Comparison the cognitive effect of anti-epileptic drugs in seizure-free children with epilepsy before and after drug withdrawal

The effects of anticholinergic medications on cognition in children: a systematic review and meta-analysis

Cognitive side effects of anticholinergic medications in older adults are well documented. Whether these poor cognitive outcomes are observed in children has not been systematically investigated. We aimed to conduct a systematic review and meta-analysis on the associations between anticholinergic medication use and cognitive performance in children. Systematic review was conducted using Medline, PsychInfo, and Embase, identifying studies testing cognitive performance relative to the presence versus absence of anticholinergic medication(s) in children. We assessed effects overall, as well as relative to drug class, potency (low and high), cognitive domain, and duration of administration. The systematic search identified 46 articles suitable for meta-analysis. For the most part, random effects meta-analyses did not identify statistically significant associations between anticholinergic exposure and cognitive performance in children; the one exception was a small effect of anticholinergic anti-depressants being associated with better cognitive function (Hedges' g = 0.24, 95% CI 0.06-0.42, p = 0.01). Anticholinergic medications do not appear to be associated with poor cognitive outcomes in children, as they do in older adults. The discrepancy in findings with older adults may be due to shorter durations of exposure in children, differences in study design (predominantly experimental studies in children rather than predominantly epidemiological in older adults), biological ageing (e.g. blood brain barrier integrity), along with less residual confounding due to minimal polypharmacy and comorbidity in children.

Cannabidiol improves survival and behavioural co-morbidities of Dravet syndrome in mice

Background and Purpose

Dravet syndrome is a severe, genetic form of paediatric epilepsy associated with premature mortality and co‐morbidities such as anxiety, depression, autism, motor dysfunction and memory deficits. Cannabidiol is an approved anticonvulsive drug in the United States and Europe for seizures associated with Dravet syndrome in patients 2 years of age and older. We investigated its potential to prevent premature mortality and improve associated co‐morbidities.

Experimental Approach

The efficacy of sub‐chronic cannabidiol administration in two mouse models of Dravet syndrome was investigated. The effect of cannabidiol on neonatal welfare and survival was studied using Scn1a^−/− mice. We then used a hybrid, heterozygote Scn1a^+/− mouse model to study the effect of cannabidiol on survival and behavioural co‐morbidities: motor deficits (rotarod and static‐beam test), gait abnormality (gait test), social anxiety (social interaction test), anxiety‐like (elevated plus maze) and depressive‐like behaviours (sucrose preference test) and cognitive impairment (radial arm maze test).

Key Results

In Scn1a^−/− mice, cannabidiol increased survival and delayed worsening of neonatal welfare. In Scn1a^+/− mice, chronic cannabidiol administration did not show any adverse effect on motor function and gait, reduced premature mortality, improved social behaviour and memory function, and reduced anxiety‐like and depressive‐like behaviours.

Conclusion and Implications

We are the first to demonstrate a potential disease‐modifying effect of cannabidiol in animal models of Dravet syndrome. Cannabidiol treatment reduced premature mortality and improved several behavioural co‐morbidities in Dravet syndrome mice. These crucial findings may be translated into human therapy to address behavioural co‐morbidities associated with Dravet syndrome.

The P300 Event-Related Potential Component and Cognitive Impairment in Epilepsy: A Systematic Review and Meta-analysis

Background: Epilepsy is one of the most prevalent chronic brain diseases worldwide and is often accompanied by cognitive impairment. Event-related potentials (ERPs) are an objectively non-invasive approach for studying information processing and cognitive functions in the brain. The P300 is an important and extensively explored late component of ERPs that has been widely applied to assess cognitive function in epilepsy in previous studies. However, consistent conclusions have not yet been reached for various reasons.

Objective: We conducted a comprehensive systematic review and meta-analysis of P300-related studies to assess the latency and amplitude of the P300 in epileptic patients.

Methods: PubMed, EMBASE, and Cochrane Library databases were systematically searched for eligible studies. The standard mean difference (SMD) and the 95% confidence interval (CI) were calculated as the effect size of the P300 component.

