Correlation between Cognition and Behavior in Epilepsy

Epilepsy surgery in an 8-year old boy with intractable seizures

Mark is an 8-year old boy with a history of intractable epilepsy. Mark's seizures started when he was five years old, lasting less than a minute, with 7-10 episodes occurring in succession. Daytime seizures were described by his parents a "staring events where he does not respond, he will pick at clothes and speak gibberish." He was often disorientated for the remainder of the day. Nighttime seizures were described as "sitting up straight in bed, staring at the ceiling, and being unresponsive." An increase in his seizure frequency after multiple anticonvulsant medications prompted a surgical evaluation. A magnetic resonance (MR) brain scan indicated mild encephalomacia in the left hemisphere. A video electroencephalogram (EEG) demonstrated that the seizures initiated from the left hemisphere in association with multiple subclinical seizures. A PET scan showed decreased uptake in the left frontal lobe compared to the right. At 7 years of age Mark underwent a left frontal temporal-parietal resection. He had a post-surgical infection, but no other medical sequelae. After surgery, there was a significant decrease in seizures with only one seizure in the 2 month post operative period. Mark had neuropsychological testing prior to and following surgery. Pre-surgical results indicated that his IQ was within the low-average range. Visual-perceptual abilities, motor tasks and attention domains indicated difficulties. Post-surgical neuropsychological evaluation revealed a positive outcome. IQ remained in the low average range and there was a mild improvement in visual-perceptual/visual-constructional areas. Academic skills were unchanged with the exception of a slight decline in reading ability. Attention scores improved although redirection was required to sustain his attention during tasks. An increase in non-compliant behavior and emotional liability was noted by his parents. At the time of referral, when Mark was 8-years 3-months old, parental concerns included inattention, anger and emotional lability. The referral question posed was: "Does Mark's inattention represent an attention deficit/hyperactivity disorder, anxiety, or other psychological problems and what it the relationship of his current behaviors to his epilepsy?"

Behavior in children with cryptogenic localization related epilepsy: a follow-up study

Using the Child Behavior Checklist, the behavior of 16 children with cryptogenic localization-related epilepsy was assessed at first admission to our epilepsy center, and approximately 2 years later. Behavior improved substantially from t(1) (first assessment, when patients were admitted to our center) to t(2) (reassessment after approximately 2 years) on almost all subscales of the Child Behavior Checklist. At t(2), all subscales scored within normal range. Furthermore, seizure frequency improved considerably in the 2 years between assessments. After a period of approximately 2 years, normalization of behavior in children with cryptogenic localization-related epilepsy occurred.

Behavioral and cognitive alterations, spontaneous seizures, and neuropathology developing after a pilocarpine-induced status epilepticus in C57BL/6 mice

Many patients with epilepsy suffer from psychiatric comorbidities including depression, anxiety, psychotic disorders, cognitive, and personality changes, but the mechanisms underlying the association between epilepsy and psychopathology are only incompletely understood. Animal models of epilepsy, such as the pilocarpine model of acquired temporal lobe epilepsy (TLE), are useful to study the relationship between epilepsy and behavioral dysfunctions. In the present study, we examined behavioral and cognitive alterations, spontaneous seizures, and neuropathology developing after a pilocarpine-induced status epilepticus in the C57BL/6 (B6) inbred strain of mice, which is commonly used as background strain for genetically modified mice. For this study, we used the same pilocarpine ramping-up dosing protocol and behavioral test battery than in a previous study in NMRI mice, thus allowing direct comparison between these two mouse strains. All B6 mice that survived SE developed epilepsy with spontaneous recurrent seizures. Epileptic B6 mice exhibited significant increases of anxiety-related behavior in the open field and light-dark box, increased locomotor activity in the open field, elevated plus maze, hole board, and novel object exploration tests, and decreased immobility in the forced swimming and tail suspension tests. Furthermore, spatial learning and memory were severely impaired in the Morris water maze, although hippocampal damage was much less severe than previously determined in NMRI mice. B6 mice in which pilocarpine did not induce SE but only single seizures did not exhibit any detectable neurodegeneration, but differed behaviorally from sham controls in several tests of the test battery used. Our data indicate that the pilocarpine model of TLE in B6 mice is ideally suited to study the neurobiological mechanisms underlying the association between seizures, brain damage and psychopathology.

