Clinical neurophysiology in the diagnosis of amyotrophic lateral sclerosis: the Lambert and the El Escorial criteria.

For many years, the only published criteria for the electrodiagnostic (EDX) recognition of amyotrophic lateral sclerosis (ALS) were those formulated by Lambert (1957; 1969). In 1990, different EDX guidelines were incorporated in the all-inclusive diagnostic criteria formulated by a subcommittee on ALS of the World Federation of Neurology, which met in El Escorial, Spain. Unfortunately, particularly in regard to the EDX requirements, the 'El Escorial criteria' have several flaws which compromise their usefulness. These include: (1) they ignore the fact that whenever upper and lower motor neuron disorders co-exist, as they characteristically do with ALS, the motor unit potential firing pattern is controlled by the upper motor neuron lesion; (2) they markedly devalue the usefulness of detecting fasciculations and, through presumably typographical error, state that the 'absence' rather than the 'presence' of fasciculations supports the diagnosis of ALS; this view is in direct conflict with the opinions expressed by most electromyographers; (3) they contain a statement regarding how the diagnosis of ALS is confirmed by the EDX studies which is confusing and, for two of the body regions (bulbar; thoracic), unrealistic; (4) finally, many of the EDX features they listed supporting the recognition of possible LMN degeneration appear to be mislabeled, while a few features in the EDX criteria are incorrect.