Clinical experience with zonisamide monotherapy and adjunctive therapy in children with epilepsy at a tertiary care referral center

Effectiveness of zonisamide in childhood refractory epilepsy

INTRODUCTION

Zonisamide (ZNS) is a new generation antiepileptic drug (AED) used in refractory epilepsy. This study assessed the effectiveness and reliability of ZNS in childhood refractory epilepsy.

METHOD

Sixty-eight epilepsy patients who were followed up in the paediatric neurology clinic, between 2013 and 2019, and in whom add-on therapy ZNS had been added as their seizures had continued despite multiple drugs being used, were included in this retrospective study. Their demographic findings, seizure aetiology, pre-treatment and post-treatment electroencephalography findings, treatment responses and any side effects of the drugs given were assessed in these patients.

RESULTS

There were 46 (67.6%) patients in the refractory generalized epilepsy (RGE) group using multiple AEDs and 22 (32.35%) patients in the refractory focal epilepsy (RFE) group. Of these patients, 12 (17.65%) were being followed up for idiopathic epilepsy and 8 (11.76%) were being followed up for epilepsy of unknown aetiology. Twenty-two (32.36%) patients were followed up for structural abnormality, 8 patients (11.77%) were followed up for genetic disease, 4 patients (5.88%) were followed up for infectious sequel, 14 patients (20.59%) were followed up for metabolic reasons. In the RGE group, a more than 50% reduction was found in the seizures of 26 (56.5%) patients, while the seizures of 7 (15.2%) patients were found to have terminated completely. In the RFE group, a more than 50% reduction was found in the seizures of 19 (86.4%) patients, while the seizures of 2 (9.1%) patients were found to have terminated completely. The termination or a more than 50% reduction in seizures in 4 of the 6 patients followed up for a diagnosis of tuberous sclerosis complex (TSC) was significant.

CONCLUSION

ZNS is an effective and reliable option as an add-on therapy in paediatric refractory epilepsy, especially in focal epilepsy. It can also be considered for treatment in TSC patients.

Treatment for the Benign Childhood Epilepsy With Centrotemporal Spikes: A Monocentric Study

Background and Purpose: To date, there is no specific treatment guideline for the benign childhood epilepsy with centrotemporal spikes (BECTS). Several countries recommend levetiracetam, carbamazepine, sodium valproate, oxcarbazepine, and lamotrigine as first-line drugs. Nevertheless, some of these drugs are associated with cognitive decline. Available studies that investigated the efficacy of levetiracetam and sodium valproate on BECTS involved small sample sizes. This study aimed to evaluate the efficacy of levetiracetam and sodium valproate on cognition, and to investigate the prognostic factors for BECTS as whole.

Methods: Clinical data and treatment status of all patients with BECTS at Xiangya Hospital, Central South University followed from 2008 to 2013 were analyzed retrospectively. Since electrical status epilepticus in sleep (ESES) has been confirmed to play a role in cognitive deterioration, in order to evaluate the response to drugs and their cognitive effects, we created two groups of patients according to the levels of spike wave index (SWI): group 1; 0–50% SWI and group 2; >50% SWI at the last follow up.

Results: A total of 195 cases were enrolled: 49.7% received monotherapies, 24.1% duotherapies and 27.2% polytherapies. Medications included; levetiracetam plus other drug (s) (75.9%), levetiracetam alone (32.8%), sodium valproate plus other drug (s) (31.3%), and sodium valproate alone (5.1%). After 2 years of treatment and follow up, 71% of the cases had a good seizure outcome, 15.9% had an improvement of SWI, and 91.7% had a normal DQ/IQ. Sodium valproate combined with levetiracetam, and sodium valproate alone correlated with good improvement of SWI, whereas, focal spikes were linked with poor improvement. For both groups (group 1 and group 2): monotherapy, levetiracetam alone, and a normal DQ/IQ at seizure onset correlated with good cognitive outcomes, in contrast, polytherapy, sodium valproate plus other drug (s), levetiracetam plus sodium valproate, an initial SWI of ≥85%, and multifocal spikes were linked to cognitive deterioration.