How can cognitive status predispose to psychological impairment?

A significant proportion of people report cognitive impairments, in particular memory problems, and express concern that these impairments will worsen with the passage of time. Unfortunately, the lack of well-designed studies has meant that disentangling the relative influences of factors likely important in the development and course of neuropsychological impairment has proved problematic. In addition to experiencing neuropsychological difficulties, people with epilepsy have to manage the psychosocial sequalae often associated with epilepsy. A diagnosis of epilepsy can have negative implications for quality of life and be associated with an increased risk of psychosocial problems; and individuals with epilepsy do not all experience its impact equally. The impacts of neuropsychological functioning on quality of life have only been rarely investigated, but there is some evidence to suggest that quality of life may correlate better with self-perceived cognitive difficulties than with scores on formal tests of cognitive functioning.

Early deficits in spatial memory and theta rhythm in experimental temporal lobe epilepsy

Patients with temporal lobe epilepsy (TLE), the most common form of epilepsy in adults, often display cognitive deficits. The time course and underlying mechanisms of cognitive decline remain unknown during epileptogenesis (the process leading to epilepsy). Using the rat pilocarpine model of TLE, we performed a longitudinal study to assess spatial and nonspatial cognitive performance during epileptogenesis. In parallel, we monitored interictal-like activity (ILA) in the hippocampal CA1 region, as well as theta oscillations, a brain rhythm central to numerous cognitive processes. Here, we report that spatial memory was altered soon after pilocarpine-induced status epilepticus, i.e., already during the seizure-free, latent period. Spatial deficits correlated with a decrease in the power of theta oscillations but not with the frequency of ILA. Spatial deficits persisted when animals had spontaneous seizures (chronic stage) without further modification. In contrast, nonspatial memory performances remained unaffected throughout. We conclude that the reorganization of hippocampal circuitry that immediately follows the initial insult can affect theta oscillation mechanisms, in turn, resulting in deficits in hippocampus-dependent memory tasks. These deficits may be dissociated from the process that leads to epilepsy itself but could instead constitute, as ILA, early markers in at-risk patients and/or provide beneficial therapeutic targets.

Behavioral status of children with cryptogenic localization-related epilepsy

Using the Child Behavior Checklist, behavior of 51 children with cryptogenic localization-related epilepsy was studied. According to parent report, children with cryptogenic localization-related epilepsy scored in the clinical range on the subscales "internalizing behavior," ''total behavior,'' and "attentional problems.'' No relation between the epilepsy factors seizure frequency, age at onset, duration of epilepsy or the number of antiepileptic drugs, and the subscales of the Child Behavior Checklist was found. Only for seizure type a relationship was found. Although in the normal range, the more severe the seizure type, the more delinquent, aggressive, and externalizing behavioral problems. Other studies have demonstrated that in children with epilepsy, internalizing problems are more common than externalizing problems, and that attentional, social, and thought problems are relatively specific. Therefore, we can conclude that the behavioral problems we found in our cohort are not very different from behavioral problems described in other epilepsy types.

