电视胸腔镜手术：胸腺切除治疗重症肌无力（图文演示）

10. Complications
There are relatively few contraindications to VATS. In addition to general contraindications such as recent myocardial infarction and severe coagulopathy, specific contraindications include pleural symphysis, severe underlying lung disease or poor lung function. Patients with severe underlying lung disease or poor lung function may not be able to tolerate the selective one-lung ventilation during general anesthesia.
Prior operation in the ipsilateral chest should not be viewed as a contraindication (Yim et al., 1998). Adhesions can usually be freed using a combination of sharp and blunt dissection under videoscopic vision. However, an open procedure may be more suitable for patients with adhesions difficult to take down.
Concerns have been raised about the use of the VATS approach for thymoma with or without associated MG. We are careful to restrict this technique to small, completely encapsulated thymoma (Masaoka stage I). Clinical judgement is of paramount importance in thymic surgery, and any sign of tissue plane invasion mandates conversion to an open dissection (Yim et al., 1999).

Possible postoperative complications include:
- prolonged ventilatory support due to MG;
- bleeding;
- wound infection;
- pneumothorax;
- surgical emphysema;
- intercostal neuralgia;
- phrenic nerve palsy: it is essential that the right phrenic nerve is clearly identified and protected at all times during dissection. Phrenic nerve palsy represents a major complication for patients with MG.

11. Benefits of VATS
Patients who underwent thoracoscopic thymectomy have significantly less analgesic requirement and shorter hospital stay compared with a historical group who underwent transternal thymectomy (Yim et al., 1995).
Superior cosmetic appearance of VATS, especially in young females should also be considered.
Pulmonary function is significantly better preserved in the immediate postoperative period following VATS compared to the median sternotomy approach (Rückert et al., 2000).
Compared with the conventional transcervical approach, VATS has the advantage of better visualization and less instrument crowding.
A meta-analysis comparing nine published series performed by various approaches showed no difference in clinical improvement after thymectomy between series (Mack, 1997).

12. Thymus resection?
Regardless of the technique, it is generally agreed that thymectomy for MG should be complete. The Columbia-Presbysterian group advocated “maximal” thymectomy involving a combination of median sternotomy with cervical incision to achieve en bloc thymectomy and anterior mediastinal exenteration, which includes mediastinal pleura from the level of the thoracic inlet to the diaphragm, pericardial fat pad, and all the mediastinal fat. However, despite this radical approach, when compared with sternotomy alone (Olanow, 1987) or the transcervical approaches (Cooper et al., 1988), results in terms of clinical improvement did not seem to be significantly different.
In addition, a detailed autopsy study identified ectopic thymic tissue in areas (such as the retrocarinal fat), which are not accessible via a median sternotomy (Fukai, 1991).
Although it may seem intuitive to remove as much mediastinal soft tissue as possible to avoid leaving behind ectopic thymus, these remnants have never been conclusively shown to be clinically relevant, and even the most radical surgical approach does not result in a remission rate greater than 40%.
We believe that we are performing the same operation thoracoscopically compared with the transternal approach by examination of the thymic beds and the resected specimens (Yim et al., 1995).

13. Patient selection
Thymectomy is accepted as standard for young patients with generalized MG. In our hospital, since 1985, we have adopted a policy of offering thymectomy to all patients younger than 70 with generalized MG, and as soon as possible after the diagnosis is established (Kay et al., 1994). It is vital that the thoracic surgeons work closely with the neurologists and anesthesiologists to achieve optimal results.
Uncertainties remain over the role of thymectomy for patients with:
- late onset of disease;
- purely ocular symptoms: arguments have been put forward not to operate on ocular symptoms alone because ocular MG is not only less likely to respond to thymectomy, but also carries a better prognosis, compared with generalized MG. On the other hand, it has been shown that between 30% to 70% of patients with initial ocular symptoms will eventually develop generalized myasthenia (Oosterhuis, 1989; Sommer et al., 1997). Although some patients with purely ocular symptoms improve following thymectomy, the patients have to clearly understand that the rationale for surgery here is not based on symptomatic improvement, but rather on the expectation of disease progression.

14. Other approaches
The most commonly adopted surgical approach to thymectomy is via a median sternotomy. Other approaches include:
- transcervical;
- transcervical and median sternotomy (“T” incision);
- video-assisted thoracic surgery (VATS) (unilateral);
- partial sternotomy :
- upper sternum (Milanez de Campos et al., 2000);
- lower sternum (Granone et al., 1999);

- video-assisted thoracoscopic extended thymectomy;
- bilateral thoracoscopic approach combined with a cervical incision (Novellino et al., 1994).

15. Conclusion
VATS thymectomy is a safe operation in experienced hands and represents a new, viable approach for patients with MG. The right-sided approach is preferred because visualization of the venous anatomy for dissection is essential. Experience shows that this approach produces results comparable to other conventional surgical techniques. By minimizing chest wall trauma, the thoracoscopic approach causes less postoperative pain, shortens hospital stay, better preserves lung function in the early postoperative period (which may be particularly important for patients with MG), and gives superior cosmesis. It is hoped that this patient-friendly approach will lead to wider acceptance by MG patients and their neurologists of earlier thymectomies.

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