Neurosarcoidosis: an update on diagnosis and therapy

Clinically overt granulomatous involvement of the nervous system (i.e. neurosarcoidosis) can be seen in up to 10% of patients with sarcoidosis. Establishing a diagnosis of neurosarcoidosis is often challenging due to the heterogeneity of clinical presentations that are sometimes nonspecific, and inaccessibility of tissue confirmation. Recommended treatments are based on expert opinions that are derived from clinical experience and limited data from retrospective studies, as data from randomized controlled studies are limited.In this article, we comprehensively review all available literature on epidemiology, clinical presentations, diagnosis, treatment, and outcomes of neurosarcoidosis. We also offer our opinions on diagnostic approach and treatment strategy.Given the invasive nature and the limited sensitivity of biopsy of the nervous system, diagnosis of neurosarcoidosis is usually made when ancillary tests (such as magnetic resonance imaging and cerebrospinal fluid analysis) are compatible, and alternative diagnoses are reasonably excluded in patients with established extraneural sarcoidosis. Several factors must be taken into consideration to formulate the initial treatment strategy, including the extent of the disease, severity, functional impairment, comorbidities, and patient's preference. In addition, treatment regimen of neurosarcoidosis should be formulated with an emphasis on long-term strategy.