Connective Tissue Diseases & Peripheral Nervous System Involvement: "The peripheral nervous system is usually involved in the majority of systemic connective tissue diseases, particularly in systemic lupus erythematosus, Sjögren's syndrome, vasculitis and systemic sclerosis . . . Structures of the nervous system may be damaged by several autoantibodies (e.g. antineuronal, anti-nerve growth factor, anti-neurotrophins), by cytotoxic effects ofproinflammatory cytokines and by activated cells of the immune system." (Kujawska-Danecka et al.) (This involvement could cause seemingly unrelated symptoms. There are tests for cytokines, immune cells that cause inflammation.)