Conclusions: Monotherapy, particularly levetiracetam seems to be a good first-line therapy which can help in normalizing the electroencephalograph and preventing cognitive decline. Polytherapy, mostly the administration of sodium valproate seems to relate with poor cognition, therefore, it is recommended to avoid it.

Our reasons for converting to valproic acid treatment in female patients with genetic generalized epilepsy: a retrospective, single-centre study

INTRODUCTION AND AIM

Valproic acid (Na valproate) is a broad-spectrum anti-seizure medication used in children and adolescents. It is thought to have fewer adverse effects; however, recent studies have restricted its use in women of reproductive age due to the teratogenic impacts on cognition. Although alternative drugs have been used to treat patients in clinical follow-up, some patients have to return to using valproic acid. Our study aimed to determine the rate of return to valproic acid treatment in female patients with follow-up in our centre and the reasons for the return.

MATERIALS AND METHODS

Female patients with genetic generalized epilepsy who were followed up in our centre were included in the study. Patient data were retrospectively obtained from file records. The patients were grouped by seizure subgroups, antiepileptic treatment used, electroencephalography characteristics, and seizure treatment response.

RESULTS

Sixty-three (31.7%) of the 199 patients had to return to VPA treatment. When the reasons for the discontinuation of other drugs were examined, non-response to treatment was found in 80.0% of patients, adverse medication effects in 18.3%, and 1.7% continued voluntarily. Patients who are JAE subtypes were more likely to return to VPA treatment than GTCS alone subtypes. A total of 7.4% of patients converted to VPA therapy had continued myoclonic seizures compared with 20.4% of patients treated with alternative drugs.

CONCLUSION

VPA treatment is not used as the first choice in females of reproductive age; however, some patients will only achieve seizure control with valproate, especially those with myoclonic seizures and JAE.

Long-term effects of adjunctive perampanel on cognition in adolescents with partial seizures

OBJECTIVE

The aim of this study was to evaluate long-term effects of adjunctive perampanel on cognition, efficacy, growth, safety, and tolerability in adolescents with inadequately controlled partial seizures.

METHODS

Study 235, a multicenter, randomized, double-blind, placebo-controlled, parallel-group, Phase II study with an open-label extension phase (NCT01161524), was primarily designed to assess the effects of adjunctive perampanel on cognition. Patients (aged ≥12 to <18years) had a diagnosis of epilepsy with inadequately controlled partial seizures, with or without secondary generalization, despite receiving 1-3 antiepileptic drugs. During the double-blind phase, adjunctive perampanel or placebo was administered over a 6-week titration period and a 13-week maintenance period up to 12mg/day. During the extension phase, all patients received perampanel. Data from the extension phase are presented here. Study endpoints included change from baseline in Cognitive Drug Research (CDR) measures of cognition, seizure frequency, growth, development, the occurrence of treatment-emergent adverse events (TEAEs), and laboratory values.

RESULTS

A total of 114 patients entered the extension phase (prior double-blind treatment: placebo, n=41; perampanel, n=73). Perampanel had no effect on the CDR system global cognition score, continuity of attention, quality of episodic memory, quality of working memory, or speed of memory but was associated with a significant decline in power of attention at end of treatment compared with baseline (p=0.03). There were no effects on language skills or manual dexterity from baseline to end of treatment. At Weeks 40-52, median reduction in seizure frequency was 74.1%, and 50% responder rate was 66.0%. There were no clinically relevant effects of perampanel on growth or development at end of treatment compared with baseline. Overall, 84.2% of patients experienced at least one TEAE and 70.2% experienced at least one treatment-related TEAE. The most common TEAEs were dizziness (29.8%) and somnolence (19.3%). The TEAEs resulted in the discontinuation of treatment in 6.1% of patients.

CONCLUSIONS

In keeping with the 19-week double-blind phase, long-term adjunctive treatment with perampanel did not have any significant overall effects on the CDR system global cognition score in adolescent patients with inadequately controlled partial seizures. Similar trends were observed across the individual CDR system domains. Adjunctive perampanel showed sustained long-term seizure control and had a safety and tolerability profile similar to that observed in prior clinical studies.

Psychiatric and behavioral side effects of anti-epileptic drugs in adolescents and children with epilepsy

PURPOSE

The objective of the study was to compare the psychiatric and behavioral side effect (PBSE) profiles of both older and newer antiepileptic drugs (AEDs) in children and adolescent patients with epilepsy.

