Interactive Cardiovascular and Thoracic Surgery 3:376-380(2004)
© 2004 European Association of Cardio-Thoracic Surgery
Institutional report - Thoracic general |
Extended rethymectomy in the treatment of refractory myasthenia gravis: original video-assisted technique of resternotomy and results of the treatment in 21 patients
M. Zieli ski*,
J. Ku da ,
B. Staniec,
M. Harazda,
T. Nabiaek,
J. Pankowski,
A. Szlubowski and
M. Narski
Department of Thoracic Surgery, Pulmonary Hospital, ul. Gadkie 1, 34-500 Zakopane, Poland
* Corresponding author. Tel.: +48-18-201-5045
marcinz{at}mp.pl
Received October 20, 2003;
received in revised form February 10, 2004;
accepted February 19, 2004
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Abstract
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The aim of the study was to analyze the impact of extended rethymectomy in patients with myasthenia gravis. Additionally, an original technique of resternotomy is described. Extended rethymectomy was performed on 21 patients with refractory myastenic symptoms after a previous transsternal thymectomy. In 8 patients the original video-assisted technique of complete longitudinal resternotomy with the aid of a special sternal retractor elevating the sternum from above and below was used. Severe intraoperative haemorrhage from the lacerated left innominate vein occurred in 3/13 patients operated on before the video-assisted technique of resternotomy had been introduced. In none of the 8 patients operated on with video-assisted resternotomy such a complication was noted. Pathological findings: retained thymic lobe (4/21 patients), ectopic foci of thymic tissue (13/21 patients) no thymic tissue (4/21 patients). Results of follow-up: complete remission (11.8%), improvement (64.7%); no improvement (35.3%) during the follow-up period (mean 3.4 years). There was neither deterioration of myasthenia nor mortality during follow-up in this group. We conclude that described technique of video-assisted resternotomy reliably prevents the laceration of the heart and great vessels, and that complete remission and improvement rates in patients operated on with the extended rethymectomy are relatively low but deterioration of myasthenia is prevented.
Key Words: Myasthenia gravis; Thymectomy; Reoperation
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1. Introduction
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Thymectomy is regarded as an important part of therapy in generalized myasthenia gravis or in ocular myasthenia poorly controlled with conservative treatment [1,2]. In some patients myasthenic symptoms subside temporarily after the operation and afterwards become more severe. In such patients the presence of the thymic tissue in form of the retained part of the thymus gland or ectopic foci of the thymic tissue is suspected and a repeated thymectomy should be considered. We present our experience on the extended transsternal rethymectomy in patients with refractory myasthenia after previous basic transsternal thymectomy.
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2. Material and methods
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There were 784 thymectomies performed for myasthenia gravis at our department including 21 patients qualified for a repeated thymectomy (rethymectomy) due to worsening or lack of improvement of the myasthenia after the first operation and suspicion of the retained thymic tissue in the mediastinum. Characteristics of all 21 patients before the initial thymectomy and before rethymectomy is presented in Table 1. In 10 patients the first operation was performed at our department and in 11 patients the operation was performed elsewhere. Characteristics of patients before the first thymectomy is comparable to another group of 58 consecutive patients with myasthenia gravis operated on at our department with the extended transsternal thymectomy in the period 1998–1999 (Table 2) [3]. The initial procedure was the basic thymectomy through the left thoracotomy (1 patient—performed elsewhere), the basic transsternal thymectomy through upper partial sternotomy approach (18 patients) and the extended transsternal thymectomy (2 patients operated on at our department). All patients were operated on in general anaesthesia with the use of the endobronchial intubation with the extended transsternal thymectomy technique, similar to that described by Bulkley et al. [4]. In the first 13 patients the resternotomy included the excision of the scar after the first operation, removal of the wire sutures from the sternum and complete longitudinal sternotomy with use of the sternal sew. In the last 8 patients a new original technique of resternotomy was used, which is as follows: after the excision of the scar and removal of the wire sutures from the sternum ventilation of the right lung was disconnected. The sternum was elevated from above and below by two hooks inserted under the sternal notch and the lower angle of the sternum. Both hooks were connected to the special traction apparatus (Fig. 1a). Elevation of the sternum considerably facilitated access to the mediastinum. With dissection from above the sternal notch, the left innominate vein was visualized and dissected off the internal surface of the sternum, when possible. Afterwards the right mediastinal pleura was opened from below the lower sternal angle and the videothoracoscopic camera was inserted through this opening to control the videothoracoscopic port insertion to the right pleural cavity through the V or VI intercostal space in the anterior axillary line. Dissection from below the lower sternal angle under control of the videothoracoscopic camera was proceeded up to the level of the left innominate vein, which was previously dissected free from the sternum (Fig. 1b). The sternum was divided longitudinally using the sternal sew. The mediastinal pleura was cut longitudinally under the sternum, near both phrenic nerves (in the distance of about 1 cm) and the mediastinal pleura were excised en block with the specimen. The residual mediastinal fat was removed completely from the level of the diaphragm, including epiphrenic fat pads bilaterally. In the areas of the aorta-pulmonary window and the aorta-caval groove the dissection was extended below the phrenic nerves. Both vagus nerves and laryngeal recurrent nerves were routinely visualized. The dissection was terminated at the level of the upper poles of the thyroid gland.
