[Topography of secondary dystonia lesions]

Biological causes provoking dystonia can not be systematized, with the exception of the small group of levodopa-responsive dystonia. Therefore the pathophysiology of the dystonic syndrome can be approached by considering the site of the lesions. In 40 cases of uni or bilateral symptomatic dystonias, this site could be identified with CT Scan or MRI. Twenty-one were located in the striatum, six in the pallidum, seven in the thalamus, six in the midbrain. Each group is characterized by etiologic and clinical criteria, sometimes associated with abnormal movements. In the striatal group, the most important, dystonia was often associated by athetosis or choreoathetoid abnormal movements. In some cases, in children, lesions were vascular due to impairment of lenticulo-striatal arteries, often following cranial trauma. The pallidal lesions were usually provoked by metabolic or infectious agents. Most thalamic dystonias were of vascular origin, sometimes accompanied by myoclonia. Midbrain lesions were usually vascular with tremor. Athetosis occurred after striatal rarely after pallidal lesions. It is advisable not to assimilate dystonia and athetosis as both are simultaneously observed if the lesions are located in the striatum, rarely in the the pallidum but not in the midbrain.