Inclusion criteria  At least 18 years of age Signature of the informed consent Covered by social security SPG5 patients identified with two mutations in the CYP7B1 gene  Exclusion criteria  Contra-indications to MRI (claustrophobia, metallic or material implants) Additional psychiatric or neurological conditions / additional major comorbidities History of severe head injury Participation in another trial (except observational trial) Pregnancy and breastfeeding Inability to understand information about the protocol Persons under AME Persons deprived of their liberty by judicial or administrative decision Adult subject under legal protection or unable to consent Unwillingness to be informed in case of abnormal MRI