Video-assisted thoracoscopic extended thymectomy (VATET) in myasthenia gravis. Two-year follow-up in 101 patients and comparison with the transsternal approach

Surgical Approaches to Myasthenia Gravis: Perspective of Anatomy and Radicality in Surgery

The effectiveness of thymectomy for nonthymomatous myasthenia gravis is analyzed with regard to extensiveness of removal of the adipose tissue of the mediastinum and the lower neck region with various techniques of thymectomy. The approach necessary to achieve maximal radicality must include access to both pleural cavity and the lower neck area up to the thyroid gland. Surgical techniques include extended transsternal approach, which might be combined with separate transcervical incision, bilateral videothoracoscopic (VATS) approach combined with transcervical incision, and extended subxiphoid approach, either uniportal or combined with bilateral VATS. Anatomic aspects of maximally extensive thymectomy are described in detail.

Definitions and standard indications of minimally-invasive techniques in thymic surgery

BACKGROUND

The minimally invasive thoracic procedures are those performed through the intercostal, subxiphoid, subcostal or transcervical incisions. In most of these procedures (with exception of some transcervical procedures) the video-assisted thoracic surgery (VATS) technique is used for performance of an operation under guidance of a video monitor.

METHODS

According to the definition the minimally invasive procedures do not include the sternal manubriotomy (upper sternal split), transverse sternotomy and subcutaneous longitudinal sternotomy. Currently, a minimally invasive extended thymectomy became a widespread procedure advised for nonthymomatous myasthenia gravis (MG) and early-stage thymomas. The definition of an extended thymectomy is a removal of the whole thymus with the surrounding adipose tissue. Instead of the term "extended thymectomy" some authors recommended a term "complete thymectomy", which means total removal of the whole thymus, without the adjacent fatty tissue.

RESULTS

There are a lot of doubts about the definition of extended thymectomy. There have been no prospective randomized trials comparing the transsternal and minimally invasive approaches for MG or thymomas. Possible scenarios for such trials are analyzed in this paper.

CONCLUSIONS

There are several issues of a minimally invasive thymectomy for MG and thymomas necessitating further clarifications.

Sternotomy versus video-assisted thoracoscopic surgery for thymectomy of myasthenia gravis patients: A meta-analysis

INTRODUCTION

The purpose of this study was to compare thymectomy by video-assisted thoracoscopic surgery (VATS) and trans-sternal thymectomy (TS) for myasthenia gravis patients.

METHODS

A meta-analysis was conducted to compare thoracoscopic surgery and sternotomy for myasthenia gravis patients with regard to long-term effect and short-term safety.

RESULTS

A total of 23 trials were included in our research. No significant differences were detected with regard to myasthenic crisis, wound infection, and muscle weakness improvement. VATS led to less blood loss than TS (standardized mean difference, -1.233; 95% confidence interval, -1.425--1.041; P < 0.001), less risk of pulmonary infection (relative risk, 1.035; 95% confidence interval, 1.001-1.070; P = 0.043), and a shorter hospital stay. TS had a shorter operative time than VATS (standardized mean difference, 0.239; 95% confidence interval, 0.113-0.365; P < 0.001). VATS and TS achieved similar mean specimen weights and complete stable remission rates.

CONCLUSION

Based on the results of this meta-analysis of retrospective cohort studies, VATS increases surgical safety and achieves an equal surgical efficacy to TS, but TS has a shorter operative time.

Bilateral Video-Assisted Thoracoscopic Thymectomy vs. Extended Transsternal Thymectomy in Myasthenia Gravis: A Prospective Study

The optimal approach to thymectomy remains controversial. This study is designed to prospectively compare the results between bilateral video-assisted thoracoscopic thymectomy (BVTx) and extended transsternal thymectomy (ETTx) in patients with myasthenia gravis (MG) without thymoma. Fifteen patients who had undergone BVTx and 16 patients who had undergone ETTx were compared for age, gender, severity of disease, preoperative duration of disease, operative time, intraoperative blood loss, postoperative complications, hospital stay, duration of chest tube drainage, thymic histopathology, pain perception by visual analog scale (VAS), remission and improvement rate, period of follow-up, and activities of daily living (ADL). Fisher's exact test, t test and paired t test were used for statistical analysis. BVTx had longer operative time and less intraoperative blood loss than that of the ETTx. Their remission rates and their degree of postoperative ADL improvement were not significantly different. However, the lowering of VAS was significantly greater in the sternotomy group at 3 months. All other parameters were not significantly different. No mortality was noted in the series. We consider BVTx as an effective alternative procedure to the transsternal approach for patients with nonthymomatous MG. As more and more people care about cosmetics, BVTx could become the future trend.

