Trapdoor Exposure of the Cervicothoracic Junction

A myriad of pathology may affect the lower cervical and upper thoracic spine, including both primary and metastatic tumors, as well as trauma blunt force and penetrating trauma. The standard anterolateral cervical approach combined with a median sternotomy provides satisfactory exposure of the cervicothoracic junction from C7 through the T2–3 junction, whereas a high posterolateral thoracotomy allows access to the thoracic spine up to the T3–4 disk space. The T3 through T4 region, on the other hand, is mostly hidden behind the great vessels, and neither of these approaches provides optimal exposure of this location. This region is located at the apex of the chest pyramid and offers little room for maneuvering instruments. The trapdoor exposure is a combination of the anterolateral cervical approach, median sternotomy, and anterolateral thoracotomy and is the most suitable intervention for gaining access not only to the T3 and T4 vertebral bodies anteriorly but also to the entire ventral cervical spinal column, as well as to the mid and upper thoracic spine. Unlike previously described approaches to the cervicothoracic junction, it also spares the sternoclavicular junction and does not require transection of the clavicle.

22.2 Patient Selection

The main indication for this surgical procedure is anteriorly located pathology that results in compression of the neural elements by retropulsed bone, disk fragments, and/or tumor mass or kyphotic angulation, affecting primarily the T3 and T4 levels. Options for reconstruction of the anterior spinal column include polymethylmethacrylate, autograft or allograft bone, as well as rigid, expandable cage devices. Several advances have been made in the development of anterior plating devices for this region, further improving the surgeon’s ability to achieve rigid internal fixation until a bony fusion occurs. Whereas anterior plate and screw constructs may be used for the fixation of this region in the absence of severe deformity or instability, additional posterior instrumentation is usually recommended for those who have significant disruption of two or more of the spinal columns.

In patients who have significant spinal cord compromise at the initial consultation, surgical intervention is usually performed within 12 to 24 hours of diagnosis. In patients with traumatic injuries, however, one may elect to postpone surgery until other concomitant injuries are dealt with and the patient is stabilized medically.

Whereas magnetic resonance imaging (MRI) is preferred for evaluating the cervicothoracic junction and upper thoracic spine in most patients, computed tomography (CT) with two-dimensional reconstructions can provide important additional details of bony integrity and is quite helpful in determining the nature of compressive pathology (i.e., the presence of retropulsed bone fragment(s) vs. tumor mass effect). This is particularly important if one is contemplating the use of radiation therapy as the primary mode of treatment.

Isolated lesions involving the spine but not the lung can be addressed in patients with marginal pulmonary function. In addition, because the right recurrent laryngeal nerve is at considerable risk during the exposure, an appropriate preoperative laryngoscopic examination is recommended to rule out vocal cord paralysis, especially in those in whom a left-sided recurrent laryngeal nerve dysfunction is already suspected. Patients who have undergone a previous cervical procedure (i.e., anterior cervical fusion or thyroidectomy) may have clinically asymptomatic dysfunction of the recurrent laryngeal nerve. It is therefore imperative to obtain a preoperative laryngoscopic examination in these patients to avoid the highly morbid complication of bilateral recurrent laryngeal nerve palsies.

22.3 Preoperative Preparation

In addition to the routine monitoring needed for general anesthesia, the patient should undergo placement of a large-bore intravenous catheter because these surgical procedures may require a significant amount of blood volume replacement during the vertebrectomy procedure. This catheter is placed in a femoral or left subclavian vein, thereby avoiding the right internal jugular and right subclavian veins, which are in the surgical field. The intravascular volume status is monitored with either a central line or a Swan-Ganz catheter, depending on the patient’s cardiopulmonary reserve. Second-generation cephalosporins are routinely administered preoperatively for prophylaxis.

22.3.1 Anesthetic Technique

The use of inhalation anesthetics should be minimized to allow somatosensory evoked potential (SSEP) monitoring for assessment of spinal cord function during surgery. A double-lumen endotracheal tube should be used for intubation to allow the selective deflation of the right lung during critical portions of the procedure.

