D.G.A. Kasteleijn-Nolst Trenité

Psychological effects of subclinical epileptiform EEG discharges. I. Scholastic skills

The possible effects of subclinical epileptiform EEG discharges on educational skills have been studied. Twenty children with proven or suspected epilepsy and known subclinical EEG discharges underwent telemetric EEG and video monitoring during standard tasks of reading, mental arithmetic and manual dexterity, and at rest. The discharge rate was significantly lower at rest than during execution of a task. For both reading and arithmetic, the discharge rate was higher when the child was presented with material appropriate to his own level of ability than when easier or more difficult material was given. High discharge rates were associated with low test performance particularly for arithmetic. Reading speed was significantly increased during the discharges, but overall reading efficiency was significantly reduced with respect to the non-discharge condition. The decrement of reading efficiency was greater for longer than for shorter discharges. The findings confirm that otherwise subclinical EEG discharges may be accompanied by momentary impairment of scholastic skills. The interaction between discharges and cognitive function is, however, complex and the nature and level of difficulty of the task in turn affects the rate of EEG discharge.

Photic Stimulation: Standardization of Screening Methods

Purpose: Differences in methodology of intermittent photic stimulation within and between countries in Europe make collaborative research and interpretation of results difficult.

Psychological effects of subclinical epileptiform EEG discharges in children. II. General intelligence tests

Twenty-one children with suspected or proven epilepsy and subclinical epileptiform EEG discharges in the waking state were studied. The EEG was telemetered and behaviour recorded by closed-circuit television during performance of a general intelligence test (RAKIT, shortened version) which comprised 6 subtests. Mean total IQ was below that of control populations and the subtests profile was abnormal, due particularly to impaired performance on a subtest concerned with verbal short-term memory. This effect was accounted for by that subgroup of children who exhibited discharges during the test; those who did not show discharges at that time were unimpaired. Performance of 3 of the subtests was impaired when discharges occurred during presentation of the test item or between presentation and response. The findings suggest that cognitive impairment found in people with epilepsy may not only represent a more or less static disability, due to drugs, cerebral pathology, etc., but may in part be an intermittent process related to the occurrence of subclinical epileptiform discharges. These preliminary findings need to be amplified but have implications both for interpretation of neuropsychological studies in persons with epilepsy and also for the drug treatment of those who continue to exhibit subclinical EEG discharges when overt seizures have been controlled.

The influence of subclinical epileptiform EEG discharges on driving behaviour

EEG and driving behaviour were monitored in 6 patients with subclinical focal and generalised epileptiform EEG discharges during 420 km of actual motorway driving in a suitably instrumented vehicle. Evidence of impaired driving performance during subclinical discharges was significant in 3 subjects (P < 0.025 or < 0.05) and was suggestive (P < 0.1) in 1. The two patients with greatest impairment had active epilepsy, whereas the others had been seizure-free for upwards of 4 years. No other features appeared to be predictive of altered driving behaviour during discharges.

Photosensitivity as a model for acute antiepileptic drug studies

A technique is described for assessing the efficacy and time course of effects of antiepileptic drugs, after a single acute dose, by means of their action on the human photo-convulsive response. The range of frequencies of intermittent photic stimulation to which the patient is sensitive (photosensitivity range) is determined in a standardized manner at hourly intervals over the course of a waking day. 82 controlled studies have established that, with the rare exceptions of patients showing a consistent circadian rhythm of photosensitivity, the photosensitivity range is stable over this time scale. A total of 72 studies have shown that representatives of all the major groups of established antiepileptic drugs, together with some experimental drugs, suppress photosensitivity following a single acute administration. By contrast barbiturates without antiepileptic action (methohexitone and quinalbarbitone) do not affect photosensitivity even in doses producing marked drowsiness. These findings suggest the technique to be a potentially useful tool for preliminary investigation of efficacy and duration of action of new potential antiepileptic drugs.

