Endoscopically Assisted Decompression for Metastatic Thoracic Neoplasms

When metastatic spinal lesions must be repaired surgically, the outlook is usually poor. With traditional thoracotomy, morbidity is often high. But by adding endoscopic assistance to a posterolateral approach, our department have been able to change that outlook, dramatically improving the results and reducing intensive care unit (ICU) and inpatient time.

Metastatic Spine Lesions
Radiotherapy is the standard of treatment for metastatic spinal lesions, but sometimes the tumors are radioresistant and produce bony compromise. Those cases require direct surgical repair, and until now, the only viable surgical option has been repair through traditional thoracotomy because results with the alternatives have been poor. Decompressive laminectomy and posterolateral decompression have shown no better results than stabilization alone. The anterior approach, however, is challenging surgically, and morbidity is high. Even though minimally invasive surgery has been tried with thoracoscopy and laparoscopy, the anterior approach with the best endoscopes still requires the surgeon to collapse a lung and keep it fully deflated for a prolonged period.

Many older patients and the very ill, especially those with advanced pulmonary disease, cannot tolerate the loss of lung volume that the anterior approach requires. They may be able to tolerate the posterolateral, transpedicular approach quite well, however. Nevertheless, results with posterolateral approaches have also been disappointing.

Risks and Difficulties
The major difficulties with decompression through a costotransversectomy or transpedicular approach are limited vision and inability to access vertebral elements anterior to the spinal cord without blindly manipulating the cord. Frequently, neurologic injury results, especially in the thoracic region. In addition, because of the limited access to anterior tumors, debridement may not be complete. Even though some surgeons have used a dental mirror to aid visualization in this approach, results were still poor.

Endoscopic Visualization Added
We added endoscopic visualization to the posterolateral technique using readily available instruments familiar to most orthopaedic surgeons. In surgery, we take the proximal origin of the rib and any rib invaded by tumor with a standard costotransversectomy approach and take down the pedicle to the back of the vertebral body using a standard transpedicular approach. That allows the surgeon to debulk the anterior tumor under direct vision until a cavity is formed in the vertebral body. Then, we introduce a standard 4-mm endoscope into the cavity while maintaining suction and irrigating the cavity frequently.

Initially, we use a 30° endoscope, which provides light, magnification, and visualization of the posterior vertebral cortex and the tumor and bone immediately anterior to the spinal cord. With Epstein curettes and pituitary rongeurs, the surgeon removes soft tissue and bone fragments from in front of the cord and moves all tissues away from the cord. Then the interval between the posterior longitudinal ligament and the posterior cortex can be examined directly through the endoscope. This allows the surgeon to collapse the posterior cortex into the vertebral cavity without touching the spinal cord. The remaining vertebral body is then removed to the far pedicle.

Next, we introduce a 70° endoscope, allowing the surgeon to visualize the posterior longitudinal ligament and dura from below and note any areas of residual compression. Any adherent tumor can then be meticulously dissected from the dura. Epidural veins can be visualized and controlled with angled bipolar cautery. A bilateral approach can be used if the tumor involves the far pedicle. Otherwise, the contralateral pedicle and lamina remain intact for posterior grafting and fusion.

Titanium Cage Use
Once the decompression is complete, the surgeon removes the involved end plates and adjacent disks with rongeurs and curettes. Then the end plates of the adjacent vertebrae are cleared of all soft and cartilaginous tissues and prepared for strut graft reconstruction. We use a titanium cage filled with autograft bone to reconstruct the vertebrectomy defect because it provides immediate stability and maximum potential for fusion. While viewing the cord, the surgeon impacts the cage in place and then completes posterior instrumentation, gently compressing the strut. Then the wound is closed and a chest radiograph obtained in the operating room to determine whether a chest tube is required.

Patient Outcome
We have now used this procedure or a modification of it to treat 15 to 20 patients. All of them recovered completely postoperatively. There have been no neurologic complications, and no patient has been made worse neurologically. ICU stays now average 1.0 day, and we have avoided ICU stays altogether for 60% of patients. That contrasts with an average 2.5 day ICU stay with traditional approach. Hospital stays now average 4 to 5 days compared with 10 to 14 days with standard anterior or posterior approaches.

Technology Improves
Since we first developed the procedure, improvements in the camera and endoscopic tools continue to make this surgery faster and more appealing. Surgical time now averages 6.5 hours skin to skin compared with 7.25 hours for our initial experience and 8.5 to 12.0 hours for the combined anterior and posterior procedures. Overall, experience has continued to be very positive, and patients and their primary doctors have been very pleased to avoid the danger and morbidity of the formal anterior approach.

Benefits and Indications
This surgery improves patients' function and speeds their return to normal activity. I have found that return to function has been significantly quicker when we can avoid the thoracic or thoracoabdominal incision needed for a formal debridement. The patients' function over the long term, of course, depends on their underlying disease.

The indications for this surgical approach have now expanded to some cases of fracture and infection, where formal anterior approaches pose specific risks for the patients. In addition, the procedure is being incorporated into the armamentarium of a number of other major medical centers, and recent reports from other centers have verified both the approach and the principles.