Results: The main results of the present meta-analysis indicated that epileptic patients have a longer P300 latency and a lower P300 amplitude than controls. Subgroup analysis based on age group demonstrated that these differences can be observed in both children and adult patients compared with healthy controls. In addition, the P300 latency was longer in patients with the five main types of epileptic seizures than in controls.

Conclusion: This study revealed that epileptic patients have abnormalities in the P300 component, which may reflect deficits in cognitive function. Thus, the P300 may be a potential objective approach for evaluating cognitive function in epileptic patients.

Risk factors for seizure reoccurrence after withdrawal from antiepileptic drugs in individuals who have been seizure-free for over 2 years

Purpose

To observe risk factors for recurrence after withdrawal from antiepileptic drugs.

Methods

We assessed 1282 patients with a definite diagnosis of epilepsy.

Results

In total, 292 patients between 14 and 80 years of age were grouped according to risk factors for recurrence. Of these individuals, 119 discontinued AED(s) and relapsed. The relapse rate was 34.4 per 100 person-years. We used a Cox regression for multivariate analysis to investigate the influence of the following on seizure recurrence: receiving more than one type of AED (HR = 2.53, 95% CI 1.24–5.16) and more than 6 months prior to initiation of AED treatment (HR 1.47, 95% CI = 1.004–2.15).

Conclusions

Although the decision to discontinue AED treatment necessitates an individual evaluation of each patient, our study suggests that there may be a high risk of recurrence in individuals who: were receiving more than one AEDs and had initiated their AED treatment more than 6 months after the initial appearance of epilepsy symptoms.

Mismatch negativity is abnormal but not lateralizing in temporal lobe epilepsy

We investigated the changes of mismatch negativity (MMN) in patients with temporal lobe epilepsy (TLE) and explored the possible role of MMN in lateralizing their seizure focus. Thirty patients with TLE and thirty healthy controls were included. MMN was elicited in each subject. Patients with TLE were divided into three subgroups: unilateral left TLE; unilateral right TLE, and bilateral TLE. MMN amplitudes and latencies were compared between the patients with TLE and the control group, and also among the three subgroups of TLE, using repeated measures analyses of variance (ANOVA). To assess the lateralizing value of MMN, MMN latencies and amplitudes at the mastoid sites between the ipsilateral and contralateral sides of epileptic focus in patients with unilateral TLE were compared using t-test. Compared with controls, each subgroup of patients with TLE had longer latencies of MMN at both fronto-central and mastoid sites, but the amplitudes of MMN were not significantly different. The amplitudes and latencies of MMN were not significantly different between the ipsilateral and contralateral sides of seizure focus at mastoid sites. The present findings of prolonged latencies of MMN are suggestive of cognitive impairment in TLE. Both the mastoid sites and the fronto-central sites are involved, which likely reflect widespread cortical abnormalities in TLE. However, the changes of MMN during the interictal phase are not useful for lateralizing the seizure focus in patients with TLE.

Comparison of auditory event-related potentials between children with benign childhood epilepsy with centrotemporal spikes and children with temporal lobe epilepsy

The abnormal brain discharges observed in benign childhood epilepsy with centrotemporal spikes (BECTS) and temporal lobe epilepsy (TLE) are located close to areas responsible for auditory and language processing. This study aimed to analyze the results of auditory event-related potentials (P300) in children with BECTS and TLE in order to assess whether the epileptic activity in centrotemporal and temporal regions may compromise the integrity and physiology of auditory system structures. This was a prospective, comparative, and cross-sectional study. Group I (GI) consisted of 13 children diagnosed with BECTS, group II (GII), 7 children diagnosed with TLE, and control group (GIII), 16 healthy children, with no hearing or academic complaints. After neurological and basic audiological assessments, P300 was applied. The P300 latency and amplitude were compared between groups. Regarding latency, GI showed 324.1 (+31.5) ms, GII 336.3 (+23.5) ms, and GIII 318 (+27.7) ms. Amplitudes were 4.80 (+3.2) μV in GI, 4.7 (+2.5) μV in GII, and 5.8 (+2.4) μV in GIII. Although children with BECTS showed prolonged latencies and reduced amplitudes, these differences were not considered statistically significant. Children with TLE showed statistically significant prolonged P300 latency compared with the control group (P=0.037). We speculate that abnormal electrical discharges in centrotemporal and temporal regions led to the slowing of auditory processing in our sample.

