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Interrater reliability of EEG-video monitoring

From the University of South Florida and Tampa General Hospital (S.R.B., K.K., K.L.), Tampa, FL; Rhode Island Hospital, Brown Medical School (W.C.L.), Providence, RI; Brown University (G.D.P.), Providence, RI; and Stanford University (H.C.K.), Palo Alto, CA.

Address correspondence and reprint requests to Dr. Selim R. Benbadis, 2 Tampa General Circle, 7th Floor, Tampa, FL 33606 sbenbadi{at}health.usf.edu

Objective: The diagnosis of psychogenic nonepileptic seizures (PNES) can be challenging. In the absence of a gold standard to verify the reliability of the diagnosis by EEG-video, we sought to assess the interrater reliability of the diagnosis using EEG-video recordings.

Methods: Patient samples consisted of 22 unselected consecutive patients who underwent EEG-video monitoring and had at least an episode recorded. Other test results and histories were not provided because the goal was to assess the reliability of the EEG-video. Data were sent to 22 reviewers, who were board-certified neurologists and practicing epileptologists at epilepsy centers. Choices were 1) PNES, 2) epilepsy, and 3) nonepileptic but not psychogenic ("physiologic") events. Interrater agreement was measured using a coefficient for each diagnostic category. We used generalized coefficients, which measure the overall level of between-method agreement beyond that which can be ascribed to chance. We also report category-specific values.

Results: For the diagnosis of PNES, there was moderate agreement ( = 0.57, 95% confidence interval [CI] 0.39–0.76). For the diagnosis of epilepsy, there was substantial agreement ( = 0.69, 95% CI 0.51–0.86). For physiologic nonepileptic episodes, the agreement was low ( = 0.09, 95% CI 0.02–0.27). The overall statistic across all 3 diagnostic categories was moderate at 0.56 (95% CI 0.41–0.73).

Conclusions: Interrater reliability for the diagnosis of psychogenic nonepileptic seizures by EEG-video monitoring was only moderate. Although this may be related to limitations of the study (diagnosis based on EEG-video alone, artificial nature of the forced choice paradigm, single episode), it highlights the difficulties and subjective components inherent to this diagnosis.

Abbreviations: ABCN = American Board of Clinical Neurophysiology; ABPN = American Board of Psychiatry and Neurology; CI = confidence interval; IRR = interrater reliability; PNES = psychogenic nonepileptic seizures.

*See the appendix for information about the NES Treatment Workshop.

The NES Treatment Workshop was sponsored by the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, and the American Epilepsy Society.

Disclosure: Author disclosures are provided at the end of the article.

Preliminary data were presented as an abstract at the 2007 American Epilepsy Society, Philadelphia, PA.

Received December 20, 2008. Accepted in final form June 22, 2009.