Effects of primary and recurrent sacral chordoma on the motor and nociceptive function of hindlimbs in rats: an orthotopic spine model.

OBJECTIVE Chordoma is a slow-growing, locally aggressive cancer that is minimally responsive to conventional chemotherapy and radiotherapy and has high local recurrence rates after resection. Currently, there are no rodent models of spinal chordoma. In the present study, the authors sought to develop and characterize an orthotopic model of human chordoma in an immunocompromised rat. METHODS Thirty-four immunocompromised rats were randomly allocated to 4 study groups; 22 of the 34 rats were engrafted in the lumbar spine with human chordoma. The groups were as follows: UCH1 tumor-engrafted (n = 11), JHC7 tumor-engrafted (n = 11), sham surgery (n = 6), and intact control (n = 6) rats. Neurological impairment of rats due to tumor growth was evaluated using open field and locomotion gait analysis; pain response was evaluated using mechanical or thermal paw stimulation. Cone beam CT (CBCT), MRI, and nanoScan PET/CT were performed to evaluate bony changes due to tumor growth. On Day 550, rats were killed and spines were processed for H & E-based histological examination and immunohistochemistry for brachyury, S100ß, and cytokeratin. RESULTS The spine tumors displayed typical chordoma morphology, that is, physaliferous cells filled with vacuolated cytoplasm of mucoid matrix. Brachyury immunoreactivity was confirmed by immunostaining, in which samples from tumor-engrafted rats showed a strong nuclear signal. Sclerotic lesions in the vertebral body of rats in the UCH1 and JHC7 groups were observed on CBCT. Tumor growth was confirmed using contrast-enhanced MRI. In UCH1 rats, large tumors were observed growing from the vertebral body. JHC7 chordoma-engrafted rats showed smaller tumors confined to the bone periphery compared with UCH1 chordoma-engrafted rats. Locomotion analysis showed a disruption in the normal gait pattern, with an increase in the step length and duration of the gait in tumor-engrafted rats. The distance traveled and the speed of rats in the open field test was significantly reduced in the UCH1 and JHC7 tumor-engrafted rats compared with controls. Nociceptive response to a mechanical stimulus showed a significant (p < 0.001) increase in the paw withdrawal threshold (mechanical hypalgesia). In contrast, the paw withdrawal response to a thermal stimulus decreased significantly (p < 0.05) in tumor-engrafted rats. CONCLUSIONS The authors developed an orthotopic human chordoma model in rats. Rats were followed for 550 days using imaging techniques, including MRI, CBCT, and nanoScan PET/CT, to evaluate lesion progression and bony integrity. Nociceptive evaluations and locomotion analysis were performed during follow-up. This model reproduces cardinal signs, such as locomotor and sensory deficits, similar to those observed clinically in human patients. To the authors' knowledge, this is the first spine rodent model of human chordoma. Its use and further study will be essential for pathophysiology research and the development of new therapeutic strategies.

Design and testing of a controlled electromagnetic spinal cord impactor for use in large animal models of acute traumatic spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) causes debilitating neurological dysfunction and has been observed in warfighters injured in IED blasts. Clinical benefit of SCI treatment remains elusive and better large animal models are needed to assess treatment options. Here, we describe a controlled electromagnetic spinal cord impactor for use in large animal models of SCI. METHODS: A custom spinal cord impactor and platform were fabricated for large animals (e.g., pig, sheep, dog, etc.). Impacts were generated by a voice coil actuator; force and displacement were measured with a load cell and potentiometer respectively. Labview (National Instruments, Austin, TX) software was used to control the impact cycle and import force and displacement data. Software finite impulse response (FIR) filtering was employed for all input data. Silicon tubing was used a surrogate for spinal cord in order to test the device; repeated impacts were performed at 15, 25, and 40 Newtons. RESULTS: Repeated impacts demonstrated predictable results at each target force. The average duration of impact was 71.2 ±6.1ms. At a target force of 40N, the output force was 41.5 ±0.7N. With a target of 25N, the output force was 23.5 ±0.6N; a target of 15Newtons revealed an output force of 15.2 ±1.4N. The calculated acceleration range was 12.5-21.2m/s2. CONCLUSIONS: This custom spinal cord impactor reliably delivers precise impacts to the spinal cord and will be utilized in future research to study acute traumatic SCI in a large animal.