Myasthenia gravis: clinical, immunological, and therapeutic advances

We give an update on clinical, immunological, and therapeutic advances in the field of myasthenia gravis, including a summary of suggested therapeutic recommendations.

Robotic video-assisted thoracoscopic thymectomy

Presentation of a minimally invasive surgical technique for thymectomy in patients affected by myasthenia gravis (MG): robotic video-assisted thoracic surgery (VATS) is a surgical technique applied to perform thymectomy and remove the entire mediastinal fat through a left transpleural approach.

Video-assisted thoracoscopic extended thymectomy and extended transsternal thymectomy (T-3b) in non-thymomatous myasthenia gravis patients: remission after 6 years of follow-up

The aims of this study were to assess the efficacy of video-assisted thoracoscopic extended thymectomy (VATET) as a treatment for myasthenia gravis (MG) and to identify prognostic factors for thymectomy success. Clinical efficacy and variables influencing outcome were assessed by life-table and Cox proportional hazards regression analysis. Complete stable remission (CSR), as defined by the MGFA Medical Task Force, was the end point for efficacy. VATET was performed in 159 MG patients and T-3b in 47 MG patients. At 6 years of follow-up, CSR, assessed by life-table analysis, was 50.6% in non-thymomatous VATET patients and 48.7% in non-thymomatous T-3b surgery. By univariate analysis, the presence of thymic hyperplasia (P=0.0002) and treatment only with anticholinesterases (P<0.0001) were positively associated with the probability of CSR. By multivariate analysis, the chance of complete remission was significantly increased by the use of anticholinesterases (odds ratio [OR] 2.45; 95% confidence interval [CI] 1.44-4.17; P=0.001) and the presence of thymic hyperplasia (OR 1.96; 95% CI 1.05-3.68; P=0.036). VATET seems to be effective in inducing CSR in MG with an efficiency similar to that of the T-3b transsternal (TS) approach; it is easy to perform in experienced hands and is associated with low morbidity and negligible esthetic sequelae.

Long-term evaluation of extended thymectomy with anterior mediastinal dissection for myasthenia gravis

BACKGROUND

Thymectomy for the treatment of myasthenia gravis (MG) is well established. The extent of resection, however, remains a source for debate. Outcomes for newer surgical techniques need to be compared to more extensive procedures.

METHODS

A retrospective review was done of 64 consecutive patients who underwent transsternal thymectomy with extended anterior mediastinal dissection for MG between 1979 and 2000 and who were operated on by a single surgeon.

RESULTS

Fifty-six patient charts were available, providing 58 operative procedures. Three patients had died of unrelated causes. The mean age of symptom onset was 36.0 +/- 2.5 years, with a mean duration of 3.3 +/- 0.5 years until surgery was undertaken. The mean length of follow-up was 6.8 +/- 0.8 years. Operative procedures were associated with a 10.3% major morbidity rate and no mortality. Drug-free remission was achieved in 50.0% of the patients, and symptoms were absent or improved in 76.8% of the patients. Patients followed up long-term (>10 years) achieved the greatest remission rate (71.4%) and symptomatic improvement (85.7%). After thymectomy, the mean dosages of prednisone and Mestinon decreased by 69.3% and 58.8%, respectively.

CONCLUSIONS

Extended thymectomy provides excellent overall symptom improvement, which is enhanced over time. This review provides a basis for long-term comparison with other less invasive and perhaps less extensive procedures.

Video-assisted thoracoscopic thymectomy in juvenile myasthenia gravis

As video-assisted thoracoscopic surgery for thymectomy has been reported to be as effective as traditional open surgical approaches in predominantly adult patients with myasthenia gravis, we applied this procedure to juvenile patients with this condition. Six patients underwent total thymectomy using the video-assisted technique (1997-98). Six patients in whom a median transsternal approach was used (1989-95) formed the comparison group. The two patient groups were similar in terms of age at thymectomy and preoperative clinical severity. There were no serious perioperative complications in either group. Minimum post-thymectomy duration of follow-up in the video-assisted thoracoscopic surgery patients was 2.3 years (mean 2.7 years), with all patients clinically improved over their baseline status. Preliminary results suggest that video-assisted thymectomies are comparably effective to transsternal procedures in treating generalized juvenile myasthenia gravis and can be safely performed in children as young as 20 months of age. In addition, video-assisted surgeries are less invasive than transsternal approaches, significantly shorten the postoperative hospital stay, and have superior cosmetic results.

