Anatomy and Surgical Approaches to the Mediastinum Flashcards
Boundaries of mediastinum
- Sternum (anterior)
- Spine (posterior)
- Thoracic inlet (superior)
- Diaphragm (inferior)
- Pleurae (laterally)
Boundaries and structures of Anterior compartment
- Sternum (anterior)
- Great vessels and percardium (posterior)
- Contents:
- Thymus
- Internal mammary arteries
- Adipose tissue
Boundaries and structures of Middle Compartment
- Great vessels and pericardium (anterior)
- Anterior surface of thoracic spine (posterior)
- Contents:
- Great vessels
- Pericardium
- Heart
- Trachea
- Proximal main stem bronchi
- Vagus and phrenic nerves
- Esophagus
- Thoracic Duct
- Descending Aorta
Boundaries and stuctures of the Posterior Compartment
- Mostly a potential space that lies laterally along spine
- Contents:
- Sympathetic chain + ganglia
- Intercostal neurovascular bundles
Definition of Medistinal LN levels
Levels 1-9
(contained in mediastinal pleura)
Surgical options for mediastinal access
- Cervical mediastinosopy
- Anterior mediastinoscopy (Left side = Chamberlain procedure)
- Median sternotomy
- Transcervical approach
- Bilateral thoracosternotomy (Clamshell)
- Unilateral thoracosternotomy (Hemi-clamshell)
- VATS
MC indication for MLN biopsy
Assess for N2 nodal involvement in stage I-III NSCLC
Rationale for pursuing MLN sampling for NSCLC
5% false-negative rate to detect MLN mets with PET/CT
Other indications for MLN biopsy
- Tissue diagnosis in setting of mediastinal lymphadenopathy (sarcoid, lymphoma)
- Biopsy mediastinal masses
Relative contraindications to cervical mediastinoscopy
- Severe kyphosis of c-spine
- tracheostomy
- Large thyroid goiter
- Aortic arch or innominate artery aneurysm
Cervical mediastinoscopy should not be performed in the presence of what conditions
SVC syndrome (high risk of bleeding)
Significant innominate artery calcifications (high risk of embolic stroke)
MLN levels accessible during cervical mediastinoscopy
Levels 2,4,7
MC complications of cervical mediastinoscopy
- Major bleeding (0.1-0.6%)
- RLN injury (0.5%)
- Pneumothorax
- Airway injury
- Esophageal perforation
MC biopsy site associated with major hemorrhage during cervical mediastinoscpy
Station 4R
(injury to azygous or SVC)
2nd MC biopsy site associated with major bleeding during cervical mediastinoscopy
Station 7
(RPA and bronchial artery bleeding)
MC biopsy site associated with RLN injury during cervical mediastinoscopy
Station 4L
(minimize use of electrocautery along left boarder of trachea)
MLN levels accessible during EBUS/TBNA
Stations 1,2,3,4,7
(Can also access 10 and 11)
Left anterior mediastinoscopy (Chamberlain procedure) can access which MLN levels
Levels 2,4,5,6,7
(Anterior medistinoscopy can be used to biopsy left or right mediastinal masses)
Surgical access for anterior mediastinoscopy
- Small transverse incision just lateral to sternal boarder in 2nd or 3rd ICS
- Resection of costal cartilage will enhance exposure
- Avoid injury to IMA and phrenic nerve
Median sternotomy most frequently used for what mediastinal condition
Thymectomy
Transcervical approach to anterior mediastinum utilized for what procedures:
- Thymectomy
- Non-invasive
- < 4 cm
- Biopsy or resection of anterior mediastinal tumors (e.g parathyroid adenoma)
Surgical technique for transcervical approach to anterior mediastinum
- 4-5 cm collar incision just above sternal notch
- Cooper thymectomy retractor placed to lift sternum
Bilateral thoracosternotomy (Clamshell) exposure utilized for what mediastinal conditions
Large anterior mediastinal tumors
Surgical technique for bilateral thoracosteronotomy
- Incision in inframammary crease bilaterally
- Subcutaneous flaps (anterior to pectoralis fascia) superiorly to 3rd-4th ICS
- Division of pectoralis muscle fibers
- Bilateral anterior thoracotomies
- Sternum division
(IMA ligated and divided)
Unilateral thoracosternotomy usefult to access
- Anterior Pancoast’s tumors
- Large thyomomas with lateral extension
- Neurogentic tumors arising from proximal brachial plexus
Surgical technique for unilateral thoracosternotomy (hemi-clamshell)
Partial upper sternal split + Anterior thoracotomy (4th ICS)
VATS used for access to what conditions
- Anterior, middle, posterior mediastinal masses
- Thymectomy
- Non-invasive tumors
MC use of VATS for mediastinal tumors
Resction of posterior mediastinal tumors (e.g. neurogenic)