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  • Author or Editor: Frederick F. Lang x
  • Journal of Neurosurgery: Spine x
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Daryl R. Fourney, Dima Abi-Said, Frederick F. Lang, Ian E. McCutcheon and Ziya L. Gokaslan

Object. Few reports are available on the use of pedicle screw fixation for cancer-related spinal instability. The authors present their experience with pedicle screw fixation in the management of malignant spinal column tumors.

Methods. Records for patients with malignant spinal tumors who underwent pedicle screw fixation at the authors' institution between September 1994 and December 1999 were retrospectively reviewed.

Results. Ninety-five patients with malignant spinal tumors underwent 100 surgeries involving pedicle screw fixation: metastatic spinal disease was present in 81 patients, and locally invasive tumors were demonstrated in 14 patients. Indications for surgery were pain (98%) and/or neurological dysfunction (80%). A posterior (48%) or a combined anterior—posterior (52%) approach was performed depending on the extent of tumor and the patient's condition. At the mean follow up of 8.2 months, 43 patients (45%) had died; median survival, as determined by Kaplan—Meier analysis, was 14.8 months. At 1 month postsurgery, self-reported pain had improved in 87% of cases (p < 0.001), which is a finding substantiated by reductions in analgesic use, and 29 (47%) of 62 patients with preoperative neurological impairments were functionally improved (p < 0.001). Postoperative complications were associated only with preoperative radiation therapy (p = 0.002) and with preexisting serious medical conditions (p = 0.04). In two patients asymptomatic violation of the lateral wall of the pedicle was revealed on postoperative radiography. The 30-day mortality rate was 1%.

Conclusions. For selected patients with malignant spinal tumors, pedicle screw fixation after tumor resection may provide considerable pain relief and restore or preserve ambulation with acceptable rates of morbidity and mortality.

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Claudio E. Tatsui, Frederick F. Lang, Joy Gumin, Dima Suki, Naoki Shinojima and Laurence D. Rhines

Object

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.

Methods

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.

Results

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.

Conclusions

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.

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Daniel K. Fahim, Claudio E. Tatsui, Dima Suki, Joy Gumin, Frederick F. Lang and Laurence D. Rhines

Object

There is currently no reproducible animal model of human primary malignant bone tumors in the spine to permit laboratory investigation of the human disease. Therefore, the authors sought to adapt their previously developed orthotopic model of spinal metastasis to a model for primary malignant bone tumors of the spine.

Methods

A transperitoneal surgical approach was used to implant osteosarcoma (Krib-1) into the L-3 vertebral body of nude mice via a drill hole. Motor function was evaluated daily using the previously validated qualitative key milestones of tail dragging, dorsal stepping, hindlimb sweeping, and paralysis. A subset of these animals was euthanized upon reaching the various milestones, and the spines were removed, sectioned, and stained. The degree of spinal cord compression was correlated with the occurrence of milestones and assessed by a ratio between the neural elements divided by the area of the spinal canal. Another subset of animals received stably transfected Krib-1 cells with the luciferase gene, and bioluminescence was measured at 10, 20, and 30 days postimplantation.

Results

Osteosarcoma xenografts grew in all animals according to a reliable and reproducible time course; the mean time for development of behavioral milestones was noted in relation to the day of implantation (Day 1). Tail dragging (Milestone 1) occurred on Day 19.06 (95% CI 16.11–22.01), dorsal stepping (Milestone 2) occurred on Day 28.78 (95% CI 26.79–30.77), hindlimb sweeping (Milestone 3) occurred on Day 35.61 (95% CI 32.9–38.32), and paralysis of the hindlimb (Milestone 4) occurred on Day 41.78 (95% CI 39.31–44.25). These clinically observed milestones correlated with increasing compression of the spinal cord on histological sections. The authors observed a progressive increase in the local bioluminescence (in photons/cm2/sec) of the implanted level over time with a mean of 2.17 (range 0.0–8.61) at Day 10, mean 4.68 (range 1.17–8.52) at Day 20, and mean 5.54 (range 1.22–9.99) at Day 30.

Conclusions

The authors have developed the first orthotopic murine model of a primary malignant bone tumor in the spine, in which neurological decline reproducibly correlates with tumor progression as evidenced by pathological confirmation and noninvasive bioluminescence measurements. Although developed for osteosarcoma, this model can be expanded to study other types of primary malignant bone tumors in the spine. This model will potentially allow animal testing of targeted therapies against specific primary malignant tumor types.

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Daniel J. Miller, Frederick F. Lang, Garrett L. Walsh, Dima Abi-Said, David M. Wildrick and Ziya L. Gokaslan

Object. A unique method of anterior spinal reconstruction after decompressive surgery was used to prevent methylmethacrylate—dural contact in cancer patients who underwent corpectomy. The purpose of this study was to assess the efficacy and stability of polymethylmethacrylate (PMMA) anterior surgical constructs in conjunction with anterior cervical plate stabilization (ACPS) in these patients.