Parents’ Subjective Assessment of Effects of Antiepileptic Drug Discontinuation

Background and Purpose:

Many parents express worries about potential negative side effects of antiepileptic drugs (AED) on cognition, behavior, mood, and academic achievement. We aimed to evaluate parents’ subjective feelings about cognitive or behavioral changes in their children and their quality of life after antiepileptic drug (AED) discontinuation.

Methods:

A modified questionnaire based on the Korean-Quality of Life in Childhood Epilepsy and the Korean-Child Behavior Checklist was answered by parents whose children were seizure-free over the course of 1 month after AED discontinuation. All children were seizure-free for at least 2 years before AED withdrawal.

Results:

Fifty-eight eligible patients (mean age, 14.1 ± 4.5 years) were examined. Except valproate in cognition (p = 0.03), parents did not feel significant change after discontinuation of different drugs. They felt improvement of behavior in generalized epilepsy (p = 0.04) and better quality of life in children less than 6 year of age at diagnosis of epilepsy (p = 0.02).

Conclusions:

We propose that factors such as earlier age at diagnosis of epilepsy or type of epilepsy might influence parents’ subjective feelings about their children’s well-being after drug discontinuation, rather than the drug itself.

Impact of early life exposure to antiepileptic drugs on neurobehavioral outcomes based on laboratory animal and clinical research

Epilepsy affects approximately 1% of children under the age of 15, making it a very common neurological disorder in the pediatric population (Russ et al., 2012). In addition, ~0.4-0.8% of all pregnant women have some form of epilepsy (Hauser et al., 1996a,b; Borthen et al., 2009; Krishnamurthy, 2012). Despite the potential deleterious effects of antiepileptic drugs (AEDs) on the developing brain, their use is still required for seizure control in pregnant women (Krishnamurthy, 2012), and they represent the standard approach for treating children with epilepsy (Chu-Shore and Thiele, 2010; Quach et al., 2010; Verrotti et al., 2011). Even when AEDs are effective, there are potential side effects, including cognitive and affective changes or altered sleep and appetite. The consequences of AED exposure in development have been studied extensively (Canger et al., 1999; Modi et al., 2011a,b; Oguni, 2011). Despite intensive study, there is still debate about the long-term consequences of early life AED exposure. Here, we consider the evidence to date that AED exposure, either prenatally or in early postnatal life, has significant adverse effects on the developing brain and incorporate studies of laboratory animals as well as those of patients. We also note the areas of research where greater clarity seems critical in order to make significant advances. A greater understanding of the impact of AEDs on somatic, cognitive and behavioral development has substantial value because it has the potential to inform clinical practice and guide studies aimed at understanding the genetic and molecular bases of comorbid pathologies associated with common treatment regimens. Understanding these effects has the potential to lead to AEDs with fewer side effects. Such advances would expand treatment options, diminish the risk associated with AED exposure in susceptible populations, and improve the quality of life and health outcomes of children with epilepsy and children born to women who took AEDs during pregnancy.

