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Scott L. Zuckerman, Ganesh Rao, Laurence D. Rhines, Ian E. McCutcheon, Richard G. Everson and Claudio E. Tatsui

OBJECTIVE

Treatment of epidural spinal cord compression (ESCC) caused by tumor includes surgical decompression and stabilization followed by postoperative radiation. In the case of severe axial loading impairment, anterior column reconstruction is indicated. The authors describe the use of interbody distraction to restore vertebral body height and correct kyphotic angulation prior to reconstruction with polymethylmethacrylate (PMMA), and report the long-term durability of such reconstruction.

METHODS

A single institution, prospective series of patients with ESCC undergoing single-stage decompression, anterior column reconstruction, and posterior instrumentation from 2013 to 2016 was retrospectively analyzed. Several demographic, perioperative, and radiographic measurements were collected. Descriptive statistics were compiled, in addition to postoperative changes in anterior height, posterior height, and kyphosis. Paired Student t-tests were performed for each variable. Overall survival was calculated using the techniques described by Kaplan and Meier.

RESULTS

Twenty-one patients underwent single-stage posterior decompression with interbody distraction and anterior column reconstruction using PMMA. The median age and Karnofsky Performance Scale score were 61 years and 70, respectively. Primary tumors included renal cell (n = 8), lung (n = 4), multiple myeloma (n = 2), prostate (n = 2), and other (n = 5). Eighteen patients underwent a single-level vertebral body reconstruction and 3 underwent multilevel transpedicular corpectomies. The median survival duration was 13.3 months. In the immediate postoperative setting, statistically significant improvement was noted in anterior body height (p = 0.0017, 95% confidence interval [CI] −4.15 to −1.11) and posterior body height (p = 0.0116, 95% CI −3.14 to −0.45) in all patients, and improved kyphosis was observed in those with oblique endplates (p = 0.0002, 95% CI 11.16–20.27). In the median follow-up duration of 13.9 months, the authors observed 3 cases of asymptomatic PMMA subsidence. One patient required reoperation in the form of extension of fusion.

CONCLUSIONS

In situ interbody distraction allows safe and durable reconstruction with PMMA, restores vertebral height, and corrects kyphotic deformities associated with severe pathological fractures caused by tumor. This is accomplished with minimal manipulation of the thecal sac and avoiding an extensive 360° surgical approach in patients who cannot tolerate extensive surgery.

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Claudio E. Tatsui, Clarissa N. G. Nascimento, Dima Suki, Behrang Amini, Jing Li, Amol J. Ghia, Jonathan G. Thomas, R. Jason Stafford, Laurence D. Rhines, Juan P. Cata, Ashok J. Kumar and Ganesh Rao

OBJECTIVE

Image guidance for spinal procedures is based on 3D-fluoroscopy or CT, which provide poor visualization of soft tissues, including the spinal cord. To overcome this limitation, the authors developed a method to register intraoperative MRI (iMRI) of the spine into a neuronavigation system, allowing excellent visualization of the spinal cord. This novel technique improved the accuracy in the deployment of laser interstitial thermal therapy probes for the treatment of metastatic spinal cord compression.

METHODS

Patients were positioned prone on the MRI table under general anesthesia. Fiducial markers were applied on the skin of the back, and a plastic cradle was used to support the MRI coil. T2-weighted MRI sequences of the region of interest were exported to a standard navigation system. A reference array was sutured to the skin, and surface matching of the fiducial markers was performed. A navigated Jamshidi needle was advanced until contact was made with the dorsal elements; its position was confirmed with intraoperative fluoroscopy prior to advancement into a target in the epidural space. A screenshot of its final position was saved, and then the Jamshidi needle was exchanged for an MRI-compatible access cannula. MRI of the exact axial plane of each access cannula was obtained and compared with the corresponding screenshot saved during positioning. The discrepancy in millimeters between the trajectories was measured to evaluate accuracy of the image guidance

RESULTS

Thirteen individuals underwent implantation of 47 laser probes. The median absolute value of the discrepancy between the location predicted by the navigation system and the actual position of the access cannulas was 0.7 mm (range 0–3.2 mm). No injury or adverse event occurred during the procedures.