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Table 2 Comparison of the group of 58 patients submitted extended transsternal thymectomy and group of 21 patients necessitating subsequently rethymectomy
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Fig. 1 Video-assisted technique of resternotomy. (A) The traction device elevating the sternum from above and below. (B) Video-assisted technique of division of the adhesions in the anterior mediastinum before dividing of the sternum.
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In pathological studies the thymus tissue was searched for with haematoxylin/eosin staining. To all patients questionnaires were sent every year with questions about symptoms (or lack of symptoms), medications (anticholinergic, corticosteroids or immunosuppressive drugs and the doses of drugs), improvement, stabilization or worsening and (in women) the effect of pregnancy on the myasthenia.
Statistical analysis was performed with STATISTICA software package. Probability values were generated with the  -test and the t-Student test or the Mann–Whitney test. Probability values  were considered to be statistically significant. The complete remission rate (number of patients both symptom- and medication-free/total number of patients in each group) and negative outcome rate (number of patients with lack of improvement, deterioration or dead because of MG/total number of patients in each group) were calculated.
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3. Results
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There were no mortality and 14.3% morbidity (3/21 patients): in three patients intraoperative bleeding from the left innominate vein lacerated during resternotomy occurred; in two of these patients the bleeding was severe. In two patients the vein was repaired with vascular suture and in one a patch from autologous pericardium was used. The operative time was 120–195 min (mean time 155 min). No patient needed respiratory support with use of the ventilator in the postoperative period.
On pathological studies a retained thymic lobe was found in 4/21 patients (initially operated on in other hospitals), in one of whom a thymoma in the retained lobe was discovered; etopic foci of the thymic tissue containing Hassall's corpuscles were found in 13 patients and foci of probable thymic origin but without Hassall's corpuscles in 8 patients. Overall, ectopic foci with and without Hassall corpuscles were found in 13 patients and the thymic tissue (retained lobe and/or ectopic foci) were found in 17/21 (81.0%) patients. In 4/21 (19.0%) no thymic tissue was found in the specimen (including both patients in whom the first procedure was the extended transsternal thymectomy). The localization of the thymic tissue in the whole group is shown in Table 3. The length of follow-up after rethymectomy was 1.0–7.0 years (mean 3.4 years). Results of follow-up can be analyzed in 17 patients, and in 4 patients operated on within 12 months before submission of this manuscript it is too early to estimate the late results of rethymectomy. In 11/17 of patients (64.7%) there is an improvement including 2/17 (11.8%) of patients with complete remission, and in 6/17 (35.3%) of patients there is no improvement (including 2 patients in whom extended thymectomy was the initial procedure). There is no deterioration of myasthenia or late mortality during follow-up in this group and in 6/12 patients corticosteroids or immunosuppressive drugs intake could have been discontinued after rethymectomy (in 2/14 patients taking steroids before rethymectomy it is too early to report the results of the follow-up).
