Seizures in alcohol-dependent patients: epidemiology, pathophysiology and management.

The relationship between alcohol and seizures is complex and multifaceted. The prevalence of epilepsy in alcohol-dependent patients of western industrialised countries may be at least triple that in the general population, whereas the prevalence of alcoholism is only slightly higher in patients with epilepsy than in the general population. The seizure threshold is raised by alcohol drinking and declines on cessation of drinking. As a result, during withdrawal from alcohol, usually 6-48 hours after the cessation of drinking, seizures may occur. Alcohol acts on the brain through several mechanisms that influence seizure threshold. These include effects on calcium and chloride flux through the ion-gated glutamate NMDA and GABA receptors. During prolonged intoxication, the CNS adapts to the effects of alcohol, resulting in tolerance; however, these adaptive effects seem to be transient, disappearing after alcohol intake is stopped. Although the relationship of seizures to alcohol use is likely to be dose dependent and causal, the available clinical data do not suggest that alcohol use results in seizure genesis. However, a genetic predisposition to alcohol withdrawal seizures is possible. Other seizures in alcohol-dependent individuals may be due to concurrent metabolic, toxic, infectious, traumatic, neoplastic and cerebrovascular diseases and are frequently partial-onset seizures. Alcohol abuse is a major precipitant of status epilepticus (9-25% of cases), which may even be the first-ever seizure type. Prompt treatment of alcohol withdrawal seizures is recommended to prevent status epilepticus. During the detoxification process, primary and secondary preventative measures can be taken. A meta-analysis of controlled trials for the primary prevention of alcohol withdrawal seizures demonstrated a highly significant risk reduction for seizures with benzodiazepines and antiepileptic drugs and an increased risk with antipsychotics. A meta-analysis of randomised, placebo-controlled trials for the secondary prevention of seizures after alcohol withdrawal showed lorazepam to be effective, whereas phenytoin was ineffective. Because withdrawal seizures do not recur if the patient remains abstinent, long-term administration of antiepileptic drugs is unnecessary in abstinent patients. The first seizure not related to alcohol withdrawal should not result in permanent drug treatment in an alcohol-dependent patient, because of poor compliance and the high likelihood of remission. The treatment of alcohol dependence is more important and should be prioritised before the prevention of further seizures.