156: Cervical Mediastinoscopy and Anterior Mediastinotomy

Introduction

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.

Surgical Principles

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 (...