Faculty Bibliography

OBJECT/OBJECTIVE:Vascular endothelial growth factor (VEGF) is the major proangiogenic factor in many solid tumors. Vascular endothelial growth factor receptor (VEGFR) is expressed in abundance in pediatric patients with medulloblastoma and is associated with tumor metastasis, poor prognosis, and proliferation. Gadolinium enhancement on MRI has been suggested to have prognostic significance for some tumors. The association of VEGF/VEGFR and Gd enhancement in medulloblastoma has never been closely examined. The authors therefore sought to evaluate whether Gd-enhancing medulloblastomas have higher levels of VEGFR and CD31. Outcomes and survival in patients with enhancing and nonenhancing tumors were also compared. METHODS:A retrospective analysis of patients with enhancing, nonenhancing, and partially enhancing medulloblastomas was performed. Primary end points included risk stratification, extent of resection, and perioperative complications. A cohort of 3 enhancing and 3 nonenhancing tumors was selected for VEGFR and CD31 analysis as well as microvessel density measurements. RESULTS:Fifty-eight patients were analyzed, and 20.7% of the medulloblastomas in these patients were nonenhancing. Enhancing medulloblastomas exhibited strong VEGFR1/2 and CD31 expression relative to nonenhancing tumors. There was no significant difference in perioperative complications or patient survival between the 2 groups. CONCLUSIONS:These results suggest that in patients with medulloblastoma the presence of enhancement on MRI may correlate with increased vascularity and angiogenesis, but does not correlate with worse patient prognosis in the short or long term.

OBJECT/OBJECTIVE:The most common indications for circumferential cervical decompression and fusion are cervical spondylotic myelopathy (CSM) and cervical osteomyelitis (COM). Currently, the informed consent process prior to circumferential cervical fusion surgery is not different for these two groups of patients, as details of their diagnosis-specific risk profiles have not been quantified. The authors compared two patient cohorts with either CSM or COM treated using circumferential fusion. They sought to quantify perioperative morbidity and postoperative mortality in these two groups to assist with a diagnosis-specific informed consent process for future patients undergoing this type of surgery. METHODS:Perioperative and follow-up data from two cohorts of patients who had undergone circumferential cervical decompression and fusion were analyzed. Estimated blood loss (EBL), length of stay (LOS), perioperative complications, hospital readmission, 30-day reoperation rates, change in Nurick grade, and mortality were compared between the two groups. RESULTS:Twenty-two patients were in the COM cohort, and 24 were in the CSM cohort. Complications, hospital readmission, 30-day reoperation rates, EBL, and mortality were not statistically different, although patients with COM trended higher in each of these categories. There was a significantly greater LOS (p < 0.001) in the COM group and greater improvement in Nurick grade in the CSM group (p < 0.001). CONCLUSIONS:When advising patients undergoing circumferential fusion about perioperative risk factors, it is important for those with COM to know that they are likely to have a higher rate of complications and mortality than those with CSM who are undergoing similar surgery. Furthermore, COM patients have less neurological improvement than CSM patients after surgery. This information may be useful to surgeons and patients in providing appropriate informed consent during preoperative planning.

STUDY DESIGN/METHODS:Retrospective study. PURPOSE/OBJECTIVE:The aim of this study was to evaluate the clinical management and outcomes of patients who underwent surgical intervention for metastatic colorectal adenocarcinoma of the spine. OVERVIEW OF LITERATURE/BACKGROUND:Gastrointestinal (GI) cancer metastasis to the spine are relatively rare and represent later manifestations of the disease. Studies and reports on the outcomes of patients who undergo surgery for spinal metastasis of GI origin are scarce. METHODS:A retrospective chart review of all patients who underwent surgery for spinal metastasis of colorectal origin was performed. Four patients were identified. Patient characteristics, outcomes, and survival were analyzed. RESULTS:Two patients experienced improvement in pain or myelopathic symptoms. Although the mean survival was 15.3 months, this average included a patient still living at 57.1 months. The mean survival was just 1.3 months for the 3 patients who expired. CONCLUSIONS:In certain cases, symptomatic improvement with prolonged survival is possible after surgery for metastatic spinal lesions of colorectal origin; however, survival is poor in the majority of cases.

