Kidd DP - In this prospective study, patients referred to and treated at the Centre for Neurosarcoidosis over a 15-year period with biopsy-proven “highly probable” disease of the central nervous system were analyzed in order to define the clinical characteristics and immunopathology of neurosarcoidosis. All those with meningeal and parenchymal diseases had abnormal imaging, while imaging was normal in 37% of those with cranial neuropathy. More severe disorder was seen in those with leptomeningeal disease, including hydrocephalus and tissue destruction, while those with pachymeningeal disease had less neurological impairment. Even when imaging was normal. the CSF was active in 70% of cases. CSF indices correlated with disability in those with a leptomeningitis. Correlation with CSF indices allows an early identification of those with a more destructive disease, will help to define treatment, and might thereby improve outcome.