Cognitive epilepsy: ADHD related to focal EEG discharges

This study was undertaken to determine the effect of antiepileptic treatment on a child with attention-deficit-hyperactivity disorder and subclinical electroencephalographic discharges without seizures. We performed a longitudinal follow-up study correlating clinical, neuropsychologic, and electroencephalographic features with antiepileptic drug therapy. The results revealed a temporal relation between subclinical epileptiform discharges and cognitive dysfunction and a significant effectiveness of antiepileptic drugs on attention-deficit-hyperactivity disorder and electroencephalographic discharges. The practice of monitoring antiepileptic treatment limited to seizure control should be revised; cognitive impairments also need to be taken into account even without occurrence of seizure. The classical principle of treating only seizures needs to be reconsidered.     

Anticonvulsant Drugs and Cognitive Function: A Review of the Literature

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.     

Epilepsy and cognition

Patients with epilepsy are more prone to cognitive and behavioral deficits. Epilepsy per se may induce or exacerbate an underlying cognitive impairment, a variety of factors contribute to such deficits, i.e., underlying neuropathology, seizure type, age of onset, psychosocial problems, and treatment side effects. Epilepsy treatment may offset the cognitive and behavioral impairments by stopping or decreasing the seizures, but it may also induce untoward effects on cognition and behavior. The neurocognitive burden of epilepsy may even start through in utero exposure to medications. Epilepsy surgery can also induce certain cognitive deficits, although in most cases this can be minimized. Clinicians should consider cognitive side effect profiles of antiepileptic medications, particularly in extreme age groups. While no effective treatments are available for cognitive and behavioral impairments in epilepsy, comprehensive pretreatment evaluation and meticulous selection of antiepileptic drugs or surgical approach may minimize such untoward effects.     

The effect of seizure type and medication on cognitive and behavioral functioning in children with idiopathic epilepsy

Antiepileptic drugs have been reported to have a variety of adverse effects on behavior and performance in children with epilepsy. Previous studies investigating these side effects, however, have not controlled for the baseline status of the child (e.g. underlying neurological condition, seizure type, socioeconomic status, family variables), making it difficult to determine whether changes in function are attributable to the use of medication. We investigated the cognitive and behavioral profiles of 43 children, aged from 4 to 16 years, with new onset, idiopathic seizures. Twenty-six of these children participated in a 6-month follow-up study, and 12 in a 12-month follow-up study, investigating the effects of antiepileptic medications on psychological functioning. The children were of average intelligence (mean 1Q108) and had not previously been treated with antiepileptic medication. Children were classified as having either generalized convulsive, generalized non-convulsive (absence), simple partial, or complex partial seizures. Prior to the initiation of treatment, children with partial seizures were found to perform better than children with generalized seizures on measures of cognitive functioning. Children with convulsive seizures obtained significantly higher cognitive scores than those with non-convulsive seizures. Children with generalized non-convulsive seizures had lower cognitive scores than subjects with other types of seizure. No differences were found between groups at baseline prior to the initiation of antiepileptic medications. Analysis of subjects' performance after 6 and 12 months of antiepileptic therapy showed no significant deterioration attributable to medication. The differences in cognitive performance of the four seizure groups at baseline were not apparent at the time of follow-up. These results indicate that intrinsic and environmental variables may play a more significant role in predisposing certain children to cognitive and learning problems than do antiepileptic medications.     

Polytherapy, Monotherapy, and Carbamazepine

Summary: Despite the widespread and traditional use of polytherapy in the treatment of epilepsy, there is little evidence of its advantages over monotherapy. Among other undesirable effects, it can produce subtle cognitive and behavioral changes and sometimes even exacerbate the epilepsy. Recent studies provide evidence that in many patients seizures can be controlled by carefully monitored monotherapy: Approximately 75% of newly diagnosed, previously untreated epileptic patients will enter a 2-year remission with this form of treatment. The theory has even been advanced that early control of seizures may help prevent the evolution of drug-resistant, chronic epilepsy. In some patients with chronic epilepsy, multiple-drug therapy can be reduced to single-drug treatment, usually with an improvement in cognitive function and without increase in seizures. Trials conducted to date have shown no evidence of superiority of any one major antiepileptic drug over another in control of a particular seizure type. The choice of antiepileptic drug for monotherapy may therefore be influenced by differences in toxic effects associated with individual agents. On the basis of clinical and psychometric evidence, carbamazepine has been shown to cause fewer adverse effects than other antiepileptic drugs on cognitive function, mood, and behavior.     

