Cognitive deterioration and electrical status epilepticus during slow sleep.

The results of long-term follow-up of 10 children with global or specific cognitive deterioration and, on the electroencephalogram, electrical status epilepticus during sleep (ESES) are described. They were referred because of cognitive deterioration and underwent repeated neurological and neuropsychological examinations and all-night electroencephalography. A previous cognitive level was known or could be estimated in all. Seven children had a continuous spikes and waves during sleep (CSWS) syndrome, with global cognitive deterioration in four and more specific cognitive decline in three, and another three children had Landau-Kleffner syndrome (LKS). Of the last three, two children never had seizures, while the other had localization-related epilepsy. No children experienced aggravation of clinical seizures. However, therapy was disappointing. Cognitive dysfunction did not respond to valproate and/or benzodiazepines in 9 of the 10 children. A frontal epileptic focus was found in 5 of 7 children with CSWS, and a left temporal focus in 2 of 3 children with LKS. The ESES persisted in CSWS for 5-9 years and in LKS for 1-5 years, and disappeared at puberty. Good cognitive recovery after disappearance of ESES occurred in only one child, and partial recovery in four. An unfavorable prognosis of cognitive deterioration seems to be related to long-duration ESES and/or early onset epileptic activity. The authors are of the opinion that cognitive deterioration in children, with or without manifest epileptic seizures, should mandate electroencephalographic investigation during sleep.

Relationships between epilepsy-related factors and memory impairment.

OBJECTIVES: In this study, we will explore the effect of epilepsy-related factors such as: 'type of epilepsy, 'site and side of focus localisation' and 'age at onset', as well as four seizure-related factors: 'years with continuing seizures', 'seizure type' and 'seizure frequency', and the treatment factor 'adverse effects of the medication', on memory impairment. Additionally, we explored whether these epilepsy factors are related to different aspects of memory, i.e. short-term recall vs long-term recall, learning, and verbal memory vs non-verbal memory. MATERIAL AND METHODS: A total of 252 patients with epilepsy and subjective memory complaints were consecutively included from the three epilepsy centres in the Netherlands. To assess memory functions the Wechsler Memory Scale-Revised (WMS-r), and the Dutch version of the California Verbal Learning Test for verbal list learning, was administered. RESULTS: A multivariate analysis of variance (MANOVA) did not show statistically significant effects of the epilepsy factors on memory for the total study sample. For the patients with a unilateral epileptogenic focus in the temporal lobes, MANOVA showed statistically significant effects of lateralisation, with most impairment for patients with left temporal lobe epilepsy and, independently, seizure frequency and 'years with seizures'. CONCLUSION: We may conclude that epilepsy-related dysfunctions in the temporal lobe are the dominant risk factor for developing memory problems, specifically verbal memory problems (verbal learning and problems consolidating verbal information), with more severe impairments with continuing seizures and when seizure frequency is high.

Long-term effects of temporal lobectomy on intelligence.

OBJECTIVE: To characterize the long-term effects of anterior temporal resection on intelligence. METHODS: Twenty-eight left temporal lobectomy (LTL) and 43 right temporal lobectomy (RTL) patients were followed at standard time points for at least 6 years after surgery. RESULTS: The average gain 6 years after operation was 3.6 Verbal IQ (VIQ) points and 10.3 Performance IQ (PIQ) points in LTL patients and 2.9 VIQ points and 7.7 PIQ points in RTL patients. A seizure-free outcome did not influence the increase in IQ, nor was the extent of resection related to IQ scores at the 6-year follow-up. Patients with exclusively mesial temporal sclerosis did not perform as well as patients with other pathologies, both before and after surgery. Major predictors of improved performance at 6 years were initial higher level of performance and lower age at surgery. Much of the observed improvement may be related to retest effects. CONCLUSIONS: The effects of epilepsy surgery on intelligence in the long term are limited. The largest gain in VIQ is seen from 2 to 6 years after surgery.

Lateralization of auditory rhythm length in temporal lobe lesions.