METHOD

We used logistic regression analysis to test the correlation between 83 non-AED/patient related potential predictor variables and the rate of PBSE. We then compared for each AED the rate of PBSEs and the rate of PBSEs that led to intolerability (IPBSE) while controlling for non-AED predictors of PBSEs.

RESULTS

922 patients (≤18 years old) were included in our study. PBSEs and IPBSEs occurred in 13.8% and 11.2% of patients, respectively. Overall, a history of psychiatric condition, absence seizures, intractable epilepsy, and frontal lobe epilepsy were significantly associated with increased PBSE rates. Levetiracetam (LEV) had the greatest PBSE rate (16.2%). This was significantly higher compared to other AEDs. LEV was also significantly associated with a high rate of IPBSEs (13.4%) and dose-decrease rates due to IPBSE (6.7%). Zonisamide (ZNS) was associated with significantly higher cessation rate due to IPBSE (9.1%) compared to other AEDs.

CONCLUSION

Patients with a history of psychiatric condition, absence seizures, intractable epilepsy, or frontal lobe epilepsy are more likely to develop PBSE. PBSEs appear to occur more frequently in adolescent and children patients taking LEV compared to other AEDs. LEV-attributed PBSEs are more likely to be associated with intolerability and subsequent decrease in dose. The rate of ZNS-attributed IPBSEs is more likely to be associated with complete cessation of AED.

Efficacy and safety of zonisamide in Thai children and adolescents with intractable seizures

This retrospective study examined the efficacy and safety of zonisamide for Thai children and adolescents with intractable seizures. The medical records of 24 patients (13 male, 11 female), aged 2 to 18 years (median 11.5, mean 10.4) who received zonisamide were reviewed. The underlying illness, etiology of epilepsy, seizure types, previous and concomitant antiepileptic drugs, dosage, and adverse effects of the drug were collected. Zonisamide's efficacy was evaluated on the basis of seizure reduction rates. At final evaluation, 7 patients were still taking zonisamide from 4.7 to 10.3 mg/kg/d (median 8). One patient became seizure-free and the other 6 experienced favorable seizure control. The median duration of zonisamide therapy was 23.75 months (range 20.5-25 months). Minor adverse effects were reported in 41.6% of patients during the first 3 months of therapy. Zonisamide is an option for the treatment of intractable seizures with favorable seizure control in children and adolescents.

Zonisamide as a treatment for partial epileptic seizures: a systematic review

Although the majority of people with epilepsy have a good prognosis and their seizures can be well controlled with pharmacotherapy, up to one-third of patients can develop drug-resistant epilepsy, especially those patients with partial seizures. This unmet need has driven considerable efforts over the last few decades aimed at developing and testing newer antiepileptic agents to improve seizure control. One of the most promising antiepileptic drugs of the new generation is zonisamide, a benzisoxazole derivative chemically unrelated to other anticonvulsant agents. In this article, the authors present the results of a systematic literature review summarizing the current evidence on the efficacy and tolerability of zonisamide for the treatment of partial seizures. Of particular interest within this updated review are the recent data on the use of zonisamide as monotherapy, as they might open new therapeutic avenues.

Update on once-daily zonisamide monotherapy in partial seizures

Zonisamide is an antiepileptic drug that is structurally different from other antiepileptic agents. Its long half-life, once-daily dosing, lack of induction of hepatic enzymes, and broad spectrum of action makes it a suitable candidate for monotherapy. It has been approved as monotherapy for partial onset epilepsy in Japan and South Korea for more than a decade, and was recently approved as monotherapy in Europe. In the USA, it is only approved by the US Food and Drug Administration for adjunctive treatment of partial onset epilepsy. In this paper, we briefly review the literature on zonisamide monotherapy in partial onset epilepsy with regard to its efficacy, safety, tolerability, and long-term side effects, including a recent noninferiority trial in comparison with extended-release carbamazepine. While European regulatory agencies use noninferiority trials for approval of monotherapy, such a trial design does not meet the current regulatory requirements for approval as monotherapy in the USA.

