Claudio E. Tatsui, Ganesh Rao and Laurence D. Rhines
Robert J. Bohinski and Laurence D. Rhines
Oncological principles for en bloc resection of bone tumors were initially developed for tumors of the long bone by orthopedic surgical oncologists. Recently, spine surgeons have adopted these principles for the treatment of vertebral column tumors. The goal of en bloc resection is to establish a surgical margin that can be designated marginal or wide. In this article, the principles of surgical oncology for bone tumors of the spine are briefly reviewed and the different surgical approaches used to remove these tumors in an en bloc fashion are described in detail.
Technical note and description of operative technique
Robert J. Bohinski, Ehud Mendel and Laurence D. Rhines
✓ The authors describe and demonstrate an innovative modification of the osteotomy procedure required to achieve a supraforaminal high sacral amputation in a patient harboring a large sacral chordoma. Via a combined anterior—posterior approach, three carefully placed threadwire saws were used to create releasing osteotomies through specific portions of the dorsal iliac crests and through the axial midportion of the S-1 vertebral body. The threadwire saws are pulled away from neurovascular and visceral structures, ensuring greater protection. Other advantages include markedly reduced blood loss while performing the osteotomies, a high degree of cutting accuracy, negligible bone loss, and ease and speed of bone cutting.
Allen W. Burton, Laurence D. Rhines and Ehud Mendel
Vertebroplasty and kyphoplasty are relatively new techniques used to treat painful vertebral compression fractures (VCFs). Vertebroplasty is the injection of bone cement, generally polymethyl methacrylate (PMMA), into a vertebral body (VB). Kyphoplasty is the placement of balloons (called “tamps”) into the VB, followed by an inflation/deflation sequence to create a cavity prior to the cement injection. These procedures are most often performed in a percutaneous fashion on an outpatient (or short stay) basis. The mechanism of action is unknown, but it is postulated that stabilization of the fracture leads to analgesia. The procedures are indicated for painful VCFs due to osteoporosis or malignancy, and for painful hemangiomas. These procedures may be efficacious in treating painful vertebral metastasis and traumatic VCFs. Much evidence favors the use of these procedures for pain associated with the aforementioned disorders. The risks associated with the procedures are low but serious complications can occur. These risks include spinal cord compression, nerve root compression, venous embolism, and pulmonary embolism including cardiovascular collapse. The risk/benefit ratio appears to be favorable in carefully selected patients. The technical aspects of the procedures are presented in detail along with guidelines for patient selection. A comprehensive review of the evidence for the procedures and the reported complications is presented.
Brian J. Williams, Patrick J. Karas, Ganesh Rao, Laurence D. Rhines and Claudio E. Tatsui
The authors present the first report of laser interstitial thermal therapy (LITT) ablation of a recurrent chordoma metastasis to the cervical spine. This patient was a 75-year-old woman who was diagnosed and treated for a sacral chordoma, and then developed metastases to the lung and upper thoracic spine. Unfortunately she experienced symptomatic recurrence at the C-7 spinous process. She underwent an uncomplicated LITT to the lesion. The patient convalesced without incident and was discharged on postoperative Day 1. She received stereotactic spinal radiosurgery to the lesion at a dose of 24 Gy in 1 fraction. At the 3-month follow-up evaluation she had radiographic response and improvement in her symptoms.
Eric Marmor, Laurence D. Rhines, Jeffrey S. Weinberg and Ziya L. Gokaslan
✓ The authors describe a technique for total en bloc spondylectomy that can be used for lesions involving the lumbar spine. The technique involves a combined anterior—posterior approach and takes into account the unique anatomy of the lumbar spine. This technique allows for the en bloc resection of lumbar vertebral tumors, thus optimizing outcome while minimizing the risk of neurological injury. The technique is described in detail with the aid of neuroimaging studies, photographs of gross pathological specimens, and illustrations, and a discussion of other authors' experiences is provided for comparison.
Stephen J. Hentschel, Ehud Mendel, Sanjay Singh and Laurence D. Rhines
✓ Despite the relatively high incidence of prostate carcinoma involving the spinal column, those that are associated with spinal intradural extramedullary metastases are rare. The role of surgery for metastases to this spinal compartment is limited and palliative because presentation tends to be late in the course of the disease, particularly for prostate carcinoma. It is also considered to be part of the spectrum of leptomeningeal carcinomatosis and is associated with a high incidence of brain metastases. The authors review a rare case of prostate carcinoma metastatic to the spinal intradural extramedullary space and discuss its clinical presentation, imaging features, and surgical management.
Paul J. Holman, Dima Suki, Ian McCutcheon, Jean-Paul Wolinsky, Laurence D. Rhines and Ziya L. Gokaslan
Object. The surgical treatment of metastatic spinal tumors is an essential component of the comprehensive care of cancer patients. In most large series investigators have focused on the treatment of thoracic lesions because 70% of cases involve this region. The lumbar spine is less frequently involved (20% cases), and it is unclear whether its unique anatomical and biomechanical features affect surgery-related outcomes. The authors present a retrospective study of a large series of patients with lumbar metastatic lesions, assessing neurological and pain outcomes, complications, and survival.
