[Dystonia in the child].

A classification of child dystonias is proposed as a guide to etiological diagnosis. The analysis of symptoms and signs provides a distinction between dystonia and other involuntary movements: dystonia is a tonic involuntary movement which appears during voluntary activity as a slow and involuntary movement. Two groups of child dystonic syndromes can be distinguished: 1) dystonic syndromes where dystonia is the main neurologic abnormality; they result mainly from toxic and anoxic disorders and from torsion dystonia; 2) dystonic syndromes with associated dystonia and intellectual impairment; they are often familial neurometabolic disorders. Analysis of child dystonias show some common features: a long interval between the causative brain lesion and the onset of dystonia is possible, and may last several years. In neuro-metabolic disorders also dystonia appears after the first year of life, when psycho-motor impairment has already appeared. Etiologic investigations can provide a diagnosis and sometimes a treatment in several varieties of dystonia, e. g. L-Dopa in torsion dystonia, correction of metabolic disturbance in Wilson disease or glutaric aciduria. Genetic counselling should be provided.