Applied Anatomy and Percutaneous Approaches to the Thoracic Spine

29 Applied Anatomy and Percutaneous Approaches to the Thoracic Spine

Gun Choi, Alfonso García, Ketan Deshpande, and Akarawit Asawasaksakul

29.1 History

Hans Christian Jacobaeus, a professor of internal medicine in Stockholm, Sweden, is credited with having performed the first thoracoscopic procedure in 1910. The groundbreaking procedure was a technique for lysis of tuberculous pleural adhesions.1 In 1990, the modern era of thoracoscopy began with the introduction of video imaging to standard endoscopy. Mack and colleagues in 1993 and Rosenthal and colleagues in 1994 first reported the technique of video-assisted thoracoscopic surgery (VATS).^2,3 Thoracic disk herniations were treated first by thoracoscopic spine procedures.

In a further attempt to reduce tissue trauma and enhance postoperative outcome, percutaneous endoscopic thoracic diskectomy (PETD) has been developed to treat thoracic disk herniations from a direct posterior or posterolateral approach. Jho described the technique of endoscopic transpedicular thoracic diskectomy with 0 and 70° 4-mm endoscopes, requiring relatively small 1.5- to 2.0-cm incisions and minimal tissue dissection. The technique avoided the need for separate skin incisions in the chest wall for postoperative chest drainage as were used in thoracoscopic approaches.⁴ Also, Chiu et al demonstrated the safety and efficacy of posterolateral endoscopic thoracic diskectomy followed by application of a low-energy nonablative laser for disk thermodiskoplasty using a 4-mm 0° endoscope.⁵ Currently, PETD has been described as a safe procedure with outcomes similar to, or better than, those seen with classic procedures for the treatment of thoracic disk herniations.

29.2 Introduction

Thoracic disk herniations present a unique challenge for the spine surgeon in terms of patient selection, surgical technique, and potential complications. Symptomatic thoracic disk herniations are a relatively rare condition, representing less than 1% of all disk herniations.^6,7 The increased rigidity of the thoracic cage, which causes the thoracic spine to have decreased flexion, extension, and rotation compared with the cervical and lumbar spine, is likely the main cause of the low incidence of symptomatic thoracic disk herniations (Fig. 29.1, Fig. 29.2, Fig. 29.3).^7,8,9

Fig. 29.1 Diagram showing the range of motion of each spinal segment, with focus on thoracic flexion and extension movements. Flexion = F_DL 105°, Extension = E_DL 60°. (Used with permission from Kapandji AI. The Physiology of the Joints: The Spinal Column, Pelvic Girdle and Head, 6th ed., 2011.)

Fig. 29.2 Global lateral flexion of the spine and range of motion experienced in this movement by each segment. The thoracic or dorsal spine has a lateral flexion = dorsal of 20° on each side. (Used with permission from Kapandji AI. The Physiology of the Joints: The Spinal Column, Pelvic Girdle and Head, 6th ed, 2011.)

Fig. 29.3 Axial rotation of each spinal segment. For the thoracic spine, the total movement is 35°, as shown. (Used with permission from Kapandji AI.The Physiology of the Joints: The Spinal Column, Pelvic Girdle and Head, 6th ed, 2011.)

Thoracic disk herniations are frequently an acute event and manifest clinically with acute paraparesis or even paraplegia. A review of the literature suggests that patient presentation may be extremely variable. Thoracic disk herniations have mimicked systemic, cardiac, renal, and orthopaedic diseases.10,11 Neurogenic claudication is most commonly attributable to lumbar stenosis, although others have reported this as a presentation of lower thoracic disk herniations.^12,13

A few patients with thoracic disk herniations may require surgical intervention, and they present with a wide variety of symptoms. In contrast, a large variety of surgical approaches have been developed to treat thoracic disk herniations. These include posterior, posterolateral, and lateral approaches, transthoracic approaches, and thoracoscopic approaches.^14,15,16 The difficulty the spine surgeon encounters when treating these patients is shown clearly by the discrepancy between the small percentage of patients seen with the disease and the large number of surgical techniques developed. Disk herniations in the thoracic region represent a challenging pathology, because although the thoracic spinal canal is the narrowest among all spinal regions, the blood supply to the thoracic cord is precarious, and the approach to the thoracic region is more difficult (Fig. 29.4).^17,18 The various approaches to thoracic disk herniations all have advantages and disadvantages.

Anterior and lateral approaches allow the surgeon the greatest access to the intervertebral disk and vertebral body, but these approaches also place the lung, heart, and great vessels at risk. Although posterior approaches are inherently safer, they are correlated with significant blood loss, paraspinal pain, and potential instability.^17,19,20

PETD is performed as an alternative to classic open diskectomy, with results that are comparable to, and in some cases better than, those of open diskectomy. PETD is usually performed under local anesthesia, postoperative pain is quite minimal, normal paraspinal and thoracic structures are preserved, and the risk of postoperative epidural scar formation and instability can be minimized. However, the PETD learning curve is steep, so the surgeon must be familiar with endoscopic lumbar spine surgery before deciding to perform PETD.

Fig. 29.4 The thoracic region has very little space to accommodate herniated nucleus pulposus, which applies pressure on the thecal sac, while decompression may lead to neural damage.

Only gold members can continue reading. Log In or Register to continue