A Study in Patients With Amyotrophic Lateral Sclerosis (ALS)

Inclusion Criteria: 1. Patients who are able to submit written informed consent. If patients are duly capable of study consent but are unable to sign (or affix a seal) by themselves due to aggravation of disease condition, written informed consent can be obtained from a legally authorized representative who can sign on behalf of the patients after confirming the patients' agreement to study participation. 2. Patients who are aged 20 years or older at the time of obtaining informed consent. 3. Patients who have clinically definite ALS, clinically probable ALS, or clinically probable-laboratory supported ALS as specified in the revised El Escorial Airlie House diagnostic criteria. 4. Patients who are at stage 1 or 2 of the severity criteria for ALS. 5. Patients within 3-year elapsed time period from disease onset at the start of observation period. 6. Patients who can visit study site for out-patient treatment. Exclusion Criteria: 1. Patients who underwent tracheostomy. 2. Patients who experienced non-invasive positive pressure ventilation. 3. Patients whose percent-predicted forced vital capacity (%FVC) is \>=60%. 4. Patients with multiple disturbances of conduction detected by nerve conduction test. 5. Patients with neurological symptom(s) due to vitamin B12 deficiency. 6. Patients who initiated newly introduced riluzole therapy after starting the observation period. Or those who received dose escalation or resumed administration of riluzole therapy after previous down titration or discontinuation. 7. Patients with cognitive impairment. 8. Pregnant women or women with a possibility of becoming pregnant. 9. Patients or their partners who are not willing to use reliable contraception. 10. Patients with severe disease in the renal, cardiovascular, hematological, or hepatic system (severe disease will be judged referring to "Ministry of Health, Labor and Welfare" (MHLW) Drug Safety Dept. Notification No. 80, Drug Safety Classification Criteria for Severity of Adverse Drug Reaction by Medicinal Products, Grade 3). 11. Patients with malignant tumor. 12. Patients who participated in another clinical study within 12 weeks before starting the observation period. 13. Patients with present illness or history of drug allergy or severe allergic disease (anaphylactic shock). 14. Patients who are judged to be ineligible for study entry by the investigator or subinvestigator.