Transsternal Maximal Thymectomy is Effective for Extirpation of Cervical Ectopic Thymic Tissue in the Treatment of Myasthenia Gravis

Abstract

PurposeExtensive extirpation of cervico-mediastinal adipose tissue increases the chance of removing ectopic thymic tissues, thus potentially improving the prognosis of myasthenia gravis after thymectomy. We sought to increase efficacy and safety of transsternal maximal thymectomy (TSMT).Materials and MethodsTwenty four patients who underwent TSMT from July 2006 to June 2007 were retrospectively reviewed and compared with 73 patients who underwent transsternal extended thymectomy (TSET) from January 2004 to May 2006. Ectopic thymic tissue in additionally excised cervicomediastinal fat tissue was examined histologically.ResultsIn TSMT group, operation time, amount of cumulative drainage and duration of drainage were significantly higher than TSET group. However, the difference in hemoglobin count, amount of transfusion, duration of intensive care, postoperative hospital stay, and complication rates were not statistically different. There was no operative mortality in either group. Ectopic thymic tissue was found in 50% of patients. All patients had ectopic thymic tissues in the cervical area. Two patients had additional ectopic tissue in the aortopulmonary window, and 1 patient had ectopic tissue at posterior of the left bracheocephalic vein and lateral of the right phrenic nerve.ConclusionTSMT is more effective in the extirpation of ectopic thymic tissues than TSET without significant impairment of safety, especially in the cervical area.

Point Counter-Point: Thymectomy in Ocular Myasthenia Gravis

“…Surgical complications that have been associated with thymectomy are by no means benign. Among these complications are myasthenic crisis, respiratory compromise requiring prolonged intubation, pneumonia, pneumothorax, pleural effusion, phrenic nerve injury leading to diaphragmatic compromise, recurrent laryngeal nerve injury resulting in vocal cord paralysis, surgical site infections, and mediastinitis (28)(29)(30)(31)(32). In addition, Yamada et al (33) showed that perioperative use of corticosteroids, a mainstay of treatment for MG, had a significant increase in wound dehiscence when compared with patients without corticosteroid treatment.…”

Unraveling the role of ectopic thymic tissue in patients undergoing thymectomy for myasthenia gravis

“…Although it could be greatly helpful to locate possible ectopic thymic tissue preoperatively, data on the diagnostic accuracy of imaging techniques in ectopic thymic tissue imaging are still lacking. [56] Anterior mediastinum fat 10 (31%); pretracheal fat 4 (13%); aortopulmonary window 3 (9%); pericardiophrenic angles 3 (9%) In pathological studies (24,32,33,37), specimens were usually dissected and labeled by anatomical locations. Tissue fragments were embedded in paraffin block after fixed in 10% formalin.…”

“…The range of the reported rate is quite wide, possibly due to different surgical procedures, methods of the histological investigation and the intensities of the workup. Ten out of 18 studies reported the common locations of ectopic thymic tissue in mediastinal fat (24,25,29,30,(32)(33)(34)(35)(36)(37). Of these ten studies, 882 patients were studied on ectopic thymic tissue in different anatomical locations, of whom 509 patients (58%) were positive.…”