Mediastinoscopy is a surgical technique that permits minimally invasive access to the mediastinum.¹ In most cases, mediastinoscopy is used to biopsy and facilitate the histologic diagnosis of enlarged mediastinal lymph nodes (carcinoma, sarcoidosis, and tuberculosis) and masses (lymphoma, germ cell tumor, and thymoma). Mediastinoscopy currently plays a particularly important role in defining the clinical stage of bronchogenic carcinoma. Staging is the first step toward determining the optimal course of management. Staging directs treatment, implementation of protocols, and permits comparison of treatment between patients.

Cervical mediastinoscopy, first described by Harken,² involves a neck incision that facilitates access to the superior mediastinum. Carlens³ and Pearson⁴ popularized a technique using a specially designed mediastinoscope through a suprasternal incision. Cervical mediastinoscopy, however, has limited access to the aorticopulmonary (AP) window. One approach to the AP window is “extended” cervical mediastinoscopy, a rarely used approach in which the mediastinoscope is inserted anterior to the aortic arch between the innominate artery and left carotid artery.⁵ A more common approach to the AP window is through an anterior mediastinotomy—so-called anterior mediastinoscopy.⁶ Extended and anterior mediastinoscopy are techniques used to sample mediastinal lymph nodes in the AP window. In addition, anterior mediastinoscopy can be used in a variety of parasternal locations to facilitate the biopsy of anterior mediastinal masses to the right or left of midline. Subxiphoid mediastinoscopy is a technique in which the mediastinoscope is used to biopsy anterior masses in the lower mediastinum.

Frequent indications for mediastinoscopy include (1) staging patients with bronchogenic carcinoma,⁷ and (2) obtaining tissue diagnoses in patients with unexplained adenopathy.⁸ Patients diagnosed with bronchogenic carcinoma are staged using a combination of modalities. Computed tomography (CT) of the chest determines the size and location of the primary tumor in conjunction with any associated lung parenchymal abnormalities (atelectasis, collapse, pneumonia, emphysema, or fibrosis). In addition, the location and size of enlarged mediastinal nodes directs further investigation to stage patients. Mediastinal nodes larger than 1 cm in their short axis are considered suspicious for tumor.

The differential diagnosis of patients with persistent and unexplained adenopathy includes sarcoidosis and lymphoma, but because these diseases may be difficult to distinguish, clinically, histologic confirmation of the diagnosis is usually recommended. Sarcoidosis is characterized by noncaseating granulomas that can readily be distinguished from both Hodgkin and non-Hodgkin lymphomas.

Although cervical mediastinoscopy can be performed with low morbidity and mortality, the potential for catastrophic complications exists. Because of this risk, surgeons must be properly trained in mediastinoscopy. The procedure is usually performed as a day surgery procedure, although it should be performed in a hospital setting because of the potential complications.

The procedure of mediastinoscopy involves a comprehensive exam of the mediastinum informed by CT scan findings. Sampling of the lymph nodes is directed by manual palpation and visual inspection (Fig. 156-1). Cervical mediastinoscopy can sample ipsilateral and contralateral nodes (stations 1, 2, 4, 7) in patients with bronchogenic cancer. The presence of positive contralateral nodes, multistation N2 disease, extracapsular spread, and extension into mediastinal structures (T4) portends a generally poor outcome and usually precludes the patient from surgical therapy. Cervical mediastinoscopy in comparison to CT scans has 90% sensitivity and 100% specificity for determining pathological mediastinal lymph nodes. In lymphomas or inflammatory diseases, lymph node mapping has limited value. The focus of the operation is obtaining an accurate tissue diagnosis.

Anterior mediastinoscopy – performed through an anterior mediastinotomy – is often indicated in patients with a bronchogenic carcinoma of the left upper lobe. The aortopulmonary window contains lymph node stations 5 and 6, which are the first drainage sites of the left upper lobe of the lung. The secondary lymphatic drainage sites of the left upper lobe include lymph node stations 2 L and 4 L, which can be examined by cervical mediastinoscopy.

Ideal Patient Characteristics

Thin patients with no previous surgery in the neck are ideal candidates for mediastinoscopy. Previous cervical mediastinoscopy or mediastinal radiation therapy does not preclude mediastinoscopy, but the procedure has to be performed with caution. The risk of inadvertent injury to an adjacent structure is increased, as is the probability of poor sampling of the various lymph node stations. Large thyroid gland, cervical spine fusion, or cervical spine arthritis make introducing the scope and positioning the patient challenging, but are not absolute contraindications for surgery.^9,10

Preoperative Assessment

Cervical mediastinoscopy and anterior mediastinotomy are performed under general anesthesia. Candidates for these procedures need to be suitable for general anesthesia. Preoperative assessment includes evaluation of cardiac status, pulmonary status, and clinical staging. Clinical stage is determined by history and physical examination, CT scan of the chest including upper abdomen for evaluation of adrenal glands, and PET scan to determine metastasis (locoregional and systemic).

A history of facial swelling and plethora (SVC syndrome), persistent neck or arm pain (Pancoast tumors with brachial plexus involvement), hoarseness (recurrent laryngeal nerve involvement), back pain, and headaches (systemic metastasis) suggests advanced disease that requires evaluation before subjecting patients to cervical mediastinoscopy or anterior mediastinotomy.

Paraneoplastic syndromes (e.g., syndrome of inappropriate antidiuretic hormone secretion [SIADH], Eaton–Lambert Syndrome, dermatomyositis, hypercalcemia) are associated with both small-cell and non–small-cell lung cancers and do not necessarily suggest the patient has metastatic disease. Large scalene or supraclavicular lymph nodes can undergo biopsy at the time of mediastinoscopy. A positive scalene or supraclavicular node renders the patient N3, and not a candidate for surgical resection.

Cervical Mediastinoscopy

Cervical mediastinoscopy is performed under general anesthesia. The patient is positioned with a roll under the shoulders and between the scapulae, which throws back the shoulders and extends the neck to improve tracheal exposure (Fig. 156-2). The head of the operating room table is elevated to 20 to 30 degrees to decrease venous congestion. The neck and entire chest is draped in the event that a median sternotomy is required to manage a major complication.