Cognitive side-effects of antiepileptic drugs in children

Although the causes of cognitive impairment in patients with epilepsy have not been completely elucidated, three factors are clearly involved: the underlying etiology of epilepsy, the effects of seizures or the epileptiform EEG discharges themselves, and the central nervous system effects of antiepileptic drugs (AEDs). All commonly used AEDs have some effect on cognitive function, and the effect may be substantial when crucial functions are involved, such as learning in children. With phenobarbital, there is a high risk for serious cognitive effects impacting attention and memory. Phenytoin may affect mental speed, mainly in higher dosing and polytherapy. Moderate monotherapy doses do not seem to induce much effect. Valproate does not seem to impair cognition if sufficiently controlled for hyperammonemia. For carbamazepine, there are conflicting reports, which may be due to selection bias or dosing. For oxcarbazepine, there is no evidence for any detrimental change compared to valproate but mild improvements on attentional tests. For topiramate, there is clear evidence for topiramate-induced cognitive impairment (attention, memory, and language function) in adults and children. Although data is sketchy, levetiracetam does not seem to have a negative impact on cognition. For lamotrigine, there is evidence of a cognitive-enhancing effect on attention. No evidence for cognitive side-effects has been found for vigabatrin. Ethosuximide is not associated with cognitive impairment although the evidence is sketchy. For gabapentin, tiagabine, zonisamide, and rufinamide no studies in children are available.

Treatment of epilepsy in children with developmental disabilities

Children with developmental disabilities are at increased risk for epilepsy with a prevalence rate higher than the general population. Some of the more common developmental disorders in childhood and the features of epilepsy in these conditions are discussed. Specifically, autism, cerebral palsy, mental retardation, and attention deficit and hyperactivity disorder are reviewed. Ideal treatment for developmentally-disabled children with epilepsy entails maximal seizure control without any significant adverse effects from the anti-epileptic drugs and good quality of life. Antiepileptic drugs' cognitive and behavioral adverse effects tend to occur more frequently in these children. Careful selection of the appropriate medication and close monitoring for drug adverse effects is important. The specific adverse effects of the older and newer antiepileptic drugs are also reviewed.

Molecular mechanisms of cognitive and behavioral comorbidities of epilepsy in children

Intellectual and developmental disabilities (IDDs) such as autistic spectrum disorders (ASDs) and epilepsies are heterogeneous disorders that have diverse etiologies and pathophysiologies. The high rate of co-occurrence of these disorders, however, suggests potentially shared underlying mechanisms. A number of well-known genetic disorders share epilepsy, intellectual disability, and autism as prominent phenotypic features, including tuberous sclerosis complex, Rett syndrome, and fragile X syndrome. In addition, mutations of several genes involved in neurodevelopment, including ARX, DCX, neuroligins, and neuropilin 2 have been identified in children with epilepsy, IDDs, ASDs, or a combination of thereof. Finally, in animal models, early life seizures can result in cellular and molecular changes that could contribute to learning and behavioral disabilities. Increased understanding of the common genetic, molecular, and cellular mechanisms of IDDs, ASDs, and epilepsy may provide insight into their underlying pathophysiology and elucidate new therapeutic approaches for these conditions.

Impaired spatial working memory in children with well-controlled epilepsy: an event-related potentials study

PURPOSE

To find out whether children with epilepsy did show different event-related potentials (ERP) compared to healthy children during performance in a visuo-spatial working memory (WM) task.

METHODS

Multichannel ERPs were measured during a visuo-spatial backmatching task. A quantitative analysis technique, based on Statistical Parametric Mapping, was used to analyze the ERP data. 62 children were tested (6-16 years old): 31 children with well-controlled epilepsy and 31 age- and intelligence-matched healthy children. One-backmatching (BM1) and two-backmatching (BM2) tasks were performed. Behavioral performance and target and nontarget ERPs were compared across groups in both tasks.

RESULTS

No behavioral differences were found between groups in the easy BM1 task. In the difficult BM2 task, children with epilepsy made significantly more omission errors. ERP analysis showed significantly higher amplitudes over frontal and central regions between 300 and 500 ms poststimulus in the epilepsy group compared to the control group. This effect was most pronounced in BM2.

DISCUSSION

This study shows that children with well-controlled epilepsy and normal intelligence demonstrate compensatory recruitment of their WM network during a visuo-spatial working memory task. Increasing the difficulty of the task (BM2) enhances this general neurophysiological finding and parallels the behavioral performance.