Factors associated with improved survival following surgery for renal cell carcinoma spinal metastases.

OBJECTIVE Renal cell carcinoma (RCC) frequently metastasizes to the spine, causing pain or neurological dysfunction, and is often resistant to standard therapies. Spinal surgery is frequently required, but may result in high morbidity rates. The authors sought to identify prognostic factors and determine clinical outcomes in patients undergoing surgery for RCC spinal metastases. METHODS The authors searched the records of patients who had undergone spinal surgery for metastatic disease at a single institution during a 12-year period and retrieved data for 30 patients with metastatic RCC. The records were retrospectively reviewed for data on preoperative conditions, treatment, and survival. Statistical analyses (i.e., Kaplan-Meier survival analysis and log-rank test in univariate analysis) were performed with R version 2.15.2. RESULTS The 30 patients (23 men and 7 women with a mean age of 57.6 years [range 29-79 years]) had in total 40 spinal surgeries for metastatic RCC. The indications for surgery included pain (70%) and weakness (30%). Fourteen patients (47%) had a Spinal Instability Neoplastic Score (SINS) indicating indeterminate or impending instability, and 6 patients (20%) had a SINS denoting instability. The median length of postoperative survival estimated with Kaplan-Meier analysis was 11.4 months. Younger age (p = 0.001) and disease control at the primary site (p = 0.005), were both significantly associated with improved survival. In contrast, visceral (p = 0.002) and osseous (p = 0.009) metastases, nonambulatory status (p = 0.001), and major comorbidities (p = 0.015) were all significantly associated with decreased survival. Postoperative Frankel grades were the same or had improved in 78% of patients. Major complications occurred in 9 patients, and there were 3 deaths (10%) during the 30-day in-hospital period. Three en bloc resections were performed. CONCLUSIONS Resection and fixation may provide pain relief and neurological stabilization in patients with spinal metastases arising from RCC, but surgical morbidity rates remain high. Younger patients with solitary spinal metastases, good neurological function, and limited major comorbidities may have longer survival and may benefit from aggressive intervention.

Adult cervicothoracic lipomyelomeningocele.

Lipomyelomeningocele (LMM) as a cause of tethered cord syndrome (TCS) commonly presents in childhood in the lumbosacral spine. Patients frequently present with cutaneous manifestations, progressive neurological deterioration, bladder dysfunction, and intractable pain. Early surgical intervention with untethering is recommended for symptomatic patients. We report an unusual case of a woman who presented with a subcutaneous lump, pain, and neurological decline found to have a cervicothoracic LMM. The patient underwent laminectomy and subtotal resection of the mass; seventeen years later she was confined to a wheelchair with severe neurological decline ultimately requiring three additional attempts at surgical excision and repair. This case emphasizes the need for early recognition of and intervention in adult patients with LMM.

Utility of the LevelCheck Algorithm for Decision Support in Vertebral Localization.

STUDY DESIGN: An automatic radiographic labeling algorithm called "LevelCheck" was analyzed as a means of decision support for target localization in spine surgery. The potential clinical utility and scenarios in which LevelCheck is likely to be the most beneficial were assessed in a retrospective clinical data set (398 cases) in terms of expert consensus from a multi-reader study (three spine surgeons). OBJECTIVE: The aim of this study was to evaluate the potential utility of the LevelCheck algorithm for vertebrae localization. SUMMARY OF BACKGROUND DATA: Three hundred ninety-eight intraoperative radiographs and 178 preoperative computed tomographic (CT) images for patients undergoing spine surgery in cervical, thoracic, lumbar regions. METHODS: Vertebral labels annotated in preoperative CT image were overlaid on intraoperative radiographs via 3D-2D registration. Three spine surgeons assessed the radiographs and LevelCheck labeling according to a questionnaire evaluating performance, utility, and suitability to surgical workflow. Geometric accuracy and registration run time were measured for each case. RESULTS: LevelCheck was judged to be helpful in 42.2% of the cases (168/398), to improve confidence in 30.6% of the cases (122/398), and in no case diminished performance (0/398), supporting its potential as an independent check and assistant to decision support in spine surgery. The clinical contexts for which the method was judged most likely to be beneficial included the following scenarios: images with a lack of conspicuous anatomical landmarks; level counting across long spine segments; vertebrae obscured by other anatomy (e.g., shoulders); poor radiographic image quality; and anatomical variations/abnormalities. The method demonstrated 100% geometric accuracy (i.e., overlaid labels within the correct vertebral level in all cases) and did not introduce ambiguity in image interpretation. CONCLUSION: LevelCheck is a potentially useful means of decision support in vertebral level localization in spine surgery. LEVEL OF EVIDENCE: N/A.

