Isolated CNS Sarcoidosis Versus Systemic Sarcoidosis with CNS Involvement: A Same Disease?

Neurological involvement occurs in 5 to 15% of patients with sarcoidosis. It rarely represents the sole manifestation of the disease, a condition called isolated neurosarcoidosis.Objectives:To describe patients with definite isolated central neurosarcoidosis. To compare their characteristics to a group of systemic sarcoidosis with central neurologic involvement.Methods:Monocentric retrospective study of all patients presenting with central neurosarcoidosis (NS) over a 10 year period, subsequently divided into 2 groups: isolated neurosarcoidosis (INS) and systemic neurosarcoidosis (SNS).Results:We report 10 cases of INS and subsequently, we compared their characteristics to a group of 30 patients with SNS. INS patients exhibited brain parenchymal involvement (8/10), meningeal disease (8/10), myelitis (3/10), cranial neuropathy (3/10), neuroendocrine impairment (1/10). Cerebro-spinal fluid (CSF) analysis was conducted in 8/10 patients and showed pleocytosis in 6/8 (75%), elevated protein level in (4/8) 50%, oligoclonal intrathecal synthesis in 1/5 (20%). All patients received steroids, 7/10 (70%) required associated immunosuppressive therapy, 5 of which TNFα inhibitors. When compared to patients with SNS, INS patients were more likely to experience seizures (60% vs 23.3%); display encephalic parenchymal enhancing lesions (80% vs 39.3%) or encephalic leptomeningeal involvement (80% vs 35.7%). Serum angiotensin converting enzyme (ACE) was elevated in a third of patients with SNS but none of those with INS.Conclusion:The phenotypes of patients with INS are similar to the ones described in SNS. Serum ACE should not be regarded as a diagnostic test in patients with isolated neurosarcoidosis but could be useful in detecting subclinical extra neurologic involvement during follow up.