Cognitive and behavioural assessment in clinical trials: when should they be done?

The issue of 'timing' of behavioural assessments in clinical trials can be approached in two different ways. Firstly the 'timing' during the process of drug development. As a rule, cognitive and behavioural side effects of antiepileptic drug treatment do not become an issue until the drug is marketed. At this stage a negative result has large marketing effects and this leads to a tendency to organise 'positive studies'('no-effect results'), that can be achieved by reducing power. A second approach is the 'timing' of cognitive assessment during a trial. The first and intuitive answer to the question 'when this should be done' is to perform assessments during an untreated baseline that is then compared with an endpoint during antiepileptic drug (AED) treatment. This is the 'gold standard design' for cognitive assessments in the majority of the cognitive trials. However, in patients with epilepsy, the behavioural drug effects are not independent from the effect of the epilepsy or the seizures. Recent studies have confirmed that the effect of uncontrolled seizures are often larger than the effects of drug treatment, leading to the so-called seizure confound, that is, adverse cognitive AED effects may be masked by beneficial effects of better seizure control. In such studies endpoint scores are thus improved, hiding possible negative drug effects. Other designs may have other limitations: e.g. in using adjunctive therapy the identification of the components of a treatment most responsible for any observed effects presents a difficult problem; in normal volunteers, exposure durations which are not representative of those in epilepsy patients on chronic treatment represent a major validity issue. We therefore consider the drug withdrawal study as the optimal design for assessing behavioural drug effects. In this design subjects are tested while still on medication and after withdrawal; larger gains in the epilepsy group relative to the controls are considered evidence for a reversible impairment, attributable to AED use.     

Complex partial seizures. Clinical features and differential diagnosis.

Complex partial seizures are the most common seizure type in patients with partial epilepsy. Most complex partial seizures emanate from the temporal lobe; however, the seizures also may be extratemporal in origin. The clinical phenomenology may distinguish complex partial seizures from nonepileptic paroxysmal disorders and other seizure types. Physiologic and psychological disorders need to be considered in the differential diagnosis of seizure activity. Long-term EEG monitoring may be necessary for select patients to confirm the diagnosis of epilepsy and to classify appropriately seizure type. Carbamazepine and phenytoin are the antiepileptic drugs of choice in the management of complex partial seizures. Polypharmacy and use of cognitively impairing antiepileptic drugs may reduce patient compliance and further impair the quality of life of the patient with epilepsy. Finally, epilepsy surgery is an important alternative for the patient with intractable partial seizures.     

Aggravation of epilepsy by antiepileptic drugs

Antiepileptic drugs may paradoxically worsen seizure frequency or induce new seizure types in some patients with epilepsy. The mechanisms of seizure aggravation by antiepileptic drugs are mostly unknown and may be related to specific pharmacodynamic properties of these drugs. This article provides a review of the various clinical circumstances of seizure exacerbation and aggravation of epilepsy by antiepileptic drugs as well as a discussion of possible mechanisms underlying the occasional paradoxical effect of these drugs. Antiepileptic drug-induced seizure aggravation can occur virtually with all antiepileptic medications. Drugs that aggravate seizures are more likely to have only one or two mechanisms of action, either enhanced gamma-aminobutyric acid-mediated transmission or blockade of voltage-gated sodium channels. Antiepileptic drug-induced seizure exacerbation should be considered and the accuracy of diagnosis of the seizure type should be questioned whenever there is seizure worsening or the appearance of new seizure types after the introduction of any antiepileptic medication.     

Selection of drugs for the treatment of epilepsy

Antiepileptic drug selection is based on efficacy for specific seizure types and epileptic syndromes. For idiopathic generalized epilepsies with absence, tonic-clonic, and myoclonic seizures, the drug of choice is valproate. Secondary generalized epilepsies with tonic, atonic, and other seizure types are difficult to treat with any single drug or combination of drugs. The drugs of choice for absence seizures are ethosuximide and valproate. For control of tonic-clonic seizures, any of the other major antiepileptic drugs can be effective. If valproate cannot be used, carbamazepine, phenobarbital, phenytoin, or primidone is effective, but ethosuximide or a benzodiazepine needs to be added to control associated absence or myoclonic seizures. The drugs of first choice for partial epilepsies with partial and secondarily tonic-clonic seizures are carbamazepine and phenytoin. Increasing evidence suggests that valproate may be a third alternative. Phenobarbital and primidone are second choice selections because of side effects. A combination of two of these five major antiepileptic drugs may be necessary for inadequately controlled patients. Other epilepsy syndromes such as neonatal and infantile epilepsies, febrile epilepsy, and alcoholic epilepsy require specific drug treatment. For all these seizure types and epilepsy syndromes, treatment ultimately must be selected to provide maximal efficacy and minimal adverse effect for each individual patient.     

