151 - Multimodality Therapy for Esophageal Cancer

Editors: Shields, Thomas W.; LoCicero, Joseph; Ponn, Ronald B.; Rusch, Valerie W.

Title: General Thoracic Surgery, 6th Edition

Copyright 2005 Lippincott Williams & Wilkins

> Table of Contents > Volume II > The Mediastinum > Section XXIX - Primary Mediastinal Tumors and Syndromes Associated with Mediastinal Lesions > Chapter 177 - Transcervical Thymectomy

Chapter 177

Transcervical Thymectomy

Thomas J. Kirby

Robert J. Ginsberg

Originally, the technique of thymectomy through a neck incision was developed by Veau and Olivier (1910) and Parker (1913) in the late 1800s and early 1900s for infants and children who were thought to be suffering from upper airway obstruction secondary to an enlarged thymus. Although Crile (1964) reported use of the technique in a variety of situations, including the removal of mediastinal parathyroids, and for its purported immunosuppressive effects in patients who were to undergo renal transplantation, its primary use today is in patients with myasthenia gravis (MG). Schumacher and Roth (1912) reported the first successful transcervical thymectomy for MG that was performed by Sauerbruch in 1912, with the patient apparently showing a modest improvement. Subsequently, Adler (1937) and Obiditsch (1937) reported that Sauerbruch performed two other transcervical thymectomies for MG, with both patients dying within a week of their operation, one from mediastinitis and the other from a streptococcal infection. Haberer in 1917 published his experiences with surgery on the thymus and included a description of a transcervical thymectomy in a myasthenic patient. A precise description of the technique using a low neck incision was published by Crotti (1938).

With the development of thoracic surgery and Blalock and associates' reports in 1939 and 1941 of successful thymectomies being performed through a sternotomy, the transcervical approach became something of a lost art. The technique was revived in the 1960s with reports by Crile (1964), Carlens and colleagues (1968), Akakura (1965), and Kirschner and associates (1969) of its usefulness in a variety of situations, including myasthenia gravis.

Considerable controversy still exists as to the best surgical approach for thymectomy in patients with MG, with strong advocates for the transcervical approach such as Cooper and colleagues (1988), simple sternotomy such as Olanow (1987) and Mulder (1989) and their associates, or for what Jaretzki and colleagues (1977,1988) have termed the maximal thymectomy, with separate sternal and neck incisions. Masaoka and co-workers (1996) have advocated an extended thymectomy via a transsternal route. Whatever approach is selected, the surgeon must be comfortable with the procedure, perform as complete a thymectomy as possible, and produce results that are in keeping with those reported by other researchers using different surgical approaches. We do not debate the pros and cons of the various surgical options or their results but point out that, as reported previously by Cooper and associates (1988), transcervical thymectomy has been found to fulfill the aforementioned criteria.

OPERATIVE TECHNIQUE

A complete and thorough understanding of the anatomy of the anterosuperior mediastinum and thymus (Fig. 177-1), as previously discussed (see Chapters 154 and 155), is essential if one is to successfully perform a complete thymectomy using the transcervical approach. It is of the utmost importance that the patient be positioned properly so that access to and exposure of the anterior mediastinum can be maximized. The patient is positioned supine, arms at the sides with the head directly at the end of the operating room table with the occiput resting on a doughnut. The endotracheal tube is positioned to the patient's right as far as possible to minimize any interference with the surgeon's view. A sand bag or an inflatable bag is placed under the patient's shoulders to increase cervical spine extension, thereby facilitating exposure. The neck and sternum are draped in a fashion that allows a sternotomy to be performed if the need arises and in particular if a thymoma is discovered at the initial exploration. A head light is invaluable for this procedure.

A 5- to 6-cm incision is made one finger's breadth above the sternal notch along a skin crease. Dissection is carried down through the platysma with skin flaps mobilized in a subplatysmal plane inferiorly to the sternal notch and superiorly to the inferior border of the thyroid cartilage. The interclavicular ligament is divided down to the manubrium. Meyers and Cooper (2001) have recommended that the ligamentous

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insertions of the sternocleidomastoid muscles be divided with electrocautery in a vertical manner to allow improved exposure into the substernal plane.

Fig. 177-1. A diagrammatic representation of the anatomy of the thymus gland. The dotted line indicates the site of the cervical incision.

