- Inclusion Criteria:  1.1/ Patients:  Aged between 18 and 60 years. Primary Progressive Multiple Sclerosis or Secondary Progressive Multiple Sclerosis as defined by Mac Donald revised criteria in 2017. Expanded Disability Status Scale lower or equal to 8.0, at inclusion. asymmetric motor deficit. The motor deficit asymmetry will be defined by a difference of 3 or more at the American Society Injury. Association motor sub-score per limb between the right lower limb and the left lower limb. No evidence of focal inflammatory activity for at least 3 years (no clinical relapse, no gadolinium enhancement on an Magnetic Resonance Imaging scan and no new T2 lesion) Provided written informed consent according to the Institutional review board approval Affiliated to the French healthcare system.  1.2 / Controls:  Aged between 18 and 60 years, sex and age matched with patients. Provided written informed consent according to the Institutional review board approval Affiliated to the French healthcare system. - Non-inclusion criteria:  2.1 /Patients:  cerebellar Expanded Disability Status Scale sub score higher than pyramidal Expanded Disability Status Scale sub score. Relapse or corticosteroids in the 30 days preceding inclusion. Other neurological diseases. Lack of ability to understand the Institutional review board consent form. Magnetic Resonance contraindications. Pregnancy and breastfeeding. Major persons subject to legal protection (legal safeguards, guardianship,curatorship), persons deprived of their liberty  2.2 / Controls:  Personal history of central nervous related disease Familial history of Multiple Sclerosis. Personal history of spinal cord injury. Personal history of spondylotic myelopathy. Magnetic Resonance Imaging contraindication. Lack of ability to understand the Institutional review board form. Major persons subject to legal protection (legal safeguards, guardianship, curatorship), persons deprived of their liberty Pregnancy and breastfeeding.