Influence of sleep disturbance on quality of life of patients with epilepsy

The frequency of sleep disturbances in patients with epilepsy and their impact on quality of life (QoL) have been documented in a few reports, and the results are conflicting. We identified 124 consecutive epilepsy out-patients who visited the epilepsy out-patient clinics at the University Hospital of Alexandroupolis, the AHEPA Hospital in Thessaloniki and the Aeginitio Hospital in Athens. We measured excessive daytime sleepiness (EDS) with the Epworth Sleepiness Scale (ESS), obstructive sleep apnea (OSA) with the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ), and insomnia with the Athens Insomnia Scale (AIS). We evaluated quality of life by the Quality of Life in Epilepsy Inventory (QOLIE-31). EDS was found in 16.9% (21/124) of epileptic patients, OSA in 28.2% (35/124), and insomnia in 24.6% (30/122). In multivariate analysis, we found that insomnia was an independent negative factor for Total score (p<0.001), Overall QoL (p=0.002), Emotional well-being (p<0.001), Energy/fatigue (p<0.001), Cognitive functioning (p=0.04) and Social functioning (p=0.03), and OSA only for Cognitive functioning (p=0.01). According to our findings, EDS, OSA, and insomnia are frequent in epileptic patients. Epileptic patients with sleep disturbance, mainly insomnia, have significant QoL impairment.

Epilepsy surgery in an 8-year-old boy with intractable seizures

Mark is an 8-year-old boy with a history of intractable epilepsy. Mark's seizures started when he was five years old, lasting less than a minute, with 7-10 episodes occurring in succession. Daytime seizures were described by his parents a "staring events where he does not respond, he will pick at clothes and speak gibberish." He was often disorientated for the remainder of the day. Nighttime seizures were described as "sitting up straight in bed, staring at the ceiling, and being unresponsive." An increase in his seizure frequency after multiple anticonvulsant medications prompted a surgical evaluation. A magnetic resonance (MR) brain scan indicated mild encephalomacia in the left hemisphere. A video electroencephalogram (EEG) demonstrated that the seizures initiated from the left hemisphere in association with multiple subclinical seizures. A PET scan showed decreased uptake in the left frontal lobe compared to the right. At 7 years of age Mark underwent a left frontal temporal-parietal resection. He had a post-surgical infection, but no other medical sequelae. After surgery, there was a significant decrease in seizures with only one seizure in the 2 month post operative period. Mark had neuropsychological testing prior to and following surgery. Pre-surgical results indicated that his IQ was within the low-average range. Visual-perceptual abilities, motor tasks and attention domains indicated difficulties. Post-surgical neuropsychological evaluation revealed a positive outcome. IQ remained in the low average range and there was a mild improvement in visual-perceptual/visual-constructional areas. Academic skills were unchanged with the exception of a slight decline in reading ability. Attention scores improved although redirection was required to sustain his attention during tasks. An increase in non-compliant behavior and emotional liability was noted by his parents.At the time of referral, when Mark was 8-years 3-months old, parental concerns included inattention, anger and emotional lability. The referral question posed was: "Does Mark's inattention represent an attention deficit/hyperactivity disorder, anxiety, or other psychological problems and what is the relationship of his current behaviors to his epilepsy?"

Cognitive impairment in juvenile myoclonic epilepsy

BACKGROUND AND PURPOSE

Cognitive impairments are frequent consequences of epilepsy, with intellectual ability reportedly being lower in patients with idiopathic generalized epilepsies than in the general population. However, neuropsychological investigations have been rarely performed in patients with juvenile myoclonic epilepsy (JME). We aimed to quantify the cognitive function in JME patients using various neuropsychological tests.

METHODS

We compared cognitive function in 27 JME patients with that in 27 healthy volunteers using tests examining cognitive performance, such as the verbal and visual memory, frontal function, attention, IQ score, and mood. In the JME group, we examined risk factors for cognitive function such as age, sex, family history, education level, age at seizure onset, seizure frequency, EEG abnormality, disease duration, and previous intake of antiepileptic drugs.

RESULTS

Verbal learning was significantly lower in JME patients than in controls, and attention and verbal fluency were impaired in JME patients compared with controls. However, general intellectual ability and mood did not differ between the groups. Early onset of seizure and long duration of disease were closely related to impaired cognitive function.

CONCLUSIONS

JME patients may exhibit impaired cognitive function, in terms of memory and execution, despite having normal intelligence and mood.