CONCLUSIONS

This study demonstrates the feasibility of image guidance based on MRI to perform laser interstitial thermotherapy of spinal metastasis. The authors' method permits excellent visualization of the spinal cord, improving safety and workflow during laser ablations in the epidural space. The results can be extrapolated to other indications, including biopsies or drainage of fluid collections near the spinal cord.

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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.

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Jonathan G. Thomas, Ganesh Rao, Yvonne Kew and Sujit S. Prabhu

OBJECTIVE

Glioblastoma (GBM) is the most common and deadly malignant primary brain tumor. Better surgical therapies are needed for newly diagnosed GBMs that are difficult to resect and for GBMs that recur despite standard therapies. The authors reviewed their institutional experience of using laser interstitial thermal therapy (LITT) for the treatment of newly diagnosed or recurrent GBMs.

METHODS

This study reports on the pre-LITT characteristics and post-LITT outcomes of 8 patients with newly diagnosed GBMs and 13 patients with recurrent GBM who underwent LITT.

RESULTS

Compared with the group with recurrent GBMs, the patients with newly diagnosed GBMs who underwent LITT tended to be older (60.8 vs 48.9 years), harbored larger tumors (22.4 vs 14.6 cm3), and a greater proportion had IDH wild-type GBMs. In the newly diagnosed GBM group, the median progression-free survival and the median survival after the procedure were 2 months and 8 months, respectively, and no patient demonstrated radiographic shrinkage of the tumor on follow-up imaging. In the 13 patients with recurrent GBM, 5 demonstrated a response to LITT, with radiographic shrinkage of the tumor following ablation. The median progression-free survival was 5 months, and the median survival was greater than 7 months.

CONCLUSIONS

In carefully selected patients with recurrent GBM, LITT may be an effective alternative to surgery as a salvage treatment. Its role in the treatment of newly diagnosed unresectable GBMs is not established yet and requires further study.

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Claudio E. Tatsui, Telmo A. B. Belsuzarri, Marilou Oro, Laurence D. Rhines, Jing Li, Amol J. Ghia, Behrang Amini, Heron Espinoza, Paul D. Brown and Ganesh Rao

OBJECTIVE

An emerging paradigm for treating patients with epidural spinal cord compression (ESCC) caused by metastatic tumors is surgical decompression and stabilization, followed by stereotactic radiosurgery. In the setting of rapid progressive disease, interruption or delay in return to systemic treatment can lead to a negative impact in overall survival. To overcome this limitation, the authors introduce the use of spinal laser interstitial thermotherapy (sLITT) in association with percutaneous spinal stabilization to facilitate a rapid return to oncological treatment.

METHODS

The authors retrospectively reviewed a consecutive series of patients with ESCC and spinal instability who were considered to be poor surgical candidates and instead were treated with sLITT and percutaneous spinal stabilization. Demographic data, Spine Instability Neoplastic Scale score, degree of epidural compression before and after the procedure, length of hospital stay, and time to return to oncological treatment were analyzed.

RESULTS

Eight patients were treated with thermal ablation and percutaneous spinal stabilization. The primary tumors included melanoma (n = 3), lung (n = 3), thyroid (n = 1), and renal cell carcinoma (n = 1). The median Karnofsky Performance Scale score before and after the procedure was 60, and the median hospital stay was 5 days (range 3–18 days). The median Spine Instability Neoplastic Scale score was 13 (range 12–16). The mean modified postoperative ESCC score (2.75 ± 0.37) was significantly lower than the preoperative score (4.5 ± 0.27) (Mann-Whitney test, p = 0.0044). The median time to return to oncological treatment was 5 days (range 3–10 days).

CONCLUSIONS

The authors present the first cohort of sLITT associated with a percutaneous spinal stabilization for the treatment of ESCC and spinal instability. This minimally invasive technique can allow a faster recovery without prejudice of adjuvant systemic treatment, with adequate local control and spinal stabilization.