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Table 3 Occurrence and localization of proven ectopic foci (Hc+) or suspected foci (Hc–) in the adipose tissue of the neck and the mediastinum in 21 patients after rethymectomy
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4. Discussion
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The importance of excision of the ectopic foci of the thymic tissue localized in the fatty tissue of the neck and mediastinum was raised by Masaoka et al. [5] and Jaretzki et al. [6]. Our comparison of late results of basic vs extended transsternal thymectomies shows a significant difference in complete remission rates after 4 years of follow-up (16.7 vs 46.6%;  ) in favour of the extended technique, which indicates that radicality of excision of the whole thymic tissue affects late results [3]. There is still no consensus which patients should be offered repeated thymectomy when the initial procedure failed to improve myasthenic symptoms. A decision about rethymectomy should be made after a considerable period of follow-up because in some patients clinical response after thymectomy occurres after several months or years. High titer of AchR antibodies may indicate possible presence of the thymic tissue. Kornfeld et al. reported that chest X-rays, CT scans of the chest and MRI examinations failed to demonstrate residual thymic tissue after a thymectomy and concluded that the decision to reoperate should be based on clinical findings rather than on imaging results alone [7]. In most of the reports concerning rethymectomy the transsternal approach was used with the exception of Pompeo et al., reporting left thoracoscopic approach [8]. In our opinion a unilateral thoracoscopic approach is insufficient in exploring all areas of the neck and mediastinum where residual thymic tissue can be found. The risk of laceration of the left innominate vein during resternotomy for rethymectomy is very high. Such complication occurred in 3/13 patients operated on in our institution (without sternal elevation and the use of the videothoracoscopic camera) with use of sternal sew, which led us to develop the described above original method of video-assisted resternotomy.
Our method of resternotomy is different from the techniques used for reoperations by cardiac surgeons during reoperations of the heart in two important aspects: first, the videothoracoscopic port used for the camera is inserted into the pleural space, which enables better visualization for the dividing of the adhesions than if the camera was inserted substernally [9–11]. Second, elevation of the sternum both from above and below (only traction of the lower angle of the sternum was described by cardiac surgeons) facilitates access to the mediastinum and enables safe dissection of the left innominate vein from the sternum, with is the critical stage of resternotomy during rethymectomy.
Overall morbidity of rethymectomy in the presented group was 14.3% which is comparable to the morbidity noted after the first thymectomy in our department.
To the best of our knowledge, our series of 21 patients is the largest reported series on the extended transsternal rethymectomy after an initial basic transsternal thymectomy [12–14]. In 13/21 patients ectopic foci of the thymic tissue were found, which cannot be considered a surgeon's mistake, contrary to retaining a part of the thymus gland in the mediastinum (as was found in 4/21 patients, initially operated on in other hospitals). The high incidence of ectopic foci of the thymic tissue (61.9%) is in accordance with our previous reports (57.6% after the extended transsternal thymectomy and 71.0% after transcervical–subxiphoid–videothoracoscopic maximal thymectomy) [15]. The results of follow-up are less favourable in comparison to those achieved by out team after the first extended transsternal thymectomy (93.1% improvement rate and 46.6% complete remission rate after 4.0 years of follow-up). Also, in other reports very few complete remissions after rethymectomy were noted [13,14]. Nevertheless, in none of our patients deterioration of myasthenia was noted and in 6/12 patients corticosteroids or other immunosuppressive drugs intake was discontinued after rethymectomy.
Unfavourable late results were reported even when the most extensive techniques of thymectomies were used. Such results were reported in 4% by Jaretzki et al., in 4.8% by Masaoka et al. and in 6.9% in our previous report [3,5,14]. Only such techniques as the extended or maximal thymectomies enable removal of the adipose tissue from regions where most of the ectopic foci can be present, therefore such techniques are recommended for surgical treatment of patients with myasthenia gravis.
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5. Conclusions
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- Described technique of video-assisted resternotomy reliably prevents laceration of the heart and great vessels.
- Complete remission and improvement rates in patients operated on with extended rethymectomy are relatively low but deterioration of myasthenia is prevented.
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Appendix A
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Conference discussion
Dr W. Weder (Zurich, Switzerland): You addressed a very important question of rethymectomy in patients who failed treatment. How is your workup? In 2 or 3 of the patients you didn't find any thymic tissue. Do you rely now on CT scan, or what is your workup for this decision-making?
Dr Zielinski: Generally, our indications for rethymectomy are made on a clinical basis. We decide to operate on the patients which have improved after the first thymectomy but later deteriorate. When there is any tissue in the anterior mediastinum seen on CT scans, it is difficult to distinguish if it is fat or residual thymic tissue. So, when such a clinical sequence of events occurs, we perform a rethymectomy. And thymic tissue was found in 80% of the patients who underwent a rethymectomy.
Dr E.A. Rendina (Rome, Italy): Can I ask you about the early group of patients in whom you have done resternotomy. In the group in which you had the complications, did you start the sternotomy from the sternal notch or from the xiphoid process?
