Anterior Thoracic Corpectomy and Diskectomy
Christopher T. Martin
Dheera Ananthakrishnan
Illustrative Case
Assess the location of the pathology on axial imaging cuts and closely review the anatomy lateral to the site in order to determine whether approaching from the patient’s right or the patient’s left is most appropriate (Figures 11-1 and 11-2). In general, approaching from the patient’s left side is easier below T6 because it is easier to work against the aorta than the inferior vena cava and because the liver is not in the way. T6-T4 may be easier to approach from the right side as you avoid having to contend with the heart and aortic arch. Above T4 it can become difficult to approach the spine laterally because of interference from the shoulder and scapula.
Figure 11-1 ▪ Preoperative lateral radiograph (right) and sagittal CT myelogram (left) from a patient with a destructive methicillin-resistant Staphylococcus aureus discitis at T8-9 that has led to near complete destruction of both the T8 and T9 vertebral bodies.
Figure 11-2 ▪ Axial CT myelogram at the T8-9 disk space from the patient in Figure 11-1 shows the liver on the right side, but a relatively clear approach from the left.
Careful review of preoperative CT and MRI scans is necessary in order to appropriately plan for the ideal amount of bony resection (orientation, length, size). The extent of resection of bone and disk will depend on the underlying diagnosis. For deformity, a circumferential release is usually required. For infection, all infected tissue should be removed, possibly even some normal bone in order to seat grafts/cages in a stable fashion. For a disk herniation, a defect should be created within the disk space and the vertebral body in order to safely pull the pathology off of the thecal sac.
Special Equipment
Chest wall retractors
Choice of interbody graft or cage and instrumentation system
Drain and chest tube
Positioning
The patient is positioned in the lateral decubitus position with an axillary roll under the down arm, with a Foley catheter in place and sequential compression devices on the legs.
The arms are supported on pillows in front of the patient. The hips and knees should start off parallel to the floor.
The hips and shoulders are taped down to the bed to prevent the patient from rotating during the case (Figure 11-3).
Fluoroscopy can be brought in prior to prepping and draping in order to verify that the pathology of interest is accessible through the draped area and to assist with planning the incision and rib resection.
Draping a wide field is imperative. The midline of the body anteriorly and posteriorly should be included within the sterile field.
Anesthesia/Neuromonitoring Concerns
The patient can be intubated with a dual-lumen endotracheal tube, in case lung deflation is necessary. However, unless a very high (above T4) dissection is planned, lung deflation is usually not needed and can predispose the patient to postoperative pulmonary issues (eg, severe
atelectasis and pneumonia). The lung can easily be packed off with moist sponges in the area the surgeon is working in. Not deflating the lung allows for continued partial ventilation on the ipsilateral side.
In myelopathic patients with cord compression, the mean arterial pressures should be maintained above 80 mm Hg to maximize cord perfusion during the decompression.
Neuromonitoring with somatosensory evoked potentials and motor evoked potentials is used when operating in spinal cord territory.
 Figure 11-3 ▪ Preoperative positioning for a low thoracic or upper lumbar lateral approach. |
Localization of Incision
Many incision localization methods are possible. The authors prefer to localize the pathology radiographically and then center the incision over the pathologic level.
Make note of local radiographic landmarks preoperatively. In patients with frank vertebral destruction, the pathology will likely be readily visible. However, even in patients without obvious vertebral body pathology, there are usually local landmarks that can be useful for radiographic localization (eg, wedged vertebrae or large distinctive osteophytes).
In the case of a patient with no radiographic landmarks, such as a young patient with a disk herniation and otherwise normal vertebrae, it may be necessary to count vertebral levels. This can be done by counting up from the first vertebrae with a rib on an anteroposterior view. Care should be taken preoperatively to note the number of thoracic vertebrae and where the first rib-bearing
vertebrae is relative to the pathology of interest. The surgeon should have a low threshold for taking multiple images to confirm the operative levels, including plain x-ray.
Alternatively, the ribs themselves can be directly palpated. Generally, the rib two levels above the pathology of interest will be resected, and the incision can be centered over this level.
Approach
The skin is sharply incised and light bleeding is controlled with electrocautery as the dissection is carried down onto the rib of interest, for a length of 10 to 15 cm. The incision is curvilinear, along the path of the rib, curving up into a C shape posteriorly toward the spine.
The latissimus dorsi, serratus anterior, and external oblique may or may not have to be transected in line with the skin incision, depending on the operative levels.
Continue cutting directly down onto the rib, incising through the periosteum and onto bone. Muscle and fascial layers are incised in line with the incision as the approach is made.
A periosteal flap is elevated toward the superior and inferior edge of the rib (Figure 11-4).