A case of atypical absence seizures after electroconvulsive treatment in a patient with treatment-resistant depression

Electroconvulsive therapy (ECT) has been used to treat severe treatment-resistant major depressive disorder. Multiple psychotropic medications are usually prescribed in high doses prior to or concomitantly with ECT. Little is known about the interaction of ECT with psychotropic medications. ECT is known to induce seizures, but its tendency to induce absence seizures is not. We present a case of a 44-year-old female, on multiple psychotropic medications, who had frequent atypical absence seizures for many days after ECT. Electroencephalography (EEG) confirmed atypical absence seizures by the presence of typical 2.5 to 3 Hz generalized sharp and slow waves with disorganized background activity.

The cognitive impact of antiepileptic drugs

Effective treatment of epilepsy depends on medication compliance across a lifetime, and studies indicate that drug tolerability is a significant limiting factor in medication maintenance. Available antiepileptic drugs (AEDs) have the potential to exert detrimental effects on cognitive function and therefore compromise patient wellbeing. On the other hand, some agents may serve to enhance cognitive function. In this review paper, we highlight the range of effects on cognition linked to a variety of newer and older AEDs, encompassing key alterations in both specific executive abilities and broader neuropsychological functions. Importantly, the data reviewed suggest that the effects exerted by an AED could vary depending on both patient characteristics and drug-related variables. However, there are considerable difficulties in evaluating the available evidence. Many studies have failed to investigate the influence of patient and treatment variables on cognitive functioning. Other difficulties include variation across studies in relation to design, treatment group and assessment tools, poor reporting of methodology and poor specification of the cognitive abilities assessed. Focused and rigorous experimental designs including a range of cognitive measures assessing more precisely defined abilities are needed to fill the gaps in our knowledge and follow up reported patterns in the literature. Longitudinal studies are needed to improve our understanding of the influence of factors such as age, tolerance and the stability of cognitive effects. Future trials comparing the effects of commonly prescribed agents across patient subgroups will offer critical insight into the role of patient characteristics in determining the cognitive impact of particular AEDs.

Behavioral adverse effects of antiepileptic drugs in epilepsy

Patient tolerability is a significant limiting factor in the treatment of epilepsy and adverse effect profiles often determine drug retention rates. A full appreciation of the behavioral effects of a wide range of antiepileptic drugs (AEDs) is therefore essential to make informed treatment decisions. In this timely review, we highlight key alterations in mood, emotional experience, and other behavioral/psychiatric features, which can exert a crucial impact on patients' quality of life and well-being. With a view to prescribing both in general and in relation to more specific clinical characteristics, the evidence reviewed indicates that the incidence and characteristics of behavioral effects may be related to age, epilepsy type, the presence of learning disability, and previous psychiatric history. Medication parameters including dosage, titration rate, efficacy in controlling seizures, and concurrent AEDs can also contribute to the occurrence of behavioral effects. However, there are a number of limitations in drawing conclusions from the available literature. These include variation in study design, treatment group, and assessment tools that lead to difficulties comparing findings across studies, and problems with the consistency of available information relating to the study methodology. Future longitudinal studies assessing the impact of tolerance or developmental change on behavioral effects and specific studies comparing the effects of commonly prescribed agents across subgroups of patients with epilepsy will make an informative contribution to the available literature. A valuable outcome of further research may be the development of specific instruments that are sensitive to the behavioral effects associated with particular AEDs.

The safety and tolerability of newer antiepileptic drugs in children and adolescents

Childhood epilepsy continues to be intractable in more than 25% of patients diagnosed with epilepsy. The introduction of new anti-epileptic drugs (AEDs) provides more options for treatment of children with epilepsy. We review the safety and tolerability of seven new AEDs (levetiracetam, lamotrigine, oxcarbazepine, rufinamide, topiramate, vigabatrin and zonisamide) focusing on their side effect profiles and safety in children and adolescents. Many considerations that are specific for children such as the impact of AEDs on the developing brain are not addressed during the development of new AEDs. They are usually approved as adjunctive therapies based upon clinical trials involving adult patients with partial epilepsy. However, 2 of the AEDs reviewed here (rufinamide and vigabatrin) have FDA approval in the U.S. for specific Pediatric epilepsy syndromes, which are discussed below. The Pediatrician or Neurologists decision on the use of a new AED is an evolutionary process largely dependent on the patient characteristics, personal/peer experiences and literature about efficacy and safety profiles of these medications. Evidence based guidelines are limited due to a lack of randomized controlled trials involving pediatric patients for many of these new AEDs.