Interictal cognitive changes in epilepsy

There is little evidence for significant intellectual deterioration in well-controlled seizure disorders. With recurrent convulsive seizures, the picture is less clear and depends on severity, type, age of onset, and frequency of toxic levels of antiepileptic drugs (see Table 1). In the interictal state, deficits in verbal language and memory have been observed, especially in patients with complex partial seizure foci in the left (dominant) hemisphere. The memory deficits appear to affect new learning and retention of material; the verbal deficits are more subtle, affecting word-finding, verbal fluency, and comprehension abilities. Both of these changes may either go unnoticed by the patient in day to day activities or be attributed to the effects of antiepileptic medication. Antiepileptic drugs can also affect interictal cognitive functioning. The worst of these appears to be phenobarbital; phenytoin has an intermediate effect; valproic acid and carbamazepine as single agents seem to produce fewer adverse effects. However, individual patients may be particularly sensitive to cognitive side effects of certain drugs. Finally, attention deficits and slowing of cognitive processes, either chronically or intermittently, appear to affect all seizure patients to some extent. The syndrome is more prominent in frontal or generalized seizure patterns. The intermittent nature of these disturbances has been emphasized in recent research on subclinical interictal spike-wave electrical phenomena.     

Kognitive Nebenwirkungen neuer Antikonvulsiva

In the treatment of epilepsy adverse effects of medication must be recognized as being as important as seizure freedom. Cognitive deficits often occur in chronic epilepsy and may sometimes reflect adverse effects of antiepileptic drugs. However, the successful treatment of seizures frequently outweighs these adverse cognitive effects. Adverse cognitive effects of medication mostly concern certain cognitive domains, such as attention or executive functions but memory and language disturbances may also occur. Psychiatric comorbidity, e.g. depression has detrimental effects on cognition which should be considered when mood stabilizing drugs are withdrawn. With the exception of topiramate, most of the newer antiepileptic drugs seem to have a favorable profile of adverse effects on cognition; however, only few studies have directly compared cognition between newer and classic antiepileptic drug treatment. In the individual patient, standardized neuropsychological assessment may help to detect even subtle signs of cognitive decline and to improve the evaluation of the cause of (subjective) cognitive decline.     

Attention deficit hyperactivity disorder in children with epilepsy

Attention deficit hyperactivity disorder (ADHD) is more frequent in children with epilepsy than in general pediatric population. Several factors may contribute to this comorbidity, including the underlying brain pathology, the chronic effects of seizures and of the epileptiform EEG discharges, and the effects of antiepileptic drugs. Symptoms of ADHD are more common in some specific types of epilepsies, such as frontal lobe epilepsy, childhood absence epilepsy and Rolandic epilepsy, and may antedate seizure onset in a significant proportion of cases. In epileptic children with symptoms of ADHD, treatment might become a challenge for child neurologists, who are forced to prescribe drugs combinations, to improve the long-term cognitive and behavioral prognosis. Treatment with psychotropic drugs can be initiated safely in most children with epilepsy and ADHD symptoms.     

Management of epilepsy in pregnancy: a report from the International League Against Epilepsy Task Force on Women and Pregnancy

The risks associated with use of antiepileptic drugs during pregnancy are a major concern for all women with epilepsy with childbearing potential. These risks have to be balanced against foetal and maternal risks associated with uncontrolled seizures. This report from the International League Against Epilepsy Task Force on Women and Pregnancy aims to provide a summary of relevant data on these risks as a basis for expert opinion recommendations for the management of epilepsy in pregnancy. The report reviews data on maternal and foetal risks associated with seizures as well as teratogenic risks associated with antiepileptic drug exposure, including effects on intrauterine growth, major congenital malformations, and developmental and behavioural outcomes. The impact of pregnancy on seizure control and on the pharmacokinetics of antiepileptic drugs are also discussed. This information is used to discuss how treatment may be optimized before conception and further managed during pregnancy.     

