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.

To describe patients with definite isolated central neurosarcoidosis. To compare their characteristics to a group of systemic sarcoidosis with central neurologic involvement.

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).

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.

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.