[Pseudo-polymyositic aspect of amyotrophic lateral sclerosis]

The causes of skeletal muscle weakness are multiple and their diagnosis is difficult, particularly in atypical myopathy. We report the observation of 58-old woman, who presents a muscle weakness of lower limbs with elevation of muscle's enzymes. These symptoms were bound initially to polymyosistis. However, the absence of inflammatory biologic syndrome and the results of muscular biopsy, make this diagnosis unlikely. The aggravation of the myopathy with extension to spinal muscles, the apparition of fasciculations and bulbar signs, the results of the electromyogram pose the diagnosis of amyotrophic lateral sclerosis.