The strap muscles are separated in the midline and the superior poles of the thymus gland are identified below the sternothyroid muscle, anterior to the inferior thyroid veins, usually abutting the inferior poles of the thyroid gland. The superior poles are freed up in an extracapsular plane, after which ligatures are placed around each pole separately to allow the thymus to be easily retracted out of the way (Fig. 177-2). The fibrous capsule investing the thymus is strong, allowing firm traction to be applied on these ligatures without their tearing free. The gland is then freed off the posterior aspect of the manubrium and sternum using a combination of blunt and sharp dissection.

Fig. 177-2. Using a short transverse cervical incision, the superior poles of the thymus gland have been mobilized and ligatures have been placed at both tips for future traction.

Fig. 177-3. With retraction of the superior poles anteriorly, the innominate vein and thymic veins are identified before ligation.

Attention is then turned to the posterior aspect of the gland, lifting it up anteriorly off the left innominate vein (Fig. 177-3). At this point it is best to place a specially developed narrow right-angle retractor (Cooper Thymectomy Retractor, Pilling Co., Atlanta, GA, U.S.A.) behind the manubrium after attaching it to a crossbar (Fig. 177-4). Traction is then applied upward on this retractor after deflating the shoulder bag. This results in maximal extension of the cervical spine, greatly enhancing exposure for the remaining part of the dissection. It is important not to apply too much traction on the manubrium such that the patient's head is lifted off the operating room table and consequently supported only by the cervical spine, which may result in neurologic embarrassment.

Fig. 177-4. A specially developed narrow right-angled retractor elevates the sternum using a crossbar apparatus, gaining further exposure to the anterior mediastinum.

Fig. 177-5. The thymus has been mobilized from the mediastinum using sharp and blunt dissection. Visualization is improved by the use of a head lamp. This figure illustrates the left inferior pole being mobilized first. We usually prefer to mobilize the right anterior pole before mobilizing the left.

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Thymic veins draining into the left innominate vein are identified during this part of the procedure (see Fig. 177-3). Usually, there are two such veins, but the number is variable. They can be divided using ligaclips or divided between ligatures. Occasionally at this point it is found that part of the gland passes posterior to the innominate vein; careful dissection of this area must be executed to ensure complete removal of all thymic tissue.

After vein division, a combination of sharp and blunt dissection is used again to free up the posterior aspect of the gland from the pericardium. The thymus is carefully dissected free from the mediastinal pleura on both sides, with special attention given to identification and preservation of the phrenic nerves. The lower poles of the gland are now identifiable and dissected free from their attachments to the pericardial fat in the pericardiophrenic sulcus (Fig. 177-5). The thymus should now be completely free and removable in its entirety. The gland should be inspected carefully to ensure that its capsule is intact and that it has been completely removed (Fig. 177-6). Mediastinal fat that is lying on the pleura or in the pericardiophrenic angle can now be more easily identified and resected as separate specimens. If at this point the surgeon is not satisfied that a complete thymectomy has been achieved, a sternotomy should be performed. Certainly if the surgeon identifies a previously unsuspected thymoma, a sternotomy also should be performed.

Fig. 177-6. A photograph of a thymus gland with an intact capsule removed through the transcervical approach. The silk ties are on the superior poles.

Hemostasis is assessed and secured. A single small red rubber catheter is placed in the anterior mediastinum and brought out through the incision. Strap muscles are reapproximated, as is the platysma. Suction is then applied to the catheter, which is then removed. This ensures that all air is removed from the mediastinum to prevent the development of a pneumothorax in the postoperative period if the mediastinal pleura has been transgressed during the operation.

RESULTS

Bril and associates (1998) at the Toronto General Hospital reviewed the long-term results in 52 patients with nonthymomatous myasthenia gravis who had undergone a transcervical thymectomy between 1977 and 1986. The mean follow-up was 8.4 6.1 years, standard deviation. Complete remission occurred in 44.2% of the patients. Similar data were obtained at Washington University by Calhoun and colleagues (1999), in which study the most recent 100 consecutive patients were used as the database. The operative morbidity rate was 8% and the mortality rate was 0%. Seventy-eight patients were followed for over 1 year. The median Ossermann grade (Table 177-1) improved from grade 3 before surgery to grade 1 afterward. Overall, 85% of the patients improved by one or more Ossermann grades (35% were in complete remission), 14% experienced no change, and only one patient (1.2%) had deteriorated by a single Ossermann grade.

