Mediastinoscopy is a procedure used to sample mediastinal lymph nodes through a cervical incision. It allows access to lymph node stations 2R, 2L, 4R, 4L, and 7. Complications can include bleeding, esophageal perforation, nerve injury, and pneumothorax. Indications include staging lung cancer and evaluating mediastinal lymphadenopathy. Proper patient evaluation and hemostasis are important to minimize risks.

1. Mediastinal anatomy and
Mediastinoscopy
DR VISHNU SURENDER

2. Surgical technique:

3. Mediastinal Anatomy:
 Superiorly- Thoracic inlet
 Inferiorly- Diaphragm
 Anteriorly- Sternum
 Posteriorly- Spine
 The pleural spaces bilaterally.

4. Four compartment model
 A classic description divides the mediastinum into four compartments: superior,
anterior, middle, and posterior.
 The superior mediastinum includes all structures from the thoracic inlet superiorly
to an imaginary plane that includes the lower edge of the manubrium and the
lower edge of the fourth thoracic vertebra.
 The inferior mediastinum, which lies below this boundary, is further divided into
the anterior, middle, and posterior compartments.
 The boundary between the anterior and middle compartments is the anterior
pericardium.
 whereas the border between the middle and posterior compartments is the
posterior aspect of the tracheal bifurcation, pulmonary vessels, and pericardium.

5.  In this four-compartment model, the upper portions of the trachea and esophagus
are contained within the superior mediastinum.
 The lower portions are contained within the middle and posterior mediastinum.

9. Three compartment model
 It consisting of an anterior compartment, a middle (or visceral) compartment, and
a posterior compartment (paravertebral sulcus).
 All three compartments are bounded inferiorly by the diaphragm, laterally by the
pleural space, and superiorly by the thoracic inlet.
 The anterior compartment is contained anteriorly by the sternum and posteriorly
by the great vessels and pericardium.
 This compartment contains the thymus, internal mammary vessels, areolar and
adipose tissue, and potentially pathologic structures such as ectopic parathyroid
tissue or a retrosternal goiter.

10.  The middle mediastinum is bordered posteriorly by the ventral surface of the thoracic spine;
it occupies the entire thoracic inlet.
 It contains the majority of mediastinal structures, namely, the great vessels, heart,
pericardium, trachea, proximal mainstem bronchi, vagus nerves, phrenic nerves, esophagus,
thoracic duct, descending aorta, and azygos venous system.
 The posterior compartment (paravertebral sulcus or sulci) consists of potential spaces along
the thoracic vertebrae.
 It contain the sympathetic chain, proximal portions of the intercostal neurovascular bundles,
thoracic spinal ganglia, and distal azygos vein.

14. Potential spaces in the mediastinum:
 The pretracheal space is a triangular space
 bounded - anterolaterally by the superior vena cava and right brachiocephalic
vein on the right, the aorta and pericardium on the left, and the trachea
posteriorly.
 Continuing inferiorly from the pretracheal space is the sub-carinal space
 Bounded - superiorly by the carina
 laterally by the two main-stem bronchi
 anteriorly by the back of the right pulmonary artery
 Posteriorly by the esophagus

15.  The pretracheal and subcarinal spaces are routinely explored in mediastinoscopy
and endobronchial ultrasound.
 The aortopulmonary window is the space bounded
 superiorly by the aortic arch
 medially by the trachea and esophagus
 inferiorly by the pulmonary artery
 laterally by the pleura.
 This space contains lymph nodes, the ligamentum arteriosum, and the left
recurrent laryngeal nerve.

16.  Routine cervical mediastinoscopy does not fully access this space
 But anterior mediastinotomy (Chamberlain procedure), extended cervical
mediastinoscopy and thoracoscopy or thoracotomy can all provide access to the
aortopulmonary window.

19. Mediastinal lymph node anatomy:
 The adoption of a common thoracic regional lymph node classification by
the American Joint Committee on Cancer and the Union for International
Cancer Control in 1997, known as the Mountain-Dresler chart, has found
wide spread acceptance.
 This system classifies lymph nodes into 14 stations.
 Of which stations 1 through 9 are contained within the mediastinal pleura
and are considered to be mediastinal lymph nodes.
 The highest mediastinal station (level 1), upper right and left paratracheal
nodes (level 2R, 2L), lower right and left paratracheal nodes (level 4R, 4L),
and the subcarinal nodes (level 7 ) are the only mediastinal nodal stations
accessible by standard cervical mediastinoscopy.

20.  while stations 5 (subaortic nodes) and 6 (paraaortic nodes) require an
alternative approach such as
 extended mediastinoscopy
 anterior mediastinotomy (Chamberlain procedure)
 Rarely -endoscopic ultrasound (EUS).

