Male or female aged 18 to 70 years old.

Patient with a diagnosis of MS certainty according to the criteria of Mac Donald (2010)

Patient with progressive form of MS: remitting, secondarily progressive, primary progressive

Patient with an Expanded Disability Status Scale score (EDSS) between 3 and 8.

Patient with clinical stability for more than 6 months (EDSS stable over 1 year)

Lack of progressive onset (and corticosteroid therapy) for at least 3 months

Patient with normal palliation or mild impairment

Patient having a muscle test at 4 or 5 on the upper limb to be treated

Patient requiring Gamma-Knife radiosurgery due to severity of tremor and functional impairment

Patient who understood and signed the informed consent form

Regional Non-comparative Prospective Study of the Impact of Gamma Knife Radiosurgery on Tremor in Multiple Sclerosis