. Patients may be less likely to discuss treatment side effects and quality of life issues than physicians perceive.

Conclusion

Physicians and patients have similar perceptions regarding treatment options for postherpetic neuralgia; however, certain gaps in communication were evident, which may be attributable to physician knowledge and communication skills with patients. Strategies to improve issues of expected outcomes and side effects of treatment may be useful to physicians.

Primary care physician attitudes and practice patterns in the management of obese adults: results from a national survey

PURPOSE

Obesity remains a serious public health problem. The purpose of this study was to identify the current attitudes and practices of primary care physicians (PCPs) with respect to obesity.

METHODS

A survey was systematically developed and administered electronically to PCPs, who received a small honorarium for their time. Results were analyzed to identify specific attitudes and practices and their associations with each other and with demographic and other variables.

RESULTS

Physicians expressed little confidence in their ability to manage obesity. In general, however, they believed that obesity could be successfully managed. Lifestyle changes were perceived to be the most effective available method for patients to lose weight, and respondents were more likely to recommend this approach over pharmacotherapy or bariatric surgery. Respondents perceive the greatest barrier to managing obese patients to be a lack of patient motivation. Physicians were significantly more likely to initiate discussions with obese patients about their weight if they believed they had positive attitudes about and knowledge of weight management, and adequate resources to manage the problem.

CONCLUSIONS

Physicians report a lack of confidence in managing obesity. Lack of patient motivation is perceived to be the greatest barrier. Physicians with greater knowledge, more positive attitudes toward obesity management, and access to more resources are more likely to provide weight management in primary care settings.

Valproate in children with newly diagnosed idiopathic generalized epilepsy

OBJECTIVES

Sparse information on dose-response characteristics for initial antiepileptic drug monotherapy in children with idiopathic generalized epilepsy (IGE) is available. The aim of this study is to characterize the therapeutic dose of valproate in children with newly diagnosed IGE.

MATERIALS AND METHODS

Effect of initial valproate monotherapy and doses associated with seizure freedom were examined in consecutive children with IGE identified from a New Onset Seizure Clinic.

RESULTS

Of 84 patients identified, 48 (57%) became seizure-free on valproate monotherapy and another 10 patients became seizure-free but discontinued VPA because of adverse effects. The mean dose in seizure-free children was 15.7 mg/kg/day and over 95% of IGE patients will respond below 25 mg/kg/day.

CONCLUSIONS

Half of children became seizure-free on valproate monotherapy and did so at modest doses.

Obesity is a common comorbidity for pediatric patients with untreated, newly diagnosed epilepsy

OBJECTIVE

This study aimed to determine the frequency and factors associated with obesity in a cohort of children and adolescents with newly diagnosed untreated epilepsy.

METHODS

Body mass index (BMI) Z-scores and percentiles, both adjusted for age, were used as measures for obesity. Potential covariates associated with these BMI measures included age, etiology (cryptogenic, idiopathic, symptomatic), seizure type (generalized, partial, unclear), concomitant medications (stimulants, nonstimulants, none), and insurance status (privately insured, Medicaid). The primary analysis compared the epilepsy patients' BMI Z-scores to Centers for Disease Control and Prevention data for healthy children. The secondary analysis compared the epilepsy patients' BMI Z-scores to those of a regional healthy control group. Additional analyses incorporated the secondary outcome measure BMI percentiles indexed for age.

RESULTS

Children with newly diagnosed untreated epilepsy had higher BMI Z-scores compared to standard CDC growth charts (p < 0.0001) and the healthy control cohort (p = 0.0002) specifically at both of the 2 tail ends of the distribution. Overall, 38.6% of the epilepsy cohort were overweight or obese (BMI > or =85th percentile for age). Differences in age, etiology, and concomitant nonepilepsy medications were significantly associated with variability in age-adjusted BMI Z-score. Patients in adolescence had higher adjusted BMI Z-scores than younger patients. Patients with symptomatic epilepsy had lower adjusted BMI Z-scores than patients with idiopathic epilepsy. Patients on stimulant psychotropics exhibited lower adjusted BMI Z-scores than patients on no medication.

CONCLUSION

Obesity is a common comorbidity in children with newly diagnosed untreated epilepsy and correlates with increasing age, idiopathic etiology, and absence of concomitant medication.

Assessing quality and normalization of microarrays: case studies using neurological genomic data

BACKGROUND

Genomic analysis using microarray tools has the potential benefit of enhancing our understanding of neurological diseases. The analysis of these data is complex due to the large amount of data generated. Many tools have been developed to assist with this, but standard methods of analysis of these tools have not been established.

OBJECTIVE

This study analyzed the sensitivity and specificity of different analytical methods for gene identification and presents a standardized approach.

METHODS

Affymetrix HG-U133 plus 2.0 microarray datasets from two neurological diseases - chronic migraine and new-onset epilepsy - were used as source data and methods of analysis for normalization of data and identification of gene changes were compared. Housekeeping genes were used to identify non-specific changes and gender related genes were used to identify specific changes.

RESULTS

Initial normalization of data revealed that 5-10% of the microarray were potential outliers due to technical errors. Two separate methods of analysis (dChip and Bioconductor) identified the same microarray chips as outliers. For specificity and sensitivity testing, performing a per-gene normalization was found to be inferior to standard preprocessing procedures using robust multichip average analysis.

CONCLUSIONS

Technical variation in microarray preprocessing may account for chip-to-chip and batch-to-batch variations and outliers need to be removed prior to analysis. Specificity and sensitivity of the final results are best achieved following this identification and removal with standard genomic analysis techniques. Future tools may benefit from the use of standard tools of measurement.

Double-blind placebo-controlled trial of adjunctive levetiracetam in pediatric partial seizures

OBJECTIVE

To evaluate the efficacy and tolerability of levetiracetam (LEV) as adjunctive therapy in children (4 to 16 years) with treatment-resistant partial-onset seizures.

METHODS

This multicenter, randomized, placebo-controlled trial consisted of an 8-week baseline period followed by a 14-week double-blind treatment period. During the treatment period, patients received either placebo or LEV add-on therapy and were up-titrated to a target dose of 60 mg/kg/day.

RESULTS

One hundred ninety-eight patients (intent-to-treat population) provided evaluable data. The reduction in partial-onset seizure frequency per week for LEV adjunctive therapy over placebo adjunctive therapy was significant (26.8%; p = 0.0002; 95% CI 14.0% to 37.6%). A 50% or greater reduction of partial seizure frequency per week was attained in 44.6% of the LEV group (45/101 patients), compared with 19.6% (19/97 patients) receiving placebo (p = 0.0002). Seven (6.9%) LEV-treated patients were seizure-free during the entire double-blind treatment period, compared with one (1.0%) placebo-treated patient. One or more adverse events were reported by 88.1% of LEV-treated patients and 91.8% of placebo patients. The most common treatment-emergent adverse events were somnolence, accidental injury, vomiting, anorexia, hostility, nervousness, rhinitis, cough, and pharyngitis. A similar number of patients in each group required a dose reduction or withdrew from the study as a result of an adverse event.

