MMCTS
(March 24, 2005). doi:10.1510/mmcts.2004.000158
Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure
Conventional mediastinoscopy
Paul De Leyn* and
Toni Lerut
University Hospitals Leuven, Department of Thoracic Surgery, Herestraat 49, B-3000 Leuven, Belgium
* Corresponding author: * Tel: +32-16-346822, fax: +32-16-346821. E-mail: Paul.Deleyn{at}uz.kuleuven.ac.be
 |
Summary
|
|---|
Involvement of mediastinal nodes has a dramatic prognostic and therapeutic impact in patients with non-small cell lung cancer. Cervical mediastinoscopy remains the most important technique for staging of the mediastinum. The technique of extended mediastinoscopy and redo mediastinoscopy are described as well. Indications, technique and complications are discussed.
Key Words: non-small cell lung cancer, nodal staging
|
Introduction
|
|---|
Cervical mediastinoscopy is an invasive staging method which is used for staging of the superior and middle mediastinum (Schematic 1
).
View larger version (80K):
[in this window]
[in a new window]
|
Schematic 1 Different compartments of the mediastinum. Mediastinoscopy is used to explore the superior and middle part of the mediastinum. a. Superior mediastinum. b. Anterior mediastinum. c. Middle mediastinum. d. Posterior mediastinum
|
|
Although cervical mediastinoscopy is used in the diagnosis of lymphoma, sarcoidosis and mediastinal tumors, it is mainly used as an invasive staging method in patients with non-small cell lung cancer (NSCLC). Surgical exploration of the mediastinum was first developed by Harken et al. Through a supraclavicular incision, a Jackson laryngoscope was inserted into the mediastinum and lymph node biopsies were taken. They reasoned that the presence of involved mediastinal lymph nodes in patients with lung cancer would preclude successfull resection of the cancer. More than fifty years later, their reasoning still proves to be very valid. Cervical mediastinoscopy through a pretracheal suprasternal incision was developed by Carlens in Sweden and subsequently popularized by Pearson in North-America. The prognostic importance of the level and extent of nodal involvement has led to the development of an internationally used lymph node map (Mountain–Dressler [1]).
|
Indications
|
|---|
- Lymph nodes or masses in the middle mediastinum of unknown origin (sarcoidosis, lymphoma, ...).
- Mediastinal staging in patients with NSCLC.
There remains controversy regarding the selected use of mediastinoscopy in patients with NSCLC. Before PET scan became available, many centers used to perform cervical mediastinoscopy in every patient since it has been proved that small nodes on CT scan can harbor metastatic disease of clinical importance [2]. There is consensus that the positive predictive value of both CT as well as PET scan is low and that positive mediastinal findings on CT or PET scan need to be proven histologically. Other less invasive techniques such as transbronchial fine needle aspiration and esophageal and tracheal endoscopic ultrasound needle aspiration have become available in specialized centers with high sensitivity in clinically obviously involved mediastinal nodes. The sensitivity and negative predictive value (NPV) of these techniques are, however, significantly lower when compared to mediastinoscopy and mediastinoscopy remains the gold standard. Cervical mediastinoscopy has a high accuracy. Its specificity is 100%, the sensitivity is dependent upon the surgeons experience but sensitivity rates of 90% are usually reported [2]. Therefore, cervical mediastinoscopy remains the gold standard to which all other techniques are to be compared.
However, because PET scan has a high NPV up to 93% in primary mediastinal staging in patients with NSCLC [3] cervical mediastinoscopy can nowadays be omitted in some circumstances (peripheral tumor, N0 on PET and CT scan).
|
Contraindications
|
|---|
Absolute contraindications for cervical mediastinoscopy are very rare.- Contraindication for general anesthesia
- Extreme kyphosis
- Cutaneous tracheostomy (after laryngectomy)
Superior vena cava syndrome, previous sternotomy and enlarged goiter do not preclude mediastinoscopy as well as previous radiotherapy and mediastinoscopy. Due to fibrosis and adhesions the intervention can be much more challenging and is more time consuming.
|
Accessible lymph node stations by cervical mediastinoscopy (Schematics 2, 3, 4, 5, 6, 7)
|
|---|
By cervical mediastinoscopy the following nodal stations (according to the Mountain–Dresler modification (1997) from Naruke/ATS-LCSG Map) can be searched for and biopsied: the left and right upper paratracheal nodes (station 2L and 2R), left and right lower paratracheal nodes (station 4L and 4R) and the subcarinal nodes (station 7).