SIGNIFICANCE

Our results illustrate that epilepsy induces different cortical activity during working memory tasks, even when behavioral performance is normal.

Epilepsy and autism spectrum disorders: are there common developmental mechanisms?

Autistic spectrum disorders (ASD) and epilepsies are heterogeneous disorders that have diverse etiologies and pathophysiologies. The high rate of co-occurrence of these disorders suggest potentially shared underlying mechanisms. A number of well-known genetic disorders share epilepsy and autism as prominent phenotypic features, including tuberous sclerosis, Rett syndrome, and fragile X. In addition, mutations of several genes involved in neurodevelopment, including ARX, DCX, neuroligins and neuropilin2 have been identified in children with epilepsy, ASD or often both. Finally, in animal models, early-life seizures can result in cellular and molecular changes that could contribute to learning and behavioral disabilities as seen in ASD. Increased understanding of the common genetic, molecular and cellular mechanisms of ASD and epilepsy may provide insight into their underlying pathophysiology and elucidate new therapeutic approaches of both conditions.

Auditory P300 in patients with bipolar disorder and their unaffected relatives

OBJECTIVES

There is evidence that genetic susceptibility may be shared between bipolar disorder (BD) and schizophrenia, but electrophysiological phenotypes which have been extensively used in studies of genetic susceptibility for schizophrenia remain far less explored in bipolar illness. This study assesses whether auditory P300 latency delays and amplitude reductions, which have been demonstrated in patients with schizophrenia and their unaffected first-degree relatives, are associated with familial liability to psychotic bipolar illness.

METHODS

The P300 auditory evoked potential was obtained using an oddball task from 37 participants with BD who had a history of psychotic symptoms, 38 of their unaffected first-degree relatives and 42 healthy unrelated comparison subjects. Patients and relatives came from families multiply affected with BD or another functional psychotic disorder. P300 amplitude and latency at midline sites were compared between the groups, using linear regression analyses and robust variance estimators for clustered data, including age and gender as covariates.

RESULTS

Bipolar disorder patients with a history of psychosis and their unaffected relatives showed significantly delayed P300 latency at Pz compared to controls. The groups did not differ in P300 amplitude.

CONCLUSIONS

P300 latency delays are associated with both psychotic BD and familial liability for this illness. Sample size limited our ability to test for multimodal distribution of P300 measures among relatives, which might be expected if only a subgroup inherits any deficits. In future it will be of interest to directly compare groups of families with psychotic and non-psychotic forms of BD to explore further the role of psychotic symptoms with regard to P300 measures in the disorder. Our results indicate that delayed P300 latency is a promising candidate endophenotype for psychotic BD, as well as schizophrenia, and may reflect the impact of shared susceptibility genes for both types of psychosis.

10-year research update review: psychiatric problems in children with epilepsy

OBJECTIVE

To critically review literature published from 1996 to 2007 on psychopathology in children with epilepsy (CWE).

METHOD

Using Ovid, we searched Medline and PsychInfo databases for original studies on epidemiology, risk factors, clinical characteristics, treatment, and outcome of psychopathology in CWE, ages 0 to 18 years, using the terms "psychopathology," "emotional and behavioral problems," and "mental health problems." We selectively present the findings of studies that are clinically relevant to mental health professionals.

RESULTS

Psychopathology occurs in 37% to 77% of CWE, and attention, internalizing, and thought problems may be specific to epilepsy. Cognitive and linguistic deficits, as well as family factors, have moderating effects on psychopathology in CWE. The association of epilepsy-related variables, including antiepileptic drugs, with psychopathology is inconsistent in cognitively normal CWE. Children with symptomatic epilepsy and devastating epilepsy syndromes have high rates of global developmental delay, hyperactivity, and autistic symptoms. The treatment of psychopathology in CWE integrates standard psychiatric practices.

