Mononeuritis multiplex: the yield of evaluations for occult rheumatic diseases.

We identified 35 patients who had electrodiagnostic evidence of mononeuritis multiplex and did not have diabetes or multiple nerve compressions. Their charts were reviewed to determine the etiologies of the mononeuritis multiplex and to determine how often the laboratory examination revealed a rheumatic disease in patients whose initial history and physical examination did not suggest that a rheumatic disease was present. In 11/35 (31%; CI = 17-49) a disorder capable of causing mononeuritis multiplex was diagnosed before the symptoms of mononeuritis multiplex began. Ten had a rheumatic disease; 1 had lymphoma. Nine of the other patients were suspected, on the basis of the history and physical examination, of having new onset of a rheumatic disease. Subsequent laboratory evaluation showed that 5/9 (56%; CI = 21-86) had a rheumatic disease, and 4/9 (44%; CI = 14-79) were unknowns. In 15/35 (43%; CI = 26-61) patients with mononeuritis multiplex, no rheumatic disease was suspected on the basis of the initial history and physical examination. The subsequent laboratory examination revealed an underlying rheumatic disease in 0/15 (0%; CI = 0-18). Mean clinical follow-up of 16 +/- 16 months in the patients with mononeuritis multiplex of unknown cause also failed to identify a rheumatic disease. Overall 19/35 (54%; CI = 37-71) did not have a rheumatic disease or any other known cause. Of the 14 patients with mononeuritis multiplex associated with a rheumatic disease, 5/14 (36%; CI = 13-15) had systemic lupus erythematosus; an additional patient had both lupus and the CREST syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)