Open-Label Extension Study to Evaluate the Safety, Tolerability and Activity of Oral Fampridine-SR in Patients With Multiple Sclerosis

Inclusion Criteria: * The subject must have been previously enrolled in an Acorda Therapeutics or an Elan Corporation sponsored study for multiple sclerosis and received either Fampridine or placebo. * The subject must have multiple sclerosis as determined by the Principal Investigator. * The subject, male or female, must be at least 18 years of age. Any subject who is now over the age of 70 must be in good overall health in the judgment of the Investigator. * The subject must be of adequate cognitive function, as judged by the Investigator. * Any subject who is female and of childbearing potential, regardless of sexual activity, must have a negative urine pregnancy test at the Screening Visit. Exclusion Criteria: * The subject is a female who is either pregnant or breastfeeding, or of child-bearing potential, who, if engaged in active heterosexual relations and has not had a hysterectomy or bilateral oophorectomy, would not use one of the following birth control methods: tubal ligation, implantable contraception device, oral, injectable or transdermal contraceptive, barrier method or sexual activity restricted to vasectomized partner. * The subject withdrew from a previous Fampridine study because of a Serious Adverse Event that was possibly, probably or definitely related to Fampridine. * The subject has a history of seizures or has evidence of past, or possible, epileptiform activity on an EEG. * The subject has either a clinically significant abnormal ECG or laboratory value(s) at the Screening Visit, as judged by the Investigator * The subject has angina, uncontrolled hypertension, clinically significant cardiac arrhythmias, or any other clinically significant cardiovascular abnormality, as judged by the Investigator. * The subject has a known allergy to pyridine-containing substances or any of the inactive ingredients of the Fampridine tablet * The subject has received an investigational drug, except for Fampridine- SR (or matching placebo) under Protocol MS-F202, within 30 days prior to the Screening Visit; or the subject is scheduled to enroll in an investigational drug trial at any time during this study. * The subject has received compounded 4-aminopyridine (4-AP) within 14 days of the Screening Visit. * The subject has had an onset of an MS exacerbation within 30 days prior to the Screening Visit, or, if in the judgment of the Investigator, has not stabilized from a prior exacerbation episode. * The subject has started on a concomitant medication regimen for an underlying disease/symptom within the past 7 days; or has started an interferon or chemotherapeutic agent for multiple sclerosis within the past 4 weeks. * The subject has a history of drug or alcohol abuse within the past year.