CONCLUSION

Levetiracetam adjunctive therapy administered at 60 mg/kg/day is efficacious and well tolerated in children with treatment-resistant partial seizures.

Randomized dose-controlled study of topiramate as first-line therapy in epilepsy

OBJECTIVES

To evaluate the efficacy and tolerability of topiramate as monotherapy, using a dose-controlled study design.

MATERIALS AND METHODS

We conducted a multinational, randomized, double-blind trial in adults and children (> or =6 years old) with epilepsy that was not being treated when randomized to 400 or 50 mg/day topiramate as target maintenance dosages. In addition to > or =2 lifetime unprovoked seizures, patients had to have one or two partial-onset seizures or generalized-onset tonic-clonic seizures in the 3-month retrospective baseline. The primary efficacy end point was time to first seizure; a secondary efficacy measure was the seizure-free rate at 6 months and 1 year. Double-blind treatment continued until 6 months after the last patient was randomized.

RESULTS

Kaplan-Meier survival analyses for time to first seizure (intent-to-treat, n = 470) favored 400 mg/day over 50 mg/day (P = 0.0002) as a target maintenance dosage. The first evaluation point with a significant difference (P = 0.046) favoring the higher dose was at day 14 when patients were receiving 100 or 25 mg/day. The probability of being seizure-free at 6 months was 83% in patients randomized to 400 mg/day and 71% in those randomized to 50 mg/day (P = 0.005). Seizure-free rates at 12 months were 76% and 59%, respectively (P = 0.001). Differences favoring the higher dose were significant in patients with partial-onset seizures (P = 0.009) and in those with generalized-onset tonic-clonic seizures (P = 0.005). The most common dose-related adverse events were paresthesia, weight loss, and decreased appetite. Discontinuations due to cognitive-related adverse events were 2% in the 50-mg group and 7% in the 400-mg group. Overall, 7% and 19%, respectively, discontinued with adverse events during the median treatment duration of 9 months.

CONCLUSION

Topiramate is effective as monotherapy in adults and children. Because a therapeutic effect emerges during titration, clinicians should adjust dosages in step-wise fashion with intermediate stopping points, e.g., 100 mg/day, to evaluate patient response and achieve the optimal maintenance dosage.

Efficacy and tolerability of the new antiepileptic drugs I: treatment of new onset epilepsy: report of the Therapeutics and Technology Assessment Subcommittee and Quality Standards Subcommittee of the American Academy of Neurology and the American Epilepsy Society

OBJECTIVE

To assess the evidence demonstrating efficacy, tolerability, and safety of seven new antiepileptic drugs (AEDs) (gabapentin, lamotrigine, topiramate, tiagabine, oxcarbazepine, levetiracetam, and zonisamide-reviewed in the order in which these agents received approval by the US Food and Drug Administration) in the treatment of children and adults with newly diagnosed partial and generalized epilepsies.

METHODS

A 23-member committee, including general neurologists, pediatric neurologists, epileptologists, and doctors in pharmacy, evaluated the available evidence based on a structured literature review including MEDLINE, Current Contents, and Cochrane library for relevant articles from 1987 until September 2002, with selected manual searches up until 2003.

RESULTS

There is evidence either from comparative or dose-controlled trials that gabapentin, lamotrigine, topiramate, and oxcarbazepine have efficacy as monotherapy in newly diagnosed adolescents and adults with either partial or mixed seizure disorders. There is also evidence that lamotrigine is effective for newly diagnosed absence seizures in children. Evidence for effectiveness of the new AEDs in newly diagnosed patients with other generalized epilepsy syndromes is lacking.

CONCLUSIONS

The results of this evidence-based assessment provide guidelines for the prescription of AEDs for patients with newly diagnosed epilepsy and identify those seizure types and syndromes where more evidence is necessary.

Efficacy and tolerability of the new antiepileptic drugs II: Treatment of refractory epilepsy: Report of the Therapeutics and Technology Assessment Subcommittee and Quality Standards Subcommittee of the American Academy of Neurology and the American Epilepsy Society

OBJECTIVE

To assess the evidence demonstrating efficacy, tolerability, and safety of seven new antiepileptic drugs (AEDs) (gabapentin, lamotrigine, topiramate, tiagabine, oxcarbazepine, levetiracetam, and zonisamide) in the treatment of children and adults with refractory partial and generalized epilepsies.

METHODS

A 23-member committee including general neurologists, pediatric neurologists, epileptologists, and doctors in pharmacy evaluated the available evidence based on a structured literature review including MEDLINE, Current Contents, and Cochrane library for relevant articles from 1987 until March 2003.

RESULTS

All of the new AEDs were found to be appropriate for adjunctive treatment of refractory partial seizures in adults. Gabapentin can be effective for the treatment of mixed seizure disorders, and gabapentin, lamotrigine, oxcarbazepine, and topiramate for the treatment of refractory partial seizures in children. Limited evidence suggests that lamotrigine and topiramate are also effective for adjunctive treatment of idiopathic generalized epilepsy in adults and children, as well as treatment of the Lennox Gastaut syndrome.

CONCLUSIONS

The choice of AED depends upon seizure and/or syndrome type, patient age, concomitant medications, AED tolerability, safety, and efficacy. The results of this evidence-based assessment provide guidelines for the prescription of AEDs for patients with refractory epilepsy and identify those seizure types and syndromes where more evidence is necessary.

Valproic acid blood genomic expression patterns in children with epilepsy - a pilot study

OBJECTIVE

Valproic acid (VPA) is a commonly used anticonvulsant with multiple systemic effects. The purpose of this pilot study is to examine the blood genomic expression pattern associated with VPA therapy in general and secondly VPA efficacy in children with epilepsy.

MATERIALS AND METHODS

Using oligonucleotide microarrays, gene expression in whole blood was assessed in pediatric epilepsy patients following treatment with VPA compared with children with epilepsy prior to initiation of anticonvulsant therapy (drug free patients).

RESULTS

The expression of 461 genes was altered in VPA patients (n = 11) compared with drug free patients (n = 7), among which a significant number of serine threonine kinases were down-regulated. Expression patterns in children seizure free on VPA therapy (n = 8) demonstrated 434 up-regulated genes, many in mitochondria, compared with VPA children with continuing seizures (n = 3) and drug free seizure patients (n = 7).

CONCLUSION

VPA therapy is associated with two significant and unique blood gene expression patterns: chronic VPA monotherapy in general and a separate blood genomic profile correlated with seizure freedom. These expression patterns provide new insight into previously undetected mechanisms of VPA anticonvulsant activity.

Pharmacokinetic study of levetiracetam in children

PURPOSE

The pharmacokinetics of the novel antiepileptic drug (AED) levetiracetam and its major metabolite, ucb L057, were studied in children with partial seizures in a multicenter, open-label, single-dose study.