Challenges of cervical reconstruction for destructive spondyloarthropathy in renal osteodystrophy.

Patients with end stage renal disease on hemodialysis may present with destructive spondyloarthropathy of the spine, most commonly in the subaxial cervical and lumbar spine, often with severe stenosis and instability. However, surgical management of these patients is challenging due to a high pseudarthrosis rate, poor bone quality, and medical frailty. We present a 49-year-old man on hemodialysis who presented with C4-C5 vertebral body destruction and a focal kyphotic deformity with myelopathy. The patient underwent a 360 degree decompression and reconstructive procedure that resulted in posterior instrumentation failure. Several salvage techniques were used in order to adequately stabilize the spine while preserving the patient's remaining cervical motion.

Prospective evaluation of 1-year outcomes in single-level percutaneous lumbar transfacet screw fixation in the lateral decubitus position following lateral transpsoas interbody fusion.

PURPOSE: Lateral transpsoas lumbar interbody fusion (LTIF) is an accepted treatment for degenerative lumbar disc disease. Bilateral percutaneous transfacet (TF) fixation is a promising option for stabilization following LTIF. Here, we describe our experience with this technique and assess the clinical outcomes and efficacy. METHODS: Thirty-eight consecutive patients were identified who underwent LTIF followed by bilateral percutaneous transfacet fixation in the lateral position. Preoperative and 1-year postoperative VAS scores, and operative data were prospectively recorded. One-year outcomes were also assessed according to the MacNab criteria. Fusion was assessed at 1 year via computed tomography and dynamic radiography. Two-tailed Student's t test was used to compare VAS scores. RESULTS: Twenty-six patients underwent fusion at L4-5, 11 at L3-4, and one at L2-3; two patients were lost to follow-up. Mean operative time was 148.0 ± 47.9 min; mean blood loss was 33.0 ± 26.1 ml; mean hospital stay was 53.5 ± 51.2 h. Mean preoperative VAS scores for back and leg pain were 7.4 ± 3.0 and 7.0 ± 2.9, respectively; mean postoperative VAS scores for back and leg pain were 1.9 ± 2.4 (p < 0.0001) and 2.0 ± 3.0 (p < 0.0001), respectively. Most (89 %) patients had some relief, 72 % good to excellent and 17 % fair outcomes; eleven percent had little to no relief. There was one postoperative complication (pulmonary embolus). All patients had evidence of solid bony fusion. CONCLUSIONS: Percutaneous transfacet fixation in the lateral position is a safe and effective alternative for fixation after LTIF and may be associated with shorter operative time and less blood loss than other posterior fixation techniques.

Tokuhashi score is predictive of survival in a cohort of patients undergoing surgery for renal cell carcinoma spinal metastases.

