Extended thymectomy was performed via median sternotomy. The incision extended for an additional 3 cm above the furcula in the direction of the neck. Mediastinal dissection extended from the most anterior-posterior portion, along the phrenic nerves, to the area inferior to the thyroid. All pre-pericardial fat, the anterior mediastinal pleurae bilaterally , cardiodiaphragmatic sinus fat pads and fat accumulation around and anterior to the phrenic nerves, as well as the thymus itself, were removed en bloc.
Subsequently, a delicate, careful dissection was performed in order to remove all fat from the space between the aorta and vena cava, near the cephalic vessels, and from the area behind the thyroid, accessed from the upper portion of the incision.
Using a spreader, the skin and subcutaneous tissues were opened for better viewing. Water-sealed multiperforated pleural drains were inserted bilaterally into the fifth intercostal space.
The drains were removed between 24 and 48 hours after surgery. All procedures were performed under general inhalation anesthesia and controlled ventilation.
During surgery, oximetry and capnography were used, heart rate was monitored, and arterial blood gases were analyzed serially. For postoperative analgesia, we used a hour peridural nerve block with continuous administration of anesthetics. The response to thymectomy during the postoperative follow-up was graded in accordance with the classification system proposed by Keynes 17 Chart 2.
In this study, 31 female and 15 male patients underwent surgery and were evaluated. The mean age was 30 years range, 10 to The mean length of disease evolution was Mean length of postoperative outpatient treatment was One patient died as the result of a pulmonary embolism, which had been clinically diagnosed.
Autopsy was not performed. Of the 46 patients, 9 Of the 7 patients receiving corticosteroids, only 1 was also given an immunosuppressant.
Table 2 relates postoperative evolution to gender, age and time from onset of symptoms, as well as to Osserman class.
Anatomopathological examination revealed benign thymoma in 3 patients, atrophic thymus in 6, normal thymus in 5, fibrotic thymus in 3 and thymic hyperplasia in 29 Table 2. Extraglandular thymic tissue was found in 5 In 2 of these patients, the thymic tissue was located in perithymic fat. In the other 3, such tissue was found in other locations: in pericardial fat, adjacent to the left phrenic nerve and in the aortopulmonary window.
Each sample sent for pathology comprised the thymus with the capsule intact, the perithymic tissues and all the fat resected from the anterior compartment of the mediastinum. Each sample component was analyzed separately. There were neither infectious complications nor hemorrhages in the chest wall or in the pleural cavity. Patients rarely complained of pain within the first 72 postoperative hours. Subsequent pain was easily controlled with common analgesics. In this study, there were no intraoperative or postoperative coagulation disturbances.
Only one patient presented respiratory insufficiency immediately after surgery and required reintubation, remaining intubated for 3 more days. Due to postoperative worsening of symptoms 5 Of those 5 patients, 1 died, 2 achieved complete remission, and symptoms continued to worsen in 2.
According to the literature, thymectomy has been used as a treatment for myasthenia gravis since It has also been shown that symptoms persist after surgery if these extrathymic areas are not excised. In this study, extended thymectomy was performed as described by Jaretzki, 9 although some modifications were made.
Rather than transverse cervicotomy, we used a longer incision through skin and subcutaneous tissue longitudinal cervicotomy towards the thyroid space and the upper lobes of the thyroid gland. This technique allowed good access for the dissection of tissues that might contain embryonic vestiges of thymic tissue. There were no infectious complications in the chest wall or in the pleural cavities.
This may have been due to the small number of patients who were under corticosteroid therapy prior to surgery. In comparison to other studies, in which rates of complete remission range from Forty-six thymectomies for non-thymomatous MG were performed through a standard cervicotomy, procedures through a partial upper sternal-splitting incision and eight through a complete median sternotomy. Results : Operative mortality was 0.
The presence of a thymoma negatively influenced the prognosis. Younger patients showed a more favorable outcome as well as patients with a shorter duration of symptoms before the operation; patients with lower classes of myasthenia showed a higher rate of remission. Conclusions : Thymectomy is effective in the management of patients with MG at all stages with low morbidity. Patients with thymoma present a less favorable outcome. Myasthenia gravis MG is characterized by an impaired neuromuscular transmission with symptoms of weakness and fatigue; it is generally related to an accelerated degradation or complement-related damage to acetylcholine receptors mediated by auto-antibodies.
Extensive clinical experience with a variety of medical treatments is actually available [1] : anticholinesterase drugs can enhance neuromuscolar transmission and decrease the immune response; steroids, plasmapheresis and immunoglobulin administration contributes to improve the clinical performance. Plasmapheresis is also used in the acute setting and to prepare patients for the operation [2]. Thymectomy has been employed extensively to remove the major source of antibodies production; in recent years it has gained increasing acceptance as the most effective form of treatment with the goals of achieving prolonged improvement.
In fact, patients with MG who undergo thymectomy, demonstrate a superior response of clinical symptoms and medication requirements when compared with those patients treated non-surgically [3]. However, controversy persists regarding the proper selection of patients, the optimal surgical approach and the extent of mediastinal dissection required. We retrospectively reviewed our experience with surgical treatment of MG with respect to long-term outcome and factors that may influence prognosis.
