Neurosarcoidosis represents up to 10% of sarcoidosis cases. Little is known about its long-term course, even if the disease remains mainly monophasic with/w.o. sequelae, or if bouts of new symptoms may arise over years (polyphasic).

Using retrospective data from patients diagnosed with neurosarcoidosis in three French referral centers for neuro-inflammation, the investigators aim to determine patterns of disease course, according to the initial presentation and the treatments used.

Sarcoidosis is a systemic inflammatory disease which a 10-20/100.000/year incidence rate. The nervous system is found to be affected in 5-10% in clinical series, rising to 14-27% in post-mortem studies. Mortality is as high as 5% mainly due to cardiac, pulmonary or neurological injury. The treatment of the disease uses cortico-steroids, and often steroid-sparing immunosuppressive agents such as methotrexate or cyclophosphamide. More recently, TNFalpha-blockers have been found to be highly effective.

Long-term data about the clinical and paraclinical course of the disease are lacking. "Bouts" or "relapse" of the disease are barely described, with no substantial information about their frequency, their sequelae, or their response to the treatments when initiated. Less is known about the risk of recurrence in each presentation of neurosarcoidosis (peripheral, spinal, brain or meningeal presentations). In the end, if a truly relapsing-remitting form of the disease exist is not sure, many patients presenting with a lond-standing pattern of invariant symptoms.

Due to this lack of knowledge about the natural history of neurosarcoidosis, even a "good treatment response" cannot be defined, and in many cases, it is difficult to attribute to treatments a seemingly favourable course af the disease.

In the current study, the investigators aim to build a retrospective cohort of patients diagnosed with neurosarcoidosis and seen at least once in three French referral centers for neuro--inflammation from Jan-1st-2000 to date : Nancy (Lorraine, North-Eastern), Bordeaux (Aquitaine, South-Western) and Strasbourg (Alsace, North-Eastern).

Demographics, clinical and paraclinical data at presentation will be collected(magnetic resonance imaging of the spine and brain, electroneuromyography if available, data of blood and cerebro-spinal fluid). After having clustered patients by presentation pattern, data about lines and types of treatments, change in clinical and paraclinical data will be collected. From this perspective, patterns of disease course on the mid/long-term will be established.

Estimated number of patients : 60-100. Estimated duration of follow-up : 5-10 years. Intervention : none (existing data).

Inclusion Criteria:

• To have at least one documented visit in one of the three referral neurological centers (Nancy, Bordeaux, Strasbourg) between Jan-1st-2000 and Jan-1st-2021
• To be diagnosed with possible/probable/definite neurosarcoidosis

Exclusion Criteria:

- Denial to participate to the study

Every patient of the three centers meeting the inclusion criteria