METHODS

Twenty-four children (15 boys, nine girls), 6 to 12 years old, received a single dose of levetiracetam (20 mg/kg) as an adjunct to their stable regimen of a single concomitant AED, followed by a 24-h pharmacokinetic evaluation.

RESULTS

In children, the half-lives of levetiracetam and its metabolite ucb L057 were 6.0 +/- 1.1 and 8.1 +/-2.7 hours, respectively. The Cmax and area under the curve (AUC) of levetiracetam equated for a 1-mg/kg dose were lower in children (Cmax, norm=1.33 plus minus 0.35 microg/ml; AUCnorm=12.4 +/- 3.5 microg/h/ml) than in adults (Cmax, norm=1.38 +/- 0.05 microg/ml; AUCnorm=11.48 +/- 0.63 microg/h/ml), whereas the renal clearance was higher. The apparent body clearance (1.43 +/- 0.36 ml/min/kg) was approximately 30-40% higher in children than in adults. Levetiracetam was generally well tolerated.

CONCLUSIONS

On the basis of these data, a daily maintenance dose equivalent to 130-140% of the usual daily adult maintenance dosage (1,000-3,000 mg/day) in two divided doses, on a weight-normalized level (mg/kg/day) is initially recommended. Clinical efficacy trials in children are ongoing with dosages of 20 to 60 mg/kg/day.

Oxcarbazepine in the treatment of epilepsy

Oxcarbazepine is a new antiepileptic drug (AED) that has been registered in more than 50 countries worldwide since 1990 and recently received approval in the United States and the European Union. Oxcarbazepine is a keto analog of carbamazepine and has a more favorable pharmacokinetic profile. It is rapidly absorbed after oral administration and undergoes rapid and almost complete reductive metabolism to form the pharmacologically active 10-monohydroxy derivative. Oxcarbazepine exhibits linear pharmacokinetics, no autoinduction, and minimal interaction with other AEDs. Ten controlled trials demonstrated that oxcarbazepine is safe and efficacious in the treatment of partial seizures across a wide range of ages (children to adults), situations (recent onset to treatment-resistant epilepsy), and uses (monotherapy and adjunctive therapy). The most common treatment-emergent adverse events are related to the central nervous system. Treatment-emergent hyponatremia (defined as serum sodium level < 125 mEq/L) occurred in 3% of patients treated with oxcarbazepine in clinical trials. According to the efficacy and safety profile established in the controlled trials, oxcarbazepine represents an important new treatment option indicated for monotherapy and adjunctive therapy in adults with partial seizures and as adjunctive therapy in children aged 4 years or older with partial seizures. Although structurally similar to carbamazepine, significant differences exist in the pharmacokinetics, drug interaction potential, adverse-effect profile, and dosage and titration between these two agents, and they should be considered distinct therapeutic agents.

Topiramate in the catastrophic epilepsies of childhood

Several epileptic syndromes that occur during childhood are characterized by severe treatment-resistant seizures, progressive loss of higher intellectual functions, and characteristic electroencephalographic abnormalities. These catastrophic epileptic syndromes include epileptic encephalopathy with diffuse slow spike waves (Lennox-Gastaut syndrome), West syndrome, progressive myoclonic epilepsies, and electrical status epilepticus during sleep. This article summarizes each syndrome and reviews the most recent information concerning the effectiveness of topiramate with respect to each condition. Suggestions are offered to help clinicians maximize topiramate's efficacy and tolerability in patients suffering with these syndromes. Overall, topiramate is a valuable antiepileptic medication in the treatment of catastrophic pediatric epileptic syndromes.

Controversies in blood-level monitoring: reexamining its role in the treatment of epilepsy

This article reexamines the role of blood-level monitoring (therapeutic drug monitoring, TDM) of antiepileptic drugs (AEDs) in the current treatment of epilepsy and identifies situations in which TDM can be useful. Basic pharmacokinetic and pharmacodynamic principles are reviewed, with specific emphasis on kinetics of absorption/distribution/metabolism, elimination half-life, time to steady state, and plasma drug concentrations. The relationship between AED intensity of effect (pharmacodynamics) and plasma concentration (pharmacokinetics) is expressed mathematically, examined in the context of the major old and new AEDs, and integrated with a historical look at the role of TDM. Situations in which TDM can be useful in the modern treatment of epilepsy are presented and discussed. For both older and newer AEDs, TDM is useful in six clinical situations: establishing "baseline" effective concentrations, evaluating potential causes for lack of efficacy, evaluating potential causes for toxicity, evaluating potential causes for loss of efficacy, judging "room to move" or when to change AEDs, and minimizing predictable problems. TDM remains a valuable tool in the modern treatment of epilepsy. It can be selectively and appropriately utilized to help maximize seizure control and minimize side effects if levels are obtained in response to a patient-specific pharmacokinetic or pharmacodynamic issue or problem.

Idiosyncratic reactions: new methods of identifying high-risk patients

This article describes the mechanisms of idiosyncratic drug reactions (IDRs) and provides an analysis of potential methods for identifying patients at high risk for antiepileptic idiosyncratic drug reactions. IDRs may be caused by toxic metabolites, either directly or indirectly (by way of an immunologic response or a free radical-mediated process). Four methods to potentially identify patients at high risk for AED IDRs are discussed: development of an "at-risk" clinical profile for a particular AED: identification of biomarkers that measure the formation of a toxic metabolite by a previously unrecognized bioactivation pathway for a particular AED; identification of biomarkers indicating deficient detoxification abilities [e.g., deficient free radical scavenging enzyme activities or low calculated oxidative protection (COP) ratios 1 and 2]; and identification of at-risk genetic markers. Clinical profiles for patients receiving valproic acid (VPA), felbamate (FBM), and lamotrigine (LTG) and who are at risk for development of AED IDRs are presented. Patients with VPA IDRs have deficient erythrocyte glutathione peroxidase activity, low plasma selenium concentrations, low COP1 ratios, and low COP2 ratios compared with age-matched controls. Patients with FBM-associated aplastic anemia have deficient erythrocyte glutathione peroxidase, superoxide dismutase (SOD), and glutathione reductase activities compared with age-matched controls. Use of at-risk clinical profiles (for VPA, FBM, and LTG) and measurement of erythrocyte glutathione peroxidase activity, erythrocyte SOD activity, and calculation of COP1 and COP2 ratios (for VPA and FBM) are inexpensive, simple methods of identifying high-risk patients for IDRs. Research is needed to further characterize the mechanism of IDRs, to investigate the clinical utility of free radical-scavenging enzyme activity measurement and calculation of COP ratios for other AED IDRs, and to develop additional methods of identifying patients at high risk for AED IDRs.

