Thymectomy for myasthenia gravis

To assess the change in clinical status of patients with generalized myasthenia gravis treated with thymectomy and to identify prognostic variables that may be of significance in optimizing patient selection.

Retrospective review. Mean follow-up period was 41 months.

Large community hospital.

Thirty-seven patients (11 male and 26 female) with generalized myasthenia gravis who were referred for thymectomy if they were refractory to medical treatment or had a thymoma. This represents all patients undergoing thymectomy for myasthenia gravis between January 1982 and December 1991.

Each patient underwent staging before and after thymectomy using a modified Osserman classification. Medication requirements were also recorded. All patients underwent transsternal thymectomy and complete mediastinal dissection.

Changes in clinical stage and medication requirement before and after thymectomy; effect of patient age, sex, duration of disease, stage of disease, antibody status, histologic characteristics of the thymus, and duration of follow-up on outcome.

Improvement after thymectomy was noted in all 37 patients. Complete remission was achieved in three patients (8%) and pharmacologic remission in 23 (62%). The remainder improved in stage, medication requirement, or both. Patients in preoperative stages IIb and IIc showed the greatest improvement. Age, sex, duration of disease, antibody status, histologic characteristics of the thymus, and duration of follow-up were not significant factors in assessing improvement.

Transsternal thymectomy was found to be beneficial to all patients with generalized myasthenia gravis. Complete or pharmacologic remission was achieved in most patients (70%) following the procedure. Patients in preoperative stages IIb and IIc showed the greatest degree of postoperative improvement.