Mediastinoscopy
Mediastinoscopy is a surgical procedure that enables visualization of the contents of the mediastinum, usually for the purpose of obtaining a biopsy.  Mediastinoscopy is often used for staging of lymph nodes of lung cancer or for diagnosing other conditions effecting structures in the mediastinum such as sarcoidosis or lymphoma.
Mediastinoscopy involves making an incision approximately 1 cm above the suprasternal notch of the sternum, or breast bone.  Dissection is carried out down to the pretracheal space and down to the carina.  A scope (mediastinoscope) is then advanced into the created tunnel which provides a view of the mediastinum.  The scope may provide direct visualization or may be attached to a video monitor.
Mediastinoscopy provides access to mediastinal lymph node levels 2, 4, and 7.

# Extended mediastinoscopy
Extended mediastinoscopy is a technique which allows access to the pre-aortic (level 6) and aortopulmonary window (level 5) lymph nodes.

# Parasternal mediastinotomy
A left anterior parasternal mediastinotomy is also called the Chamberlain procedure.  It involves an incision in the left third intercostal space, and allows access to levels 5 and 6 lymph node stations.
The Chamberlain procedure is a minimally invasive operation performed by a thoracic surgeon. A related procedure, known as the Jolly Procedure, is also an anterior mediastinotomy. An extended
Chamberlain procedure is called an anterior thoracotomy.
The Chamberlain procedure is used to biopsy lymph nodes in the center of the chest, or to biopsy
a mass in the center of the chest. The Chamberlain procedure differs from a cervical
mediastinoscopy by the location of the incision, and the location of the lymph nodes or mass to
be biopsied.
The Chamberlain procedure is used to biopsy lymph nodes or masses in the aorto-pulmonary
window on the left side of the chest, or nodes in the hilar areas of the lung. (In contrast, the
cervical mediastinoscopy procedure is used to biopsy nodes or masses to the front or side of the
trachea, or windpipe.) The aorto-pulmonary window is the area in the center of the chest bound
by the aorta superiorly, and the pulmonary artery inferiorly. This area contains lymph nodes that
filter lymph coming from the left lung, especially the left upper lobe. If a lung cancer is present in the left lung, the Chamberlain procedure is useful for staging the cancer (determining the extent
-f spread.) The hilar areas of the lung (the hilum) are the areas of the lung where the pulmonary
artery and vein (the blood supply) join the lung.
The Chamberlain procedure is usually done on the left side of the chest, because the aorto-
pulmonary window is on the left side. However, the procedure is used for the right side under
certain conditions.
The patient is placed under general anesthesia. The skin of the chest is prepped with a sterile
solution. A small, two inch incision is made over the second rib where it joins the breast bone (at
the Angle of Louis.) The incision is carried down through the pectoralis major muscle (the "pecs")
by spreading the muscle fibers apart. The cartilage of the second rib is located (the costal 
cartilage) and is removed. The internal mammary artery and vein deep to the cartilage are
sometimes tied and cut. The parietal pleura (the inside lining of the chest wall) is then dissected
to the side, and the surgery is directed into the center of the chest, between the aorta and the
pulmonary artery. Great care is taken not to injure the large blood vessels. Biopsies are taken
-f the respective abnormal lymph nodes or mass. The incision is then closed, without replacing
the cartilage.
Occasionally, the nodes or mass cannot be safely located or biopsied by this technique. Under
those circumstances, a decision is made by the surgeon to enlarge the incision slightly, open the
parietal pleura, move the lung out of the way, and approach the nodes or mass from inside the
pleural space. By opening the pleura and extending the incision, an anterior thoracotomy is
created. Because air has been introduced into the area around the lung (the pleural space),
a chest tube may be required to remain overnight to drain the air from the chest.
When the nodes or mass have been biopsied, the incision is closed with absorbable suture, and
air is evacuated from the chest.
The risk of a Chamberlain procedure is very low. The chief risk is that of opening the pleura, and the requirement for placement of a chest tube (drain.)
Although very rare, there is a risk of bleeding from a large blood vessel such as the aorta or
pulmonary artery. Such bleeding would require a sternotomy or thoracotomy to stop the bleeding.
Most patients go home the same day as surgery. Most return to work within a few days or a
week, and will require pain pills for only a few days. The patient may shower 48 hours after
surgery, and should not soak the incision under water in a bath tub or spa for three weeks.
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