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Ann Thorac Surg 1999;67:592-593
© 1999 The Society of Thoracic Surgeons

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Correspondence

Outcome after transcervical thymectomy

^a Department of Surgery, Columbia Presbyterian Medical Center, New York, NY 10032 USA

The conclusion by Bril and colleagues [1] that transcervical thymectomy in the treatment of myasthenia gravis (I assume that they are referring to the "extended" resection described by Cooper and associates [2]) produces results equivalent to the more aggressive transsternal resections is not supported by the available evidence. An analysis of this controversy has been reviewed in detail elsewhere [3].

In summary, (1) the crude, uncorrected remission rate for the transcervical transsternal maximal thymectomy in the treatment of nonthymomatous myasthenia gravis is correctly quoted by Bril and colleagues [1] as 46% and is compared with a rate for the transcervical procedure of 44.2%. The problem is that the mean follow-up at the time of these calculations was 8.4 years for the transcervical procedure and only 3.3 years for the maximal procedure, and it is well recognized that remission rates improve with time. (2) The error of this comparison is confirmed when one notes (Fig 1) that the remission rate for the maximal operation at a mean follow-up of 5.5 years was 57% and at 7.5 years, this rate was 62%. Accordingly, using crude data corrected for length of follow-up, the transcervical procedure clearly does not produce results equivalent to those of the maximal procedure, and the difference is perhaps more striking than previously recognized. (3) In addition, the patient cohorts in the two series are not comparable. The transcervical series had much milder myasthenia gravis than did the maximal series [3], and it has been demonstrated that for the same operative procedure, the milder the clinical manifestations the better the results. Accordingly, the difference in the two series is actually even greater than the crude data corrected for mean follow-up suggest.

View larger version (19K): [in this window] [in a new window]   Fig 1. Comparison of "crude" remission rates corrected for mean length of follow-up after thymectomy for myasthenia gravis. The analysis suggests that the more extensive the resection, the better the results. (1 = transcervical–transsternal maximal thymectomy [Ashour [5]]; 2 = VATS thymectomy [Mack [6]]; 3 = basic transsternal thymectomy [collected series]; 4 = standard transsternal thymectomy [collected series]; 5 = extended transsternal thymectomy [collected series]; 6 = extended transsternal thymectomy [Bril and Cooper [1, 2]]; 7 = standard transsternal thymectomy [Mayo Clinic [7]]; 8 = standard transsternal thymectomy [Massachusetts General Hospital [8]]. All data, except for bar 6 are referenced in the original publication. Modified from [3] by permission of Lippincott, Raven, Williams & Wilkin’s Publishers.) CPMC = Columbia Presbyterian Medical Center

Although this and other evidence strongly suggest that the more aggressive transsternal resections, especially the maximal resection, give better results than the less extensive procedures, the issue will not be unequivocally resolved, as pointed out by the authors and the invited discussant, until prospective studies using common definitions, classifications, and acceptable statistical techniques are used. The Medical Advisory Board of the Myasthenia Gravis Foundation of America, Inc., has appointed a Thymectomy Task Force to define appropriate methods of evaluating the response to therapy [4]. The task force expects to submit its recommendations by mid-1999.

References

1. Bril V., Kojic S., Ilse W., Cooper J. Long-term clinical outcome after transcervical thymectomy for myasthenia gravis. Ann Thorac Surg 1998;65:1520-1522.[Abstract/Free Full Text]
2. Cooper J., Al-Jilaihawa A., Pearson F., Humphrey J., Humphrey H.E. An improved technique to facilitate transcervical thymectomy for myasthenia gravis. Ann Thorac Surg 1988;45:242-247.[Abstract]
3. Jaretzki A., III Thymectomy for myasthenia gravis: an analysis of the controversies regarding technique and results. Neurology 1997;48(Suppl 5):S52-S63.
4. Jaretzki A., III, Barohn R.J., Ernstoff R.M., et al. Thymectomy Task Force of the Medical Advisory Board of the Myasthenia Gravis Foundation of America. Ann Thorac Surg 1997;64:1311.
5. Ashour M.H., Jain S.K., Kattan K.M., et al. Maximal thymectomy for myasthenia gravis. Eur J Cardiothorac Surg 1995;9:461-464.[Abstract]
6. Mack M.J., Landreneau R.D., Yim A.P., Hazelrigg S.R., Scruggs G.R. Results of video-assisted thymectomy in patients with myasthenia gravis. J Thor Cardiovasc Surg 1996;112:1352-1360.[Abstract/Free Full Text]
7. Buckingham J.M., Howard F.M., Bernatz P.E. The value of thymectomy in myasthenia gravis: a computer-assisted matched study. Ann Surg 1976;184:453-458.[Medline]
8. Wilkins E.W., Jr Thymectomy. Modern Techn in Surg 1981;38:1-13.

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Alfred Jaretzki, III Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Jaretzki, A. Search for Related Content PubMed Articles by Jaretzki, A., III Related Collections Related Article