Methods. Approximately 700 patients underwent spinal surgery at The University of Texas M. D. Anderson Cancer Center over a 4-year period. The authors conducted a retrospective outcome study for 29 of these patients who underwent anterior cervical or upper thoracic tumor resections while in the supine position. These patients were all treated using the coaxial, double-lumen, PMMA technique for anterior spinal reconstruction with subsequent ACPS. No postoperative external orthoses were used. Twenty-seven patients (93%) harbored metastatic spinal lesions and two (7%) harbored primary tumors. At 1 month postsurgery, significant improvement was seen in spinal axial pain (p < 0.001), radiculopathy (p < 0.00 1), gait (p = 0.008), and Frankel grade (p = 0.002). A total of nine patients (31%) underwent combined anterior—posterior 360° stabilization. Twenty-one patients (72%) experienced no complications. Complications related to instrumentation failure occurred in only two patients (7%). There were no cases in which the patients' status worsened, and there were no neurological complications or infections. The median Kaplan—Meier survival estimate for patients with spinal metastases was 9.5 months. At the end of the study, 13 patients (45%) had died and 16 (55%) were alive. Postoperative magnetic resonance images consistently demonstrated that the dura and PMMA in all patients remained separated.

Conclusions. The anterior, coaxial, double-lumen, PMMA reconstruction technique provides a simple means of spinal cord protection in patients in the supine position while undergoing surgery and offers excellent results in cancer patients who have undergone cervical vertebrectomy.

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Julie E. York, Garrett L. Walsh, Frederick F. Lang, Joe B. Putnam, Ian E. McCutcheon, Stephen G. Swisher, Ritsuko Komaki and Ziya L Gokaslan

Object. Traditionally, superior sulcus tumors of the lung that involve the chest wall and spinal column have been considered to be unresectable, and historically, patients harboring these tumors have been treated with local radiation therapy with, at best, modest results. The value of gross-total resection remains unclear in this patient population; however, with the recent advances in surgical technique and spinal instrumentation, procedures involving more radical removal of such tumors are now possible. At The University of Texas M. D. Anderson Cancer Center, the authors have developed a new technique for resecting superior sulcus tumors that invade the chest wall and spinal column. They present a technical description of this procedure and results in nine patients in whom stage IIIb superior sulcus tumors extensively invaded the vertebral column.

Methods. These patients underwent gross-total tumor resection via a combined approach that included posterolateral thoracotomy, apical lobectomy, chest wall resection, laminectomy, vertebrectomy, anterior spinal column reconstruction with methylmethacrylate, and placement of spinal instrumentation. There were six men and three women, with a mean age of 55 years (range 36–72 years). Histological examination revealed squamous cell carcinoma (three patients), adenocarcinoma (four patients), and large cell carcinoma (two patients). The mean postoperative follow-up period was 16 months. All patients are currently ambulatory or remained ambulatory until they died. Pain related to tumor invasion improved in four patients and remained unchanged in five. In three patients instrumentation failed and required revision. There was one case of cerebrospinal fluid leakage that was treated with lumbar drainage and one case of wound breakdown that required revision. Two patients experienced local tumor recurrence, and one patient developed a second primary lung tumor.

Conclusions. The authors conclude that in selected patients, combined radical resection of superior sulcus tumors of the lung that involve the chest wall and spinal column may represent an acceptable treatment modality that can offer a potential cure while preserving neurological function and providing pain control.

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Daryl R. Fourney, Dima Abi-Said, Laurence D. Rhines, Garrett L. Walsh, Frederick F. Lang, Ian E. McCutcheon and Ziya L. Gokaslan

Object. Thoracic or lumbar spine malignant tumors involving both the anterior and posterior columns represent a complex surgical problem. The authors review the results of treating patients with these lesions in whom surgery was performed via a simultaneous anterior—posterior approach.

Methods. The hospital records of 26 patients who underwent surgery via simultaneous combined approach for thoracic and lumbar spinal tumors at our institution from July 1994 to March 2000 were reviewed. Surgery was performed with the patients in the lateral decubitus position for the procedure. The technical details are reported.

The mean survival determined by Kaplan—Meier analysis was 43.4 months for the 15 patients with primary malignant tumors and 22.5 months for the 11 patients with metastatic spinal disease. At 1 month after surgery, 23 (96%) of 24 patients who complained of pain preoperatively reported improvements (p < 0.001, Wilcoxon signed-rank test), and eight (62%) of 13 patients with preoperative neurological deficits were functionally improved (p = 0.01). There were nine major complications, five minor complications, and no deaths within 30 days of surgery. Two patients (8%) later underwent surgery for recurrent tumor.

Conclusions. The simultaneous anterior—posterior approach is a safe and feasible alternative for the exposure tumors of the thoracic and lumbar spine that involve both the anterior and posterior columns. Advantages of the approach include direct visualization of adjacent neurovascular structures, the ability to achieve complete resection of lesions involving all three columns simultaneously (optimizing hemostasis), and the ability to perform excellent dorsal and ventral stabilization in one operative session.