Pulmonary function after thoracoscopic thymectomy versus median sternotomy for myasthenia gravis

BACKGROUND

Impaired pulmonary function due to myasthenia gravis (MG) is further compromised by thymectomy, which is necessary in most cases. Thoracoscopic thymectomy (tThx) can achieve the same resection and functional improvement of MG as median sternotomy (sThx). The possible advantage of tThx in maintaining better perioperative lung function was quantified.

METHODS

In a prospective trial, 20 patients with MG were randomly allocated to undergo tThx (n = 10) by three-trocar left-sided approach or sThx (n = 10) performed as an extended procedure. Complete pulmonary function was measured at 12-hour intervals, beginning 6 hours postoperatively. Effective postoperative pain control in both groups was achieved by patient-controlled analgesia with morphine sulfate assessed by a visual analogue scale. Statistical analysis for comparison of tThx and sThx was performed using the Mann-Whitney U test.

RESULTS

Postoperative vital capacity, forced vital capacity, forced expiratory volume per second, and peak expiratory flow, measured as a percentage of the individual preoperative capacity, were significantly better with tThx compared with sThx. Immediate postoperative lung function was reduced to 35% and 65% after tThx and sThx, respectively. By the third postoperative day, recovery of pulmonary function was complete after tThx but only 55% after sThx.

CONCLUSIONS

Less pronounced impairment and faster recovery of pulmonary function after tThx characterize this new approach for thymectomy as minimally invasive. These results could make tThx the preferred surgical treatment of MG, which was improved to the same extent as after sThx.

Results of transcervical thymectomy for myasthenia gravis in 100 consecutive patients

OBJECTIVE

To review the results of the authors' most recent 100 consecutive cases of transcervical thymectomy for myasthenia gravis (MG) in terms of complications and outcome in comparison with other reported techniques.

SUMMARY BACKGROUND DATA

Myasthenia gravis is believed to be an autoimmune disorder characterized by increasing fatigue with exertion. The role of thymectomy in the management of the disease remains unproven, but there is widespread acceptance of the notion that complete thymectomy improves the course of the disease. Complete excision of the thymus is the goal in all cases; however, the best technique to achieve complete thymectomy remains controversial. The authors favor a transcervical approach through a small collar incision aided by a specially designed sternal retractor. Others prefer a transsternal, a combined transcervical and transsternal ("maximal"), or a video-assisted thoracoscopic surgical approach.

METHODS

A retrospective review of the authors' most recent 100 consecutive transcervical thymectomies for nonthymoma-associated MG was performed using medical records and telephone interviews. Patients' symptoms were graded before surgery and at the most recent (within the last 6 months) postoperative time point, using the modified Osserman classification: 0 = asymptomatic, 1 = ocular signs and symptoms, 2 = mild generalized weakness, 3 = moderate generalized weakness, bulbar dysfunction, or both, and 4 = severe generalized weakness, respiratory dysfunction, or both.

RESULTS

There were 61 female patients and 39 male patients with a mean age of 38 years (range, 14 to 84). The median hospital stay was 1 day. There were no deaths and no significant complications. Seventy-eight patients who had undergone surgery >12 months ago were available for analysis. In these patients, with a mean follow-up time of 5 years (median 5.3; range, 12 months to 10 years), the median preoperative Osserman grade improved from 3.0 (mean 2.73) before surgery to 1.0 after surgery (mean 0.94).

CONCLUSIONS

The transcervical approach for thymectomy for the treatment of MG produces results similar to those of other surgical approaches, with the added benefits of shortened hospital stay, decreased complications, reduced cost, and broader physician and patient acceptance of surgical treatment.

Myasthenia Gravis

The treatment of patients with myasthenia gravis should be individualized according to the extent (ocular versus generalized) and severity (mild to severe) of disease, the presence or absence of concomitant disease (including but not limited to other autoimmune diseases and thymoma), and, to a lesser degree, the age of the patient. Thymectomy should be performed in patients with generalized disease, especially those who have detectable levels of circulating antibodies to acetylcholine receptor (anti-AChR), as it should be in all patients thought to have an operable thymoma (observed on imaging studies of the chest). Symptomatic therapy consists of anticholinesterase drugs (usually pyridostigmine); occasionally, other drugs are required to reduce the muscarinic side effects. At times, patients need immunosuppressive or immunomodulatory therapy with glucocorticoids, azathioprine, cyclospor-ine or cyclophosphamide, plasma exchange, and intravenous immunoglobulin. Remission, whether spontaneous or pharmacologically induced, or significant improvement can be achieved in most patients, but some treatments entail significant side effects and considerable cost.