View larger version (102K):
[in this window]
[in a new window]
|
Schematic 3 Station 1 nodes are not routinely accessed by cervical mediastinoscopy. Station 1 nodes are located above the suprasternal notch.
|
|
View larger version (113K):
[in this window]
[in a new window]
|
Schematic 4 A horizontal line drawn tangential at the upper margin of the aortic arch delineates the lower border of station 2 nodes.
|
|
View larger version (87K):
[in this window]
[in a new window]
|
Schematic 5 Station 3 nodes are also not accessible by conventional cervical mediastinoscopy. Station 3A lymph nodes are located prevascular (in front of vena cava) and 3P lymph nodes are located in the upper paraesophageal region, above the tracheal bifurcation.
|
|
View larger version (110K):
[in this window]
[in a new window]
|
Schematic 6 The posterior subcarinal nodes (station 7p), the para-esophageal nodes (station 8), the inferior pulmonary ligament nodes (station 9) are not accessible by conventional media-stinoscopy.
|
|
View larger version (77K):
[in this window]
[in a new window]
|
Schematic 7 The subaortic nodes (station 5) and para-aortic nodes (station 6) cannot be biopsied through a standard cervical mediastinoscopy.
|
|
Operative technique
Installation
Mediastinoscopy is performed under general anesthesia (Photo 1
, Schematics 8
and 9
).
View larger version (106K):
[in this window]
[in a new window]
|
Photo 1 The endotracheal tube is positioned at the left corner of the mouth, with the anesthesia equipment at the patients left side. The table should be level or slightly tilted foot downwards to reduce venous congestion. For left handed surgeon, the installation may be mirrored to the right side.
|
|
View larger version (20K):
[in this window]
[in a new window]
|
Schematic 9 Operation room setup for conventional mediastinoscopy. The surgeon is standing at the head of the table.
|
|
Instruments
(Photos 2
and 3
)
View larger version (115K):
[in this window]
[in a new window]
|
Photo 2 For mediastinoscopy, only few instruments are needed. Scalpel, dissection scissors, pickups, small retracting instrument, suction and cautery device, needle holder and biopsy forceps.
|
|
Incision
(Schematics 10, 11, 12, 13
)
View larger version (97K):
[in this window]
[in a new window]
|
Schematic 10 A 3 cm transverse cervical incision is made one-finger breadth above the suprasternal notch.
|
|
View larger version (77K):
[in this window]
[in a new window]
|
Schematic 12 Sharp dissection exposes the pretracheal muscles which are separated vertically in the midline to expose the anterior surface of the trachea. The thyroid isthmus is retracted superiorly and the tracheal surface is exposed just below the isthmus. One has to be careful not to avulse the inferior thyroid veins. These small veins can usually be avoided. In case of bleeding, they need to be ligated or electrocoagulated.
|
|
View larger version (108K):
[in this window]
[in a new window]
|
Schematic 13 Incision of the pretracheal fascia. The tissues are cleared down to the anterior surface of the trachea exposing the dense white pretracheal fascia which is incised and dissected off the trachea exposing the cartilaginous rings. At this point one should avoid to dissect downward into the mediastinum. It is easier to incise the pretracheal fascia just below the isthmus of the thyroid and then to carry down the dissection along the anterior surface of the trachea.
|
|
Dissection
(Schematics 14, 15, 16
and Photo 4
)
View larger version (66K):
[in this window]
[in a new window]
|
Schematic 14 The surgeon's middle finger is advanced along the pretracheal plane and blunt dissection is carried out along the anterior surface of the trachea down to the carina.
