Eligibility criteria. Inclusion criteria are focal or diffuse encephalic lesions leading to coma (Glasgow score <8), age 18 years or over, in waking phase (spontaneous eye-opening) since at least one month and less than six months, severe hypertonia of the lower members (mean Ashworth score >= 3) with neurovegetative episodes (at least 10 in 48 hours) and/or decortication after failure of treatment per os (clonidine, beta-blocker, baclofen per os). Non inclusion criteria are surgical, anesthetic or allergic contraindication to baclofen, uncontrolled sepsis directly threatening the implanted device or associated medullary trauma.