In the visual modality, short rhythmic stimuli have been proven to be better processed (sequentially) by the left hemisphere, while longer rhythms appear to be better (holistically) processed by the right hemisphere. This study was set up to see if the same holds in the auditory modality. The rhythm task as originally designed by Seashore was computerized and is part of the Fepsy Neuropsychological battery. This task was performed by 85 patients with intractable temporal lobe epilepsy (left TLE = 32; right TLE = 53) enrolled in the Dutch Collaborative Epilepsy Surgery Program. They performed the task before and 6 months after surgery. The task consists of 30 pairs of rhythmic patterns in 3 series of 10 items. The series contains patterns of 5, 6, or 7 notes. The purpose is to indicate whether the two patterns are the same or different. Reaction times are also measured. If the hypothesis is true, the short-item sequence will be better processed by patients with right temporal lobe epilepsy (nonimpaired left temporal lobe), the longer sequence will be better processed by the left temporal epilepsy group (nonimpaired right temporal lobe). No overall laterality effect on rhythm perception could be found and no difference was found between both test moments. IQ did not correlate with rhythm performance. However, there was an interaction effect of laterality and rhythm length on performance and reaction time. This effect can be explained by the increase after the operation of the score of the left focus group and a decrease in the right focus group on the longer rhythms. This effect was somewhat less strong in the reaction times: a clear tendency for faster reaction times after surgery in the left and longer reaction times in the right focus group. The effect could not be explained for by the difference in extent of resection in either temporal lobe. This study showed that memory for and discrimination of auditory rhythm is dependent on which hemisphere is used in processing. The effect could be demonstrated for the right hemisphere, which uses a holistic processing of stimuli, which outperforms the left in rhythms consisting of a long sequence. In left temporal resections an improvement occurs on the longer rhythms and in right temporal resections the performance on the longest rhythms decreases.

The A-B neuropsychological assessment schedule (ABNAS): the relationship between patient-perceived drug related cognitive impairment and results of neuropsychological tests.

Our intention was to evaluate the relationships between the A-B neuropsychological assessment schedule (ABNAS) as a measure of patient-perceived cognitive effects of antiepileptic drugs (AEDs) and the results of neuropsychological tests. The measure was developed specifically to assess patient-perceived cognitive effects of AED treatment. Evidence of its reliability and validity has been previously documented. In this study 96 patients were included using stratified inclusion-criteria to guarantee variability of performance: 55 patients were included from a 'low risk condition' with respect to possible cognitive effect (i.e. monotherapy carbamazepine within a dose range of 600-1200 mg/day) and 41 patients were included from a 'high risk condition' (i.e. polytherapy of three or two AEDs including either phenytoin, phenobarbitone or a benzodiazepine; treatment with topiramate with a titration speed using 50 mg or higher increments per week and within the first 6 months of treatment). All patients were prospectively assessed using the ABNAS and five neuropsychological tests (all part of the FePsy test system) with proven sensitivity of cognitive effects of antiepileptics: three tasks using reaction-time to measure speed ('simple (visual) reaction-time measurement', 'the binary choice reaction test' and 'the computerized visual searching task'); one test measuring motor speed ('the finger tapping task'); and a memory test ('recognition of words'). The three reaction-time tasks and the finger tapping test were significantly correlated with the ABNAS-score with correlations ranging from 0.22 to 0.35. The highest correlation was with 'simple (visual) reaction-time measurement' (0.35). Discriminant analysis showed that with the neuropsychological tests 61.5% of the patients were correctly identified as having high/low ABNAS-scores. The ABNAS underestimated impairment in 17.8% of the patients ( = low ABNAS-score but impairment on the neuropsychological tests). The present study contributes to the already existing evidence of validity of the ABNAS as a screening instrument for clinical practice as the relationship between the ABNAS-score and results of neuropsychological tests can help to identify who is at risk and needs further referral for neuropsychological assessment. Moreover the correlation between ABNAS-score and those neuropsychological tests that are sensitive for drug-effects may provide a sensitive instrument in early drug-development phases while keeping the burden on financial and time resources to a minimum.

Memory Complaints in Medically Refractory Epilepsy: Relationship to Epilepsy-Related Factors.

This study reports the results of a multicenter study on memory complaints in 252 patients with epilepsy who presented with subjective complaints about memory problems in daily life. Memory complaints were measured with a standardized memory questionnaire (GKLE). The main purpose was to analyze the type of memory complaints and to examine the relationship between subjective complaints and several epilepsy-related factors. These include seizure type, lateralization and location of the focus, etiology, duration, age at onset, and antiepileptic medication. As expected patients experienced significantly more memory complaints. In particular, patients of older age and higher intelligence level complained more about their memory functioning. Although the clinical significance is marginal, neuroticism showed a significant relationship to the total complaint score. The total amount of subjective complaints is not related to the localization or lateralization of the epileptic disturbances. Patients with a longer duration of epilepsy complained significantly more about memory problems, especially about retrieving information from memory. All other epilepsy-related factors showed no relationship to memory complaints.