22. Indication for mediastinal LN assessment:
 The most common indication for surgical assessment of mediastinal lymph nodes
is non–small cell lung cancer (NSCLC).
 Other indications include
 mediastinal lymphadenopathy of unknown etiology
 mediastinal masses
 primary tracheal tumors
 occasional esophageal tumors.
 Rare indications for mediastinoscopy include drainage of bronchogenic cysts,
abscess drainage, identification of ectopic parathyroid tissue, and tissue sampling
for causes of superior vena cava syndrome.

24. Efficacy and utility of mediastinoscopy:
 Ideally, levels 2R, 2L, 4R, 4L, and 7 should be sampled (with at least one specimen
from each level) during mediastinoscopy.
 It is estimated that approximately half of false-negative mediastinoscopy results
were due to pathologically positive mediastinal nodes not accessible by the
mediastinoscope.
 A retrospective series comparing conventional mediastinoscopy to video-assisted
mediastinoscopy has demonstrated a significantly lower complication rate.
 Higher number of sampled lymph nodes, and lower number of missed positive
lymph nodes after definitive lung resection with the use of video mediastinoscopy
at the time of staging

25.  The most frequent nodal station to be implicated in a false-negative result at time
of eventual pulmonary resection was level 7 (approximately 70% of surprise N2
cases found at thoracotomy).
 The use of modern imaging techniques, including high-resolution computed
tomography (CT) and positron emission tomography (PET), has led to an
appropriately selective strategy for invasive mediastinal lymph node assessment.
 Any patient with suspected N1 disease after CT or PET scan should undergo
mediastinal evaluation.

28. Preoperative evaluation:
 History and physical examination with a special focus on any history of neck or
chest surgery
 A coexistent pathologic process such as a goiter or aneurysms of the aortic arch
or innominate artery that may prevent safe access to the pretracheal space.
 Prior neck or sternal incisions, including prior mediastinoscopy, can complicate the
initial dissection, but they are not absolute contraindications to the procedure.
 Patients undergoing both cervical mediastinoscopy and left anterior
mediastinotomy with a history of sternotomy (half with left internal mammary
artery coronary grafts) over two decades showed no differences in the efficacy or
safety of these two procedures.

29.  Significant vascular calcification in the innominate artery can increase the risk of
embolic events as this vessel is manipulated during the procedure.
 In addition, total atherosclerotic occlusion of the left common carotid artery can
predispose a patient for stroke if the innominate artery supplying the right
common carotid artery is compressed by the mediastinoscope.
 The evaluation should also note cervical spine arthritis because moderate neck
extension is required for the procedure.
 Severe cervical kyphosis can make insertion of the mediastinoscope impossible.
 Patients should undergo laboratory workup as they might for any general
anesthetic and should have typical preparations for the small possibility of a blood
transfusion.

30. Complication of Mediastinoscopy:
 Hemostasis of minor bleeding can help to prevent subsequent bigger problems.
 Morbidity rate of 0.6%
 Mortality rate of 0.2%
 Major vessel hemorrhage (aorta, innominate artery, pulmonary artery, bronchial
artery, vena cava, azygos vein)
 Esophageal perforation
 Stroke secondary to innominate artery compression in the setting of severe
atherosclerosis.
 Left (and rarely right) recurrent laryngeal nerve injury
 Pneumothorax
 wound infection, and tumor seeding of the neck incision.

31.  For lung cancer patients undergoing restaging after induction chemoradiation
therapy for N2 disease and without a history of prior mediastinoscopy (i.e., EBUS-
TBNA determined N2 positivity before induction treatment), mediastinal changes
from the treatment may be present.
 Mediastinoscopy after radiation therapy, approximately 10% of these patients had
complications including two permanent recurrent laryngeal nerve injuries, an
azygous injury that resulted in emergent right thoracotomy, and two aborted
procedures that were truncated for safety
 The overall performance of mediastinoscopy in terms of sensitivity, specificity, and
negative predictive value were similar to metrics for mediastinoscopy done
without prior therapy.

32.  The severity of these complications were higher than those seen in primary
procedures, including biopsy of lung tissue, bronchial injury requiring patch repair,
superior vena cava puncture requiring emergent right thoracotomy, and proximal
innominate artery hemorrhage resulting in cardiac tamponade and death.
 Patients undergoing restaging after induction therapy for stage IIIA NSCLC, the
safer and less invasive alternatives offered with EBUS-TBNA and endoscopic
ultrasound–fine needle aspiration.
 Reoperative mediastinoscopy seems unnecessary given these safer alternatives.

