[What are the clinical criteria of amyotrophic lateral sclerosis by clinical form?].

The diagnosis of ALS requires the presence of lower and upper motor neuron degeneration and a progressive spread of symptoms and signs. Due to the lack of any biological diagnostic marker, the World Federation of Neurology established clinical and paraclinical criteria (El Escorial 1991; Airlie House 1998). These criteria allow to establish a diagnosis with various levels of certainty. In practice they have a low sensitivity, especially at the beginning of the disease, and may delay the diagnosis. They exclude also some clinical forms and are not helpful in the differential diagnosis.