Dean Chou

A novel classification system for spinal instability in neoplastic disease: an evidence-based approach and expert consensus from the Spine Oncology Study Group.

Study Design. Systematic review and modified Delphi technique. Objective. To use an evidence-based medicine process using the best available literature and expert opinion consensus to develop a comprehensive classification system to diagnose neoplastic spinal instability. Summary of Background Data. Spinal instability is poorly defined in the literature and presently there is a lack of guidelines available to aid in defining the degree of spinal instability in the setting of neoplastic spinal disease. The concept of spinal instability remains important in the clinical decision-making process for patients with spine tumors. Methods. We have integrated the evidence provided by systematic reviews through a modified Delphi technique to generate a consensus of best evidence and expert opinion to develop a classification system to define neoplastic spinal instability. Results. A comprehensive classification system based on patient symptoms and radiographic criteria of the spine was developed to aid in predicting spine stability of neoplastic lesions. The classification system includes global spinal location of the tumor, type and presence of pain, bone lesion quality, spinal alignment, extent of vertebral body collapse, and posterolateral spinal element involvement. Qualitative scores were assigned based on relative importance of particular factors gleaned from the literature and refined by expert consensus. Conclusion. The Spine Instability Neoplastic Score is a comprehensive classification system with content validity that can guide clinicians in identifying when patients with neoplastic disease of the spine may benefit from surgical consultation. It can also aid surgeons in assessing the key components of spinal instability due to neoplasia and may become a prognostic tool for surgical decision-making when put in context with other key elements such as neurologic symptoms, extent of disease, prognosis, patient health factors, oncologic subtype, and radiosensitivity of the tumor.

Hemangioblastomas of the central nervous system in von Hippel-Lindau syndrome and sporadic disease.

OBJECTIVE The presentation, screening, management, and clinical outcomes of patients who presented to our institution from 1973 to 1999 with central nervous system (CNS) hemangioblastomas in von Hippel-Lindau (VHL) syndrome and sporadic disease were analyzed. METHODS The surgical pathology database of our institution was searched to identify all patients with histologically verified CNS hemangioblastomas occurring from 1973 to 1999. The medical, radiological, surgical, pathological, and autopsy records from these patients were reviewed retrospectively and statistically analyzed. RESULTS Forty patients (21 males and 19 females) presented with CNS hemangioblastomas. Twenty-five patients (62%) harbored sporadic hemangioblastomas. Fifteen patients (38%) had VHL syndrome. These 40 patients presented with 61 hemangioblastomas (8 patients had multiple lesions). Ten patients (25%) harbored spinal cord hemangioblastomas (5 patients had multiple lesions). Patients with VHL disease tended to present with neurological symptoms and signs at a younger age than patients with sporadic disease (P = 0.09), to present with multiple lesions (53%), and to develop new lesions (rate, 1 lesion/2.1 yr). Hemangioblastomas of the spinal cord were more prevalent in patients with VHL syndrome (P = 0.024). Neuroradiological screening of patients with VHL syndrome allowed identification of more than 75% of new lesions before they became symptomatic. Sixty-six surgical procedures were performed (12 patients required multiple operations). Six patients with VHL syndrome required surgery for new lesions. Surgical complications occurred in six patients (15%). Symptom resolution or arrest of progression at 1 year was documented in 88% of patients. Recurrence of symptoms from partially resected lesions occurred in eight patients (20%). No deaths associated with surgery occurred. One patient with sporadic disease and one patient with VHL syndrome (5%) died as a result of late medical complications from CNS hemangioblastomas. CONCLUSION Surgical outcomes for patients with CNS hemangioblastomas are favorable. However, management of hemangioblastomas is a more difficult and prolonged endeavor for patients with VHL syndrome. In patients with VHL syndrome, neuroradiological screening allows identification of lesions before they become symptomatic. Because patients with VHL syndrome are at risk for development of new lesions, they require lifelong follow-up.