Expanding first-line therapy options for children with partial seizures

Carbamazepine and phenytoin are considered first-line therapies for children with partial seizures on the basis of the adult Veterans Administration studies, open-label controlled and uncontrolled pediatric studies, and clinical experience. Although many new antiepileptic drugs (AEDs) have demonstrated efficacy in controlled trials in adults with partial seizures, additional issues must be examined before these new AEDs are considered as first-line therapy for children with partial seizures. This article proposes three criteria for assessing the suitability of a new AED as first-line therapy for pediatric partial seizures: (a) demonstrated efficacy against pediatric partial seizures in two or more randomized, double-blind controlled trials involving patients less than 12 years old (with at least one of the trials utilizing a monotherapy design); (b) a favorable safety profile in monotherapy trials and no severe idiosyncratic reactions; and (c) ease of use in children across a wide range of ages. On the basis of these criteria, two new AEDs, oxcarbazepine (OXC) and topiramate (TPM), are suitable for consideration. OXC has demonstrated efficacy in monotherapy and adjunctive therapy in pediatric partial seizures, along with good tolerability and the ability to be titrated rapidly. TPM has also demonstrated efficacy and tolerability in pediatric partial seizures but should be titrated slowly. In addition, gabapentin (GBP) can be considered as first-line therapy for pediatric partial seizures if the preliminary analysis of a monotherapy trial is confirmed. There are not yet enough data on efficacy to support consideration of lamotrigine, tiagabine, felbamate, levetiracetam, or zonisamide as first-line therapy for pediatric partial seizures.

Adjunctive therapy with oxcarbazepine in children with partial seizures. The Oxcarbazepine Pediatric Study Group

OBJECTIVE

To evaluate the safety and efficacy of oxcarbazepine (OXC) as adjunctive therapy in children with inadequately controlled partial seizures on one or two concomitant antiepileptic drugs (AEDs).

BACKGROUND

OXC has shown antiepileptic activity in several comparative monotherapy trials in newly diagnosed patients with epilepsy, and in a placebo-controlled monotherapy trial in hospitalized patients evaluated for epilepsy surgery.

DESIGN

A total of 267 patients were evaluated in a multicenter, randomized, placebo-controlled trial consisting of three phases: 1) a 56-day baseline phase (patients maintained on their current AEDs); 2) a 112-day double-blind treatment phase (patients received either OXC 30-46 mg/kg/day orally or placebo); and 3) an open-label extension phase. Data are reported only from the double-blind treatment phase; the open-label extension phase is ongoing.

METHODS

Children (3 to 17 years old) with inadequately controlled partial seizures (simple, complex, and partial seizures evolving to secondarily generalized seizures) were enrolled.

RESULTS

Patients treated with OXC experienced a significantly greater median percent reduction from baseline in partial seizure frequency than patients treated with placebo (p = 0.0001; 35% versus 9%, respectively). Forty-one percent of patients treated with OXC experienced a > or =50% reduction from baseline in partial seizure frequency per 28 days compared with 22% of patients treated with placebo (p = 0.0005). Ninety-one percent of the group treated with OXC and 82% of the group treated with placebo reported > or =1 adverse event; vomiting, somnolence, dizziness, and nausea occurred more frequently (twofold or greater) in the group treated with OXC.

CONCLUSION

OXC adjunctive therapy administered in a dose range of 6 to 51 mg/kg/day (median 31.4 mg/kg/day) is safe, effective, and well tolerated in children with partial seizures.

Effectiveness, tolerability, and safety of topiramate in children with partial-onset seizures. Topiramate YP Study Group

PURPOSE

Children with partial-onset seizures, with or without secondary generalization, participating in a double-blind, placebo-controlled trial of topiramate (TPM) as adjunctive therapy were eligible to participate in an open-label, long-term extension study.

METHODS

A total of 83 children (mean age, 9 years) continued long-term open-label TPM therapy in which the dosages of TPM and concomitant antiepileptic drugs (AEDs) were adjusted according to clinical response (mean TPM dosage, 9 mg/kg/day).

RESULTS

Seizure frequency over the last 3 months of therapy was reduced > or =50% in 57% of children; 14% of children were seizure-free > or =6 months at the last visit. During treatment periods up to 2 1/2 years (mean, 15 months), 6% of children discontinued because of treatment-emergent adverse events; 13% discontinued because of inadequate seizure control.

CONCLUSIONS

From these findings, TPM is well tolerated and provides long-term seizure control in children with partial-onset seizures.

Long-term response to topiramate in patients with West syndrome

PURPOSE

The long-term effectiveness of topiramate (TPM) was evaluated in children with West syndrome previously refractory to antiepileptic drug (AED) therapy.

METHODS

Children with infantile spasms who completed a pilot study were eligible to enter a long-term extension phase in which the dosages of TPM and other AEDs could be adjusted to optimal response (maximum, 50 mg/kg/day TPM). The mean duration of long-term therapy was 18 months in the 11 children who were followed; the mean TPM dosage was 29 mg/kg/day.

RESULTS

Eight (73%) children were continuing TPM therapy at the time data were analyzed; four (50%) children were spasm free, seven (88%) had experienced a > or =50% reduction in spasms, and three (38%) were able to achieve TPM monotherapy.

CONCLUSIONS

TPM was well tolerated in that no patients discontinued because of adverse events. The response achieved with TPM during the pilot study was maintained in most children.

Topiramate in Lennox-Gastaut syndrome: open-label treatment of patients completing a randomized controlled trial. Topiramate YL Study Group

PURPOSE

The response to topiramate (TPM) as long-term adjunctive therapy was evaluated in patients with Lennox-Gastaut syndrome (LGS) in a long-term, open-label extension to a double-blind, placebo-controlled trial.

METHODS

In 97 patients with LGS (mean age, 11 years), dosages of TPM and concomitant antiepileptic drugs (AEDs) were adjusted to optimal clinical response (mean TPM dosage, 10 mg/kg/day).

RESULTS

For those patients who had completed 6 months of TPM therapy, drop attacks were reduced > or =50% in 55% of patients; 15% of patients had no drop attacks for > or =6 months at the last visit. After treatment up to 3+ years, 71% of patients who started open-label TPM were continuing therapy at the last visit.

CONCLUSIONS

During long-term therapy, TPM is effective and well tolerated in controlling the treatment-resistant drop attacks and seizures associated with LGS.

An improved gas chromatography assay for topiramate monitoring in pediatric patients

An improved micromethod involving capillary gas chromatographic assay with liquid-liquid extraction and nitrogen phosphorus detection (GC/NPD) was developed and validated for the determination of topiramate (TPM) in human body fluids. The galactopyranose analog of TPM was used as the internal standard. Capillary gas chromatographic conditions yielded typical retention times of 6.8 min for TPM and 7.2 min for the internal standard. Calibrations were linear between 1.0 and 32 microg/mL. Between-day precision (n = 17) for three serum controls (3.0, 10, and 24.5 microg/mL) resulted in coefficients of variation of 6.9%, 7.3%, and 4.9%, respectively. The limit of detection was 0.42 microg/mL. There was an excellent linear correlation between the fluorescence-polarization immunoassay (FPIA) and GC/NPD determinations of 56 patient specimens (r2 = 0.981). Chromatograms showed no interfering peaks with the respective blank human samples or from many commonly prescribed drugs. Because of improved specificity and decreased sample volume requirements, this micromethod should be particularly useful for monitoring TPM therapy in pediatric patients, for patients with impaired renal function, and for research studies.