Review of therapeutic options for adjuvant treatment of focal seizures in epilepsy: focus on lacosamide

Epilepsy is one of the most common serious neurological conditions worldwide, with an age-adjusted incidence of approximately 50 per 100,000 persons per year in developed countries. Antiepileptic therapy can result in long-term remission in 60-70% of patients, but many patients will require combination treatment to achieve optimal seizure control, as monotherapy is ineffective at controlling seizures in 30-53% of patients. Despite the increase in available treatment options, patient outcomes have not improved significantly and there is still a need for more effective therapies. Drugs used in the treatment of focal-onset seizures are a diverse range of compounds, and in most cases their mechanism of action is unknown or poorly defined. This review discusses the efficacy and safety of the newer adjuvant antiepileptic therapies that may improve outcomes in patients unresponsive to monotherapy, including clobazam, vigabatrin, lamotrigine, gabapentin, topiramate, tiagabine, levetiracetam, oxcarbazepine, pregabalin, zonisamide and eslicarbazepine, with focus on lacosamide. Lacosamide has been shown to exert its anticonvulsant effects predominantly by enhancement of the slow inactivation of voltage-gated sodium channels. Lacosamide is indicated for use as adjuvant treatment of focal-onset seizures in patients with epilepsy, and there is some evidence that it may also be of use in patients with status epilepticus and cancer patients with epilepsy. The efficacy of lacosamide has been assessed in three randomized, double-blind, placebo-controlled clinical trials, all of which have shown lacosamide to be effective at reducing seizure frequency and increasing 50% responder rates in patients with focal-onset seizures. Long-term lacosamide treatment is generally well tolerated and is not associated with significant drug interactions; the availability of an intravenous form of the drug also makes it particularly useful for a broad range of patients.

Update on the newer antiepileptic drugs in child neurology: advances in treatment of pediatric epilepsy

The goal of epilepsy treatment is the prevention of recurrent seizures, and antiepileptic drugs (AEDs) are the mainstay. Uncontrolled seizures may cause medical, developmental, and psychologic disturbances. Treatment advances include 1) identification of the basic mechanisms of epilepsy and action of AEDs, 2) the introduction of many new AEDs, and 3) the use of neurostimulation, starting with vagus nerve stimulation. We must balance the efficacy of an AED versus its side effects, which if persistent, lead to patient discontinuation of the AED. Although all AEDs have a proven efficacy, they are differentiated by their efficacy for a given seizure type or epilepsy syndrome versus the side effects or tolerability. The many new AEDs give us a larger armamentarium for epilepsy treatment. We refer to studies and expert opinion consensus.

The safety and tolerability of newer antiepileptic drugs in children and adolescents

The newer antiepileptic drugs (AEDs) provide more therapeutic options and overall improved safety and tolerability for patients. To provide the best care, physicians must be familiar with the latest tolerability and safety data. This is particularly true in children, given there are relatively fewer studies examining the effects of AEDs in children compared with adults. Since we now have significant paediatric literature on each of these agents, we provide a comprehensive and current literature review of the newer AEDs, focusing on safety and tolerability data in children and adolescents. Because the safety profiles in children differ from those in adults, familiarity with this literature is important for child neurologists and other paediatric caregivers. We have organized the data by organ system for each AED for easier reference.

