Retropleural Thoracotomy
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Neurosurg Focus 10 (1):Clinical Pearl 1, 2001, Click here to return to Table of Contents Retropleural thoracotomy Technical note PETER D. ANGEVINE, M.D., AND PAUL C. MCCORMICK, M.D., M.P.H. Department of Neurological Surgery, Neurological Institute of New York, New York Presbyterian Hospital, New York, New York Herniated thoracic discs, unlike their lumbar counterparts, are difficult to read and safely resect using traditional posterior approaches. Historically, the use of a laminectomy for thoracic disc resection has yielded poor clinical out- comes. Posterolateral and anterolateral approaches have become the standard surgical means of treating these lesions. The traditional anterolateral approach, the transpleural thoracotomy, is an extensive procedure that requires direct retraction of the lung, a deep surgical field, and postoperative closed-chest drainage. An alternative to this anterior approach, the retropleural thoracotomy, is described here. This approach provides the shortest direct route to the tho- racic spine and leaves the pleura intact. A smaller incision and less retraction than traditional approaches may reduce postoperative pain and pulmonary-related complications. The retropleural thoracotomy is a valuable technique for the neurosurgeon treating thoracic disc disease. KEY WORDS • retropleural thoracotomy • intervertebral disc • thoracic spine • discectomy Thoracic disc disease is not amenable to the posterior of large central discs, calcified discs, or discs with intra- surgical approaches and techniques used in the lumbar dural extension. spine. The thoracic spinal cord occupies a greater propor- There are three general anterolateral approaches to the tion of the spinal canal than the lumbar thecal sac. The thoracic spine. The transpleural thoracotomy, first de- spinal cord, too, tolerates less retraction than the free- scribed by Perot and Munro5 and Ransohoff, et al.,6 is the floating nerve roots of the lumbar spine. These factors, traditional route, and it affords wide exposure of the ven- often exacerbated by calcification of herniated thoracic tral thoracic spine from T-3 to T-11. The operative field is discs, limit the ability of the surgeon to work around the deeper than with other techniques, which necessitates sig- thecal sac to extract disc fragments in this region. Pos- nificant retraction of visceral structures, including the terolateral and anterolateral approaches that provide ac- unprotected lung. The rib head, aorta, or vena cava may cess to the disc space without requiring excessive retrac- partially obscure the spinal canal. Depending on the pa- tion of the spinal cord have been developed for the tient’s anatomy, the spinal canal may not be visible until surgical treatment of thoracic discs. the lesion has been resected. A chest tube must be placed The advantage of posterolateral approaches, such as the at the end of the procedure to prevent the development of costotransversectomy and the lateral extracavitary ap- a pneumothorax. Although the standard transthoracic ap- proach, is that the surgeon is familiar with the anatomy. proach allows wide access to the ventral thoracic spine, it These approaches are most useful for soft or lateral discs, is an extensive undertaking associated with potential mor- but they may, in experienced hands, be used for resection bidity that may make it unsuitable for some patients, espe- of midline or calcified discs as well. The anterolateral ap- cially those with marginal pulmonary function. proaches provide exposure across the midline and a visi- The retropleural thoracotomy, refined by McCormick,4 ble corridor so that the disc may be removed away from the spinal cord. These factors may facilitate the removal is described in this paper. By more directly approaching the spine and avoiding pleural entry, this technique ad- dresses some of the shortcomings of the transpleural ap- Abbreviations used in this paper: CSF = cerebrospinal fluid; proach. Because there is no direct retraction of the unpro- PLL = posterior longitudinal ligament; VB = vertebral body. tected lung, the risk of pulmonary complications may be Neurosurg. Focus / Volume 10 / January, 2001 1 Unauthenticated | Downloaded 09/29/21 09:32 PM UTC P. D. Angevine and P. C. McCormick because if it is small, it may be confused with a transverse process. Knowing the number of ribs and the number of non-ribbed lumbar vertebrae, as well as the anatomical appearance of the lumbosacral region (with particular at- tention to the presence of a transitional vertebra), will help to ensure proper intraoperative determination of the path- ological level. An epidural catheter for the perioperative delivery of morphine may be placed prior to patient positioning and Fig. 1. Artist’s drawing. Patient position for retropleural thora- induction of anesthesia. The patient is placed on the oper- cotomy. Incision A is used for upper thoracic lesions, and Incisions ating table in a lateral postion. A