Topiramate therapy of epilepsy associated with Angelman's syndrome

Angelman's syndrome, a genetic disorder involving a defect in the DNA coding for subunits of the gamma-aminobutyric acid (GABA) type A receptor, often is associated with intractable epilepsy. Topiramate is a novel anticonvulsant that enhances GABAergic neurotransmission. Five children with Angelman's syndrome and epilepsy were treated with topiramate for clinical indications. The drug was effective and well tolerated, possibly because of its GABAergic properties. Further studies are necessary to confirm and elucidate this observation.

Topiramate

Six studies are cited to demonstrate that topiramate is effective as adjunctive therapy for refractory partial-onset seizures in adults. Subsequent studies indicate that topiramate is also effective as monotherapy in adults and as adjunctive therapy for partial-onset seizures in children, tonic-clonic seizures of nonfocal origin in children and adults, and drop attacks in Lennox-Gastaut syndrome. Adverse effects for adults and children included dizziness, fatigue, ataxia, confusion, somnolence, nephrolithiasis, paresthesia, and weight loss. More adverse effects were observed at higher doses. Topiramate exhibits rapid absorption, long duration of action, and minimal interaction with other antiepileptic drugs.

Efficacy and mortality in treatment of refractory generalized convulsive status epilepticus in children: a meta-analysis

There is no consensus on the choice of drug treatment for refractory generalized convulsive status epilepticus in children. The objective of this meta-analysis of the published literature was to determine the effects of drug treatments on efficacy (seizure cessation) and mortality in children with this condition, controlling for potential confounding factors. One hundred eleven children, treated with diazepam, midazolam, thiopental, pentobarbital, or isoflurane, met strict inclusion criteria. Diazepam was significantly less efficacious than other treatments (P = .006) stratifying for etiology. Overall mortality was 20% in symptomatic cases and 4% in idiopathic cases (P = .038). Mortality was less frequent in midazolam-treated patients (P = .021) stratifying for etiology. Midazolam appears to be a good choice for initial treatment of refractory generalized convulsive status epilepticus in children, but the attribution of differences in efficacy and mortality solely to drug effect is not possible based on the published literature.

Complications and costs of treatment of refractory generalized convulsive status epilepticus in children

Multiple case series in the literature suggest that benzodiazepines and barbiturates are highly efficacious at stopping seizures. Apparent differences in mortality might not be due solely to drug effect. In this systematic review of the medical literature, we assessed the complications and costs of treatment of refractory status epilepticus in 111 children who met strict inclusion criteria, as part of an effort to provide an evidenced-based recommendation for optimal therapy. All children treated with barbiturates required mechanical ventilation, versus 13% of patients treated with benzodiazepines. Benzodiazepine treatment was associated with pressor use in 3.5% of cases, versus 35% with barbiturate treatment. Midazolam treatment was for the shortest duration and allowed the most rapid return to consciousness. Differences in mean 24-hour drug costs were small compared to savings produced by shorter length of treatment and return to consciousness. Benzodiazepines appear to have higher drug costs but lower complications and overall costs than barbiturates.

A double-blind, randomized trial of topiramate in Lennox-Gastaut syndrome. Topiramate YL Study Group

OBJECTIVE

To evaluate the efficacy and safety of topiramate as adjunctive therapy for Lennox-Gastaut syndrome in a multicenter, double-blind, placebo-controlled trial.

BACKGROUND

Conventional antiepileptic drugs are frequently ineffective against multiple-seizure types of Lennox-Gastaut syndrome.

METHODS

Ninety-eight patients >1 year to <30 years of age, with slow spike-and-wave patterns on EEG, seizure types including drop attacks, and either a history of or active atypical absence seizures, were assigned to an 11-week, double-blind treatment phase with either topiramate or placebo. Topiramate was titrated to target doses of approximately 6 mg/kg/d.

RESULTS

For drop attacks, the most severe seizures associated with this syndrome, the median percentage reduction from baseline in average monthly seizure rate was 14.8% for the topiramate group and -5.1% (an increase) for the placebo group (p = 0.041). Topiramate-treated patients demonstrated greater improvement in seizure severity than did placebo-treated patients based on parental global evaluations (p = 0.037). The percentage of patients with a > or = 50% reduction from baseline in major seizures (drop attacks and tonic-clonic seizures) was greater in the topiramate group (15/46 or 33%) than in the control group (4/50 or 8%; p = 0.002). The most common adverse events in both groups were CNS related; there were no discontinuations from topiramate therapy due to adverse events.

CONCLUSIONS

Topiramate adjunctive therapy was effective in reducing the number of drop attacks and major motor seizures and in improving seizure severity as determined by parental global evaluation.

Racial differences in free radical scavenging enzyme activity in children

Oxygen-derived free radicals play an important role in multiple pediatric neurologic diseases. Five intracellular free radical scavenging enzymes and three trace elements provide a significant portion of the body's defenses against free radical-mediated injury. Although the effects of age, sex, and ethnicity on the body's antioxidant defenses have been described, no study has examined whether racial differences exist. This pilot study sought to determine the effect of racial differences on the activity of five free radical scavenging enzymes and the concentrations of three associated trace elements in normal, healthy American children. The erythrocyte and plasma activities of five major free radical scavenging enzymes (glutathione peroxidase, glutathione reductase, glutathione-S-transferase, catalase, and superoxide dismutase) and plasma concentrations of three associated trace elements (selenium, copper, and zinc) were determined for 83 healthy American children, aged 1 to 18 years. One- and two-way interactions of race, age, and sex with each dependent variable were analyzed. African-Americans had higher erythrocyte glutathione peroxidase activity, erythrocyte superoxide dismutase activity, and selenium and copper concentrations than Caucasians. Racial inequalities do exist in free radical scavenging enzyme activity and trace element concentration in healthy children. African-American children had higher activity in the two most important free radical scavenging enzymes used by the brain compared to age- and sex-matched Caucasian children. Future clinical research in free radical-mediated pediatric neurologic diseases needs to consider race along with age and sex in both study design and data analysis.

Topiramate pharmacokinetics in infants

PURPOSE

This study's goal was to provide preliminary data on the pharmacokinetics of topiramate (TPM) in a cohort of infants (younger than 4 years) participating in an open-label trial of TPM in refractory infantile spasms.

METHODS

The pharmacokinetics of TPM were assessed in infants receiving a stable TPM dose for >7 days during the extension phase of this trial. Blood samples were drawn just before and 0.5. 1, 1.5, 2, 4, 6, 8, and 12 h after the morning TPM dose. TPM plasma concentrations were determined by fluorescence polarization immunoassay. The noncompartmental analysis module of WinNonlin was used to calculate individual patient pharmacokinetics profiles.