Absence seizures: a review of recent reports with new concepts

Absence seizures with bilateral spike-wave (SW) complexes at 3Hz are divided into the childhood form, with onset at around 6 years of age, and the juvenile form, with onset usually at 12 years of age. These seizures typically last 9-12s and, at times, are activated by hyperventilation and occasionally by photic stimulation. Generalized tonic-clonic (GTC) seizures may also occur, especially in the juvenile form. There may be cognitive changes, in addition to linguistic and behavioral problems. Possible mechanisms for epileptogenesis may involve GABAergic systems, but especially T-calcium channels. The thalamus, especially the reticular nucleus, plays a major role, as does the frontal cortex, mainly the dorsolateral and orbital frontal areas, to the extent that some investigators have concluded that absence seizures are not truly generalized, but rather have selective cortical networks, mainly ventromesial frontal areas and the somatosensory cortex. The latter network is a departure from the more popular concept of a generalized epilepsy. Between the "centrencephalic" and "corticoreticular" theories, a "unified" theory is presented. Proposed genes include T-calcium channel gene CACNA1H, likely a susceptible gene in the Chinese Han population and a contributory gene in Caucasians. Electroencephalography has revealed an interictal increase in prefrontal activity, essential for the buildup of the ictal SW complexes maximal in that region. Infraslow activity can also be seen during ictal SW complexes. For treatment, counter to common belief, ethosuximide may not increase GTC seizures, as it reduces low-threshold T-calcium currents in thalamic neurons. Valproic acid and lamotrigine are also first-line medications. In addition, zonisamide and levetiracetam can be very helpful in absence epilepsy.

Open-label, long-term safety study of zonisamide administered to children and adolescents with epilepsy

BACKGROUND

Zonisamide is licensed in the EU and USA for the adjunctive treatment of partial-onset seizures in adults but there are few data about its use in children.

AIMS

To assess the long-term safety and efficacy of zonisamide in children and adolescents.

METHODS

Zonisamide-naïve patients (n=109, aged 3-15 years, weight >or=12.5 kg) with a clinical diagnosis of epilepsy (>or=4 seizures/month, receiving 1-2 antiepileptic drugs [AEDs] daily) received zonisamide once or twice daily in an open-label trial. The starting dose was 1mg/kg/day, increased by 2 mg/kg/day every 1-2 weeks at the investigator's discretion to an initial maximum of 12 mg/kg/day. The occurrence of adverse events (AEs) was the primary safety measure. Efficacy was measured via the reductions in seizure frequency and via investigator- and carer-rated global assessment ratings.

RESULTS

The mean dose received was 8.5 mg/kg/day. Of the 109 children, 52 (48%) completed 15 months' treatment. Treatment-related AEs, mostly mild-to-moderate in severity, were reported by 58 patients. Seven patients discontinued due to treatment-related AEs. Serious AEs (pancreatitis, decreased sweating, and vertigo) were reported by three patients. A significant (p=0.033) median reduction in 'all seizure' frequency of 2.60 seizures per week was observed. Additionally, a significant (p=0.029) median reduction of 1.80 seizures/week in 'complex partial' seizures was reported. Improvements in investigator- and carer-rated global assessments were noted.

CONCLUSIONS

Zonisamide treatment was generally well tolerated and was associated with significant reductions in seizure frequency in this pediatric population with a variety of both partial and generalized medically refractory epilepsy syndromes.

Zonisamide in children and young adults with refractory epilepsy: an open label, multicenter Italian study

PURPOSE

To report on the first multicenter Italian experience with zonisamide as an add-on drug for refractory generalised or partial epilepsy in children, adolescents and young adults.

METHODS

The patients were enrolled in a prospective, add-on, open-label treatment study from eight Italian centres for children and adolescent epilepsy care. Eighty-two young patients (45 males, 37 females), aged between 3 and 34 years (mean 13.1 years), all affected by partial (47) or generalised (35) refractory epilepsy, were enrolled in the study. ZNS was added to the baseline therapy at a starting dose of 1 mg/kg/day twice daily. This dose was increased by 2 mg/kg every 1-2 weeks over a period of up 3 months, according to the patient's response and tolerability, up to a maximum dose of 12 mg/kg. ZNS was given at the mean daily dose of 5.7/mg/kg/24 h (range 1-12 mg/kg).

RESULTS

After a mean follow-up period of 11.9 months (range 2-64 months), 9 patients (10.9%) were seizure-free. The number of seizures decreased by 50-99% in 31 cases (37.8%), by 25-49% in 5 cases (6.1%), remained the same in 29 cases (35.4%) and increased in 8 cases (9.7%). After 15 months of follow-up, 61 patients (74.4%) were still taking ZNS, while the remaining 21 (25.6%) had stopped. Twenty-two patients (26.8%) reported adverse effects while taking ZNS. They generally appeared during the first weeks of treatment, and were mild to moderate. The most frequent adverse effects were irritability and a reduced appetite.

