Tourette's syndrome is a disabling neuropsychiatric disorder with major psychosocial consequences in some patients. The pathophysiology is still unknown. Some data suggest an dysfunction of limbic circuits in basal ganglia. The aim of this study is to evaluate the effect of high frequency stimulation of the internal part of the globus pallidus and/or parafascicular-median centre of the thalamus, two structures implicated in the limbic circuit, in patients with severe Tourette's syndrome.