Retropleural Approach to the Thoracolumbar Spine

The retropleural approach provides the shortest direct route to the ventral thoracic and thoracolumbar spine while avoiding entry into the pleural cavity. ¹ The retropleural corridor maintains the visceral pleura intact, which decreases the likelihood of injury to the lung. The ventrolateral trajectory allows the surgeon to identify the ventral spinal canal early to reduce the probability of neural injury. The retropleural approach also provides access to the thoracolumbar junction without the need to incise and subsequently reattach the diaphragm. ²

30.2 Patient Selection

The retropleural thoracotomy approach is appropriate for the treatment of ventral or ventrolateral spinal pathology, including herniated thoracic intervertebral disks and primary and metastatic tumors, in the thoracic spine caudal to T4. It is most appropriate for the treatment of localized pathology, typically two or fewer contiguous vertebral segments.

30.3 Preoperative Preparation

Multiaxial imaging, either magnetic resonance imaging or myelography followed by computed tomography, is necessary for surgical planning. The relationship between the pathology and the spinal cord should be clearly understood and will help to determine the exact approach. The great vessels are also visible on the axial images, and their location should be noted.

It is essential that the surgeon obtain the appropriate radiographic studies before surgery to ensure the confident and accurate intraoperative identification of the proper level and surrounding structures. Ribs may be used as landmarks for midthoracic levels, but the surgeon must be sure that he or she can consistently identify either most rostral or most caudal rib. A high-quality chest radiograph is useful for surgical planning to determine the number and radiographic appearance of the ribs and their angulation.

Routine preoperative angiography is not typically necessary. The surgeon must consider, however, the potential benefit of angiography and possible embolization for specific pathologies. The resection of highly vascular lesions, such as renal cell carcinoma metastases and vertebral hemangiomas, may be facilitated by preoperative embolization. In these cases, the preoperative identification of the location of significant arterial supply to the spinal cord may also help in the surgical planning.

30.4 Operative Procedure

For lesions at or above T6, a double-lumen endotracheal tube is helpful in establishing adequate exposure by allowing single-lung ventilation. An arterial line, Foley catheter, and neurophysiologic monitoring electrodes are placed for motor and somatosensory evoked potentials. Perioperative antibiotic coverage for gram-positive skin organisms is administered. Steroids may be indicated, particularly in the presence of spinal cord compression.

The patient is positioned in a lateral position with the operative side up. The patient is held in a true lateral position with a beanbag underneath and wide cloth tape across the greater trochanter. A soft roll or gel pad is placed in the dependent axilla to prevent positioning-related neuropathies. The arm on the operative side is placed on folded pillows or on a table-mounted arm rest ( ▶ Fig. 30.1 a).

Fig. 30.1 (a) Patient positioning and incision for approach to L1. (b) Incisions for the retropleural approach to lesions in the A, upper; B, mid; C, lower thoracic regions.

The skin incision extends from approximately 4 cm lateral to the midline along the rib for approximately 15 cm. At upper thoracic levels, a curvilinear incision follows the inferior and medial borders of the scapula ( ▶ Fig. 30.1 b). Monopolar cautery is used to dissect through the subcutaneous tissue and the latissimus dorsi and trapezius muscles. The rib that will be removed is identified by palpation and correlated with fluoroscopy. For a thoracic diskectomy, the rib associated with the vertebra just caudal to the operative disk is removed. For a corpectomy, the rib one or two levels rostral to the operative level is selected depending on the slope of the ribs and the level involved. The periosteum along the rib is incised with the monopolar cautery and then elevated circumferentially off of the rib with periosteal and Doyen elevators ( ▶ Fig. 30.2). The rib is then cut at the margins of the incision. The cut edges are smoothed and waxed thoroughly. The tissue layer deep to the rib and continuous with the periosteum is the endothoracic fascia. This layer is sharply divided, ensuring that the tissue plane deep to it is preserved, which is the parietal pleura ( ▶ Fig. 30.3).