The association of myasthenia gravis and connective tissue diseases. Effects of thymectomy in six cases with rheumatoid arthritis and one case with systemic lupus erythematosus

Abstract

Objectives: To describe the effects of thymectomy in a group of patients with myasthenia gravis (MG) with associated connective tissue diseases (CTD).

Patients and methods: We analyzed six patients with CTD and myasthenia. They were followed-up for at least 3 years.

Results: Records of a cohort of 132 patients with established diagnosis of MG undergoing thymectomy in our institution between 1987-1999 were reviewed. The percentage of patients with CTD was 5 % (6/132). Five patients had rheumatoid arthritis (RA) and one patient systemic lupus erythematosus (SLE). All patients were women, and the mean age was 38.5 years old (SD 13.7). Mean time of MG diagnosis to operation was 16 months (range from 1 to 144 months). Preoperative Osserman classification was the following: stage IIb, four patients; stage III, one patient; and stage IV, one patient. Before surgery all patients were on anticholinesterase agent (pyridostigmine), and four patients were on corticosteroids. An extended transsternal thymectomy was practiced on five patients and a transcervical thymectomy was performed in the remaining patient. Pathologic findings were as follows: thymic hyperplasia in four patients and thymic atrophy in the other two. Good response (remission or improvement) was present in three patients (50 %) and poor response (no change or worse) in the other three (50 %).

Conclusions: A low response to the thymectomy is observed in patients with MG and associated CTD (RA and an SLE).