33. Surgical techniques:
 Standard cervical mediastinoscopy involves access of the middle mediastinal
structures through a lighted, hollow, metal mediastinoscope introduced through a
cervical incision.
 Large-bore venous access
 Right radial arterial catheter to monitor blood pressure and to watch for
innominate artery compression during the procedure.
 Once patients are intubated, they are placed in the supine position with the neck
gently hyper-extended and supported with an inflatable bag or rolled blanket
placed behind the shoulders.
 The endotracheal tube is brought out to the patient’s right and kept as lateral and
low in profile as possible.

36.  Care must be taken to avoid turning the patient’s chin to the side as this can result
in an off-center incision.
 The entire sternum and anterior cervical areas are typically prepared and draped
to facilitate a sternotomy for the rare event that massive bleeding is encountered.
 A 2.5-cm transverse incision is made one fingerbreadth above the sternal notch
 The platysma is divided in the line of the skin incision.
 The midline raphe between the strap muscles is opened vertically, and dissection
is carried down to the trachea.

38.  On occasion, it is necessary to divide a low-lying thyroid isthmus or a thyroidea
ima artery to reach the trachea.
 The pretracheal fascia is divided, and blunt finger dissection is undertaken to
develop a plane anterior to the trachea in a caudal direction.
 A high-riding innominate artery can be seen in aneurysmal disease, in the setting
of an enlarged station 2 (right) lymph node.
 Initial finger dissection of the pretracheal space -the exact location of the
ascending aorta and the angle and level at which the innominate artery crosses
the field
 Firm pathologic lymph nodes along side the distal trachea can be palpated and
partially dissected free of surrounding tissue.

40.  The mediastinoscope is then inserted into the pretracheal plane that has been
created.
 A standard mediastinoscope is a hollow, lighted, metal tube that permits only one
individual to visualize the operative field.
 Video mediastinoscopy
 With a first assistant stabilizing the scope, the video mediastinoscope can be used
by the surgeon to introduce two instruments into the field for bimanual dissection
and hemostasis.

46. High Paratracheal dissection:
 The major anatomic landmark of the high paratracheal level is the innominate
artery.
 which is seen as a pulsatile structure crossing anterior to the trachea.
 Station 2 lymph nodes lie to the left and right of the trachea at this level and
above.

49.  The operator’s initial view of the paratracheal tissue often shows no obvious nodal
tissue.
 Subsequent blunt dissection through the pretracheal tissue plane, assisted by
careful use of the suction cautery tip, usually exposes the underlying lymph nodes.
 Dark pigmentation facilitates recognition of lymph nodes.
 It is recommended by the authors that blunt lymph node dissection be carried out
to the point that the node bulges into the operative field.

51.  This technique helps to prevent inadvertent biopsy of other “dark” paratracheal
structures, such as the vena cava or the right brachiocephalic vein, which do not
bulge into the field.

52. Lower paratracheal dissection:
 Dissection inferior to the innominate artery reaches the lower paratracheal area
and station 4 lymph nodes.
 Which lie to the right and left of the trachea cephalad to the carina.
 After blunt dissection of the paratracheal tissue permitting the nodes to bulge
into the operative field.
 If there is any question about whether the tissue Considered for biopsy is a lymph
node, it is wise to aspirate the tissue first with a small-bore needle to rule out a
vascular structure.
 This is important because inflammatory or malignant adhesions between the
lymph node and the underlying major vessel can lead to avulsion injury to the
vessel during vigorous lymph Node biopsy.

55.  The non–lymph node structures lying to the right of the trachea at this level
include the azygos vein, the superior vena cava, the mediastinal pleura, and the
adjacent right upper lobe of the lung.
 The visceral pleura can appear darkly pigmented like a node, but the lung is
characteristically seen to move behind the pleura with respiration.
 Structures lying to the left of the trachea at this level are the aortic arch, the left
recurrent laryngeal nerve, a bronchial artery branch from the aorta, and the
esophagus.
 The esophagus lies posterior and to the left of the trachea at this level and can be
mistaken for a white tumor-filled lymph node.
 It can be recognized by the longitudinal muscle fibers of its outer muscular layer.

56.  The use of electrocautery should be avoided in the left lower paratracheal region
to prevent inadvertent injury to the esophagus or left recurrent laryngeal nerve.
 If esophageal injury is identified, the esophagus should immediately be repaired
through a right or left thoracotomy.

58. Carinal dissection:
 The major anatomic landmarks of carinal dissection are widening of the
trachea, the triangular tracheal cartilage at the carina, the proximal left main
bronchus, and the right pulmonary artery crossing anteriorly.
 Identification of the triangular cartilage of the distal trachea helps to identify the
level and prevents misidentification of the proximal left main bronchus as the
trachea.
 Dissection at the carinal level must be performed with meticulous attention paid
to the location of the right pulmonary artery.
 It passes transversely across the field anterior to the airway.