PURPOSE: Renal cell carcinoma (RCC) is an aggressive disease that metastasizes to the spine often requiring surgery. However, selecting the appropriate surgical intervention can be challenging. The Tokuhashi scoring system can be used to predict survival and inform the surgical strategy. We set out to determine the Tokuhashi score for patients with RCC spine metastases and compare expected and observed survival. METHODS: Records were reviewed for all patients who underwent surgery for spinal metastases at a single institution from January 2000 to December 2011 to determine the Tokuhashi score and survival. Kaplan-Meier estimates and log-rank test for univariate analysis were performed with R version 2.15.12 (R Foundation, 2012). RESULTS: Thirty patients underwent 40 spinal operations for metastatic RCC. Median survival was 11.4 months. Preoperative Tokuhashi scores were: 12-15, 15 patients; 9-11, seven patients; 0-8, eight patients. Median survival was 32.9, 11.7, and 5.4 months, respectively. Bone (p=0.01) and visceral metastases (p=0.005), and KPS (p=0.002) significantly affected survival. Tokuhashi score predicted survival (p=0.016); survival differed between the high and low score groups (p=0.006). CONCLUSIONS: RCC is an aggressive disease with short life expectancy when metastatic to the spine. However, patients with low systemic disease burden and solitary spinal metastases can have long survival and benefit from excisional surgery. Tokuhashi score can be useful in selecting surgical intervention in patients with RCC spinal metastases, and may be more relevant than in other cancers with spinal metastases.

Minimally invasive lateral retroperitoneal corpectomy for treatment of focal thoracolumbar kyphotic deformity: case report and review of the literature.

BACKGROUND: Corpectomy is a frequently performed procedure for pathologies of the anterior spine including neoplasms, fractures, deformities, and osteomyelitis. Traditional approaches to the anterior thoracic spine and thoracolumbar junction are associated with significant perioperative pulmonary complications and morbidity. Posterior and posterolateral approaches minimize some of these complications but are somewhat limited in visualization of the anterior elements. PATIENT AND METHODS: Here we report the case of a 49-year-old man with a remote thoracolumbar fracture and subsequent focal deformity treated with a minimally invasive lateral retroperitoneal corpectomy and open posterior arthrodesis. CONCLUSION: Minimally invasive lateral corpectomy is a safe and effective option for deformity correction. We discuss the relative advantages and disadvantages of this approach and review the relevant literature.

Large occipital aneurysmal bone cyst causing obstructive hydrocephalus in a pediatric patient.

Aneurysmal bone cyst (ABC) is an uncommon benign, tumorlike lesion of bone that is usually located in the long bones and spine. On rare occasions, ABCs are found in the bones of the cranial vault and skull base, occasionally causing mass effect and cranial nerve findings. In this report the authors detail the case of a patient who presented with incidentally discovered hydrocephalus due to a large ABC of the occipital bone that produced mass effect and obstruction of CSF. The diagnosis, imaging findings, and surgical management of this interesting and rare case are discussed.

Percutaneous computed tomography fluoroscopy-guided conformal ultrasonic ablation of vertebral tumors in a rabbit tumor model. Laboratory investigation.

OBJECT: Radiofrequency ablation (RFA) has proven to be effective for treatment of malignant and benign tumors in numerous anatomical sites outside the spine. The major challenge of using RFA for spinal tumors is difficulty protecting the spinal cord and nerves from damage. However, conforming ultrasound energy to match the exact anatomy of the tumor may provide successful ablation in such sensitive locations. In a rabbit model of vertebral body tumor, the authors have successfully ablated tumors using an acoustic ablator placed percutaneously via computed tomography fluoroscopic (CTF) guidance. METHODS: Using CTF guidance, 12 adult male New Zealand White rabbits were injected with VX2 carcinoma cells in the lowest lumbar vertebral body. At 21 days, a bone biopsy needle was placed into the geographical center of the lesion, down which an acoustic ablator was inserted. Three multisensor thermocouple arrays were placed around the lesion to provide measurement of tissue temperature during ablation, at thermal doses ranging from 100 to 1,000,000 TEM (thermal equivalent minutes at 43°C), and tumor volumes were given a tumoricidal dose of acoustic energy. Animals were monitored for 24 hours and then sacrificed. Pathological specimens were obtained to determine the extent of tumor death and surrounding tissue damage. Measured temperature distributions were used to reconstruct volumetric doses of energy delivered to tumor tissue, and such data were correlated with pathological findings. RESULTS: All rabbits were successfully implanted with VX2 cells, leading to a grossly apparent spinal and paraspinal tissue mass. The CTF guidance provided accurate placement of the acoustic ablator in all tumors, as corroborated through gross and microscopic histology. Significant tumor death was noted in all specimens without collateral damage to nearby nerve tissue. Tissue destruction just beyond the margin of the tumor was noted in some but not all specimens. No neurological deficits occurred in response to ablation. Reconstruction of measured temperature data allowed accurate assessment of volumetric dose delivered to tissues. CONCLUSIONS: Using a rabbit intravertebral tumor model, the authors have successfully delivered tumoricidal doses of acoustic energy via a therapeutic ultrasound ablation probe placed percutaneously with CTF guidance. The authors have thus established the first technical and preclinical feasibility study of controlled ultrasound ablation of spinal tumors in vivo.