|
|
View larger version (63K):
[in this window]
[in a new window]
|
Schematic 15 The mediastinum is carefully palpated for the presence of nodal disease. This palpation is of extreme importance, pretracheal nodes are more easier palpated rather than being visualized. In many cases massive infiltration of the upper mediastinal nodes is mainly diagnosed by palpating them in the mediastinum!
|
|
View larger version (124K):
[in this window]
[in a new window]
|
Photo 4 The plane in front of the mediastinoscope is developed with the use of blunt dissection, using a metal sucker through the channel of the mediastinoscope. Small bleeding vessels can be coagulated. The tissue planes are developed to the level of the carina and both tracheobronchial angles. The left and right border of the trachea are dissected.
|
|
Biopsying of lymph nodes (Schematics 17, 18, 19)
Prior to biopsying the lymph node, the node should be mobilized as much as possible to ensure that it is a lymph node and not a vessel. This mobilization is performed by the use of the suction device. For the upper paratracheal lymph nodes this can be safely performed with the finger. In case of doubt, a long aspiration needle can be placed in the lymph node and suction is applied to the attached syringe, to ensure that the structure to be biopsied is not a vessel. An experienced surgeon will find this seldom necessary when the nodes were adequately mobilized and the anatomical structures are clearly identified. The lymph node is grasped with a biopsy forceps. In case of resistance, one should be cautious not to pull too strongly because the diseased lymph node may be attached to an adjacent vascular structure such as the azygos vein, the first branch of the right PA or the innominate artery. This may lead to a vascular tear with major bleeding (Schematics 17, 18, 19
).
View larger version (75K):
[in this window]
[in a new window]
|
Schematic 17 To avoid and to handle major complications, it is important to visualize the anatomical landmarks such as the azygos vein, the right and left main bronchus and the first branch of the right pulmonary artery before biopsies are taken.
|
|
View larger version (51K):
[in this window]
[in a new window]
|
Schematic 18 The left recurrent nerve lies approximately 1 cm lateral to the trachea and can usually be visualized in the mid tracheal plane. From there it can be followed more distally.
|
|
View larger version (69K):
[in this window]
[in a new window]
|
Schematic 19 Sequentially, the paratracheal tissues are entered to expose the lymph nodes at the various stations. The lymph nodes lie outside of the fascial envelope and the pretrachial fascia has to be broken with the suction device (for instance in the subcarinal area and the lower paratracheal area) or by the finger (upper paratracheal and pretracheal area). When the mediastinoscope reaches the subcarinal area, a thin layer of firm fibrous tissue has to be broken to visualize the subcarinal nodes. Beneath the subcarinal nodes, the esophagus can be visualized. One has to be careful not to damage the esophagus.
|
|
One starts to biopsy the obvious enlarged nodes and those nodes that felt firm by palpation. However, small lymph nodes may also contain metastatic deposits.
Routine sampling of all accessible mediastinal nodal stations is advised. The standard is that biopsies of the subcarinal nodal station, two ipsilateral nodal stations and one contralateral nodal station are biopsied or removed (Photos 5
and 6
). The author uses adhesive labels on which the stations according to the Mountain–Dressler map are printed. This increases the accuracy in labelling (Table 1).
View larger version (59K):
[in this window]
[in a new window]
|
Photo 5 The biopsies are stored in separate vials, labelled with these adhesive labels and sent for pathology.
|
|
View larger version (119K):
[in this window]
[in a new window]
|
Photo 6 When biopsies are taken from the different nodal stations the biopsy forceps is cleaned each time to prevent contamination and false positive results.
|
|
In the subcarinal area, bronchial arteries are frequently encountered and bleeding frequently occurs from the subcarinal lymph node biopsy sites. This bleeding, although usually modest, obscures clear vision and further dissection and sampling. In case a bronchial artery is visualized, a vascular clip can be placed. Pushing the scope deeper into the subcarinal space the bleeding will stop which allows to take more representative biopsies before the bleeding sites are electrocoagulated.