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Arvind Rao, Ganesh Rao, David A. Gutman, Adam E. Flanders, Scott N. Hwang, Daniel L. Rubin, Rivka R. Colen, Pascal O. Zinn, Rajan Jain, Max Wintermark, Justin S. Kirby, C. Carl Jaffe, John Freymann and TCGA Glioma Phenotype Research Group

OBJECT

Individual MRI characteristics (e.g., volume) are routinely used to identify survival-associated phenotypes for glioblastoma (GBM). This study investigated whether combinations of MRI features can also stratify survival. Furthermore, the molecular differences between phenotype-induced groups were investigated.

METHODS

Ninety-two patients with imaging, molecular, and survival data from the TCGA (The Cancer Genome Atlas)-GBM collection were included in this study. For combinatorial phenotype analysis, hierarchical clustering was used. Groups were defined based on a cutpoint obtained via tree-based partitioning. Furthermore, differential expression analysis of microRNA (miRNA) and mRNA expression data was performed using GenePattern Suite. Functional analysis of the resulting genes and miRNAs was performed using Ingenuity Pathway Analysis. Pathway analysis was performed using Gene Set Enrichment Analysis.

RESULTS

Clustering analysis reveals that image-based grouping of the patients is driven by 3 features: volume-class, hemorrhage, and T1/FLAIR-envelope ratio. A combination of these features stratifies survival in a statistically significant manner. A cutpoint analysis yields a significant survival difference in the training set (median survival difference: 12 months, p = 0.004) as well as a validation set (p = 0.0001). Specifically, a low value for any of these 3 features indicates favorable survival characteristics. Differential expression analysis between cutpoint-induced groups suggests that several immune-associated (natural killer cell activity, T-cell lymphocyte differentiation) and metabolism-associated (mitochondrial activity, oxidative phosphorylation) pathways underlie the transition of this phenotype. Integrating data for mRNA and miRNA suggests the roles of several genes regulating proliferation and invasion.

CONCLUSIONS

A 3-way combination of MRI phenotypes may be capable of stratifying survival in GBM. Examination of molecular processes associated with groups created by this combinatorial phenotype suggests the role of biological processes associated with growth and invasion characteristics.

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Jonathan N. Sellin, Dima Suki, Viraat Harsh, Benjamin D. Elder, Daniel K. Fahim, Ian E. McCutcheon, Ganesh Rao, Laurence D. Rhines and Claudio E. Tatsui

OBJECT

Spinal metastases account for the majority of bone metastases from thyroid cancer. The objective of the current study was to analyze a series of consecutive patients undergoing spinal surgery for thyroid cancer metastases in order to identify factors that influence overall survival.

METHODS

The authors retrospectively reviewed the records of all patients who underwent surgery for spinal metastases from thyroid cancer between 1993 and 2010 at the University of Texas MD Anderson Cancer Center.

RESULTS

Forty-three patients met the study criteria. Median overall survival was 15.4 months (95% CI 2.8–27.9 months) based on the Kaplan-Meier method. The median follow-up duration for the 4 patients who were alive at the end of the study was 39.4 months (range 1.7–62.6 months). On the multivariate Cox analysis, progressive systemic disease at spine surgery and postoperative complications were associated with worse overall survival (HR 8.98 [95% CI 3.46–23.30], p < 0.001; and HR 2.86 [95% CI 1.30–6.31], p = 0.009, respectively). Additionally, preoperative neurological deficit was significantly associated with worse overall survival on the multivariate analysis (HR 3.01 [95% CI 1.34–6.79], p = 0.008). Conversely, preoperative embolization was significantly associated with improved overall survival on the multivariate analysis (HR 0.43 [95% CI 0.20–0.94], p = 0.04). Preoperative embolization and longer posterior construct length were significantly associated with fewer and greater complications, respectively, on the univariate analysis (OR 0.24 [95% CI 0.06–0.93] p = 0.04; and OR 1.24 [95% CI 1.02–1.52], p = 0.03), but not the multivariate analysis.

CONCLUSIONS

Progressive systemic disease, postoperative complications, and preoperative neurological deficits were significantly associated with worse overall survival, while preoperative spinal embolization was associated with improved overall survival. These factors should be taken into consideration when considering such patients for surgery. Preoperative embolization and posterior construct length significantly influenced the incidence of postoperative complications only on the univariate analysis.