Diagnosis and management of metastatic spine disease. A review.

With continued growth of the elderly population and improvements in cancer therapies, the number of patients with symptomatic spinal metastases is likely to increase, and this is a condition that commonly leads to debilitating neurological dysfunction and pain. Advancements in surgical techniques of resection and spinal reconstruction, improvements in clinical outcomes following various treatment modalities, generally increased overall survival in patients with metastatic spine disease, and a recent randomized trial by Patchell and colleagues demonstrating the superiority of a combined surgical/radiotherapeutic approach over a radiotherapy-only strategy have led many to suggest increasingly aggressive interventions for patients with such lesions. Optimal management of spinal metastases encompasses numerous medical specialties, including neurosurgery, orthopedic surgery, medical and radiation oncology, radiology, and rehabilitation medicine. In this review, the clinical presentation, diagnosis, and management of spinal metastatic disease are discussed. Ultimately, the goal of treatment in patients with spinal metastases remains palliative, and clinical judgment is required to select the appropriate patients for surgical intervention.

Solitary spinal metastasis of Hürthle cell thyroid carcinoma.

Hürthle cell carcinoma is a rare variant of differentiated thyroid cancer that occasionally forms distant metastases. However, even in the presence of metastases, patients with Hürthle cell carcinoma have a relatively good prognosis. There are few reports of Hürthle cell carcinoma metastases to the vertebral column, and none describing aggressive resection of spinal metastases. Here, we report a 68-year-old woman with a solitary metastasis of Hürthle cell carcinoma to the T1 vertebral body causing severe kyphotic deformity, myelopathy, and pain. The patient was treated with aggressive excisional decompression of the spinal cord and T1 vertebral body resection from an entirely posterior approach. Reconstruction and stabilization of the anterior spine was accomplished with a transforaminal lumbar interbody fusion allograft spacer and posterior instrumentation. We discuss aspects of the diagnosis, management, patient selection, and surgical treatment of metastatic Hürthle cell carcinoma in reference to the literature.

Transthoracic surgical treatment for centrally located thoracic disc herniations presenting with myelopathy: a 5-year institutional experience.

STUDY DESIGN: Retrospective review. OBJECTIVE: Review clinical outcomes for myelopathic patients undergoing transthoracic discectomies for central calcified herniations. SUMMARY OF BACKGROUND DATA: Ideal surgical treatment for thoracic disc herniation is controversial due to variations in patient presentation, pathology, and possible surgical approach. Although discectomy may lead to improvements in neurologic function, it can be complicated by approach-related morbidity, especially for ventral calcified disc herniations. Review of clinical outcomes for myelopathic patients undergoing transthoracic discectomies for central calcified herniations was completed, paying special attention to neurologic status and procedure-related complications. METHODS: Between 2002 and 2007, 27 myelopathic patients were treated with 28 transthoracic surgeries for centrally located symptomatic calcified thoracic disc herniations over the last 5 years at a single institution. Demographic data, details of surgery, preoperative and postoperative Nurick and American Spinal Injury Association scores, length of stay, complications, and follow-up data were collected in all patients. RESULTS: A total of 27 patients, 8 male (30%) and 19 female (70%) with an average age of 52.3 years (range: 19 to 72) underwent 28 thoracotomies. All had myelopathy whereas 6/27 also had radicular pain syndromes. Fourteen patients had anterior instrumentation alone, 3 had anterior and posterior instrumentation, and 1 had posterior instrumentation alone. Average Nurick grade was 2.5 preoperatively and 1.4 postoperatively. Of note, American Spinal Injury Association scores improved postoperatively in 12/27 patients (10D to 10E; 2C to 2D), remained unchanged in 13/27 (11E to 11E, 2D to 2D), and worsened in 2/27 (2D to 2C). Average length of stay was 7 days (range: 3 to 15). All patients required chest tube placement with average duration of 4 days (range: 1 to 7). Major complications occurred in 6 cases (21.4%) over an average follow-up of 12 months (range: 1 to 40 mo). CONCLUSIONS: Thoracotomy for treatment of centrally located thoracic disc herniations is associated with improvement in or stabilization of myelopathic symptoms in the majority of patients with an acceptable rate of complications. Interestingly, most patients with weakness improved in strength (12/16, 75%), no patients with normal strength developed new weakness (10/10, 100%), and only 2 patients had new weakness noted postoperatively (7.4%).