Comparative double blind clinical trial of phenytoin and sodium valproate as anticonvulsant prophylaxis after craniotomy: efficacy, tolerability, and cognitive effects

OBJECTIVE To determine the efficacy, tolerability, and impact on quality of life and cognitive functioning of anticonvulsant prophylaxis with phenytoin or sodium valproate in patients after craniotomy. METHODS A prospective, stratified, randomised, double blind single centre clinical trial was performed, comparing two groups of 50 patients each, who underwent craniotomy for different pathological conditions and who were treated for 1 year after surgery with either 300 mg phenytoin/day or 1500 mg sodium valproate/day. During the study period patients were seen in the outpatient clinic at 1.5, 3, 6, and 12 months, when medical history, adverse events, and drug plasma concentrations were evaluated. Neuropsychological functioning and quality of life were assessed on the last three visits. In cases of a seizure an EEG was performed, drug plasma concentration assessed, and medication subsequently increased. RESULTS Of the 100 included patients 14 (seven in each group) experienced one or more postoperative seizures. Severity of the seizures was comparable in the two groups. In all patients, drug plasma concentrations were in the low or subtherapeutic ranges at the time of the first postoperative seizure. Five patients in the phenytoin group and two in the valproate group had to stop their treatment due to drug related adverse events. Sixty patients completed the 12 month period. Analysis of neuropsychological and quality of life data showed no significant differences. CONCLUSION For efficacy, tolerability, impact on cognitive functioning, and quality of life, no major differences were found between phenytoin and valproate prophylaxis. Valproate is an alternative for anticonvulsant prophylaxis in patients after craniotomy.

Influence of an evacuation in February 1995 in the Netherlands on the seizure frequency in patients with epilepsy : A controlled study

Summary: Purpose: Stress is often noted by patients to be a precipitating factor in causing seizures. No precise data are, however, available. In 1995 for 250,000 inhabitants in the Netherlands, a serious life event occurred within a period of seven days. An extreme high water level in the province of Gelderland, with the possibility of a flood, made the government decide to evacuate people and their livestock. This retrospective study investigated the influence of this forced evacuation on the seizure frequency of patients with epilepsy, compared with patients of the same age and type of epilepsy living outside the evacuation area at the time of the threatening flood.

On‐Line Detection of Transient Neuropsychological Disturbances During Eeg Discharges in Children with Epilepsy

Short‐term memory tasks (visual‐spatial and verbal) were devised to identify the influence of transient EEG discharges, without clinically manifest disturbances, on neuropsychological performance. 53 children with subclinical focal and generalized EEG discharges were tested 72 times and 16‐channel telemetered EEG and video‐recordings were made. 36 per cent of test sessions showed a significant preponderance of errors when discharges were recorded. Children with right‐sided discharges had impaired performance in 50 per cent of their test sessions, with performance on the visual‐spatial task most affected: left‐sided discharges appeared to exert greater influence on the verbal task. These tests can easily be used to monitor six‐ to 15‐year‐old children.

Levetiracetam: a long‐term follow‐up study of efficacy and safety

Objectives –  To evaluate the efficacy and safety of long‐term add‐on treatment with levetiracetam 1,000–4,000 mg/day.

Photic stimulation - Standardization of screening methods.

PURPOSE Differences in methodology of intermittent photic stimulation within and between countries in Europe make collaborative research and interpretation of results difficult. METHOD Experts in the field of photic stimulation from European countries have given an overview of methods used in routine photic stimulation. A consensus meeting was organized in May 1996 in the Netherlands. RESULTS Methodology, including specification of a photo stimulator, procedure of photic stimulation, and interpretation of EEG results, has been defined according to available scientific and clinical knowledge. CONCLUSIONS Consensus was reached in setting up a safe, quick, simple and reliable method to determine whether or not patients are photosensitive. A specification of an international standard for intermittent photic stimulation in the routine EEG examination is given with the purpose of improving patient care and facilitating collaborative research.