62. Node biopsy technique and closure of the
incision:
 Mediastinal node biopsy is initiated by dissection through the pretracheal fascia
with a blunt suction cautery instrument.
 Next, the suspected lymph node is aspirated with a needle to confirm that it is not
a vascular structure.
 Finally, a biopsy specimen is taken with a biopsy forceps .
 Often, the first biopsy removes only the outer capsule of the node and exposes
the underlying parenchyma, which can then be further sampled.
 If no node is seen at the desired station, it is often helpful to withdraw the
mediastinoscope slightly and even to rotate it to see tissue lying more anterior or
anterolateral to the trachea.

63.  After biopsy, hemostasis is achieved with electrocautery or with temporary
packing with long length gauze.
 Once hemostasis has been achieved at all levels, the mediastinoscope is removed
and the wound is closed in several layers.
 The strap muscles are reapproximated with interrupted sutures vertically in the
midline and the platysma muscle transversely; the skin is closed with a
subcuticular suture.
 Obtain postprocedure chest radiographs of all patients to ensure the absence of a
pneumothorax, a retained pack, or other visible abnormality.
 The patient can subsequently be discharged to home after standard
postanesthesia care.

64. Management of major bleeding:
 The first thing that is likely to happen is a complete loss of visualization.
 Recommend leaving the mediastinoscope in place and immediately packing the
operative field with long gauze.
 This maneuver will temporarily contain most hemorrhage except that from
systemic arteries.
 Attention is then turned to volume resuscitation and blood replacement if
necessary.
 Waiting several minutes and then removing the packing often accomplishes
hemostasis.

65.  If not, repeated packing preceded by a topical hemostatic agent such as oxidized
cellulose can control venous and minor arterial bleeding without having to resort
to median sternotomy or thoracotomy.
 Aortic, innominate artery, and bronchial artery injury adjacent to the aorta and
major pulmonary artery injuries will not be contained with packing.
 Management should start with compression of the vessel with the
mediastinoscope or removal of the mediastinoscope and compression of the
vessel against the sternum with one’s finger until either a median sternotomy or a
thoracotomy can be performed to allow direct vascular control.

66. Extended Mediastinoscopy:
 The term extended mediastinoscopy to encompass techniques that go beyond the
routine assessment of station 2, 4, and 7 lymph nodes in the mediastinum.
 A common misconception is that routine mediastinoscopy permits evaluation of
the anterior mediastinum.
 Extended cervical mediastinoscopy has been described that can access the
anterior mediastinum as well as station 5 and 6 nodes in the aortopulmonary
window.
 This procedure is started through the same cervical incision, but the surgeon
subsequently creates a plane anterior to the innominate artery and posterior to
the left brachiocephalic vein.

67.  It is rarely done, because of the inherent difficulty of the procedure involving
dissection of major vessels in a confined anatomic space and the easy accessibility
to the aortopulmonary window by an anterior mediastinotomy or thoracoscopy.
 In addition the tumors of the left upper lobe with involvement of nodes in stations
5 and 6 (if limited to intracapsular spread and in the absence of other mediastinal
node involvement) have a better prognosis with surgical resection than do tumors
in other lobes.

69.  TEMLA – TRANSCERVICAL EXTENDED MEDIASTINAL LYMPHADENECTOMY
 Is also a mediastinal staging option for NSCLC and is performed through a 5- to 8-
8-cm collar incision in the neck.
 Complete removal of all mediastinal nodal stations except for the pulmonary
ligament nodes (station 9) and the most distal left paratracheal nodes (station 4L).
 In general, TEMLA is an open procedure performed partly with mediastinoscopy-
assisted and video thoracoscopy–assisted techniques.
 The operative technique of TEMLA includes the elevation of the sternal
manubrium with a special retractor and bilateral visualization of the laryngeal
recurrent and vagus nerves.

74.  VAMLA- VIDEO ASSISTED MEDIASTINOSCOPE LYMPHADENECTOMY
 Is a mediastinoscopic dissection technique proposed for a radical mediastinal
assessment and as an adjunct to open lymphadenectomy at the time of
pulmonary resection.
 VAMLA dissection includes the en bloc resection of the subcarinal, right
paratracheal, right tracheobronchial, and pretracheal compartments and
dissection and lymphadenectomy of the left-sided tracheobronchial and
paratracheal compartments.
 A specialized mediastinoscope with spreadable blades is used.

75.  A retrospective series comparing conventional mediastinoscopy to VAMLA
demonstrated significantly increased mean number of lymph nodes sampled,
improved sensitivity and negative predictive value, and even improved 5-year
survival rates with VAMLA.
 VAMLA also has a significantly higher complication rate (9.0% versus 4.1% in the
conventional mediastinoscopy group), with the most common complication being
dysphonia.