CONCLUSIONS

Epilepsy is a neuropsychiatric disorder characterized by seizures, psychopathology, cognitive, and linguistic problems. Improved early identification of CWE at risk for psychopathology, evidence-based psychiatric treatment, and multidisciplinary management strategies would advance clinical practice in this highly complex field of pediatric neuropsychiatry.

Influence of major antiepileptic drugs on neuropsychological function: results from a randomized, double-blind, placebo-controlled withdrawal study of seizure-free epilepsy patients on monotherapy

The aim of this study was to assess cognitive effects of anticonvulsants in a way that would yield results that are most directly applicable to epilepsy populations. This was done with a placebo-controlled, prospective, randomized, double-blind, parallel group study of anticonvulsant withdrawal in a population of subjects taking a single anticonvulsant with completely controlled seizures. Outcomes of this study on cognitive measures from the California Computerized Assessment Package have recently been reported. To aid comparison with results of prior studies, we report outcomes here on several more standard measures of neuropsychological function. The major findings were that, in subjects with therapeutic drug levels at baseline, drug withdrawal was associated with significant improvement in performance on the Controlled Oral Word Association Test and the Stroop Color-Word Interference Test. Comparable results were achieved in the subgroup taking carbamazepine.

Seizures and Antiepileptic Drugs: Does Exposure Alter Normal Brain Development?

Seizures and antiepileptic drugs (AEDs) affect brain development and have long-term neurological consequences. The specific molecular and cellular changes, the precise timing of their influence during brain development, and the full extent of the long-term consequences of seizures and AEDs exposure have not been established. This review critically assesses both the basic and clinical science literature on the effects of seizures and AEDs on the developing brain and finds that evidence exists to support the hypothesis that both seizures and antiepileptic drugs influence a variety of biological process, at specific times during development, which alter long-term cognition and epilepsy susceptibility. More research, both clinical and experimental, is needed before changes in current clinical practice, based on the scientific data, can be recommended.

Deterioration

Intellectual deterioration in epilepsy may be real or apparent. The latter refers to delay in cognitive development such that performance against age-related norms appears to drop. The former, real deterioration can occur due to concomitant degenerative neurological disease of which epilepsy is also a symptom, or it may happen as a consequence of one or more of a number of other factors. These include (1) direct effects of seizures and abnormal electroencephalogram activity on brain function, (2) traumatic brain injury secondary to seizures, including status epilepticus, (3) the influence of antiepileptic therapy, both drugs and surgery, on cognitive function, (4) psychosocial sequelae of diagnosis. Some epilepsy syndromes include intellectual deterioration as a frequent feature, with various causes. Developmental factors may also play a part. Cognitive functioning may be impaired by the presence of an epileptogenic lesion, and also in different ways and at different times by other brain areas involved with partial seizures, including irritative and functional deficit zones. Abnormal activity in these areas at critical periods in development may interact and disrupt pathways necessary for maturation of frontal lobe and limbic system functioning, leading to long-term neurological deficits. Increased understanding of the mechanisms by which this may happen raises intriguing possibilities for prevention and remediation.

Influence of Major Antiepileptic Drugs on Attention, Reaction Time, and Speed of Information Processing: Results from a Randomized, Double-blind, Placebo-controlled Withdrawal Study of Seizure-free Epilepsy Patients Receiving Monotherapy

PURPOSE

All major antiepileptic drugs (AEDs) have been reported to be associated with cognitive side effects. Uncertainty exists regarding the degree of cognitive effects, primarily because many studies do not adhere to basic standards of methodology and design. The aim of this study was to assess the effect of discontinuation of AEDs in patients receiving monotherapy on measures of attention, reaction time, and speed of information processing.

METHODS

The 150 subjects who had been seizure free>2 years on drug monotherapy went through a randomized, double-blind, placebo-controlled study. Each patient was included for 12 months or until seizure relapse. Cognitive function was assessed with the California Computerized Assessment Package at baseline and 7 months after discontinuation.

