CHAPTER 31 Thoracoscopic Approach to Spinal Deformities
Introduction
In December 1993, at Children’s Hospital Medical Center in Cincinnati, we began performing VATS for the anterior release of severe spinal deformities in children and adolescents. The benefits of this procedure include minimal invasiveness, better visualization and magnification, diminished postoperative pain and ventilatory compromise, reduced blood loss, decreased hospitalization, reduced health-care costs, improved wound care, and earlier return to prehospital activities with minimal shoulder dysfunction.1
Indications for Children and Adolescents
♦ Rigid idiopathic scoliosis deformities at or above 75 degrees in magnitude with correction to less than 50 degrees seen on side-bending radiographs
♦ Prevention of crankshaft phenomenon in the skeletally immature child who has more than a 50-degree curvature
We have extended our indications to include all the procedures addressing the thoracic spine that were previously approached by thoracotomy.2
Approach to Minimally Invasive Exposure of the Thoracic Spine
Key Points
♦ Working ports should be placed in order to align the instruments fairly straight into the disk spaces.
♦ At least three ports are recommended. One port is needed for a pediatric Wolf or Yankauer suction (Scanlon International, St. Paul, Minn). One port is used for the thoracoscope. This leaves one working port. An additional lower port or incision is used for the Endokittner (Ethicon Endosurgery, Cincinnati, Ohio) to depress the diaphragm. By shifting the instruments from port to port, T2 to L1 can be instrumented (Figure 31-1).
♦ The Harmonic scalpel is used to open the parietal pleura and, when indicated, to divide the intercostal vessels.
Video-Assisted Thoracic Spinal Surgery
Step 1. Setup and Patient Positioning
Step 2. Establishing Working Ports
♦ Because curves are usually convex to the right, the surgeon usually stands on the patient’s right side. However, the approach, based on the curve, should be confirmed with the surgeon before placing the patient on the operating table.
♦ The topographic anatomy, specifically the scapular borders, the twelfth rib, and the iliac crest, are identified and outlined with a marker. If simultaneous posterior approach is used, confirm the levels by fluoroscopy.
♦ Three to five portals usually are necessary. The first portal is most frequently placed at or about the T6 or T7 interspace in the posterior axillary line. Entry at this level usually avoids the diaphragm.
♦ Insufflation in the thoracic cavity is not necessary because of the rigidity of the chest wall and the ability to collapse the ipsilateral lung. Open trocars are used, and a variety of disposable trocars are available (e.g., Ethicon Endosurgery).
♦ Use a 15-mm simple trocar, through which a 10-mm, 30-degree, rigid telescope is placed. We use rigid and flexible ports (Ethicon Endosurgery) for positioning and inserting instruments.
Step 3. Visualization and Assessment
♦ The 30-degree thoracoscope allows direct vision into the intervertebral disk spaces without impeding the surgical instrumentation or obscuring the operative field.
♦ The instruments can be switched from portal to portal, keeping the working portal aligned straight with the area of interest, usually the disk.
♦ The camera and viewing field are rotated 90 degrees from the standard VATS position, because the spinal surgeon is most comfortable viewing and approaching the spine through a horizontal projection.
♦ Carry out a panoramic assessment and evaluation of the intrathoracic space to determine the anatomy and possible sites for other ports that allow a more direct working approach to the intervertebral disks. The ports are usually two interspaces apart (see Figure 31-1B).
♦ Retraction of the diaphragm is necessary below T7 to L1. An endokittner works well for this maneuver.
Step 4. Opening the Parietal Pleura
♦ Use a dissecting hook Harmonic scalpel (Ethicon Endosurgery) for opening the parietal pleura (Figure 31-3).
♦ Identify the intervertebral disk by the mounds observed on the spinal column and the vertebral bodies by the valleys. The segmental vessels nest in the valleys directly overlying the bodies (see Figure 31-3).
♦ Multilevel anterior diskectomies are necessary for correcting severe spinal deformity. This anterior release of the spinal curvature usually requires diskectomy at six to eight levels. For degenerative disease, fewer levels are targeted.
Step 5. Excision of the Thoracic Disk
♦ After the pleura has been completely dissected at the appropriate levels, proceed directly to excision of the annulus at the level of the intervertebral disk. Use a technique that is comfortable.
♦ The assistant surgeon keeps vessels retracted from another port using a long Wolf pediatric or Yankauer suction.
♦ Make a transverse cut across the vertebral body, anterior to the rib heads, and parallel to the disk that is rostral and caudal to it.
♦ Make a transverse cut across the annulus fibrosus, and continue down to the level of the nucleus pulposus. Use rongeurs, curettes, periosteal elevators, and high-rpm protected drills as necessary to ensure complete removal of the disk material and the endplates (Figure 31-4).
♦ The length of the rongeurs’ jaws should be measured to the hinge so that the depth of penetration toward the posterior longitudinal ligament can be determined. In a young child, it is often possible to elevate the vertebral endplate apophysis and completely excise the intervertebral contents back to the posterior longitudinal ligament.
♦ With experience, the surgeon improves the ability to excise the annulus and disk space contents in an approximately 250-degree arc, or almost from pedicle to pedicle. Direct particular attention to the release of the annulus on the concave side (Figure 31-5).
♦ Stress the spinal column segment by rotating the periosteal elevator in the disk space and exercising moderate force after each release to determine whether mobility has been achieved. Bone cages usually are placed into disk spaces (Figure 31-6). Insert a small piece of Gelfoam or Surgicel around the cage (Figure 31-7).
♦ After completion of the procedure, remove all disk fragments and debris from the thoracic cavity; the pleura remains open (Figure 31-8).
♦ During the procedure, the greater splanchnic nerve is usually transected at one of several levels. This does not cause permanent residual problems, but parents and the pediatric patient should understand that there is a possibility of a hot and cold “sympathetic release” phenomenon on the contralateral or ipsilateral lower extremity after this kind of surgery. This phenomenon is similar to what is experienced after a transthoracic thoracotomy is performed.
1 Crawford A.H., Wolf R.K. Spinal deformities. In: Yim A.P., Hazler S.R., Izzat M.B., et al, editors. Minimal access cardiothoracic surgery. Philadelphia: Saunders; 2000:316-327.
2 Crawford A.H., Wolf R.K., Wall E.J., et al. Pediatric spinal deformity. In: Regan J.J., McAfee P.C., Mack M.J., editors. Atlas of endoscopic spine surgery. St Louis: Quality Medical Publishing, 1995.
3 Crawford A.H. Video-assisted thoracoscopy. In: Spine: State of the Art Reviews II. Philadelphia: Hanely & Belfus; 1997.
4 Mack M.J., Regan J.J., McFee P.C., et al. Video-assisted thoracic surgery for the anterior approach to the thoracic spine. Ann Thorac Surg. 1995;59:1102-1106.
