Cerebrospinal fluid immunoglobulin abnormalities in neurosarcoidosis

A retrospective chart review of neurosarcoidosis at the University of Texas Medical Branch (Galveston) between 1982 and 1987 revealed 99 patients with sarcoidosis. Six patients were diagnosed with neurosarcoidosis and had electrophoresis of serum and cerebrospinal fluid performed (one patient with a ventriculoperitoneal shunt was later excluded). Cerebrospinal fluid immunoglobulins and albumin levels were determined followed by calculation of an IgG index and synthesis rate for each patient. Four (80%) of five patients had elevated IgG indexes and synthesis rates indicative of intrathecal immunoglobulin production. No patient had immunoglobulin oligoclonal bands detected. To date, results of electrophoresis of cerebrospinal fluid in neurosarcoidosis have been reported in 37 patients among four series. Of these, only nine patients (24%) have had either an elevated IgG index or synthesis rate. Our series suggests that intrathecal immunoglobulin production in neurosarcoidosis occurs more frequently than previously described. Furthermore, the elevated indexes and synthesis rates without associated oligoclonal bands suggests a polyclonal immunoglobulin response.