Should epileptiform discharges be treated?

Abstract

To evaluate the impact of epileptiform discharges (EDs) that do not occur within seizure patterns--such as spikes, sharp waves or spike waves--on cognitive function and to discuss the circumstances under which treatment of EDs might be considered. Methods used in this article is "Review of the literature". EDs may disrupt short-term cognition in humans. Frequent EDs for a prolonged period can potentially impair long-term cognitive function in humans. However, there is conflicting evidence on the impact of EDs on long-term cognitive outcome because this relationship may be confounded by multiple factors such as underlying etiology, seizures, and medication effects. Limitations of existing studies include the lack of standardized ED quantification methods and of widely accepted automated spike quantification methods. Although there is no solid evidence for or against treatment of EDs, a non-evidence-based practical approach is suggested. EDs in otherwise asymptomatic individuals should not be treated because the risks of treatment probably outweigh its dubious benefits. A treatment trial for EDs may be considered when there is cognitive dysfunction or regression or neurologic symptoms that are unexplained by the underlying etiology, comorbid conditions, or seizure severity. In patients with cognitive or neurologic dysfunction with epilepsy or EDs, treatment may be warranted to control the underlying epileptic syndrome. EDs may cause cognitive or neurologic dysfunction in humans in the short term. There is conflicting evidence on the impact of EDs on long-term cognitive outcome. There is no evidence for or against treatment of asymptomatic ED.

Keywords: Antiepileptic drugs; Cognition; Epileptiform discharges; Memory; Sleep.

Conflict of interest statement

DISCLOSURE OF CONFLICTS OF INTERESTS

None of the authors has any conflict of interest to disclose.

Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Figures

Figure 1.. Comparison of spike percentage and spike frequency for epileptiform discharge quantification.

The spike percentage considers that both tracings are equally severe with 100% of one-second bins occupied by, at least, one spike-wave in them. In contrast, the spike frequency considers that the upper tracing would be more severe as there is a higher number of spikes per unit of time.

Figure 2.. Suggested management of patients with EDs and different clinical conditions.

When EDs appear in otherwise asymptomatic subjects, treatment is usually not recommended. In patients with cognitive dysfunction or regression and no ongoing seizures there is insufficient evidence to recommend treatment although treatment may be justified in individual cases when suspicion that cognitive dysfunction relates to EDs exists. When EDs occur in the setting of cognitive dysfunction or regression and ongoing seizures, treatment is warranted. Treatment in this case may address the entire syndrome. Therapies targeting the EDs may be considered if EDs are suspected to underlie the cognitive dysfunction and if risk is lower than benefit. Legend: B: Benefits. EDs: epileptiform discharges. R: Risks.