Shrager and co-workers (2002) at the University of Pennsylvania reported a retrospective review of 121 consecutive patients who underwent attempted transcervical thymectomy between 1992 and 1999. Of the 98 patients with myasthenia gravis, 492 were available for follow-up evaluations. Of these, 78 patients met the criteria for inclusion in their study. There was a 7.7% morbidity rate and a 0% mortality rate. With a mean follow-up of 54.6 months, the following results were observed: (a) a complete remission rate of 39.7%, (b) 19.2% were asymptomatic with medication, (c) 28.2% were symptomatic but improved by two Ossermann

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grades, and (d) 10.3% had no clinical improvement. In the remaining 3.8% of patients, relapse occurred, although no patient deteriorated from their original Ossermann grade. These researchers concluded that the results of the transcervical approach are as satisfactory as those obtained via a transsternal removal of the thymic gland.

Table 177-1. Ossermann Classification for Myasthenia Gravis

Ossermann Score Description
0 Asymptomatic
1 Occular symptoms and signs
2 Mild generalized weakness
3 Moderate generalized weakness
4 Severe generalized weakness, respiratory dysfunction, or both

REFERENCES

Adler H: Thymus and myasthenia. Arch Chir 189:529, 1937.

Akakura L: Mediastinoscopy. Presented at the XIth International Congress of Bronchoesophagology, Hakone, Japan, 1965.

Blalock A, et al: Myasthenia gravis and tumors of the thymic region. Ann Surg 110:544, 1939.

Blalock A, et al: The treatment of myasthenia gravis by removal of the thymus gland. JAMA 117:1529, 1941.

Bril V, et al: Long-term clinical outcome after transcervical thymectomy for myasthenia gravis. Ann Thorac Surg 65:1520, 1998.

Calhoun RF, et al: Results of transcervical thymectomy for myasthenia gravis in 100 consecutive patients. Ann Surg 23:555, 1999.

Carlens E, et al: Thymectomy for myasthenia gravis with the aid of a mediastinoscopy. Opuscula Med 13:175, 1968.

Cooper JD, et al: An improved technique to facilitate transcervical thymectomy for myasthenia gravis. Ann Thorac Surg 45:242, 1988.

Crile G: Thymectomy through the neck. Surgery 59:213, 1964.

Crotti A: Diseases of the Thyroid, Parathyroid and Thymus. 3rd Ed. Philadelphia: Lea & Febiger, 1938.

Haberer H: Zur klinischen Bedeutung der Thymusdruse. Arch Chir 109: 193, 1917.

Jaretzki A III, Wolff M: Maximal thymectomy for myasthenia gravis. Surgical anatomy and operative technique. J Thorac Cardiovasc Surg 96:711, 1988.

Jaretzki A III, et al: A rational approach to total thymectomy in the treatment of myasthenia gravis. Ann Thorac Surg 24:120, 1977.

Jaretzki A III, et al: Maximal'' thymectomy for myasthenia gravis: results. J Thorac Cardiovasc Surg 95:747, 1988.

Kirschner PA, Osserman KE, Kark AE: Studies in myasthenia gravis transcervical total thymectomy. JAMA 209:906, 1969.

Masaoka A, et al: Extended thymectomy for myasthenia gravis patients: a 20-year review. Ann Thorac Surg 62:853, 1996.

Meyers BF, Cooper JD: Transcervical thymectomy for myasthenia gravis. Chest Surg Clin North Am 11:363, 2001.

Mulder DG, Graves M, Herrmann C: Thymectomy for myasthenia gravis: recent observations and comparisons with past experience. Ann Thorac Surg 48:551, 1989.

Obiditsch RA: Beitrage zur Kenntnis der Thymusgeschwulste im Besonderen Dergenigen bei Myasthenie. Virchows Arch 300:319, 1937.

Olanow CW, et al: Thymectomy as primary therapy in myasthenia gravis. Ann NY Acad Sci 1505:595, 1987.

Parker CA: Surgery of the thymus gland: thymectomy, report of 50 operated cases. Am J Dis Child 5:89, 1913.

Schumacher ED, Roth P: Thymektomie bei einem Fall von Morbus Basedowi mit Myasthenie. Mitteil Grenzgeb Med Chir 25:746, 1912.

Shrager JB, et al: Transcervical thymectomy for myasthenia gravis achieves results comparable to thymectomy by sternotomy. Ann Thorac Surg 74:320, 2002.

Veau V, Olivier E: Ablation du thymus: technique, resultats. Presse Med 18:257, 1910.



General Thoracic Surgery. Two Volume Set. 6th Edition
General Thoracic Surgery (General Thoracic Surgery (Shields)) [2 VOLUME SET]
ISBN: 0781779820
EAN: 2147483647
Year: 2004
Pages: 203

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