Management of epilepsy in mentally retarded children using the newer antiepileptic drugs, vagus nerve stimulation, and surgery

Clusters of seizures, prolonged seizures, and status epilepticus occur more frequently in children with multiple disabilities, and chronic seizures are more likely to be refractory to treatment. In many patients, the seizures appear to contribute to the mental retardation. Thus, if the lives of these children are to improve, seizure control is essential. However, medical treatment can interfere with cognition and cause behavioral disturbances, making life very difficult for the child and the child's family. With the introduction of 10 new antiepileptic drugs in the last decade, the treatment of epilepsy in multiply handicapped children has significantly advanced. These new antiepileptic drugs may improve seizure control, medication tolerance, or both. Although the ultimate therapeutic goal is to keep children seizure free and alert, compromises regarding medication choice and dosage are still necessary in many cases. Novel treatment options, such as the vagus nerve stimulator, may decrease seizure frequency without behavioral or cognitive side effects. In carefully selected children with specific epilepsy syndromes, epilepsy surgery can provide partial or complete relief from seizures.     

Dravet syndrome and SCN1A gene mutation related-epilepsies: cognitive impairment and its determinants

Some studies have demonstrated that cognitive decline occurs in Dravet syndrome, starting shortly after the onset of seizures, rapidly progressing and then plateauing within a few years. It is unclear whether children that develop the syndrome had entirely normal cognitive skills before seizure onset, since subtle impairment easily escapes recognition in small infants. It is also difficult to demonstrate whether a recognisable profile of cognitive impairment or a definite behavioural phenotype exists. No clear-cut imaging or neuropathological marker or substrate has been recognised for cognitive impairment in this syndrome. However, there are different potentially causative factors, including the specific effects on the Nav1.1 channels caused by the underlying genic or genomic defect; frequent and prolonged convulsive and non-convulsive seizures or status epilepticus; recurrent subtle ictal phenomena, such as that accompanying pronounced visual sensitivity; the use of antiepileptic drugs with cognitive side effects, especially in heavy multiple-drug therapy; and the restrictions that children with severe epilepsy inevitably undergo.     

Role of antiparasitic therapy for seizures and resolution of lesions in neurocysticercosis patients: An 8 year randomised study

Neurocysticercosis is a common cause of acquired seizure disorder in developing countries, including India. The role of antiparasitic (albendazole) therapy for seizure control and resolution of lesions is still controversial due to a lack of adequately controlled studies. The objective of the present study was to evaluate the role of albendazole therapy for neurocysticercosis patients with two or more lesions to achieve seizure-free status and resolution of lesions. This was a randomised controlled study in which patients suffering from neurocysticercosis were prospectively followed up for more than 5 years (from January 1997 to January 2005). Patients were divided into two groups: patients in group A (n=150) were treated with a combination of tapered doses of dexamethasone and albendazole, plus antiepileptic drugs; patients in group B (n=150) were treated with antiepileptic drugs plus a placebo control. Patients were followed up every month for the first 6 months and then at 3-month intervals thereafter up to 5 years. Variables of interest were (i) recurrence of seizures; (ii) encephalopathy (headache/vomiting/altered sensorium); (iii) need for subsequent hospital admission; (iv) death; (v) resolution of lesions on follow-up CT. During the first 6 months and at intervals thereafter, increased seizure frequency and hospital readmissions, and increased incidence of encephalopathy were observed in group A (p=0.01), and two patients in this group died with intractable seizures and encephalopathy. A greater proportion of lesions completely resolved in group B (p=0.05), whereas a greater proportion of lesions calcified in group A (p=0.05). Albendazole plus antiepileptic drugs did not have greater beneficial effects than antiepileptic drugs alone, but may have an adverse effect with respect to seizure control, encephalopathy, recurrent hospital admissions, calcification of lesions and cost of treatment.     

