The El Escorial criteria: strengths and weaknesses.

The El Escorial criteria for the diagnosis of amyotrophic lateral sclerosis (ALS) were established 20 years ago and have been used as inclusion criteria for clinical trials. However, concerns have been raised concerning their use as diagnostic criteria in clinical practice. Moreover, as modern genetics have shed new light on the heterogeneity of ALS and the close relationship between ALS and frontotemporal dementia (FTD) recognized, the World Federation of Neurology Research Group on ALS/MND has initiated discussions to amend and update the criteria, while preserving the essential components for clinical trial enrolment purposes.