En bloc spondylectomy for treatment of tumor-induced osteomalacia.

En bloc spondylectomy represents a radical resection of a spinal segment most often reserved for patients presenting with a primary extradural spine tumor or a solitary metastasis in the setting of an indolent, well-controlled systemic malignancy. The authors report a case in which en bloc spondylectomy was conducted to control a metabolically active spine tumor. A 56-year-old woman, who suffered from severe tumor-induced osteomalacia, was found to have a fibroblast growth factor-23-secreting phosphaturic mesenchymal tumor in the T-8 vertebral body. En bloc resection was conducted, leading to resolution of her tumor-induced osteomalacia. This case suggests that radical spondylectomy may be beneficial in the management of metabolically or endocrinologically active tumors of the spine.

Chordoma of the sacrum and vertebral bodies.

Chordomas are relatively rare tumors of bone. These primary malignant lesions occur throughout the spinal column and often show advanced growth at the time of diagnosis. Because such tumors are minimally responsive to radiation and chemotherapy, surgical resection is the mainstay of treatment. Patient survival and local control are associated with the ability to achieve wide surgical margins during excision. However, surgical morbidity may be substantial given the propensity for chordomas to abut or surround neural, vascular, and visceral structures. Thus, early recognition is essential, and treatment by a multidisciplinary team is ideal.

Evaluation of blunt cervical spine injury.

Injuries resulting from blunt cervical spine trauma are common problems seen in emergency departments and treated by trauma care specialists. Timely and appropriate imaging studies are essential to the cervical spine evaluation in the trauma patient. Despite advances in imaging techniques, cervical injuries may still be missed. Several specialty bodies have published guidelines for the evaluation of the cervical spine with slightly differing recommendations. The purpose of this review is to summarize the current recommendations for radiographic evaluation of patients with blunt cervical spine trauma.

Regression of intracranial meningioma following intratumoral hemorrhage.

An intratumoral hemorrhage within a meningioma occurs infrequently; in less than 3% of all lesions. When hemorrhage does occur, however, it is associated with a poor prognosis and significant mortality rates. We report a 66-year-old woman with a 10-year history of multiple intracranial meningiomas managed conservatively who underwent surgical resection of a spheno-orbital lesion for decompression of the right optic nerve. Postoperatively, an intratumoral hemorrhage developed in a contralateral lesion, which was managed conservatively. During follow up, the hemorrhaged lesion became significantly smaller. To our knowledge there are no published reports of spontaneous resolution of a meningioma after intratumoral hemorrhage without surgical management. We review the literature on hemorrhage in meningiomas and postulate some pathophysiologic mechanisms for the bleeding and subsequent tumor resolution seen in this patient.

Diagnosis and management of sacral tumors.

Sacral tumors pose significant challenges to the managing physician from diagnostic and therapeutic perspectives. Although these tumors are often diagnosed at an advanced stage, patients may benefit from good clinical outcomes if an aggressive multidisciplinary approach is used. In this review, the epidemiology, clinical presentation, imaging characteristics, treatment options, and published outcomes are discussed. Special attention is given to the specific anatomical constraints that make tumors in this region of the spine more difficult to effectively manage than those in the mobile portions of the spine.