Between and , we performed thymectomies for MG. MG was staged according to a modified Osserman classification Table 1. Thymoma was classified histologically according to Marino, Muller-Hermelink and Pescarmona [4] , [5] : 38 Clinical staging was accomplished according to the modified Masaoka classification [6] : 19 Forty-six thymectomies for non-thymomatous myasthenia were performed through a transcervical approach, through a partial upper sternal -splitting incision and eight through a complete median sternotomy.
Current follow-up information was obtained in Distribution of the different types of myasthenia according to the modified Osserman classification. Survival rates were calculated according to the Kaplan—Meier method; zero time was the time of surgery; death related to causes other than myasthenia was treated as a censoring case to construct disease-related survival curves.
The age distribution of patients with and without thymoma showed some differences: the non-thymomatous group peaked between 20 and 40 years with a mean age of The distribution of the different classes of MG is reported in Table 1.
The pattern of distribution of MG in the group of patients with and without thymoma was quite similar. Histologically, cortical thymomas were more frequent The titer of the acetylcholine receptor antibody was measured only in patients; the mean values of titers in the thymomatous and non-thymomatous group did not differ mean: After the operation, the medical treatment was continued as preoperatively and subsequently modified after discharge by the neurologist.
Only one patient required plasmapheresis in the immediate postoperative period. Two hundred and twelve patients There were two operative deaths 0. Minor complications were arrhythmia 1. Mean hospital stay after the operation was 6. MG wasn't a negative prognostic factor in the thymoma population as previously reported by our group [6] , [7].
The distribution of deaths related to MG is similar when comparing the duration of symptoms more or less than 18 months , the age of the patients above or below 45 years and class of MG Fig. Cumulative disease-related survival for patients undergoing thymectomy for myasthenia gravis. The group of patients with thymoma presented a lower remission rate Remission and palliation were similar in patients operated through cervicotomy and upper sternal splitting.
The curve of remission and palliation plotted against time could not be constructed since the retrospective collection of the data didn't allow the establishment of the exact time of remission and palliation of symptoms.
The progress in medical therapy have attenuated the debilitating and life-threatening characteristics of the natural history of MG. Thymectomy has been considered beneficial as part of a multidisciplinary approach and the positive results have been repeatedly demonstrated since the initial report by Blalock et al.
However, the specific indications to the operation remain controversial. Most centers consider the operation suitable for selected patients with generalized disease, with specific consideration to age, severity of symptoms, type of MG, response to medical treatment and duration of symptoms [9]. The indications to thymectomy for ocular MG are still ill-defined; in fact, type I MG is not a life-threatening disease and may also have natural remission.
However, ocular MG often progresses to generalized MG [11] , [12] and may be complicated by thymoma. It is generally believed that 'radical thymectomy' should include the removal of all the thymic gland and the surrounding mediastinal fat tissue.
Different surgical approaches have been proposed, from the simple transcervical thymectomy [14] , [15] to the 'extended thymectomy' [13] and the 'maximal thymectomy' [17]. After the initial 46 transcervical thymectomies, we have approached the anterior mediastinum through a partial upper sternal splitting incision.
This incision allows a good exposure with direct control of the inferior region of the neck and, after placement of a retractor behind the sternum, also the fat located anteriorly to the pericardial sac can be removed. It is necessary to remove of the thymus and all the surrounding mediastinal fat and this can be well-accomplished through a partial sternotomy. Our careful attempts to remove all the mediastinal tissue is confirmed by the high number of patients in which we opened the mediastinal pleura during the dissection patients, Previous reports did not show any relationship between preoperative Osserman classification and outcome after thymectomy [14] ; however, even if our population was more weighted in favor of class I and II A patients, we observed a better improvement in the lower classes of MG, especially when compared with MG class III, and this is in line with other reports [14] , [16] , [17] , [18] , [20].
Younger patients showed improved results if compared with the older group, but the difference was not statistically significant, as in other series [13].
Thymoma associated to MG present special clinical features. Most of the lesions were histologically classified as cortical thymomas, however, the distribution among the different Masaoka stages and MG classes was uniform; we have previously demonstrated that MG is not a negative prognostic factor for patients with thymoma [6] , however, patients with thymomatous MG present worse results in terms of functional improvement and long-term survival.
In fact, especially in the era preceding the multimodality treatment of these tumors [6] , the recurrence of the mediastinal lesion was the most frequent cause of failure 14 patients, 6.
The improved control of the tumor with neoadjuvant chemotherapy and postoperative treatment will contribute to modify also the outcome of patients with thymomatous MG. The aim of treatment for MG patients is long-term improvement of the clinical status and prevention of life-threatening complications.
Fifteen patients were lost to follow-up; the remaining form the object of our study. Sixty-two patients Myasthenia was graded according to a modified Osserman classification: 51 patients Fifty-eight thymectomies for thymoma were performed through a median sternotomy and four through a clamshell incision.
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