Autoimmune Neurological Diseases and Those Secondary to Immunotherapy: Study of Immunological Mechanisms and Research Into Targets of Immune Attack

Inclusion Criteria: * Adult patient (aged ≥ 18 years) * Affiliated with a social security scheme * Express consent to participate in the study * Indication for lumbar puncture And * Patients with cancer, undergoing treatment with ICIs, presenting neurological symptoms after starting treatment with ICIs. These symptoms must have appeared no more than 3 months after the last administration of ICIs. Or * Patients with an autoimmune disease of the central nervous system (diagnosis made by teams 1, 2 and 3) according to internationally recognised criteria, with no history of active cancer in the last 3 years and no other autoimmune disease Or * Patients with normal pressure hydrocephalus (NPH) or idiopathic intracranial hypertension (diagnosed based on imaging (brain MRI) and clinical findings), with no history of active cancer in the last 3 years and no active autoimmune disease Exclusion Criteria: * Contraindication or refusal to perform a lumbar puncture * Sample not suitable for research (volume of CSF collected for treatment \>5 mL) * Corticosteroid therapy or other immunomodulatory treatment in progress (discontinued less than 15 days prior to inclusion) * Pregnant or breastfeeding women * Not affiliated with the social security system, patients under French State Medical Aid for undocumented migrants * Patients under guardianship or curatorship, under judicial protection measures, or deprived of their liberty by judicial or administrative decision