Spinal cord sarcoidosis in Japan: utility of cerebrospinal fluid examination and nerve conduction study for diagnosis and prognosis prediction.

Spinal cord sarcoidosis (SCS) is rare, and its diagnosis is challenging. We examined clinical, laboratory, and imaging features in patients with SCS to obtain useful clues for diagnosis and prognosis. Eleven consecutive patients (four males, seven females) at a single Japanese institution were investigated. Median age at onset was 66 years old. The most frequent site affected, other than the nervous system, was the respiratory system. While histological confirmation of non-caseating granulomas was often found there, no patient had respiratory symptoms. Peripheral nerve involvement was detected in 64% of patients. Soluble IL-2 receptor (sIL-2R) levels in serum and cerebrospinal fluid (CSF) were elevated in 64% and 45% of patients, respectively, and this finding was more common than elevation of angiotensin-converting enzyme (ACE). 18F-fluorodeoxyglucose (FDG) positron emission tomography showed abnormally high uptake in spinal lesions of all examined patients. Although corticosteroids were administrated to all patients, and immuno-suppressants were prescribed to six (55%), the modified Rankin Scale was unchanged or worsened in four (36%) patients during the follow-up period. Neurological exacerbation of myelopathy was seen in four (36%) patients. Complete response rate was only seen in 9%. High levels of cell count, protein, ACE, and sIL-2R in CSF were significantly more frequent in patients with a marked improvement after immunotherapy than in the other patients. These results suggest that high serum and CSF sIL-2R, high uptake of FDG, and peripheral nerve involvement are indicative of SCS. Given that SCS is commonly intractable, CSF abnormalities may predict efficacy of immunotherapies.