RESULTS

Five infants (ages, 23.5-29.5 months) formed the study cohort. These infants had been given TPM for a median of 9 months (range, 6-11 months) and were currently receiving between 11 and 38.5 mg/kg/day TPM. One was receiving TPM monotherapy, whereas four were taking concomitant antiepileptic medications (AEDs; n = 2, enzyme-inducing agents; n = 2, non-enzyme-inducing drugs). TPM pharmacokinetics in infants appears to be linear. In this cohort, mean TPM plasma clearance (CL/F, 66.6+/-27.4 ml/h/kg) was slightly higher than that reported for children and adolescents and therefore substantially higher than that reported for adults. TPM CL/F was higher and the calculated half-life shorter in the infants receiving concomitant enzyme-inducing AEDs.

CONCLUSIONS

Based on this small cohort of patients, it appears that infants may require significantly larger TPM doses, based on weight, than children, adolescents, or adults. Titration to effect and not absolute TPM dose should guide therapy in this age group.

Automated microanalysis of gabapentin in human serum by high-performance liquid chromatography with fluorometric detection

An automated high-performance liquid chromatographic method for the determination of gabapentin, 1-(amino-methyl)cyclohexaneacetic acid, in serum is described. The procedure involves protein precipitation with methanol followed by using a robotized derivatization with o-phthaldialdehyde reagent and automated high-performance liquid chromatography. The analog of gabapentin, 1-(aminomethyl)cycloheptaneacetic acid, was used as the internal standard. Blank serum was fortified with gabapentin (0.1-10.0 microg/ml) and internal standard. Separation was achieved on a Waters 5-microm reversed-phase column (10 cmx4.6 mm) with mobile phase consisting of 0.02 M phosphate buffer (pH 4.5)-acetonitrile (50:50, v/v). Eluents were monitored by fluorescence spectroscopy with excitation and emission wavelengths of 230 and 420 nm, respectively. The calibration curve for gabapentin in serum was linear (r=0.999) over the concentration range 0.1-10.0 microg/ml. The inter- and intraassay variations for three different gabapentin concentrations were < or =10% throughout. The lower limit of quantitation was found to be 0.1 microg/ml. Chromatography was unaffected by a range of commonly employed antiepileptic drugs or selected amino acids.

A double-blind, randomized trial of topiramate as adjunctive therapy for partial-onset seizures in children. Topiramate YP Study Group

OBJECTIVE

To evaluate the efficacy and safety of topiramate 6 mg/kg/day in children (age 2 to 16 years) as adjunctive therapy for uncontrolled partial-onset seizures with or without secondarily generalized seizures in a multicenter, randomized, double-blind, placebo-controlled trial.

METHODS

Patients with at least six partial-onset seizures during the 8-week baseline phase were treated with either topiramate (n = 41) or placebo (n = 45) for 16 weeks.

RESULTS

Topiramate-treated patients had a greater median percent reduction from baseline in average monthly partial-onset seizure rate than placebo-treated patients (33.1% versus 10.5%, p = 0.034), a greater proportion of treatment responders (i.e., patients with a > or = 50% seizure rate reduction; 16 of 41 [39%] versus 9 of 45 [20%], p = 0.080), and patients with a > or = 75% seizure rate reduction (7 of 41 [17%] versus 1 of 45 [2%], p = 0.019), and better parental global evaluations of improvement in seizure severity (p = 0.019). Emotional lability (12% versus 4%), fatigue (15% versus 7%), difficulty with concentration or attention (12% versus 2%), and forgetfulness/impaired memory (7% versus 0%) were more frequent among topiramate-treated than placebo-treated patients. Most treatment-emergent adverse events were mild or moderate in severity. No topiramate-treated patients discontinued the study due to adverse events.

CONCLUSIONS

Topiramate was safe and effective in the treatment of partial-onset seizures in children.

A pilot study of topiramate in the treatment of infantile spasms

PURPOSE

West syndrome is a rare epileptic syndrome associated with infantile spasms, a specific abnormal electroencephalographic pattern (termed hypsarrhythmia), and mental retardation. Management of this disorder is difficult because current treatment regimens, including many anticonvulsants and hormones, are often ineffective. Topiramate (TPM) is a new antiepileptic drug that may be effective in pediatric epilepsies. We conducted a pilot study to test the effects of rapid TPM dosing in patients with refractory infantile spasms.

METHODS

Eleven children with refractory infantile spasms were given an initial dose of 25 mg TPM per day in addition to their current therapy. Dosage was increased by 25 mg every 2-3 days until spasms were controlled, the maximal tolerated dose was reached, or the maximal dose of 24 mg/kg/day was achieved. Efficacy was primarily assessed by video EEG and secondarily by parental count of spasm frequency.

RESULTS

Five (45%) subjects became spasm free during the study, with absence of infantile spasms and hypsarrhythmia (either classic or modified) proven by video EEG. Nine subjects, including the five spasm free, achieved a spasm reduction of > or =50%. Spasm frequency decreased from 25.6+/-19.3 to 6.9+/-5.9 spasms/day. Sixty-four percent of the subjects were able to achieve TPM monotherapy.

CONCLUSIONS

Results in this cohort of 11 patients with refractory disease show TPM to be a promising new agent for the treatment of infantile spasms.

Need for electroencephalogram video confirmation of atypical absence seizures in children with Lennox-Gastaut syndrome

Children with childhood epileptic encephalopathy (Lennox-Gastaut syndrome) frequently have both multiple seizure types and nonepileptic stereotyped events that are difficult to differentiate. We hypothesize that electroencephalogram (EEG) video monitoring is essential for correct identification of atypical absence seizures in this population. All video/EEG monitoring records on patients with confirmed Lennox-Gastaut syndrome between September 1992 and December 1996 were reviewed for clinical events and EEG changes. A subset of patients with suspected atypical absence seizures during the video/EEG formed the cohort for analysis. Thirty-eight patients had 48 monitoring periods ranging from 1 to 4 days (mean, 2.2 days). Twenty-six monitoring periods captured suspected atypical absence seizures and formed the study cohort. Suspected atypical absence seizures were epileptic seizures in only 27% (7 of 26) of the study cohort. By contrast, parents reliably and correctly identified tonic, atonic, and tonic-clonic seizures in the study cohort. Reliable diagnosis and subsequent counting of atypical absence seizures in patients with Lennox-Gastaut syndrome cannot be made on the basis of observation and/or history alone. Future outpatient studies of investigational anticonvulsant medications for patients with Lennox-Gastaut syndrome should consider parental counts of atypical absence seizures unreliable. We recommend that video/EEG monitoring be done on all Lennox-Gastaut syndrome patients with suspected atypical absence seizures not controlled by medication.

Altered antioxidant enzyme activities in children with a serious adverse experience related to valproic acid therapy

Specific oxidative metabolites of valproic acid (VPA) have been associated with the clinically defined toxicity of the drug. To investigate the role of enzymatic detoxification in clinical toxicity, we compared activities of five antioxidant enzymes in 15 patients with a serious adverse experience (SAE) related to VPA therapy, to enzyme activities measured in 35 patients with good clinical tolerance of VPA, and 50 healthy, age-matched subjects. These enzymes included glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), glutathione transferase, superoxide dismutase, and catalase in erythrocytes; and GSH-Px in plasma. We also determined levels of Se, Cu, and Zn, trace elemental cofactors for these enzymes, in plasma from each individual. In patients with a VPA-associated SAE, GSH-Px was significantly depressed and GSSG-R was significantly elevated relative to values for the other groups. Selenium and zinc concentrations were lower in SAE patients than in controls. These findings may indicate a role for selenium dependent antioxidant activity in individual susceptibility to an SAE related to VPA therapy.