Sufficient tissue has to be removed. In case of doubt, frozen section can be performed to confirm that sufficient tissue will be available. When there is no histological diagnosis part of the lymph node is sent for culture.
Bleeding
Small bleedings from biopsy sites can be electrocoagulated. Bleeding is best handled with resorbable hemostatic resorbable gauze placed through the mediastinoscope.
When a major bleeding occurs, packing is the first thing to do. By packing for at least 10 minutes, most of the even dramatic bleedings will stop. A long strip of wide gauze packing should always be available in the operating room for such instances. In case of uncontrollable hemorrhage (for instance injury of aorta or innominate artery), the mediastinum is packed or the bleeding site is compressed with the surgeon's finger, or the mediastinoscope, and the decision is made whether thoracotomy or sternotomy will be performed. Decision is based on the location of the bleeding and the location of the tumor if resection is indicated. Right thoracotomy might be indicated when the bleeding is from the first branch of the right pulmonary artery or from the azygos vein. In all other cases sternotomy offers the best chances to control the bleeding.
Closure
The strapmuscles are approximated with one suture. Drainage of the mediastinal bed is usually not required. A subcutaneous interrupted suture will obliterate the dead space. The skin is closed according to the surgeons preferences.
|
Complications
|
|---|
Cervical mediastinoscopy is a low-risk procedure but the potential for catastrophic complications is apparent. Unless additional or more extensive procedures are done under the same general anesthesia, and the patient's condition permits, the procedure can be performed on an outpatient basis [4]. In experienced hands, cervical mediastinoscopy has no mortality and minimal morbidity. In a recent review of over 20000 cases complications did not surpass 2.5% and mortality was under 0.5% [5]. Only 0.1 to 0.5% of complications are considered major. The most important major complication is severe hemorrhage. On the right side, the azygos vein and the anterior branch of the right pulmonary artery are at risk of injury. The azygos vein can be mistaken for an anthracotic lymph node. Other major complications are injury of the esophagus, damage to the recurrent laryngeal nerve (usually the left) and tracheobronchial tree injuries.
In a twenty-year period, we performed well over 4000 cervical mediastinoscopies. There was no hospital mortality. Major bleeding requiring immediate intervention occurred in four patients, injury to the esophagus was seen in one patient in whom the mediastinum was drained through the mediastinoscopy incision and this fistula dried up after a few days of conservative treatment [6]. In one case a tear of the left main bronchus was made by the biopsy forceps. This was sutured by the endoscopic suturing technique using the videomediastinoscope and healed without any problems.
Extended cervical mediastinoscopy
Left upper lobe tumors may metastasize to the subaortic lymph nodes (station 5) and paraaortic nodes (station 6). These nodes cannot be biopsied through routine cervical mediastinoscopy. Ginsberg and associates described a technique to explore these stations through the cervical incision. This technique is an alternative for the anterior-second interspace mediastinotomy which is more commonly used for exploration of these nodal stations. The advantage of the extended mediastinoscopy is the saving of an additional incision (Schematics 20
and 21
).
View larger version (93K):
[in this window]
[in a new window]
|
Schematic 20 If the standard cervical mediastinoscopy is negative, a plane is developed anterior to the aortic arch, down to the subaortic space. To do so, blunt dissection is performed with the finger anterior to the innominate artery, between the innominate artery and the innominate vein. The mediastinoscope is introduced through the cervical incision above the aortic arch. The scope is advanced over the top of the aortic arch down to the aortopulmonary window.
|
|
In experienced hands the procedure has a high accuracy and minimal morbidity. It is important to state that this procedure is far less easy and therefore is less routinely performed compared with the conventional mediastinoscopy.