Adult absence semiology misinterpreted as mesial temporal lobe epilepsy

Correct diagnosis of seizure type and epilepsy syndrome is the foundation for appropriate antiepileptic drug selection. Inappropriate medication choices occur in the treatment of generalized epilepsy and may aggravate some seizure types, including absence seizures, potentially leading to pseudo‐drug resistance. Fortunately, a correct diagnosis of absence seizures is usually not difficult, though rarely demonstrates electroclinical overlap with focal seizures. EEG can be especially misleading when secondary bilateral synchronous discharges occur in patients with focal seizures. However, the semiology of focal seizures associated with mesial temporal lobe epilepsy has a characteristic and consistent semiology that is the mark of this common epilepsy syndrome in adulthood. We recently encountered a 53‐year‐old female with refractory seizures and a semiology strongly suggesting mesial temporal lobe epilepsy. Instead of focal seizures, prolonged absence seizures were validated by video‐EEG monitoring and she became seizure‐free after a change to broad‐spectrum antiepileptic drugs. This case further expands our understanding of the complexity of semiology in electroclinical classification and the spectrum that may occur in adult absence seizures. It serves to underscore the need for ictal EEG recordings and the importance of concordance with the clinical course during the pre‐surgical evaluation of patients with lesions and drug‐resistant epilepsy. [Published with video sequences]     

Epilepsy and hormones

The paper contains a review of reports concerned with how for hormones, epileptic seizures and antiepileptic drugs can be influenced by one another. Hormones influence brain excitability but, on the other hand, both epileptic seizures and antiepileptic drugs may alter hormone secretion and metabolism. Effect of hormones on seizures--Experimental studies revealed the properties which inhibit or stimulate convulsive reactivity of different hormones. Progesterone, testosterone, adrenocorticotropin and desoxycorticosterone are responsible for an increase in seizure threshold, while estradiol, cortisol and thyroid hormones cause a reduction. Effect of seizures on hormones--Epileptic seizures, chiefly tonic-clonic, also complex partial and sometimes simple partial seizures, result in "the hormonal storm". Immediately after an epileptic seizure, an increase is found in serum concentrations of prolactin, cortisol, adrenocorticotropin, triidothyronine, thyroxin, thyrotropin, luteotropin, follicular stimulating hormone and growth hormone. These changes may persist for two hours, while prolactin concentration even for 24 hours after a seizure. Effect of antiepileptic drugs on hormones--Antiepileptic drugs may affect hypothalamus-pituitary function directly or indirectly through neurotransmitter system. By induction of hepatic microsomal enzymes, some antiepileptic drugs cause acceleration of hormone metabolism, reducing hormone serum concentrations. Moreover, antiepileptic drugs enhance sex hormone binding globulin SHBG/synthesis, increase binding of these hormones and reduce their active fraction concentration in serum. Recognition of the relationship between epilepsy and hormonal system is necessary to obtain better understanding of this disease.     

Efficacy and Safety of Antiepileptic Drugs: A Review of Controlled Trials

Summary: Twenty randomized, double-blind, controlled clinical trials of antiepileptic drugs (AEDs) in mostly adult patients with mostly partial onset and/or generalized tonic-clonic seizures have been reported, with a total of 1,336 patients. None of these studies has demonstrated significant differences in antiepileptic efficacy between available antiepileptic drugs, but the results show that there are considerable individual differences between patients' responses to the same drug. While side effects are common with all of the antiepileptic drugs currently available, these are usually mild and reversible. Although some toxic effects may occur more frequently with certain drugs, there is sufficient overlap between the effects of various antiepileptic drugs that most side effects cannot be attributed with certainty to any one drug. Since side effects are generally dose-related, they can frequently be avoided or minimized by careful dosage titration and individualization of therapy.     

Education and Epilepsy: Assessment and Remediation

Summary: Learning difficulties in children with epilepsy may be caused by brain damage and should be investigated. In many cases, however, seizures and/or electroencephalographic (EEG) findings are the only signs of pathology. Frequency and type of seizures may be determining factors that should, if necessary, be evaluated by long-term EEG monitoring, preferably during school performance or in conjunction with neuropsychological assessment. This may prove that subclinical epileptiform discharges in the EEG can adversely affect the child's performance. Secondary psychological problems in epilepsy patients, combined with side effects of antiepileptic drugs, may cause or heighten learning problems. Prophylactic control of seizures with one appropriate drug may alleviate learning problems. Computerized neuropsychological testing with simultaneous EEG recording may reveal the influence of epileptiform discharges on cognitive function and also help to evaluate the effects of antiepileptic drugs. Objective assessment of subclinical epileptiform activity makes it easier to treat the pathology identified by the EEG with optimal dosage of the most appropriate drug. A balance is required because epileptiform discharges and even occasional seizures may be less disabling than side effects from large doses of several drugs. Information to the school and the parents concerning the patient's abilities and limitations may be as important as seizure control. Specialized teaching should be started early, when necessary, with the patient integrated into a normal school if possible. However, good functioning in a special school is preferable to marginal functioning in a normal school.