[Partial seizures in childhood]

INTRODUCTION AND OBJECTIVE

Partial seizures make up 49.3% of the epilepsies of school-age children and adolescents, and is the most prevalent type of epilepsy. Patients with complex partial seizures have more recurrences than other patients who have generalized seizures. We analyze the factors which worsen the prognosis in refractory partial epilepsies, their cost in childhood, the characteristics of the new drugs, and the few comparative studies of combinations of these drugs in resistant partial crises of childhood.

DEVELOPMENT

The essential factors for prediction are previous brain damage, early onset of the seizures and presence on the EEG recording of marked paroxystic anomalies. Convincing studies on the economic aspects of the epilepsies should not be limited to the cost of the disease, but be descriptive studies which measure all the costs caused by epilepsy. It has been shown that the economic impact of the disorder on children with refractory epilepsy is 2.7 times the average cost of children whose seizures are well-controlled. There are no marked differences between the new antiepileptic drugs in the treatment of seizures of this type. Their appearance has led to reconsideration of what is rational bitherapy and what benefit may be obtained with it.

CONCLUSIONS

When possible associations of antiepileptic drugs are considered, one should take into account criteria of efficacy and toxicity, the pharmacodynamic characteristics of the drugs to be used together and their pharmacokinetic interactions. It is necessary to avoid drugs with a low therapeutic index to which tolerance may develop or which interact frequently, and antiepileptic drugs with a broad spectrum, high therapeutic index and few pharmacokinetic interactions should be preferred. The association of valproate and viagabatrin may be very beneficial, since it has been suggested that there is a synergistic reaction in patients with partial seizures that are resistant to other drugs. The efficacy of the association of valproate and viagabatrin has been shown in patients with refractory partial seizures, since they have different modes of action and different spectrums, different profiles of toxicity and no pharmacokinetic interactions. Finally, we describe the basic principles of treatment of refractory partial seizures of childhood.

Vagus nerve stimulation for medically refractory epilepsy; efficacy and cost-benefit analysis

INTRODUCTION

Vagus nerve stimulation is a novel treatment for patients with medically refractory epilepsy, who are not candidates for conventional epilepsy surgery, or who have had such surgery without optimal outcome. To date only studies with relatively short follow-up are available. In these studies efficacy increased with time and reached a maximum after a period of 6 to 12 months. Implantation of a vagus nerve stimulator requires an important financial investment but a cost-benefit analysis has not been published.

PATIENTS AND METHODS

Our own experience with VNS in Gent comprises 15 patients with mean age of 29 years (range: 17-44 years) and mean duration of epilepsy of 18 years (range: 4-32 years). All patients underwent a comprehensive presurgical evaluation and were found not to be suitable candidates for resective epilepsy surgery. Mean post-implantation follow-up is 24 months (range: 7-43 months). In patients with follow-up of at least one year, efficacy of treatment in terms of seizure control and seizure severity was assessed one year before and after the implantation of a vagus nerve stimulator. Epilepsy-related direct medical costs (ERDMC) before and after the implantation were also compared.

RESULTS

A mean reduction of seizure frequency from 14 seizures/month (range: 2-40/month) to 8 seizures/month (range: 0-30/month) was achieved (Wilcoxon signed rank test n = 14; p = 0.0016). Five patients showed a marked seizure reduction of > or = 50%; 6 became free of complex partial seizures, 3 of whom became entirely seizure free for more than 12 months; 2 patients had a worthwhile reduction of seizure frequency between 30-50%; in 2 patients seizure frequency reduction has remained practically unchanged. Seizure freedom or > or = 50% seizure reduction was achieved within the first 4 months after implantation in 6/11 patients. Before the implantation, the mean yearly epilepsy-related direct medical costs per patient were estimated to be 8830 US$ (n = 13; range: 1879-31,129 US$; sd = 7667); the average number of hospital admission days per year was 21 (range: 4-100; sd = 25.7). In the 12 months after implantation, ERDMC had decreased to 4215 US$ (range: 615-11,794 US$; sd = 3558) (Wilcoxon signed rank test n = 13; p = 0.018) and the average number of admission days to 8 (range: 0-35) (Wilcoxon signed rank test n = 13; p = 0.023).

CONCLUSION

VNS is an effective treatment of refractory epilepsy and remains effective during long-term follow-up. Cost-benefit analysis suggests that the cost of VNS is saved within two years following implantation.

Seizure control after stimulation of the vagus nerve: clinical outcome measures

BACKGROUND

Currently, decreases in seizure frequency are the accepted efficacy outcome measure of therapeutic interventions in the management of patients with epilepsy. In a longitudinal randomized controlled trial of 10 subjects with intractable complex partial seizures who received left vagal nerve stimulation (VNS) to control seizures, it was found that the total number of consecutive seizure-free days is a significant efficacy outcome measure. Unlike measures in which percentage decreases in seizure frequency are calculated, measures of consecutive seizure days indicate improvement in the amount of time for which patients may function at a higher level in activities of daily living.

METHODS

Fourteen day blocks of consecutive seizure-free days and 14 day blocks of consecutive days in which subjects had seizures were tabulated.

RESULTS

A Pearson correlation coefficient showed that prior to VNS subjects had few, if any, seizure free blocks of time and after VNS they had more blocks of time seizure free r = -1.00 and r = -0.99. The blocks of seizure-free days increased tenfold (mean 0.85 to mean 8.00) from 1991-1995 while mean seizure frequency in those blocks in which subjects had seizures only decreased from (mean 20.14 to mean 17.59) for the same time period. Correlations between total number of seizures after 24 months of VNS and after 50 months of VNS were r = 0.85 showing a consistency in the effect of VNS.

CONCLUSIONS

Monitoring the number of consecutive seizure-free days is a significant clinical outcome measure of VNS.

Cost-effectiveness of anterotemporal lobectomy in medically intractable complex partial epilepsy

PURPOSE

The value of high-cost health technologies is being increasingly scrutinized by providers of health care. An understanding of the costs and outcomes of high-technology epilepsy care is required to ensure efficient resource allocation.

METHODS

Decision analysis was used to estimate the cost effectiveness of anterotemporal lobectomy (ATL) as compared with standard medical management in medically-intractable epilepsy. Local (Rochester, NY, U.S.A.) cost data were applied to a model of lifetime discounted costs and outcomes of evaluation, ATL, and follow-up in a hypothetical cohort of patients.

RESULTS

Base case analysis yielded a marginal cost-effectiveness ratio (MECR) of $15.581/quality-adjusted life year (QALY). Extensive sensitivity analyses identified extreme conditions in which evaluation for ATL was dominant (more effective and less costly) or in which it might be considered not worth the cost (MCER > $50,000/QALY).

CONCLUSIONS

Estimates of ATL cost effectiveness fall within a generally acceptable range, even when uncertainty about many model parameters is taken into account. Under assumptions based on available data in the literature, the cost effectiveness of ATL compares favorably with that of other health technologies. Prospective multicenter studies of regional-cost and practice variations; long-term probabilities of year-to-year transitions between seizure outcome states and their effects on quality of life (QOL), and the effect of nonsurgical treatments on seizure control and QOL are needed to provide the critical data to confirm and constrain these estimates.