Spinal Instability Neoplastic Score: An Analysis of Reliability and Validity From the Spine Oncology Study Group

PURPOSE Standardized indications for treatment of tumor-related spinal instability are hampered by the lack of a valid and reliable classification system. The objective of this study was to determine the interobserver reliability, intraobserver reliability, and predictive validity of the Spinal Instability Neoplastic Score (SINS). METHODS Clinical and radiographic data from 30 patients with spinal tumors were classified as stable, potentially unstable, and unstable by members of the Spine Oncology Study Group. The median category for each patient case (consensus opinion) was used as the gold standard for predictive validity testing. On two occasions at least 6 weeks apart, each rater also scored each patient using SINS. Each total score was converted into a three-category data field, with 0 to 6 as stable, 7 to 12 as potentially unstable, and 13 to 18 as unstable. RESULTS The κ statistics for interobserver reliability were 0.790, 0.841, 0.244, 0.456, 0.462, and 0.492 for the fields of location, pain, bone quality, alignment, vertebral body collapse, and posterolateral involvement, respectively. The κ statistics for intraobserver reliability were 0.806, 0.859, 0.528, 0.614, 0.590, and 0.662 for the same respective fields. Intraclass correlation coefficients for inter- and intraobserver reliability of total SINS score were 0.846 (95% CI, 0.773 to 0.911) and 0.886 (95% CI, 0.868 to 0.902), respectively. The κ statistic for predictive validity was 0.712 (95% CI, 0.676 to 0.766). CONCLUSION SINS demonstrated near-perfect inter- and intraobserver reliability in determining three clinically relevant categories of stability. The sensitivity and specificity of SINS for potentially unstable or unstable lesions were 95.7% and 79.5%, respectively.

Pilot clinical trial of gabapentin to decrease postoperative delirium in older patients

In this randomized pilot clinical trial, the authors tested the hypothesis that using gabapentin as an add-on agent in the treatment of postoperative pain reduces the occurrence of postoperative delirium. Postoperative delirium occurred in 5/12 patients (42%) who received placebo vs 0/9 patients who received gabapentin, p = 0.045. The reduction in delirium appears to be secondary to the opioid-sparing effect of gabapentin.

Predictive factors for proximal junctional kyphosis in long fusions to the sacrum in adult spinal deformity

Study Design. A retrospective study. Objective. To assess the mechanisms and the independent risk factors associated with proximal junctional kyphosis (PJK) in patients treated surgically for adult spinal deformity with long fusions to the sacrum. Summary of Background Data. The occurrence of PJK may be related to preoperative and postoperative sagittal parameters. The mechanisms and risk factors for PJK in adults are not well defined. Methods. Consecutive patients who underwent long instrumented fusion surgery (≥6 vertebrae) to the sacrum with a minimum of 2 years of follow-up were retrospectively studied. Risk factors included patient factors, surgical factors, and radiographical parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis, pelvic tilt, and pelvic incidence. Results. Ninety consecutive patients (mean age, 64.5 yr) met inclusion criteria. Radiographical PJK occurred in 37 of the 90 (41%) patients with a mean follow-up of 2.9 years. The most common mechanism of PJK was fracture at the upper instrumented vertebra (UIV) in 19 (51%) patients. Twelve (13%) patients with PJK were treated surgically with proximal extension of the instrumented fusion. Preoperative TK more than 30°, preoperative proximal junctional angle more than 10°, change in LL more than 30°, and pelvic incidence more than 55° were identified as predictors associated with PJK. Achievement of ideal global sagittal realignment (sagittal vertical axis <50 mm, pelvic tilt <20°, and pelvic incidence-LL <±10°) protected against the development of PJK (19% vs. 45%). A multivariate regression analysis revealed changes in LL more than 30°, and preoperative TK more than 30° were the independent risk factors associated with PJK. Conclusion. Fracture at the UIV was the most common mechanism for PJK. Change in LL more than 30° and pre-existing TK more than 30° were identified as independent risk factors. Optimal postoperative alignment of the spine protects against the development of PJK. A surgical strategy to minimize PJK may include preoperative planning for reconstructions with a goal of optimal postoperative alignment. Level of Evidence: 3

Degenerative magnetic resonance imaging changes in patients with chronic low back pain: A systematic review

