Neurologic manifestations of systemic immunopathological diseases.

Systemic immunopathological diseases with prominent neurological features include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren's Syndrome (SS), and the systemic vasculitides. These systemic conditions can affect the nervous system in diverse ways. In many cases, the neurological disease heralds the onset of the systemic condition. Recognizing the pattern of neurological and systemic features of these conditions is critical in order to uncover the systemic condition in a timely manner. Although treatment of these conditions is usually directed at the underlying systemic disease, discovery of certain types of neurological involvement such as rapidly progressive mononeuritis multiplex may often necessitate more robust immunosuppressive therapy. The larger treatment trials addressing optimal therapy in these conditions are coordinated by rheumatologists and rarely address the neurological complications in isolation. As such, the evidence supporting neurology-specific therapy regimens is generally an extrapolation of findings that apply to the systemic condition as a whole and cannot be considered as Class I. Less severe neurological manifestations are often treated with glucocorticoids and immunosuppressive treatments such as azathioprine as a steroid-sparing strategy. More severe neurological involvement requires early and aggressive therapy with powerful immunosuppressive agents, often in combination with glucocorticoids and plasma exchange. Cyclophosphamide is the most established immunosuppressive therapy in this context but is limited by its toxicity. Rituximab is emerging as a highly promising alternative although its high cost is a major limitation.