Methods. The authors retrospectively reviewed data obtained in 139 patients who underwent 166 surgical procedures for lumbar metastatic disease between August 1994 and April 2001. The impact of operative approach on outcomes was also analyzed.
Among the wide variety of metastatic lesions, pain was the most common presenting symptom (96%), including local pain, radicular pain, and axial pain due to instability. Patients underwent anterior, posterior, and combined approaches depending on the anatomical distribution of disease. One month after surgery, complete or partial improvement in pain was demonstrated in 94% of the cases. The median survival duration for the entire population was 14.8 months.
Conclusions. The surgical treatment of metastatic lesions in the lumbar spine improved neurological and ambulatory function, significantly reducing axial spinal pain; results were comparable with those for other spinal regions. Analysis of results obtained in the present study suggests that outcomes are similar when the operative approach mirrors the anatomical distribution of disease. When lumbar vertebrectomy is necessary, however, anterior approaches minimize blood loss and wound-related complications.
Claudio E. Tatsui, Frederick F. Lang, Joy Gumin, Dima Suki, Naoki Shinojima and Laurence D. Rhines
There is currently no reproducible animal model of human spinal metastasis that allows for laboratory study of the human disease. Consequently, the authors sought to develop an orthotopic model of spinal metastasis by using a human lung cancer cell line, and to correlate neurological decline with tumor growth.
To establish a model of spinal metastasis, the authors used a transperitoneal surgical approach to implant PC-14 lung tumors into the L-3 vertebral body of nude mice via a drill hole. In 24 animals, motor function was scored daily by using the validated semiquantitative Basso-Beattie-Bresnahan (BBB) scale. A second group of 26 animals (6 or 7 per time point) were sacrificed at specific times, and the spines were removed, sectioned, and stained. Canal compromise was analyzed quantitatively by determining the ratio of the area of the neural elements to the area of the spinal canal on histological sections (neural/canal ratio). Correlations between BBB score and histological evaluation of tumor growth were assessed.
Lung cancer xenografts grew in all animals undergoing functional evaluation (24 mice) according to a reliable and reproducible time course, with paraplegia occurring at a median interval of 30 days following tumor implantation (95% CI 28.1–31.9 days). Importantly, the analysis defined 4 key milestones based on components of the BBB score; these were observed in all animals, were consistent, and correlated with histological progression of tumor. From Days 1 to 14, the mean BBB score declined from 21 to 19. The animals progressed from normal walking with the tail up to walking with the tail constantly touching the ground (milestone 1). The median time to tail dragging was 12 days (95% CI 10.8–13.2). Histological studies on Day 14 demonstrated that tumor had progressed from partial to complete VB infiltration, with initial compression of the neural elements and epidural tumor extension to adjacent levels (mean neural/canal ratio 0.32 ± 0.05, 7 mice). From Days 15 to 20/21 (left/right leg), the mean BBB score declined from 19 to 14. Animals showed gait deterioration, with the development of dorsal stepping (milestone 2). The median time to dorsal stepping was 21 days (95% CI 19.4–22.6) in the left hindlimb and 23 days (95% CI 20.6–25.4) in the right hindlimb. Histological studies on Day 21 demonstrated an increase in the severity of the neural element compression, with tumor extending to adjacent epidural and osseous levels (mean neural/canal ratio 0.19 ± 0.05, 6 mice). From Days 22 to 26/27 (left/right leg), the mean BBB score declined from 14 to 8. Animals had progressive difficulty ambulating, to the point where they showed only sweeping movements of the hindlimb (milestone 3). The median time to hindlimb sweeping was 26 days (95% CI 23.6–28.4) and 28 days (95% CI 27.1–28.9) in the left and right hindlimbs, respectively. Histological studies on Day 28 revealed progressive obliteration of the spinal canal (mean neural/canal ratio 0.09 ± 0.01, 7 mice). From Days 29 to 36, the animals progressed to paralysis (milestone 4). The median time to paralysis was 29 days (95% CI 27.6–30.4) and 30 days (95% CI 28.1–31.9) in the left and right hindlimbs, respectively.
The authors have developed an orthotopic murine model of human spinal metastasis in which neurological decline reproducibly correlates with severity of tumor progression. Although developed for lung cancer, this model can be expanded to study other types of metastatic or primary spinal tumors. Ultimately, this will allow testing of targeted therapies against specific tumor types.
Case report and review of the literature
Robert J. Bohinski, Ehud Mendel, Kenneth D. Aldape and Laurence D. Rhines
✓ Solitary fibrous tumor is a spindle cell tumor deriving from mesenchymal cells that arises most commonly in the pleura. Only very recently has this tumor been reported in the spine. A solitary fibrous tumor strongly resembles other spindle cell neoplasms of the spine and may be an unrecognized entity if not routinely considered in the differential diagnosis of spinal neoplasms. The authors report an unusual intra- and extramedullary location for a solitary fibrous tumor of the cervical spine. Findings in this case and a comprehensive review of the literature indicate that solitary fibrous tumors can originate from various spinal anatomical substrates and mimic both intra- and extramedullary tumor types.