22.3.2 Operative Positioning

The patient is positioned as described in ▶ Fig. 22.2 a.

22.4 Operative Procedure

The skin incision’s path and the location of critical cuts through the chest wall that are needed to expose the important anatomical structures are illustrated in ▶ Fig. 22.1 (with inset). This exposure is carried out through the right side. The incision extends along the anterior border of the sternocleidomastoid muscle down to the sternal notch, as shown in the intraoperative photograph ( ▶ Fig. 22.2 a). From there the incision is carried down the midline and over the sternum to the fourth intercostal space, where it curves laterally and follows the fourth interspace.

Fig. 22.1 Artist’s depiction of the trapdoor exposure. (a) Anterolateral chest wall is retracted superolaterally. Retractors in the upper cervical region and over the sternal angle allow visualization of all important anatomical structures in the midline. The right carotid artery and right vagus nerve are pulled laterally, whereas the right recurrent laryngeal nerve (shown exaggerated to demonstrate its entire course and relationship to the subclavian artery and tracheoesophageal structures) is retracted ventrally and medially. The anterior cervical spinal column is visualized through the space between the carotid artery and the tracheoesophageal viscera. In the chest cavity, the aorta, the left common carotid artery (origin), the innominate artery, the right subclavian artery, and the take-off of the right common carotid artery are shown. Also visible are the transected azygos vein, the superior vena cava, and the left brachiocephalic vein. Rib heads have been removed, and T3 and T4 vertebrectomies have been completed. Through the vertebrectomy defect, the dura and the right T3 nerve root are seen. (b) Close-up artist’s depiction of the vertebrectomy performed via the trapdoor exposure.

Fig. 22.2 Intraoperative photographs of the patient presented as an illustrative case. (a) The position of the patient and planned skin incision before draping. The patient’s head is turned to the left, and his neck is slightly extended by placing a roll between the scapulae. The arms are tucked in at the sides and padded. The incision follows the anterior border of the sternocleidomastoid muscle down to the sternal notch, from which it is carried to the fourth intercostal space over the sternum in the midline. The incision is then curved laterally, following the space between the fourth and fifth ribs. Also visible is a double-lumen endotracheal tube that allows selective ventilation of the lungs during surgery. (b) Use of a sternal saw after cervical dissection and completion of the anterolateral thoracotomy. (c) Close-up view showing the transition from the lower cervical region to the chest cavity. The anterolateral parietal pleura along with the chest wall are retracted superolaterally. Also visualized are the right lung and the right brachiocephalic vein, as well as the pericardium (more medially). (d) All the anatomical structures of importance. The lower cervical dissection has been completed, and the right lung has been selectively deflated. Visualized structures include the right common carotid artery, right vagus nerve, right innominate artery, right subclavian arteries (origin), right brachiocephalic vein, pericardium, and aorta. Also seen is the right recurrent laryngeal nerve, which loops around the right subclavian artery and enters the tracheoesophageal groove, crossing the C7–T1 vertebral region. The surgeon’s hand is retracting the tracheoesophageal viscera medially. (e) Close-up view of the posterior chest wall and the upper thoracic spine. The surgeon’s hand is retracting the right lung to show the thoracic spinal column, which is covered by parietal pleura extending from the mediastinum. The parietal pleura was resected over the spine inferiorly, down to the T5–6 disk space. Also seen are the DeBakey forceps, which have been passed from the lower cervical region into the chest cavity through an opening in the apical pleura. The azygos vein, which crosses the field at the T4–5 level, has been ligated and transected, allowing further medial retraction of mediastinal pleura. (f) Close-up view showing the final construct. The T2 through T4 vertebrectomy has been completed, and the anterior spinal column has been reconstructed with polymethylmethacrylate, which is hidden from view under the plate. Lateral to the plate, decompressed dura can be observed. The cervical plate extends from T1 to T5 and has vertebral body screws located at the T1 and T5 levels.