RESULTS

The major finding in this study is that discontinuation of major AEDs significantly improved performance on tests that require complex cognitive processing under time pressure. The difference in speed of cognitive processing between the two groups on these tasks was between 24 to 43 ms. Simple tasks of attention and reaction time revealed no significant differences between the discontinuation group and the nondiscontinuation group. Most of the subjects in the study were medicated with carbamazepine (CBZ) and valproate (VPA). The outcome of discontinuation of CBZ was similar to the outcome for the total study population, whereas withdrawal of VPA revealed only a nonsignificant tendency in the same direction.

CONCLUSIONS

The results suggest that seizure-free epilepsy patients receiving monotherapy can obtain improvement in cognitive function if they discontinue AED treatment.

Cognitive side effects of anti-epileptic drugs

In recent years several new anti-epileptic drugs have been introduced, also for the treatment of childhood epilepsy. A major concern is their effect on learning and cognitive development. Testing the genuine effects on cognition of the anti-epileptic drugs is methodologically not easy. At this moment there are very few controlled trials that systematically examine the cognitive side effects of anti-epileptic drugs in childhood epilepsy. The available data indicate that the newer anti-epileptic drugs have a safe cognitive profile when prescribed correctly at the right dose and in monotherapy. Possible negative effects are mainly found for speed of processing and attention processes. As these processes are important instruments in every day learning and cognition, it is necessary to test these newer anti-epileptic drugs in well designed studies and in specific childhood epilepsy syndromes.

Neurocognitive effects of phenobarbital discontinuation in epileptic children

PURPOSE

Phenobarbital (PB) is the most widely used antiepileptic drug in the world, but its possible deleterious cognitive and behavioral side effects remain an important concern among physicians and patients.We therefore investigated whether discontinuation of PB in children with epilepsy is accompanied by improvement in cognitive function.

METHODS

Neuropsychiatric performance was evaluated with the Wechsler Intelligence Scale for Children-Revised (WISC-R), in two consecutive 7-month periods, in two groups of children with epilepsy 6-12 years old who had been seizure-free for at least 2 years and whose only antiepileptic drug was PB. The case group comprised 24 patients who discontinued PB, and the control group was comprised of the 21 children who continued to take PB.

RESULTS

Discontinuation of PB improved Total IQ in the case group compared to the control group (P = 0.027). This increase was mostly in performance (nonverbal) items; verbal items remained almost unchanged.

CONCLUSION

These findings suggest that PB affects cognitive function, and the performance (nonverbal) deficits are diminished after discontinuation of therapy.

Uncontrolled epilepsy following discontinuation of antiepileptic drugs in seizure-free patients: a review of current clinical experience

PURPOSE

We reviewed the impact of planned discontinuation of antiepileptic drugs (AEDs) in seizure-free patients on seizure recurrence and the seizure outcome of reinstituted treatment.

METHODS

A literature review was performed yielding 14 clinical observations of seizure recurrence after discontinuation and its treatment outcome.

RESULTS

Seizure recurrence rate after AED discontinuation ranged between 12 and 66% (mean 34%, 95%CI: 27-43) in the 13 reviewed studies (no data in one study). Reinstitution of AEDs after recurrence was efficacious between 64-91% (mean of 14 studies, 80%, 95%CI: 75-85%) at follow-up. Mean follow-up ranged from 1-9 years. Seizure outcome of resumed treatment was not different for series in children and adolescents (84%, mean of 4 studies, 95%CI: 75-93) or in adults only (80%, mean of 9 studies, 95%CI: 74-86). Although seizure control was regained within approximately one year in half of the cases becoming seizure free, it took some patients as many as 5-12 years. In addition, in 19% (mean of 14 studies, 95%CI: 15-24%), resuming medication did not control the epilepsy as before, and chronic drug-resistant epilepsy with many seizures over as many as five years was seen in up to 23% of patients with a recurrence. Factors associated with poor treatment outcome of treating recurrences were symptomatic etiology, partial epilepsy and cognitive deficits.

