Ann Thorac Surg 2009;88:1646. doi:10.1016/j.athoracsur.2009.08.038
© 2009 The Society of Thoracic Surgeons
Original Articles: General Thoracic
Invited Commentary
Cameron Wright, MD
Thoracic Surgery, Massachusetts General Hospital, 55 Fruit St, Blake 1570, Boston, MA 02114
(Email: wright.cameron{at}mgh.harvard.edu).
The authors [1] describe the results of a "modified maximal thymectomy" in a series of patients who have myasthenia gravis with and without a thymoma. The authors claim the operation is analogous to a T-4 maximal thymectomy as described by Jaretzki and colleagues [2], but in reality it is a T-3b thymectomy. Although it is doubtful that there is much of a difference in outcome between these two "aggressive" thymectomy operations, a T-4 thymectomy implies a cervical incision and radical resection of all fat around the cervical thymus. The details of the evaluation of the neurologic outcome are somewhat vague. I would assume the two neurologists who are co-authors performed all the neurologic evaluations personally within a reasonably short time period, but we are not told these details in the article. The perioperative morbidity was very low, attesting to the clinical skills of the neurologist's preparation for surgery and surgical technique. The complete stable remission (CSR) rate was essentially the same for the patients with and without thymoma, as was the Kaplan Meir estimate and the mean time to a CSR. The absence of steroids in the preoperative treatment was a strong predictor of obtaining a CSR in both groups, whereas the World Health Organization histologic type also predicted a higher CSR rate in the patients with thymoma. Both of these observations have been made by others as noted in their references, but the reason why remains unknown.
The strengths of this study include an apparent uniform operative approach during the long time period of the study, the low perioperative morbidity, the use of the Osserman classification to describe the preoperative condition of the patients, the use of the CSR as a "hard" end-point of the study, the relatively long mean follow-up, and the use of Kaplan-Meier actuarial analysis of the CSR rate, because it is a time-related event.
The authors postulate that because they had a very low incidence of postoperative myasthenic crisis, it was attributable to early ligation of thymic veins. I believe this hypothesis is unfounded and rather premature. I believe it is more likely due to chance. Whether a T-3b thymectomy is superior to a transcervical T1b thymectomy is still unclear, because the patient populations reported are so dissimilar, as to make quick comparisons meaningless. A randomized trial would be ideal to settle this longstanding controversy. Due to a lack of equipoise on the part of surgeons, this trial is unlikely to ever happen. Perhaps an international group of interested neurologists and thoracic surgeons could agree what a common dataset requires and then submit cases to an independent for analyses with proper adjustment (perhaps with a propensity analysis) to attempt to settle this important question.
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References
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- Prokakis C, Koletsis E, Salakou S, et al. Modified maximal thymectomy for myasthenia gravis: effect of maximal resection on late neurologic outcome and predictors of disease remission Ann Thorac Surg 2009;88:1638-1646.[Abstract/Free Full Text]
- Jaretzki A, Steinglass KM, Sonett JR. Thymectomy in the management of myasthenia gravis Sem Neurol 2004;24:49-62.[Medline]
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Modified Maximal Thymectomy for Myasthenia Gravis: Effect of Maximal Resection on Late Neurologic Outcome and Predictors of Disease Remission
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Ann. Thorac. Surg. 2009 88: 1638-1645.
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References