THYMECTOMY FOR MYASTHENIA-GRAVIS

Objectives: To assess the change in clinical status of patients with g eneralized myasthenia gravis treated with thymectomy and to identify p rognostic variables that may be of significance in optimizing patient selection. Design: Retrospective review. Mean follow-up period was 41 months. Setting: Large community hospital. Patients: Thirty-seven pati ents (11 male and 26 female) with generalized myasthenia gravis who we re referred for thymectomy if they were refractory to medical treatmen t or had a thymoma. This represents all patients undergoing thymectomy for myasthenia gravis between january 1982 and December 1991. Interve ntions: Each patient underwent staging before and after thymectomy usi ng a modified Osserman classification. Medication requirements were al so recorded. All patients underwent transsternal thymectomy and comple te mediastinal dissection. Main Outcome Measures: Changes in clinical stage and medication requirement before and after thymectomy; effect o f patient age, sex, duration of disease, stage of disease, antibody st atus, histologic characteristics of the thymus, and duration of follow -up on outcome. Results: Improvement after thymectomy was noted in all 37 patients. Complete remission was achieved in three patients (8%) a nd pharmacologic remission in 23 (62%). The remainder improved in stag e, medication requirement, or both. Patients in preoperative stages II b and IIc showed the greatest improvement. Age, sex, duration of disea se, antibody status, histologic characteristics of the thymus, and dur ation of follow-up were not significant factors in assessing improveme nt. Conclusions: Transsternal thymectomy was found to be beneficial to all patients with generalized myasthenia gravis. Complete or pharmaco logic remission was achieved in most patients (70%) following the proc edure. Patients in preoperative stages IIb and IIc showed the greatest degree of postoperative improvement.