CONCLUSION

ZNS effectively reduced seizure frequency in this pediatric population with both partial and generalised crypto/symptomatic refractory epilepsy. Its overall tolerability was good.

Long-term use of zonisamide in refractory childhood-onset epilepsy

This open label study examined the long-term efficacy and safety of zonisamide as adjunctive therapy in mentally retarded and multiple-handicapped patients with severe childhood-onset epilepsy. The study included 24 patients (mean age 12.5 years, range 2-40 years) which had different severe epilepsy syndromes (75% focal, 12.5% generalized, 12.5% refractory status epilepticus) refractory to at least 6 (median 10) anti-epileptic drugs. All patients were followed for at least 18 months after beginning of zonisamide treatment. Mean duration of zonisamide therapy was 55 weeks (range 5-168 weeks) and mean maintenance dosage was 7.7 mg/kg/day (range: 4-16 mg/kg/day). The patients received an average of 1.9 (range 1-3) concomitant antiepileptic drugs. The initial response rate defined as a > or =50% reduction of seizure frequency after 8 weeks was 58.3% (14 of 24 patients). Four of 14 initial responders developed loss of efficacy during long-term treatment. The retention rate after 18 months was 41.7% (10 of 24 patients). One patient (4.2%) became completely seizure-free after initiation of zonisamide treatment and remained seizure-free for the entire observation period of 18 months. Overall, zonisamide was well tolerated. Side effects were observed in 46% of patients and were mild to moderate. They mostly occurred during titration and subsided in maintenance dosing. Only in two patients (8.3%) zonisamide therapy was discontinued due to side effects (loss of appetite). No serious side effects were observed. These results are similar to the findings of Japanese studies suggesting that long-term use of adjunctive zonisamide therapy may be beneficial for treating mentally retarded, multiple handicapped patients with highly refractory childhood-onset epilepsy.

Zonisamide prophylaxis in refractory pediatric headache

INTRODUCTION

Currently, no medications are approved for pediatric headache prophylaxis in the United States. Zonisamide is an antiepileptic drug with preliminary studies suggesting some efficacy in the adult headache population.

METHODS

A retrospective chart review was conducted on refractory headache patients in our multidisciplinary Headache Clinic who were treated with zonisamide, an antiepileptic drug, for headache prophylaxis. Records were reviewed for pertinent data including patient history, diagnosis, prior treatment regimens, and zonisamide response, along with headache frequency.

RESULTS

Twelve patients were identified (8 girls); mean age was 13.5 years. Eight of the 12 patients had a positive response to zonisamide with greater than 50% reduction in headaches from pretreatment values.

CONCLUSION

Zonisamide had some efficacy in headache reduction. It was well tolerated with only minor side effects. Further prospective studies with zonisamide are warranted in refractory pediatric headache patients.

Efficacy and safety of zonisamide monotherapy in a cohort of children with epilepsy

The aim of this study was to evaluate the efficacy and safety of zonisamide monotherapy in a cohort of children and adolescents with various types of epilepsy. Retrospective review of charts of our institution from 2001 through 2004 identified 69 children (19 males and 50 females, mean age 13.2 years) with epilepsy on zonisamide monotherapy. Seizure count and side effect profile were maintained during therapy. Sixty-one percent had idiopathic generalized epilepsy, 4% symptomatic generalized epilepsy, and 35% partial-onset epilepsy. Zonisamide was the first-line and second-line monotherapy for 32% and 68% of patients, respectively. The mean duration of follow-up on treatment was 22 months (range 3-48 months). The overall efficacy of zonisamide was 75.4% (> or = 50% seizure frequency reduction: good responders). Sixty-seven percent of good responders became seizure-free. Seventy-nine percent of patients with partial epilepsy and 71% with generalized epilepsy were good responders, of whom 79% and 63% were free of seizure, respectively. Eighteen (26%) patients developed side effects: weight loss (9), cognitive impairment (3), sleepiness (3), dizziness (2), and decreased appetite (1). In seven patients (10%), zonisamide had to be discontinued: four due to side effects and three because of poor seizure control. Zonisamide was demonstrated to be effective as monotherapy in children with epilepsy.