beanbag is placed be- B and C for midthoracic and thoracolumbar lesions, respectively. neath the patient to avoid pressure points and add stabili- (Used with permission from McCormick.) ty. The dependent axilla is padded with a soft roll. The lower leg is flexed at the knee and hip for additional sta- bility. A pillow may be placed between the legs. Thora- reduced. The trajectory to the spine is shorter and more columbar lesions should be centered over the table break, lateral than traditional approaches, which provides early if possible, to aid intraoperative exposure. A double-lu- identification of the ventral dura and the foramen. The men endotracheal tube will aid approaches to the upper surgeon can see and therefore protect critical neurovascu- thoracic spine (above T-6) by allowing the anesthesiolo- lar structures, which may reduce the risks of anterolateral gist to deflate the ipsilateral lung. The anesthetic and in- exposure of the thoracic spine. strument tray should be arranged to allow the operating The techniques for a final alternative, thoracoscopic table to be lowered completely. surgery, have been evolving at a rapid pace in the last decade. It offers minimally invasive ventral access to the Retropleural Thoracotomy thoracic spine. Proponents of thoracoscopic surgery point to equivalent operative time, reduced postoperative pain, Intraoperative fluoroscopy or radiography is used to and comparable clinical results compared with those of confirm the proper rib level of the incision. For upper and traditional approaches.7 These procedures require highly middle thoracic lesions the incision is made over the rib of specialized equipment and training, and they are practiced the involved level. In the upper thoracic spine (T3–4) a at a few dedicated centers. With further study the indica- hockey stick–shaped incision is made along the medial tions for thoracoscopic surgery may increase. and inferior border of the scapula, which is then freed of muscular attachments and rotated superiorly. A standard incision is made for lesions between T-5 and T-10. Be- SURGICAL TECHNIQUE ginning 4 cm lateral to the posterior midline, the incision is made along the rib at the involved segment (T-8 rib for Preoperative Planning a T7–8 intervertebral disc) and extended to the posterior The side of approach is determined by a combination of axillary line. At the thoracolumbar junction, the incision is factors, including the vertebral level and location of the made two levels rostral to the involved segment (T-10 lesion. If the herniated disc is predominantly on one side incision for a T-12 lesion)1,4 (Fig. 1). A subperiosteal dis- of the spine, an ipsilateral approach provides the most section is used to free the intercostal muscles along an direct surgical route. Many surgeons are more comfort- 8- to 10-cm length of rib. The exposed portion of the rib able approaching the upper thoracic spine from the right, is resected and saved for use as an autograft, and the cut avoiding the heart and great vessels. The aorta is mobi- ends are waxed (Fig. 2 upper left). The proximal rib re- lized during a left-sided approach in the middle and lower mains attached to the VB and transverse process. thoracic spine; it is more tolerant of retraction than the In the rib bed a distinct tissue layer, the endothoracic vena cava.2 At the thoracolumbar junction, a left-sided ap- fascia, is identified. This layer is continuous with the inner proach has the additional advantage of allowing surgeons periosteum of the ribs and thoracic vertebral bodies. It is to avoid the liver. Another consideration in the lower tho- analagous to the transversalis fascia that lines the abdom- racic spine is the artery of Adamkiewicz, which is found inal cavity. Within this layer lie the intercostal nerves and between T-9 and L-2 in 85% of specimens and enters from vessels, thoracic sympathetic chain, thoracic duct, and the left in 80%.3 If the use of cautery in the neural foram- azygous vein.4 ina is avoided, the medullary arteries are protected and The endothoracic fascia is sharply incised in the rib bed, routine preoperative angiography is unnecessary. exposing the parietal pleura (Fig. 3). A thin layer of loose It is important to evaluate the vertebral level of the le- areolar tissue may be found in the potential space between sion and determine a suitable method for verifying that the endothoracic fascia and the pleura. The pleura is blunt- segment in the operating room. The level of the herniated ly dissected free from the endothoracic fascia by using a disc is often determined by the radiologist and surgeon by Kittner clamp. Any small tears in the pleura are repaired using the sacrum or odontoid process as a reference point. primarily with suture. For lesions above T-6 the ipsilater- These fixed landmarks, however, may not be available in al lung should be deflated. The ribs are then spread with a the operating room, either on the neuroimages or on fluo- crank retractor, and a malleable table-mounted retractor is roscopy.