Study Design. Systematic review. Objective. To systematically search for critically appraise and summarize studies that (1) evaluated the association between degenerative magnetic resonance imaging (MRI) changes and chronic low back pain (CLBP) and (2) compared surgical and nonsurgical treatment of these degenerative MRI changes. Summary of Background Data. The role of routine MRI in patients with CLBP is unclear. It is also uncertain whether or not surgical treatment of degenerative MRI changes results in alleviation of back pain. Methods. Systematic literature searches were conducted in PubMed for studies published through March 1, 2011. To evaluate whether MRI degenerative changes are associated with CLBP, studies that were designed to compare the prevalence of MRI changes among subjects with and without CLBP were sought. The prevalence odds ratio was used to compare the odds of degenerative MRI findings in subjects with CLBP to the odds of such findings among those without CLBP. To evaluate whether surgical treatment of degenerative MRI changes is associated with different outcomes compared with nonsurgical treatment, comparative studies were sought. The GRADE system as applied to describe the strength of the overall body of evidence. Results. Regarding the association of degenerative changes on MRI and CLBP, five studies were included, all of which were cross-sectional in design. On the basis of these studies, a statistically significant association was found in all but one study regarding the presence of disc degeneration and CLBP (odds ratio range: 1.8–2.8). The overall strength of evidence across studies was considered to be insufficient, however. No comparative studies of surgical versus nonsurgical treatment of degenerative MRI changes were identified. Conclusion. Although there may be an association between degenerative MRI changes and CLBP, it is unknown if these estimates accurately represent the association given the quality of included studies, lack of a direct link between degenerative MRI changes and CLBP, and heterogeneity across studies. Thus, a strong recommendation against the routine use of MRI for CLBP evaluation is made. Since there are no data evaluating the efficacy of the surgical treatment of degenerative MRI changes, a strong recommendation is made against the surgical treatment of CLBP based solely upon degenerative MRI changes. Clinical Recommendations.Recommendation 1: There is insufficient evidence to support the routine use of MRI in patients with CLBP. Recommendation: StrongRecommendation 2: Surgical treatment of CLBP based exclusively on MRI findings of degenerative changes is not recommended. Recommendation: Strong

Complications and perioperative factors associated with learning the technique of minimally invasive transforaminal lumbar interbody fusion (TLIF)

Before the advent of minimally invasive spine surgery (MIS), open transforaminal lumbar interbody fusion (TLIF) was performed to treat spondylosis, spondylolisthesis, and spondylolysis. Minimally invasive TLIF has recently become more popular based upon the premise that a smaller, less traumatic incision should afford better recovery and outcomes. However, the learning curve associated with this technique must be considered. To analyze the perioperative factors associated with the learning curve in patients who underwent MIS TLIF versus open TLIF, we identified 22 patients who underwent TLIF from 2005 to 2008 within levels L4-S1 by the senior author (D.C.). Patients were subdivided into two groups according to whether they underwent: (i) MIS TLIF (10 patients, the first MIS TLIF procedures performed by D.C.); or (ii) open TLIF (12 patients). Preoperative, perioperative and postoperative factors were evaluated. Patients who underwent MIS TLIF had a statistically significant lower intraoperative transfusion rate, and rate of required postoperative surgical drains; and shorter periods of required drainage, and time to ambulation. However, the MIS TLIF group tended to have a higher rate of complications, which might have been associated with the learning curve. Both groups had a minimum of 1-year follow-up.

Surgical site infection in spinal surgery: description of surgical and patient-based risk factors for postoperative infection using administrative claims data.