And in the case you started from the sternal notch, did you consider starting the resternotomy from the xiphoid in order to have better control of the vessels?
Dr Zielinski: It's a valid option of resternotomy. Nevertheless we found that in almost all patients, when the first thymectomy is performed in the proper way, there is a firm adhesion between the inner surface of the sternum and the left innominate vein. I believe that in most patients, of course, it is possible to perform safely a resternotomy with the oscillating saw. Nevertheless it is much safer to perform resternotomy in the way we presented.
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Footnotes
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Presented at the joint 17th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 11th Annual Meeting of the European Society of Thoracic Surgeons, Vienna, Austria, October 12–15, 2003
doi:10.1016/j.icvts.2004.02.008
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References
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- Jaretzki A. Thymectomy for myasthenia gravis: analysis of the controversies regarding technique and results. Neurology. 1997;48(Suppl 5):S52–S63
- Roberts PF, Venuta F, Rendina E, De Giacomo T, Coloni GF, Follette DM, Richman DP, Benfield JR. Thymectomy in the treatment of ocular myasthenia gravis. J Thrac Cardiovasc Surg. 2001;122:562–568
- Zieli
 ski M, Pankowski J, Harazda M, Staniec B, Nabiaek T, Modkowski J, Kuzdza J, Medo J, Narski M, Szlubowski A. Comparison of late results of basic transsternal and extended transsternal thymectomies in the treatment of myasthenia gravis. Ann Thorac Surg. 2004;: in press
- Bulkley GB, Bass KN, Stephenson GR, Diener-West M, Simeon G, Reilly PA, Baker RR, Drachman DB. Extended cervicomediastinal thymectomy in the integrated management of myasthenia gravis. Ann Surg. 1997;226:324–335[CrossRef][Medline]
- Masaoka A, Yamakawa Y, Niwa H, Fukai I, Kondo S, Kobayashi M, Fujii Y, Monden Y. Extended thymectomy for myasthenia gravis patients: a 20-year review. Ann Thorac Surg. 1996;62:853–859[Abstract/Free Full Text]
- Jaretzki A, Wolff M. Maximal thymectomy for myasthenia gravis. Surgical anatomy and operative technique. J Thorac Cardiovasc Surg. 1988;96:711–716[Abstract]
- Kornfeld P, Merav A, Fox S, Maier AK. How reliable are imaging procedures in detecting residual thymus after previous thymectomy? Ann NY Acad Sci. 1993;681:575–576[CrossRef][Medline]
- Pompeo E, Nofroni I, Iavicoli N, Mineo TC. Thoracoscopic completion thymectomy in refractory nothymomatous myasthenia. Ann Thorac Surg. 2000;79:918–923[CrossRef]
- Athanasiou T, Stanbridge RD, Kumar P, Cherian A. Video assisted resternotomy in high-risk redo operations—the St Mary's experience. Eur J Cardiothorac Surg. 2002;21:932–934[Abstract/Free Full Text]
- Eddy AC, Miller D, Johnson D, Gartman D, Gregg M, Allen M, Verrier ED. Anterior sternal retraction for reoperative median sternotomy. Am J Surg. 1991;161:556–559[CrossRef][Medline]
- Gazzaniga AB, Palafox BA. Substernal thoracoscopic guidance during sternal reentry. Ann Thorac Surg. 2001;72:289–290[Abstract/Free Full Text]
- Miller RG, Filler-Katz A, Kiprov D, Roan R. Repeat thymectomy in chronic refractory myasthenia gravis. Neurology. 1991;41:923–924[Abstract/Free Full Text]
- Kirschner PA. Reoperation on the thymus. Chest Surg Clin N Am. 2001;11:439–445[Medline]
- Jaretzki A III, Penn AS, Younger DS, Wolff M, Olarte MR, Lovelace RE, Rowland LP. Maximal thymectomy for myasthenia gravis. Results. J Thorac Cardiovasc Surg. 1988;95:747–757[Abstract]
- Zieliski M, Pankowski J, Harazda M, Staniec B, Nabiaek T, Modkowski J, Kuzdza J, Medo J, Narski M, Szlubowski A. Transcervical-subxiphoid-VATS maximal thymectomy-operative technique and early results. Ann Thorac Surg. 2004;: in press
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Abstract
1. Introduction