Safety of Intrathecal Riluzole in Patients With Amyotrophic Lateral Sclerosis

Inclusion Criteria: * Men and women aged 18 years or older. * Participants are ambulatory with or without an assistive device. * Sporadic or familial ALS diagnosis with possible, laboratory-supported probable, probable, or definite as defined by revised El Escorial criteria. * Slow vital capacity (SVC) measure ≥70% of predicted for gender, height, and age. * Medically able to undergo implantation of the SynchroMed II Infusion Pump according to the judgment of the investigator, or the presence of a previously implanted IT pump (not to be used for concurrent IT infusion of another IT agent). * Capable of reading and providing informed consent and following study procedures. * Geographic accessibility to the study center and the ability to travel to the clinic for study visits by ground transportation. * Women must not be able to become pregnant (eg, post menopausal, surgically sterile, or using adequate birth control methods) for the duration of the study and 3 months after study completion. Adequate contraception includes: abstinence, hormonal contraception (oral contraception, implanted contraception, injected contraception or other hormonal (patch or contraceptive ring, for example) contraception), intrauterine device in place for ≥3 months, barrier method in conjunction with spermicide, or another adequate method. * Taking and tolerating oral riluzole 50 mg twice a day for at least 30 days prior screening and willingness to continue oral riluzole throughout duration of the study. * Patients may take other drugs approved for treatment of ALS at the dose prescribed by their neurologist. Exclusion Criteria: * Participants with bulbar-onset ALS * Participants at risk of increased bleeding or uncontrolled bleeding during the SynchroMed II Infusion Pump implantation or following explant. This includes but is not limited to: 1. Anatomical factors at or near the site of implantation; 2. Underlying disorders of the coagulation cascade or platelet function (eg, hemophilia, Von Willebrand's disease, liver disease); 3. Administration of antiplatelet or anticoagulant medication within 7 days before or after pump implantation (eg, aspirin, clopidogrel bisulfate, rivaroxaban, nonsteroidal anti-inflammatory agents \[NSAIDs\]), or 4. Use of nutritional supplements (eg, St John's Wort) within 7 days before or after pump implantation. * Presence of infection including but not limited to: meningitis, ventriculitis, skin infection, bacteremia, or septicemia. * Testing positive for HIV (anti-HIV antibody), HBV (HBV surface antigen) or HCV (anti-HCV antibody; HCV RNA if anti-HCV antibody is positive) at screening. * Inability to have the infusion pump implanted ≤ 2.5 cm below the skin surface. * Body weight and size unable to accept the infusion pump bulk and weight. * Spinal anomalies which would complicate the implantation and fixation of the catheter for IP delivery. * Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) value \> 2.0 times the upper normal. * A life expectancy of less than 6 months, based on the judgment of the investigator. * Presence of tracheostomy. * The presence of unstable psychiatric disease, cognitive impairment, or dementia that would impair the ability of the participant to provide informed consent, per investigator judgment. * History of active substance abuse within the prior year. * At risk for committing suicide per investigator judgment. * Clinically significant history of unstable or severe cardiac, oncologic, hepatic, or renal disease, or other medically significant illness. * Pregnant women or women currently breastfeeding. * Exposure to any investigational drug, device, or biologic within 30 days of screening.