Long-term Surveillance of the MedStream Programmable Infusion System

Inclusion Criteria: * The subject is a viable candidate for "de novo" or continued (pump replacement) therapy for the treatment of severe spasticity with intrathecal Baclofen delivered by an implantable programmable pump. * The subject or his/her Legally Authorized Representative must voluntarily provide Informed Consent for participation in this study in accordance with 21 Code of Federal Regulations (CFR) Part 50. * The subject is willing to comply with the protocol-specified follow-up visit requirements for a period of 36 months after implant. * The subject has an anticipated life expectancy of 24 months or greater. * The subject must be 18 years of age or older at time of MedStream implant procedure. * The subject is of sufficient body size to accommodate pump placement, in the opinion of the Investigator. * The subject will receive a de novo or replacement implant of the MedStream 20 mL or 40 mL pump, MedStream approved catheter(s) and MedStream accessories. * The Investigator intends to use Baclofen in the pump for treatment of severe spasticity * The subject is capable of self-reporting spasm frequency. Exclusion Criteria: * Concurrent enrollment in an investigational device or drug study that has not completed the required follow-up period. * Subject has had an infection and/or inflammation at or near the pump and/or catheter implantation site(s) within 30 days preceding enrollment. * Evidence of a fever or infection within 10 days prior to the surgical implant procedure that, in the opinion of the Investigator might impact a successful pump implant. * The subject has known hypersensitivity/allergies or contraindication to Baclofen or the materials in the infusion pump or catheter(s). * The subject has a co-morbid condition that could limit his/her ability to participate in the study or to comply with the follow-up requirements or, which might impact the scientific integrity of the study. * The subject has a rapid degenerative neurological disease such as lateral sclerosis, amyotrophic lateral sclerosis (ALS), rapidly progressive Multiple Sclerosis, inherited or rapidly progressive leukodystrophies, Moyamoya disease, cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL), thrombophilias, rapidly progressive autoimmune disorders, or any disorder where progression of the underlying spinal cord or a central nervous system (CNS) disease is expected to progress significantly over the next 3 years * Subject is a prisoner. * Subject was previously enrolled in this study. * Subject is pregnant or breastfeeding. (Note: females of child bearing potential must have a negative pregnancy test prior to enrollment in the study).