Article

The neurobiology of cognitive disorders in temporal lobe epilepsy.

Department of Neurology, University of Wisconsin School of Medicine and Public Health, 600 North Highland Avenue, Madison, WI 53792, USA.
Nature Reviews Neurology (Impact Factor: 15.52). 02/2011; 7(3):154-64. DOI: 10.1038/nrneurol.2011.3
Source: PubMed

ABSTRACT Cognitive impairment, particularly memory disruption, is a major complicating feature of epilepsy. This Review will begin with a focus on the problem of memory impairment in temporal lobe epilepsy (TLE). We present a brief overview of anatomical substrates of memory disorders in TLE, followed by a discussion of how our understanding of these disorders has been improved by studying the outcomes of anterior temporal lobectomy. The clinical efforts made to predict which patients are at greatest risk of experiencing adverse cognitive outcomes following epilepsy surgery are also considered. Finally, we examine the vastly changing view of TLE, including findings demonstrating that anatomical abnormalities extend far outside the temporal lobe, and that cognitive impairments extend beyond memory function. Linkage between these distributed cognitive and anatomical abnormalities point to a new understanding of the anatomical architecture of cognitive impairment in epilepsy. Clarifying the origin of these cognitive and anatomical abnormalities, their progression over time and, most importantly, methods for protecting cognitive and brain health in epilepsy, present a challenge to neurologists.

0 Bookmarks
 · 
97 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Epilepsy is a mystery even though it affects an estimated 50 million people worldwide. Its management is enigmatic and as such, is not curative, but rather aims to attain freedom from seizures without side-effects. However, an approach for the selection of the most effective drugs and doses for individual patients is lacking. Almost all of the antiepileptic drugs in current use are associated with adverse reactions, some of which are severe and life-threatening. A more comprehensive treatment strategy requires improved research on epilepsy. This is the key to developing a treatment plan focused on the individual needs of each patient. Pharmacogenetics can offer a novel line of attack in the treatment of epilepsy. The potential advantages of gene therapy in the management of epilepsy are manifold. It encompasses the principle of testing as to how genetic variation among individuals affects variation in drug response, efficacy, and potential adverse drug events. Pharmacogenomics is the investigation of relationships between patient genotype and responses to drug treatment. It holds the promise of selecting the right drug at the right dose for the right person. A conceptual framework that outlines the pharmacogenetic and pharmacogenomic aspects of epilepsy presented here. Future directions for research and the application of these technologies to the clinical practice of individualising treatment for epilepsy are also discussed. A combination of research strategies and prudent policies from government may lead to a better understanding of treatment effects and futuristic but realistic management in epilepsy.
    progress and communication in sciences. 10/2014; 1(1):27.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Normal brain functioning is presumed to depend upon interacting regions within large-scale neuronal networks. Increasing evidence exists that interictal network alterations in focal epilepsy are associated with cognitive and behavioral deficits. Nevertheless, the reported network alterations are inconclusive and prone to low statistical power due to small sample sizes as well as modest effect sizes. We therefore systematically reviewed the existing literature and conducted a meta-analysis to characterize the changes in whole-brain interictal focal epilepsy networks at sufficient power levels. We focused on the two most commonly used metrics in whole-brain networks: average path length and average clustering coefficient. Twelve studies were included that reported whole-brain network average path length and average clustering coefficient characteristics in patients and controls. The overall group difference, quantified as the standardized mean average path length difference between epilepsy and control groups, corresponded to a significantly increased average path length of 0.29 (95% confidence interval (CI): 0.12 to 0.45, p = 0.0007) in the epilepsy group. This suggests a less integrated interictal whole-brain network. Similarly, a significantly increased standardized mean average clustering coefficient of 0.35 (CI: 0.05 to 0.65, p = 0.02) was found in the epilepsy group in comparison with controls, pointing towards a more segregated interictal network. Sub-analyses revealed similar results for functional and structural networks in terms of effect size and directionality for both metrics. In addition, we found individual network studies to be prone to low power due to the relatively small group differences in average path length and average clustering coefficient in combination with small sample sizes. The pooled network characteristics support the hypothesis that focal epilepsy has widespread detrimental effects, that is, reduced integration and increased segregation, on whole brain interictal network organization, which may relate to the co-morbid cognitive and behavioral impairments often reported in patients with focal epilepsy.
    PLoS ONE 12/2014; 9(12):e114606. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Patients with Temporal lobe epilepsy (TLE) frequently display cognitive comorbidity and can have widespread network abnormalities, which might affect a variety of cognitive and intellectual functions. As a result, refractory TLE seems to be associated with slow but ongoing cognitive deterioration. The case is of a 32 year old, right handed male, engineering graduate, diagnosed with TLE- right mesial, 12 years ago. A number of head injuries were caused due to the seizure present, which includes a fall from height of 12 feet in childhood. The neuropsychological tests administered were Gesell's Drawing Test, Mini Mental State Examination, PGI Memory Scale, Battery of Performance Tests of Intelligence, Verbal Adult Intelligence Scale, Hamilton Rating Scale for Depression, Bender Visual Motor Gestalt Test and Dysfunction Analysis Questionnaire. No impairment found on orientation; average cognitive functioning; above average attention and concentration, verbal working memory, visual and verbal memory; average practical ability, abstract ability, average verbal intellectual ability; superior ability on comprehension and average performance ability. Mild to moderate impairment on perceptuo-motor functioning and an evidence of depression were present. Patient showed high dysfunction in personal, social, vocational and cognitive areas. The study highlights that even despite chronic epilepsy, with a series of head injuries due to the seizures; an individual can still have average neuropsychological abilities. Holistic neuropsychological rehabilitation along with Vocational Retraining would go a long way in the functional independence of the patient. Neuropsychologists have a significant role in the assessment, treatment, and rehabilitation of people with epilepsy.
    Annals of Neurosciences 10/2014; 21(4):155-159.

Full-text (2 Sources)

Download
65 Downloads
Available from
May 17, 2014