OBJECTIVE: Early and accurate diagnosis of amyotrophic lateral sclerosis (ALS) 
is important for patient care and for entry in clinical trials. Retrospective 
studies suggest that the use of the Awaji algorithm for the diagnosis of ALS is 
more sensitive for early diagnosis than the currently used revised El Escorial 
criteria.
METHODS: We prospectively compared the revised El Escorial criteria with the 
Awaji algorithm in patients seen with suspected ALS at the University Hospitals 
Leuven between January 2008 and April 2010.
RESULTS: Out of 200 patients referred for the diagnosis of ALS, 66% and 85% 
could be categorized to definite or probable ALS at first presentation according 
to the revised El Escorial and the Awaji algorithm, respectively (p < 5.6 × 
10(-17) ). This corresponds to a >50% reduction of patients not eligible for 
clinical trial entry. Application of the Awaji algorithm made the diagnosis of 
ALS more likely by at least 1 diagnostic category in 25.7% of patients and 
identified at least 1 additional region with electrodiagnostic signs of ongoing 
lower motor neuron loss in 46.4% of electrodiagnostic investigations. 
Application of the Awaji algorithm did not result in a single false-positive 
diagnosis of ALS in this study.
INTERPRETATION: Our data demonstrate that the Awaji algorithm is significantly 
more sensitive compared to the revised El Escorial criteria, without resulting 
in false-positive diagnoses of ALS. It should therefore be used in clinical 
trials.