The incidence of tremor in Multiple Sclerosis (MS) has been estimated to affect up to 2/3rds of patients. Over half of the tremors involve the upper limb and frequently lead to further disability. Medical treatment of MS tremor is generally unrewarding, although carbamazepine, clonazepam, glutethimide, hyoscine, isoniazid, ondansetron, primidone, and tetrahydrocannabinol have been reported to have some beneficial effect but published evidence of effectiveness is very limited. The investigators' experience to date suggests that many of the upper limb tremors may potentially be responsive to Botulinum toxin injection therapy.

Aims:

1. The investigators aim to determine the efficacy of commonly used doses of BOTOX on the patients with symptomatic unilateral or bilateral arm tremor due to MS; and any side effects associated with this treatment.

Inclusion Criteria:

• Relapsing-remitting MS or secondary progressive MS according to the Mc Donald criteria
• Age 18-80 years of age
• Competent to understand and sign informed consent
• Presence of symptomatic head and/or limb tremor

Exclusion Criteria:

• Treatment with botulinum toxin type A of any brand within the 4 months prior to enrollment
• A known contraindication to Botox injection
• Pregnancy