Inclusion Criteria:

1. Clinical diagnosis of ALS classified as definite, or probable with or without additional laboratory evidence, according to the revised WFN El Escorial criteria.
2. Age 18 to 75 years inclusive.
3. If patients are being treated with riluzole, they must have been on a stable dose for at least 30 days.
4. Ophthalmological examination at screening with normal findings regarding vascular structure and function.
5. MRI/magnetic resonance angiography (MRA) examination of the brain and cervical spinal cord at screening with no findings of tumors or potential sources of pathological bleedings, or abnormality that may interfere with the assessments of safety or efficacy or that would, in the judgement of the investigator, represent a surgical risk to the subject.
6. Values of coagulation parameters including platelet count, normalized prothrombin complex (PK-INR), activated partial thromboplastin time (APTT) within normal ranges.
7. Patient is medically able to undergo the surgery required for stereotactic implantation of the catheter and infusion pump.
8. Patient has been given written and verbal information, has had the opportunity to ask questions about the study, and understands the time and procedural commitments.
9. Patient has given signed consent (written) to participate in the study. In the event that a patient who gives oral informed consent is not physically able to sign the informed consent form (ICF) due to disease progression, a witness may sign the ICF on the patient's behalf.

Exclusion Criteria:

1. Impaired respiratory function judged to pose a risk to the patient during anaesthesia for the device implantation.
2. Hypertension defined as blood pressure >160 mmHg systolic or >90 mmHg diastolic.
3. Diagnosis of diabetes mellitus.
4. Proliferative retinopathy.
5. Non-proliferative retinopathy of moderate severity or higher.
6. Concurrent clinically significant dementia as determined by the investigator.
7. Concurrent clinically significant depression as determined by the investigator.
8. History of structural brain disease other than ALS, including tumours and hyperplasia.
9. Any disorder that precludes a surgical procedure (e.g., signs of sepsis or inadequately treated infection), alters wound healing (e.g., including bleeding disorders), or renders chronic ICV delivery or device implants medically unsuitable.
10. Presence of risk for increased or uncontrolled bleeding and/or risk of bleeding that is not managed optimally. Physicians should specifically investigate anatomical factors at or near the implant site (e.g., vascular abnormalities, neoplasms, or other abnormalities), underlying disorders of the coagulation cascade, platelet function, or platelet count (e.g., haemophilia, Von Willebrand's disease, liver disease, or other medical conditions), and the administration of any antiplatelet or anticoagulant medication (e.g., aspirin, Plavix, NSAIDs) in the pre- or perioperative period. Any of those conditions or drugs could place a patient at an increased risk for intraoperative or postoperative bleeding.
11. Presence of an implanted shunt for the drainage of CSF or an implanted CNS catheter.
12. Presence of cardiac pacemakers, spinal cord stimulators, implantable programmable intraspinal drug pumps, or any other device that may interfere or interact with the programmer, without prior approval by Medtronic.
13. Clinically significant abnormalities in hematology or clinical chemistry parameters as assessed by the investigator.
14. Ongoing medical condition that according to the investigator would interfere with the conduct and assessments in the study. Examples are medical disability (e.g., severe degenerative arthritis, compromised nutritional state, peripheral neuropathy) that would interfere with the assessment of safety and efficacy of investigational product or device performance, or would compromise the ability of the subject to undergo study procedures (e.g., MRI), or to give informed consent.
15. Participation in another clinical trial with an investigational drug or device within 3 months prior to Screening visit.
16. For female subjects, ongoing pregnancy or planned pregnancy during the period of treatment with study drug.
17. Breast feeding during the period of treatment with study drug.