One Year Extension Study To Protocol C2/5/TZ:MS-05

Inclusion Criteria: * Successful completion of previous protocol, Study C2/5/TZ:MS-05 * Have a definitive diagnosis of Multiple Sclerosis * Patients may be allowed to take other anti-spasticity medication during the study (other than Baclofen pump)as per their individual daily dosing regimen, with the following qualification: (1) No dose after 18:00 on any study day (2) No dose at all on a clinic evaluation day * Females must agree to use a medically accepted form of birth control, be surgically sterile, or be two years post-menopausal. Oral contraception in NOT acceptable as it is contraindicated for tizanidine use. * Patients must meet criteria for stable 24 hour BP values based on the screening ABPM monitorings (with and without tizanidine challenge) as determined by the study's BP consultant Exclusion Criteria: * Use of CYP1A2 inhibitors \[e.g. ciprofloxacin or fluvoxamine as well as zileuton, other fluroquinolones (norfloxacin), antiarrythmics (amiodarone, mexiletine, propafenone), cimetidine, famotidine, oral contraceptives, acyclovir, and ticlopidine\] from baseline and for the duration of the study * Taking medications from baseline and for the duration of the study that would potentially interfere with the actions of the study medication or outcome variables as determined by the PI * Previous history of dementia, unstable psychiatric disease or current signs and symptoms of significant medical disorders such as severe, progressive or uncontrolled renal, hepatic hematological, endocrine, pulmonary, cardiac, neurological or cerebral disease * Significant abnormalities in screening laboratory parameters as described below: * ALT \> 2xULN * AST \> 2xULN * Creatinine \> 2.0 mg/dL * Bilirubin \> 2xULN * WBC \< 2,300/mm3 * Platelets \< 80,000/mm3 * History of allergy to tizanidine or any inactive component (including lactose intolerance) of the sublingual tizanidine tablet * History of substance abuse within past 12 months * Patients who are non-cooperative or unwilling to sign consent form