Repeat mediastinoscopy
Precise restaging of the mediastinum after induction therapy for patients with involved mediastinal nodes (N2 or N3) disease is of utmost importance since confirmation of downstaging of mediastinal nodes is a very important prognostic factor in these patients. Although long-term survival has been reported in patients with persistent N2 disease undergoing resection after induction therapy, most of these patients will not benefit from surgery since resectability and long-term survival is low. Although PET scan has a high accuracy in primary staging of the mediastinum, its accuracy is much less in restaging of the mediastinum after induction therapy. So, thoracic surgeons will be faced more and more frequently with the need to repeat the mediastinoscopy. Several authors have shown that repeat mediastinoscopy is feasible with an accuracy of 85% and a sensitivity of 73% [7].
Technique of repeat mediastinoscopy
Positioning of the patient is not different from mediastinoscopy but the whole sternum is disinfected in case a sternotomy or hemiclamshell would be necessary. The primary incision is reopened. Usually the isthmus or even the thyroid may be adherent to the trachea. Sharp dissection is performed to find the anterior surface of the trachea. The brachiocephalic trunk is adherent to the anterior surface of the trachea due to fibrosis (Photo 7
and Schematic 22
).
View larger version (94K):
[in this window]
[in a new window]
|
Photo 7 Repeat mediastinoscopy.
Blunt dissection is started on the left side of the trachea. This region was usually not extensively dissected at the previous mediastinoscopy and thus containing less fibrosis.
|
|
View larger version (52K):
[in this window]
[in a new window]
|
Schematic 22 A left paratracheal tunnel is created (medial border is trachea, the surface is part of the esophagus) and the scope is inserted.
|
|
Dissection is continued on the left side until the left tracheobronchial angle is visualized. From this tunnel, blunt dissection to the right side is performed from below in a retrograde fashion. The anterior surface of the trachea is freed from the adherent major vascular structures. Initially this is perfomed with a dissection pledget. Once additional space is gained this can be continued by finger dissection. One has to do this carefully to avoid injury to the brachiocephalic artery. The pretracheal space now being liberated, the scope can be changed in its normal position. Dense fibrosis and adhesions render the thorough exploration of all nodal stations very difficult or even impossible. To reach the subcarinal region, the pulmonary artery has to be pushed away. Adhesions can be divided with the endoscopic shears. When there is a lot of precarinal fibrosis, we advise to dissect as far as possible on the left main bronchus. From there the subcarinal space can be dissected and biopsied.
|
Acknowledgements
|
|---|
The authors wish to thank Patrick Meeze for the illustrations.
|
References
|
|---|
- Mountain CF, Dresler CM. Regional lymph node classification for lung cancer staging. Chest 1997;111:1718–1723.[Abstract/Free Full Text]
- De Leyn P, Vansteenkiste J, Cuypers P, Deneffe G, Van Raemdonck D, Coosemans W, Verschakelen J, Lerut T. Role of cervical mediastinoscopy in staging of non-small cell lung cancer without enlarged mediastinal lymph nodes on CT scan. Eur J Cardiothorac Surg 1997;12:706–712.[Abstract]
- Toloza EM, Harpole L, McCrory DC. Noninvasive staging of non-small cell lung cancer. Chest 2003;123:137S–146S.[Abstract/Free Full Text]
- Bonadies J, D'Agostino RS, Ruskis AF, Ponn RB. Outpatient mediastinoscopy. J Thorac Cardiovasc Surg 1993;106:686–688.[Abstract]
- Kirschner PA. Cervical mediastinoscopy. Chest Surg Clin N Am 1996;6:1–20.[Medline]
- De Leyn P, Lerut T. Videomediastinoscopy. Minimal access in cardiothoracic surgery. W.B. Saunders Company 2000. Chapter 22:169–174.
- Van Schil P, Van der Schoot J, Poniewierski J, Pauwels M, Carp L, Germonpre P, De Backer W. Remediastinoscopy after neoadjuvant therapy for non-small cell lung cancer. Lung Cancer 2002;37:281–285.[CrossRef][Medline]
|
|
Top
Summary
Introduction