Topiramate use in pediatric patients

Topiramate (TPM), a new antiepileptic medication, is efficacious as adjunctive therapy in adults with partial onset seizures. Its efficacy as adjunctive therapy in children was evaluated in two randomized double-blind placebo-controlled trials involving childhood epileptic encephalopathy (the Lennox-Gastaut syndrome) and partial onset seizures. In these studies, topiramate adjunctive therapy resulted in a significant reduction in drop attacks (tonic or atonic seizures) in patients with the Lennox Gastaut syndrome and a significant reduction in partial onset seizures in children with refractory partial epilepsy. In both trials, TPM's efficacy improved as the dose escalated from the double-blind phase to the open-label portion. The minimally effective topiramate dose for adjunctive therapy in children with refractory epilepsy appears to be 6 mg/kg/day. Topiramate was well tolerated with mild or moderate side effects, predominantly related to the central nervous system. Practical tips are provided that may increase the chance that topiramate will be effective and well tolerated. The most important advice is a "start low, go slow" approach. An initial TPM dose of 0.5-1 mg/kg/day followed by weekly increments of 0.5-1 mg/kg is usually well tolerated. Based on these studies, topiramate appears to be an important addition to our pediatric AED armamentarium.

Short-term and long-term memory in early temporal lobe dysfunction

Following medial temporal damage, mature humans are impaired in retaining new information over long delays but not short delays. The question of whether a similar dissociation occurs in children was addressed by testing children (ages 7-16) with unilateral temporal lobe epilepsy (TLE) and controls on short- and long-term memory tasks, including a spatial delayed response task (SDR). Early-onset TLE did not affect performance on short delays on SDR, but it did impair performance at the longest delay (60 s), similar to adults with unilateral medial temporal damage. In addition, early-onset TLE affected performance on pattern recall, spatial span, and verbal span with rehearsal interference. No differences were found on story recall or on a response inhibition task.

Topiramate

Clinical evidence is emerging that topiramate (TPM) may be effective in pediatric epilepsies. Topiramate pharmacokinetics appear to be linear in children when administered in dosages up to 9 mg/kg/d. Mean oral clearance is 44% to 54% higher in children when compared with historical data from adults; steady-state plasma TPM concentrations for the same mg/kg dose are expected to be 33% lower in children. While double-blind, placebo-controlled trials of adjunctive TPM therapy in Lennox-Gastaut syndrome, primary generalized tonic-clonic seizures, and refractory partial-onset seizures in children are ongoing, preliminary results of pilot studies and the open-label extension phases of these double-blind studies suggest TPM may be effective as adjunctive therapy in a broad range of seizure disorders. In the open-label extension phase of a double-blind trial, the proportion of patients with Lennox-Gastaut syndrome experiencing 50% or greater reduction in seizures was 47%. Likewise, seizures were reduced 50% or more with TPM adjunctive therapy in 64% of children with partial-onset seizures and in 67% of patients with primary generalized tonic-clonic seizures treated with open-label during the extension phase of two separate double-blind studies. Preliminary experience suggests that TPM monotherapy can be successfully substituted for another antiepileptic drug in some children. The results of the well-controlled trials are needed to confirm these preliminary observations of TPM effectiveness in pediatric epilepsies.

Preliminary observations on topiramate in pediatric epilepsies

Preliminary results of studies of topiramate (TPM) in children are now available. In a pharmacokinetic study among 18 male and female children, target daily dosages of up to 9 mg/kg/day were evaluated. TPM pharmacokinetics in children were linear. Mean TPM oral clearance (CL/F) was 44-54% higher in children [depending on concomitant antiepileptic drugs (AEDs)] compared with historical data from adults, and steady-state plasma TPM concentrations for the same mg/kg dose were 33% lower in children compared with historical adult data. In a long-term, open-label pilot study of adjunctive TPM therapy in 18 patients with Lennox-Gastaut syndrome, six of the eight patients (75%) still receiving TPM report a greater than 50% reduction in total seizures, with the best results observed in tonic-atonic, atypical absence, and generalized tonic-clonic seizures. Subsequent large double-blind, placebo-controlled trials of adjunctive TPM therapy in Lennox-Gastaut syndrome and refractory partial-onset pediatric epilepsy are ongoing, with high percentages of enrolled patients in both studies completing double-blind treatment and entering long-term TPM open extension trials. A small TPM monotherapy substitution trial in children with well controlled partial onset seizures showed that TPM monotherapeutic substitution can be achieved successfully with an acceptable amount of adverse experiences with a weekly increase of 1 mg/kg/day to a maximal dose of 3 mg/kg/day. These preliminary results suggest that TPM may be a useful new AED in pediatric patients with a variety of seizure disorders.

Lamotrigine adjunctive therapy in childhood epileptic encephalopathy (the Lennox Gastaut syndrome)

PURPOSE

We assessed efficacy and safety of adjunctive lamotrigine (LTG) therapy in patients with the Lennox-Gastaut syndrome (LGS).

METHODS

The study was a single-center, retrospective chart review of open-label adjunctive LTG therapy in patients with LGS. Initial LTG dose and titration was dependent on concomitant antiepileptic drugs (AEDs). Efficacy was based on the change in seizure frequency between the initiation of LTG therapy and December 1, 1995 (or LTG discontinuation). Seizure diaries were used to count patient seizures. A secondary evaluation of efficacy was a parental or guardian assessment of the patient's global status. The evaluation of safety involved chart review for treatment-emergent adverse events (AE).

RESULTS

Data from 16 LGS patients were analyzed. Fifty-three percent (8 of 15) had a > 50% reduction in seizure frequency with LTG adjunctive therapy. Tonic, atonic, generalized tonic-clonic (GTCS), and atypical absence seizure frequency but not myoclonic seizure frequency decreased significantly during LTG therapy. Fifty-three percent of the patient's parents (8 of 15) reported that their child's quality of life (QOL) was much or very much improved during the study. The major treatment-emergent AE were infection (50%, 8 of 16) and sleep disturbance (19%, 3 of 16). A rash was noted in 13% (2 of 16) of the patients and resulted in LTG discontinuation in 1. No clinically significant changes were noted in neurologic examination or laboratory tests during the study.

CONCLUSIONS

Our results indicate that LTG adjunctive therapy is effective and well tolerated in patients with LGS.

