[Zinc and epilepsy: is there a causal relation between them?]. / Zinc y epilepsia: existe una relación causal?

INTRODUCTION: Zinc is a fundamental trace element for an adequate nervous system function. It has been suggested that in the brain, a zinc homeostasis alteration may be associated with the genesis of epilepsy, although it is not yet determined if concentrations of zinc are a cause or a consequence of seizures. Another poorly studied aspect is the relationship between antiepileptic drugs and the neuronal zinc behaviour. DEVELOPMENT: We perform a systematic review of the literature to evaluate the role that zinc plays in epilepsy as well as the antiepileptic effect of zinc concentrations. Databases such as MEDLINE, EMBASE, SCISEARCH and LILACS were consulted from January 1974 to July 2005. All articles published in English and Spanish were considered. A manual review of the references present in each article was done in order to identify the articles that the electronic search may have not found itself. The title and abstract of the potential articles were analyzed before asking for the complete article. However, articles that seemed ambiguous were completely analyzed later to establish their relevance. CONCLUSIONS: Clinical research in epilepsy presented contradictory results. In fact, the reviewed studies, both animal and human, did not give enough evidence to determine if organic zinc variations are directly related to epilepsy. Most of them gave not statistically significant results.

[Changes in selenium levels in epilepsy]. / Alteración de la concentración de selenio en la epilepsia.

INTRODUCTION: It has been suggested that antiepileptic drug therapies deplete total body selenium stores and failure to give appropriate selenium supplementation, especially to patients receiving valproic acid during pregnancy may increase the risk of neural tube defects or other free radical mediated damage. Selenium is essential for the synthesis of selenoproteins, including glutathione peroxidase. AIMS: To review the present state of knowledge about selenium behaviour in people with epilepsy taking antiepileptic drugs and to develop guidelines for the appropriate use of selenium supplements. DEVELOPMENT: Databases such as Medline, Embase, Scisearch and Lilacs were consulted to have access to literature. A search in said databases was performed in order to find articles published from January 1966 to August 2004. All articles published in English and Spanish were considered. A manual review of the references present in each produced article was done in order to identify the articles that the electronic search may have not found itself. The title and abstract of the potential articles were analyzed before asking for the complete article. However, articles which seemed ambiguous were completely analyzed later to establish their relevance. CONCLUSIONS: There is insufficient evidence to fully evaluate the effect of selenium supplementation. The possible beneficial effects on pregnancy need to be evaluated in further studies.