Electrodiagnosis of Guillain-Barre syndrome in the International GBS Outcome Study: Differences in methods and reference values
Samuel Arends, Judith Drenthen, Peter Van den Bergh, Hessel Franssen, Robert D. M. Hadden, Badrul Islam, Satoshi Kuwabara, Ricardo Reisin, Nortina Shahrizaila, Hiroshi Amino, Giovanni Antonini, Shahram Attarian, Claudia Balducci, Fábio Barroso, Tulio E. Bertorini, Davide Binda, Thomas H. Brannagan, Jan Buermann, Carlos Casasnovas, Guido Cavaletti, Chi‐Chao Chao, Mazen M. Dimachkie, E. Fulgenzi, Giuliana Galassi, Gerardo Gutiérrez‐Gutiérrez, Thomas Harbo, Hans‐Peter Hartung, Sung‐Tsang Hsieh, Lynette Kiers, Helmar C. Lehmann, Fiore Manganelli, Girolama Alessandra Marfia, Giorgia Mataluni, Julio Pardo, Yann Péréon, Yusuf A. Rajabally, Lucio Santoro, Yukari Sekiguchi, Beth E. Shubin Stein, Mark Stettner, Antonino Uncini, Christine Verboon, Camiel Verhamme, Michal Vytopil, Waqar Waheed, Min Wang, Sasha Živković, Bart C. Jacobs, David R. Cornblath, Jean Addington, Senda Ajroud‐Driss, Henning Andersen, Giovanni Antonini, Shahram Attarian, Umesh A. Badrising, G. Balloy, Fábio Barroso, Kathleen Bateman, I.R. Bella, Luana Benedetti, Peter Van den Bergh, T. E. Bertoríni, R. Bhavaraju-Sanka, Mariangela Bianco, Thomas H. Brannagan, Chiara Briani, Buerrmann, Mark Busby, S. Butterworth, Carlos Casasnovas, Guido Cavaletti, Chi‐Chao Chao, Govindsinh Chavada, Shiping Chen, Kristl G. Claeys, M.E. Conti, David R. Cornblath, Jeremy Cosgrove, Marinos C. Dalakas, Philip Van Damme, Efthimios Dardiotis, Andrew R. Davidson, Miroslawa Derejko, Gert W. van Dijk, Mazen M. Dimachkie, Pieter A. van Doorn, Charlotta Dornonville de la Cour, Andoni Echaniz‐Laguna, Filip Eftimov, Catharina G. Faber, Raffaella Fazio, Thomas E. Feasby, C. Fokke, T. Fujioka, E. Fulgenzi, Giuliana Galassi, Tania García‐Sobrino, Marcel P.J. Garssen, C.J. Gijsbers, James M. Gilchrist
Abstract
OBJECTIVE: To describe the heterogeneity of electrodiagnostic (EDx) studies in Guillain-Barré syndrome (GBS) patients collected as part of the International GBS Outcome Study (IGOS). METHODS: Prospectively collected clinical and EDx data were available in 957 IGOS patients from 115 centers. Only the first EDx study was included in the current analysis. RESULTS: Median timing of the EDx study was 7 days (interquartile range 4-11) from symptom onset. Methodology varied between centers, countries and regions. Reference values from the responding 103 centers were derived locally in 49%, from publications in 37% and from a combination of these in the remaining 15%. Amplitude measurement in the EDx studies (baseline-to-peak or peak-to-peak) differed from the way this was done in the reference values, in 22% of motor and 39% of sensory conduction. There was marked variability in both motor and sensory reference values, although only a few outliers accounted for this. CONCLUSIONS: Our study showed extensive variation in the clinical practice of EDx in GBS patients among IGOS centers across the regions. SIGNIFICANCE: Besides EDx variation in GBS patients participating in IGOS, this diversity is likely to be present in other neuromuscular disorders and centers. This underlines the need for standardization of EDx in future multinational GBS studies.