Zonisamide as a Treatment for Partial Epileptic Seizures: A Systematic Review

Effective treatment of epilepsy depends on medication compliance across a lifetime, and studies indicate that drug tolerability is a significant limiting factor in medication maintenance. Available antiepileptic drugs (AEDs) have the potential to exert detrimental effects on cognitive function and therefore compromise patient wellbeing. On the other hand, some agents may serve to enhance cognitive function. In this review paper, we highlight the range of effects on cognition linked to a variety of newer and older AEDs, encompassing key alterations in both specific executive abilities and broader neuropsychological functions. Importantly, the data reviewed suggest that the effects exerted by an AED could vary depending on both patient characteristics and drug-related variables. However, there are considerable difficulties in evaluating the available evidence. Many studies have failed to investigate the influence of patient and treatment variables on cognitive functioning. Other difficulties include variation across studies in relation to design, treatment group and assessment tools, poor reporting of methodology and poor specification of the cognitive abilities assessed. Focused and rigorous experimental designs including a range of cognitive measures assessing more precisely defined abilities are needed to fill the gaps in our knowledge and follow up reported patterns in the literature. Longitudinal studies are needed to improve our understanding of the influence of factors such as age, tolerance and the stability of cognitive effects. Future trials comparing the effects of commonly prescribed agents across patient subgroups will offer critical insight into the role of patient characteristics in determining the cognitive impact of particular AEDs.

The etiology of epilepsy is a major determinant of clinical course and prognosis, yet the current classifications of epilepsy do not list etiology in any detail. In this article, a classification (database) of the etiologies of epilepsy is proposed. In this scheme, the etiology of epilepsy is divided into four categories: idiopathic, symptomatic, provoked, and cryptogenic. These are defined and subcategories are proposed. A commentary addressing the following points is included: problems associated with assigning causation, symptomatic versus idiopathic epilepsy, focal versus generalized epilepsy, acquired epilepsy, acute symptomatic epilepsy, risk factor analysis, provoked epilepsy genetic and developmental epilepsy, and epilepsy as a disease not a symptom. Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.

Additional options are needed for monotherapy treatment of adults newly diagnosed with partial epilepsy. This trial compares the efficacy and tolerability of once-daily zonisamide with twice-daily controlled-release carbamazepine monotherapy for such patients.