Study Design. Retrospective analysis. Objective. The objective of this study was to investigate the accuracy of using an automated approach to administrative claims data to assess the rate and risk factors for surgical site infection (SSI) in spinal procedures. Summary of Background Data. SSI is a major indicator of health care quality. A wide range of SSI rates have been proposed in the literature depending on clinical setting and procedure type. Methods. All spinal surgeries performed at a university-affiliated tertiary-care center from July 2005 to December 2010 were identified using diagnosis-related group, current procedural terminology, and International Classification of Diseases, Ninth Revision (ICD-9) codes and were validated through chart review. Rates of SSI and associated risk factors were calculated using univariate regression analysis. Odds ratios were calculated through multivariate logistic regression. Results. A total of 6628 hospital visits were identified. The cumulative incidence of SSI was 2.9%. Procedural risk factors associated with a statistically significant increase in rates of infection were the following: sacral involvement (9.6%), fusions greater than 7 levels (7.8%), fusions greater than 12 levels (10.4%), cases with an osteotomy (6.5%), operative time longer than 5 hours (5.1%), transfusions of red blood cells (5.0%), serum (7.4%), and autologous blood (4.1%). Patient-based risk factors included anemia (4.3%), diabetes mellitus (4.2%), coronary artery disease (4.7%), diagnosis of coagulopathy (7.8%), and bone or connective tissue neoplasm (5.0%). Conclusion. Used individually, diagnosis-related group, current procedural terminology, and ICD-9 codes cannot completely capture a patient population. Using an algorithm combining all 3 coding systems to generate both inclusion and exclusion criteria, we were able to analyze a specific population of spinal surgery patients within a high-volume medical center. Within that group, risk factors found to increase infection rates were isolated and can serve to focus hospital-wide efforts to decrease surgery-related morbidity and improve patient outcomes.

Image-Guided Robotic Stereotactic Body Radiotherapy for Benign Spinal Tumors: The University of California San Francisco Preliminary Experience

We evaluate our preliminary experience using the Cyberknife® Radiosurgery System in treating benign spinal tumors. A retrospective review of 16 consecutively treated patients, comprising 19 benign spinal tumors, was performed. Histologic types included neurofibroma [11], chordoma [4], hemangioma [2], and meningioma [2]. Three patients had Neurofibromatosis Type 1 (NF1). Only one tumor, recurrent chordoma, had been previously irradiated, and as such not considered in the local failure analysis. Local failure, for the remaining 18 tumors, was based clinically on symptom progression and/or tumor enlargement based on imaging. Indications for spine stereotactic body radiotherapy (SBRT) consisted of either adjuvant to subtotal resection (5/19), primary treatment alone (12/19), boost following external beam radiotherapy (1/19), and salvage following previous radiation (1/19). Median tumor follow-up is 25 months (2–37), and one patient (with NF1) died at 12 months from a stroke. The median total dose, number of fractions, and prescription isodose was 21 Gy (10–30 Gy), 3 fx (1–5 fx), 80% (42–87%). The median tumor volume was 7.6 cc (0.2–274.1 cc). The median V100 (volume V receiving 100% of the prescribed dose) and maximum tumor dose was 95% (77–100%) and 26.7 Gy (15.4–59.7 Gy), respectively. Three tumors progressed at 2, 4, and 36 months post-SR (n=18). Two tumors were neurofibromas (both in NF1 patients), and the third was an intramedullary hemangioblastoma. Based on imaging, two tumors had MRI documented progression, three had regressed, and 13 were unchanged (n=18). With short follow-up, local control following Cyberknife spine SBRT for benign spinal tumors appear acceptable.

The use of allograft or autograft and expandable titanium cages for the treatment of vertebral osteomyelitis.

OBJECTIVEThe results of the surgical treatment of osteomyelitis with expandable titanium cages and either allograft or autograft are presented. METHODSThirty-six patients with vertebral osteomyelitis are presented. There were 7 cervical, 17 thoracic, 4 thoracolumbar (involving T12–L1), 5 lumbar, and 3 lumbosacral (involving L5–S1) lesions. The most frequently identified organisms were Staphylococcus aureus, Mycobacterium tuberculosis, and Coccidioides immitis. Imaging studies included x-rays, computed tomographic scans, and magnetic resonance imaging scans. All patients were treated with corpectomies and expandable cage reconstruction. Fusion was performed with rib autograft, iliac crest autograft, or allograft. Most patients who had an anterior approach also underwent posterior instrumentation, whereas a few had anterior instrumentation only. Four patients underwent a posterior approach (transpedicular corpectomy) only. RESULTSThe median follow-up period was 21 months. There were no implant failures. Two recurrences of infection were noted: 1 case involved allograft, and the other involved autograft. At follow-up, neurological deficits improved in all patients, and 81% of patients were pain-free. CONCLUSIONThis study suggests that the treatment of vertebral column osteomyelitis can be performed with expandable titanium cages, and allograft does not appear to increase the rate of recurrence, as compared with autograft.