[What electroneuromyographic criteria are required for the diagnosis of amyotrophic lateral sclerosis?].

Electroneuromyography is essential for the diagnostic of amyotrophic lateral sclerosis. The aim of conventional needle examen is to detect peripheral motoneuron involvement by the identification of active and chronic diffuse neurogenic activities. This brings up the problem of the selection of the muscle to test to enhance the sensitivity of the exam. Recent techniques permit to study the reorganization of the motor units more precisely. Motoneuron loss is appraised by several methods for macro-EMG estimates of the number of motor units. The collateral reinnervation can be evaluated by single fibre EMG. The other main objective is to detect conduction abnormalities. These lead to differential diagnoses of pure motor neuropathy with conduction blocks. The different prognostic value of these different conditions required defining both sensitive and specific electrophysiological diagnostic criteria.