Epidemiology of psychogenic nonepileptic seizures.

We critically review the existing literature about the epidemiology (i.e., diagnosis, occurrence, age, gender, comorbidity with epilepsy, associated factors, prognosis, mortality, and cost) of psychogenic nonepileptic seizures (PNES) and provide suggestions for future research. Psychogenic nonepileptic seizures are commonly diagnosed at epilepsy centers. The diagnosis of PNES relies on a multidisciplinary evaluation and is usually based on different combinations of data. Recording a seizure, while under video-EEG monitoring, is the most reliable diagnostic test. However, not all patients present with seizures while under video-EEG monitoring. Furthermore, not all epileptic seizures produce visible changes in the scalp EEG. The incidence of PNES was estimated to be 1.4-4.9/100,000/year in three previous studies, and the prevalence was calculated to be between 2 to 33 per 100,000 in one study, making it a significant neuropsychiatric condition. However, there remains a scarcity of data about the epidemiology of PNES, and extant studies that assessed the epidemiological characteristics of PNES have significant limitations. For example, inconsistencies with regard to the age of patients studied and lack of standardization of the diagnostic criteria are some of the significant limitations among studies. In conclusion, PNES merit further epidemiological and pathophysiological investigation. A more precise definition and clear guidance on standards for the diagnosis might influence the direction of future research. Well-designed prospective population-based studies to clarify the epidemiology of PNES in various parts of the world, including an evaluation of the predisposing, precipitating, and perpetuating factors in cross-cultural comparisons is required.