Good interobserver and intraobserver agreement in the evaluation of the new ILAE classification of focal cortical dysplasias

Roland Coras, Onno J. De Boer, Dawna Armstrong, Albert Becker, Thomas S. Jacques, Hajime Miyata, Maria Thom, Harry V. Vinters, Roberto Spreafico, Buge Oz, Gianluca Marucci, Jose Pimentel, Angelika Mühlebner, Josef Zamecnik, Anna Maria Buccoliero, Fabio Rogerio, Nathalie Streichenberger, Nobutaka Arai, Marianna Bugiani, Silke VogelgesangRob MacAulay, Carolin Salon, Volkmar Hans, Marc Polivka, Felice Giangaspero, Dyah Fauziah, Jang Hee Kim, Lei Liu, Wang Dandan, Jing Gao, Benjamin Lindeboom, Ingmar Blümcke, Eleonora Aronica

Research output: Contribution to journalArticle


Summary Purpose: An International League Against Epilepsy (ILAE) consensus classification system for focal cortical dysplasias (FCDs) has been published in 2011 specifying clinicopathologic FCD variants. The aim of the present work was to microscopically assess interobserver agreement and intraobserver reproducibility for FCD categories among an international group of neuropathologists with different levels of experience and access to epilepsy surgery tissue. Methods: Surgical FCD specimens covering a broad histopathology spectrum were retrieved from 22 patients with epilepsy. Three surgical nonepilepsy specimens served as controls. A total of 188 slides with routine or immunohistochemical stainings were digitalized with a slide scanner to allow Internet-based microscopy review. Nine experienced neuropathologists were invited to review these cases twice at a time gap of 3 months and different orders of case presentation. The 2011 ILAE FCD consensus classification served as instruction. Kappa analysis was calculated to estimate interobserver and intraobserver agreement levels. In a third evaluation round, 21 additional neuropathologists with different experience and access to epilepsy surgery reviewed the same case series. Key Findings: Interobserver agreement was good (ΰ = 0.6360), with 84% consensus of diagnoses during the first evaluation (21 of 25 cases). Kappa values increased to 0.6532 after reevaluation, and consensus was obtained in 24 (96%) of 25 cases. Overall intraobserver reproducibility was also good (ΰ = 0.7824, ranging from 0.4991 to 1.000). Fewest changes in the classification were made in the FCD type II group (2.2% of 225 original diagnoses), whereas the majority of changes occurred in FCD type III (13.7% of 225 original diagnoses). In the third evaluation round, interobserver agreement was reflected by the level of experience of each neuropathologist, with ΰ values ranging from moderate (0.5056; high level of experience >40 cases/year) to low (0.3265; low level of experience

Original languageEnglish
Pages (from-to)1341-1348
Number of pages8
Issue number8
Publication statusPublished - Aug 2012


  • Agreement
  • Brain
  • Classification
  • Epilepsy
  • Neuropathology
  • Reproducibility

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology

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    Coras, R., De Boer, O. J., Armstrong, D., Becker, A., Jacques, T. S., Miyata, H., Thom, M., Vinters, H. V., Spreafico, R., Oz, B., Marucci, G., Pimentel, J., Mühlebner, A., Zamecnik, J., Buccoliero, A. M., Rogerio, F., Streichenberger, N., Arai, N., Bugiani, M., ... Aronica, E. (2012). Good interobserver and intraobserver agreement in the evaluation of the new ILAE classification of focal cortical dysplasias. Epilepsia, 53(8), 1341-1348.