CONCLUSIONS

These serious and substantial risks weigh against discontinuation of AEDs in seizure-free patients, except perhaps for selected patients with idiopathic epilepsy syndromes of childhood or patients with rare seizures.

Determining the effects of antiepileptic drugs on cognitive function in pediatric patients with epilepsy

The majority of children with epilepsy are of normal intelligence; however, a significant subset suffers from temporary or permanent cognitive impairment. Factors that affect cognitive function are myriad and include the neuropathology underlying the epilepsy, seizures, epileptiform activity, psychosocial problems, and antiepileptic drug side effects. Although cognitive impairment is often wrongly attributed to the effects of antiepileptic drugs, antiepileptic drugs do impair cognition in some children. Clinicians should be aware of the differential cognitive effects of antiepileptic drugs and should monitor cognitive function closely when adding or changing therapy. Based on published data from prospective, chronic dosing studies, phenobarbital and topiramate have the highest potential for causing cognitive dysfunction.

Antiepileptic drug withdrawal: literature review

Of patients with epilepsy, 60% to 70% achieve control with antiepileptic medication. Antiepileptic drugs may be associated with unwanted adverse effects, inconvenience, and cost. Remission may occur in some patients, raising the issue of whether continued treatment is necessary. Identifying patients from whom treatment can be withdrawn successfully would be beneficial on many levels, but selecting patients may be difficult. Several published antiepileptic drug withdrawal studies show variable rates of success, with relapse rates ranging from 12% to 63%. Several prognostic factors help identify patients who may be amenable to antiepileptic drug withdrawal. The results and limitations described in the antiepileptic drug withdrawal literature, prognostic factors, and general guidelines for antiepileptic drug withdrawal are presented in this article.

Surgical versus medical treatment for severe epilepsy: consequences for intellectual functioning in children and adults. A follow-up study

We compared the effects of medical and combined surgical and medical treatment of refractory epilepsy on intellectual functioning in a group of children (n=13) and a group of adults (n=15). The patients were tested with the age-appropriate versions of Wechsler's intelligence scales twice prior to and once after epilepsy surgery. There were no significant differences between the groups in preoperative epilepsy-related variables, including age at onset. The IQ scores were submitted to two-way analyses of variance (ANOVA). We also evaluated individual changes in IQ scores. Adult patients maintained stable levels of performance after drug treatment as well as following surgery, while children declined in Full Scale IQ after both kinds of treatment. Children also declined in Performance IQ, but not in Verbal IQ after drug treatment, and in Verbal IQ, but not in Performance IQ after surgery. Three of six children who underwent a significant decline in Full Scale IQ before surgery did not show any further decline postoperatively. We have proposed a developmental model to account for the different findings in children and adults, and conclude tentatively that refractory, long-standing epilepsy may interfere with intellectual development both during drug treatment and following combined surgical and medical treatment in children, while the impact of long-standing refractory epilepsy of similar severity as in children is not strong enough to reduce intellectual performance in adults, irrespective of treatment modality.

Overtreatment in children with epilepsy

Children with epilepsy are at risk for overtreatment, defined as the use of an excessive number or amount of antiepiletic drugs (AEDs). While the extent of overtreatment of epilepsy in children is not known, there is increasing awareness that overtreatment with AEDs contributes to the morbidity associated with childhood epilepsy. Reasons for overtreatment include using AEDs in a child with seizures who does not require therapy, choosing an inappropriate AED for the seizure type or syndrome; treating non-epileptic behaviors as seizures, use of polytherapy when monotherapy would suffice, and inadequate therapeutic options. Despite the introduction of eight new AEDs in the United States during the last decade, many children continue to be treated with the older generation sedative AEDs. Numerous investigators have now demonstrated that sedative AEDs can be safely removed from the drug regimen of children with epilepsy with resultant improvement in behavior, alertness, and improved seizure control. However, the biggest obstacle to overtreatment is the lack of effective therapies for many of the childhood epileptic syndromes. Until there are more effective therapies developed it is highly likely that children will continue to be over-medicated on ineffective and detrimental AEDs.