Pediatric epilepsy syndromes

The development of an international classification for epilepsies and epileptic syndromes has led to substantial progress in the understanding and treatment of patients with epilepsy. Epilepsies and epileptic syndromes are partitioned first by seizure type and then by etiology. This manuscript describes recent advances in six major pediatric epilepsy syndromes. The first three discussed (benign childhood epilepsy with centrotemporal spikes, juvenile myoclonic epilepsy, and childhood absence epilepsy) are the three most common epilepsy syndromes, and each has been the focus of significant research. Patients with benign childhood epilepsy with centrotemporal spikes (benign rolandic epilepsy) may not require anticonvulsant therapy, and their seizures always remit by midadolescence. Juvenile myoclonic epilepsy was the first major epilepsy syndrome for which a gene locus was found. The underlying neuronal pathways and cellular mechanisms of the generalized absence seizures of childhood absence epilepsy are well delineated. The last three syndromes discussed (West syndrome, Lennox-Gastaut syndrome, and acquired epileptic aphasia) are devastating catastrophic epileptic syndromes. The focus of research in West syndrome (infantile spasms) has been to develop better therapeutic interventions (both medical and surgical) and an improved understanding of its pathogenesis. New effective medications are available for patients with Lennox-Gastaut syndrome (childhood epileptic encephalopathy), but one of them (felbamate) has been associated with previously unrecognized serious side effects. Lastly, acquired epileptic aphasia is an example of a poorly understood epilepsy syndrome. A multicenter group has been organized to reexamine this syndrome and produce a better understanding of its pathogenesis and treatment.

Comparison of erythrocyte antioxidant enzyme activities and embryologic level of neural tube defects

Increased exposure to oxidant-derived free radicals or inadequate systems for antioxidant defense could alter cellular response at critical points in development. We measured 5 antioxidant enzymes, glutathione peroxidase (GSH-Px), glutathione reductase, glutathione-S-transferase, catalase and superoxide dismutase in erythrocytes and their plasma cofactor trace elements (Se, Zn, Cu) in 37 children with myelomeningocele and in 37 age-matched controls. We placed the patients into 3 groups according to motor level of the lesion at birth. We found significantly lower GSH-Px activities (p = 0.007) in children with myelomeningocele. For paired comparisons among the 3 patient groups and controls, there were significant differences (p < 0.05) between controls and both high (thoracic) and raid (lumbar) level embryologic lesions. The finding of antioxidant enzyme variations in our patients with myelomeningocele may indicate a role for abnormal oxidative metabolism in the development of this defect. The contribution of oxidative stress to human birth defects warrants investigation. We discuss potential relationships between oxidative stress and energy metabolism during primary neurulation.

Cerebral infarction in sickle cell disease: transcranial Doppler US versus neurologic examination

PURPOSE

To evaluate flow velocity measurements in the middle cerebral artery (MCA) and/or neurologic examination for detection of cerebral infarction in sickle cell disease (SCD).

MATERIALS AND METHODS

Twenty-four pediatric patients aged 6 1/2-17 years with SCD underwent magnetic resonance (MR) imaging, MR angiography, neurologic examination, and transcranial Doppler ultrasonography (US). Transcranial Doppler studies were evaluated for maximum flow velocity in the right and left MCAs. Combinations of cut-off values were used to determine the sensitivity and specificity of transcranial Doppler US for detection of infarction.

RESULTS

Neurologic examination had 58% sensitivity and 92% specificity for cerebral infarction. Maximal flow velocity > 200 cm/sec or < 100 cm/sec (including no flow) helped identify nine of 12 patients with infarcts proved at MR imaging, with only one false-positive result (sensitivity, 75%; specificity 92%). The combination of neurologic examination and transcranial Doppler US produced 92% sensitivity and 83% specificity for cerebral infarction.

CONCLUSION

The combination of transcranial Doppler US and neurologic examination has potential as a screening technique for infarction in SCD.

Accuracy of neurologic examination and history in detecting evidence of MRI-diagnosed cerebral infarctions in children with sickle cell hemoglobinopathy

We determined the accuracy of neurologic examination and the history of a previous neurologic event in detecting clinical evidence of a magnetic resonance imaging (MRI)-diagnosed cerebral infarction in 30 children with sickle cell hemoglobinopathy. Each patient had an MRI of the brain, neurologic examination, chart review, and psychometric evaluation. Seventeen children (57%) had MRI evidence of cerebral infarction based on demonstration of parenchymal abnormalities in a vascular distribution. Among the 17 children with MRI evidence of cerebral infarction, only 12 (71%) had an abnormal neurologic examination, and 11 (65%) had a history of a prior neurologic event. In contrast, among the 13 children with normal MRIs, 12 (92%) had normal neurologic examinations, and no child had a previous history of a neurologic event. Multiple, bilateral, heterogeneous cerebral infarctions frequently occur without overt neurologic signs or symptoms in children with sickle cell hemoglobinopathy. Previous studies that relied on a focal neurologic examination or a history of a neurologic event to identify cerebral infarctions in patients with sickle cell hemoglobinopathy most likely underrepresented the true frequency of cerebral infarctions in this population. Future prospective studies of cerebral infarctions in children with sickle cell hemoglobinopathy should include MRIs for identification and classification, rather than neurologic examination or clinical history alone.

Noninvasive central nervous system imaging in sickle cell anemia. A preliminary study comparing transcranial Doppler with magnetic resonance angiography

PURPOSE

We evaluated the accuracy of transcranial Doppler (TCD) and magnetic resonance angiography (MRA) as a screening modality for cerebral infarct in patients with sickle cell disease.

PATIENTS AND METHODS

Twenty-four patients with sickle cell disease were assessed for a cerebral infarct. Each patient underwent neurologic examination, psychometric evaluation, magnetic resonance imaging (MRI), MRA, and TCD. Presence of a cerebral infarct was determined by an MRI and supported by neurologic and neuropsychometric evaluation. All investigators were unaware of the patient's status. Cerebral vasculature by MRA was categorized as being occluded, stenotic, or normal. The maximum TCD velocity of the right and left middle cerebral artery were assessed. Various cutoffs were used to determine the sensitivity and specificity of TCD.

RESULTS

MRA had a sensitivity and specificity of 100% and 92%, respectively. At a maximum velocity cutoff of 180 cm/s, the sensitivity and specificity of TCD were 20% and 67%, respectively. No maximum velocity on TCD produced both sensitivity and specificity > 50%.

CONCLUSION

MRA is more sensitive than TCD when the middle cerebral artery for maximum velocity is compared. Prospective evaluation is warranted to determine if TCD is useful as a screening technique for cerebral infarction in children with SCD.

Reversible metabolic myopathy in biotinidase deficiency: its possible role in causing hypotonia

A 5-year-old girl diagnosed with biotinidase deficiency at 9 months of age demonstrated limb and axial hypotonia which improved on biotin therapy. In this patient, electromyographic (EMG) studies prior to treatment were compatible with a mild myopathic process. Serial EMGs performed on biotin therapy demonstrated a gradual resolution of the myopathy. This is the first documented case of a reversible myopathy in a patient with biotinidase deficiency, which may contribute to the clinical findings of hypotonia.