The McDonald criteria are the clinical criteria used to diagnose multiple sclerosis. Established in 2001, by an international panel of experts in the disease led by Ian McDonald, they have been modified in revisions in 2005, 2010 and 2017, with the aim of facilitating their use in clinical practice, shortening the time to diagnosis and initiation of treatment and improving case detection.

"Since the last review in 2017, new evidence and data have emerged that made it necessary to carry out a new update of the McDonald criteria," states Dr. Xavier Montalban, director of Cemcat and head of the Neurology service of the Vall d'Hebron University Hospital and the Clinical Neuroimmunology group of the Vall d'Hebron Research Institute (VHIR). Montalban is also chair of the International Advisory Committee on Clinical Trials in Multiple Sclerosis, the body that has classically been in charge of reviewing the McDonald criteria. "A year and a half ago, at a conference, I proposed reexamining some of the more established concepts. This first seed culminated in a meeting held between November 29 and December 2 of this year, in Barcelona."

The meeting was attended by more than 55 experts and opinion leaders in multiple sclerosis from all over the world. Among them, in addition to Dr. Montalban, Dr. Jaume Sastre-Garriga, deputy director of Cemcat, assistant of the Neurology Service of the Vall d'Hebron University Hospital and principal investigator of the Clinical Neuroimmunology group of VHIR, Dr. Mar Tintoré, head of care of Cemcat, clinical head of the Neurology Service of the Vall d'Hebron University Hospital and principal investigator of the Clinical Neuroimmunology group of VHIR, Dr. Georgina Arrambide, neurologist and researcher of Cemcat and the Clinical Neuroimmunology group of VHIR, and Dr. Susana Otero-Romero, researcher at Cemcat, assistant physician at the Preventive Medicine Service of the Vall d'Hebron University Hospital and head of the Epidemiology and Public Health group at VHIR.

During the meeting, topics such as the isolated radiological syndrome, in which a person presents with white matter lesions suggestive of multiple sclerosis, the concepts of dissemination in time and space of lesions and the value of kappa-free light chains were discussed. The possibility of including the optic nerve as one of the typical topographies was also discussed, as well as the central vein sign (CVS) and paramagnetic rim lesions (PRL) as MRI biomarkers or the need to determine anti-MOG antibodies, among others.

"It was an honor to chair and collaborate in thoughtful discussions with key leaders from around the world to comprehensively explore and review numerous innovative concepts and advances in the field of multiple sclerosis," highlights Montalban. "We hope that the profound changes we have agreed upon will enable early diagnosis of multiple sclerosis, while maintaining or increasing its sensitivity and specificity. We also encourage the entire community of multiple sclerosis professionals to provide their comments, as we believe that all points of view are important."