[Dejerine-Roussy syndrome].

The description of the thalamic syndrome by J. Dejerine and G. Roussy in 1906 was a consecration of the clinicopathologic method, announcing the end of discussions relative to the role of the thalamus as a sensorial relay center, discussions opposing B. Luys to Türk and to Charcot and which animated the end of the 19th century. Since then, the thalamic syndrome has not ceased to arouse the attention of neurologists, who have developed four major themes: the specificity of the thalamic hemianesthesia; the mechanism of the central pain; the semiologic value and physiopathology of the abnormal movements; and finally the pupillary and vasomotor disorders. Exploration of each of these topics led to a definition of neurologic semiology and to the development of neurophysiology during the second half of the XXth century. By reviewing this the confrontation between different men and schools appears behind the opposition of ideas. The revision of the thalamic syndrome ceased when the discovery of the non-specific functions of the thalamus opened the way to new concepts. Dejerine-Roussy's syndrome expresses the semiology of the relay nuclei. For the last thirty years, experience has accumulated on the semiology of lesions affecting the nuclei of convergence. Neuropsychology of thalamic lesions has demonstrated the regulatory role performed by the thalamus within each hemisphere and in the relative activation of each hemisphere. But this is another story.