OBJECT/OBJECTIVE:Minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) has been demonstrated in previous studies to offer improvement in pain and function comparable to those provided by the open surgical approach. However, comparative studies in the obese population are scarce, and it is possible that obese patients may respond differently to these two approaches. In this study, the authors compared the clinical benefit of open and MI TLIF in obese patients. METHODS:The authors conducted a retrospective cohort study based on review of electronic medical records at a single institution. Eligible patients had a body mass index (BMI) ≥ 30 kg/m(2), were ≥ 18 years of age, underwent single-level TLIF between 2007 and 2011, and outcome was assessed at a minimum 6 months postoperatively. The authors categorized patients according to surgical approach (open vs MI TLIF). Outcome measures included postoperative improvement in visual analog scale (VAS), Oswestry Disability Index (ODI), estimated blood loss (EBL), and hospital length of stay (LOS). RESULTS:A total 74 patients (21 open and 53 MI TLIF) were studied. Groups had similar baseline characteristics. The median BMI was 34.4 kg/m(2) (interquartile range 31.6-37.5 kg/m(2)). The mean follow-up time was 30 months (range 6.5-77 months). The mean improvement in VAS score was 2.8 (95% CI 1.9-3.8) for the open group (n = 21) and 2.4 (95% CI 1.8-3.1) for the MI group (n = 53), which did not significantly differ (unadjusted, p = 0.49; adjusted, p = 0.51). The mean improvement in ODI scores was 13 (95% CI 3-23) for the open group (n = 14) and 15 (95% CI 8-22) for the MI group (n = 45), with no significant difference according to approach (unadjusted, p = 0.82; adjusted, p = 0.68). After stratifying by BMI (< 35 kg/m(2) and ≥ 35 kg/m(2)), there was still no difference in either VAS or ODI improvement between the approaches (both unadjusted and adjusted, p > 0.05). Complications and EBL were greater for the open group than for the MI group (p < 0.05). CONCLUSIONS:Obese patients experienced clinically and statistically significant improvement in both pain and function after undergoing either open or MI TLIF. Patients achieved similar clinical benefit whether they underwent an open or MI approach. However, patients in the MI group experienced significantly decreased operative blood loss and complications than their counterparts in the open group.

OBJECT/OBJECTIVE:Long-segment spinal instrumentation ending at the sacrum places substantial biomechanical stress on sacral screws. Iliac (pelvic) screws relieve some of this stress by supplementing the caudal fixation. It remains an open question whether there is any clinically significant difference in sacropelvic fixation with bilateral versus unilateral iliac screws. The primary purpose of this study was to compare clinical and radiographic complications in the use of bilateral versus unilateral iliac screw fixation. METHODS:The authors retrospectively reviewed 102 consecutive spinal fixation cases that extended to the pelvis at a single institution (University of California, San Francisco) in the period from 2005 to 2012 performed by the senior authors. Charts were reviewed for the following complications: reoperation, L5-S1 pseudarthrosis, sacral insufficiency fracture, hardware prominence, iliac screw loosening, and infection. The t-test, Pearson chi-square test, and Fisher exact test were used to determine statistical significance. RESULTS:The mean follow-up was 31 months. Thirty cases were excluded: 12 for inadequate follow-up, 15 for lack of L5-S1 interbody fusion, and 3 for preoperative osteomyelitis. The mean age among the 72 remaining cases was 62 years (range 39-79 years). Forty-six patients underwent unilateral and 26 bilateral iliac screw fixation. Forty-one percent (n = 19) of the unilateral cases and 50% (n = 13) of the bilateral cases were treated with reoperation (p = 0.48). In addition, 13% (n = 6) of the unilateral and 19% (n = 5) of the bilateral cases developed L5-S1 pseudarthrosis (p = 0.51). There were no sacral insufficiency fractures. Thirteen percent (n = 6) of the unilateral and 7.7% (n = 2) of the bilateral cases developed postoperative infection (p = 0.70). CONCLUSIONS:In a retrospective single-institution study, single versus dual pelvic screws led to comparable rates of reoperation, iliac screw removal, postoperative infection, pseudarthrosis, and sacral insufficiency fractures. For spinopelvic fixation, placing bilateral (vs unilateral) pelvic screws produced no added clinical benefit in most cases.

Severe thoracic kyphosis caused by pathologic fractures often needs to be corrected by resection of the collapsed vertebral body, reconstruction of the anterior spinal column, and correction of the kyphosis with long-segment fixation. The resection of this pathologic bone functions essentially as a vertebral column resection. With the advent of minimally invasive technology, the powerful corrective forces afforded in open cases can be applied using a less invasive approach. In this article, we describe a mini-open posterior technique for thoracic kyphosis via a vertebrectomy and cantilever technique. Two patients underwent kyphosis correction via mini-open vertebrectomy. One patient was corrected from 92 degrees to 65 degrees, and the second patient was corrected from 70 degrees to 53 degrees. Both patients underwent a mini-open approach. Cantilever correction was accomplished over an expandable cage with a minimally invasive pedicle screw system. We describe our technique of mini-open vertebral column resection and kyphosis correction in the thoracic spine.

Holospinal epidural abscess (HEA) is an extremely rare condition in which spinal epidural abscesses extend from the cervical to the sacral spine. We report two patients who presented with myelopathy secondary to HEA. Both patients underwent urgent surgical decompression and abscess drainage, and had significant improvement in neurological function. We discuss the surgical management strategies and briefly review the literature regarding HEA.

BACKGROUND:Local recurrence of spinal metastasis after surgical resection is relatively common. We sought to determine risk factors and independent predictors for local recurrence after primary surgical resection of spinal metastasis. METHODS:Demographic and clinical variables were collected for patients who underwent surgery for spinal metastasis June 2005 to June 2011. Primary outcome of interest was local recurrence. Significant associations between covariates of interest and recurrence were identified using the chi-square test. Multivariable logistic regression models for recurrence risk were fit and adjusted for potential confounders. RESULTS:A total of 99 patients were analyzed. Mean time to metastatic recurrence was 9.8 months. Thirty-two patients (32.3 %) had local recurrence of metastatic disease following initial surgery. Patients who underwent radiotherapy had significantly higher recurrence rates than patients who did not (39.2 % vs. 12.0 %, respectively; P = 0.012). Patients with metastatic disease affecting more levels had significantly lower recurrence rates. On multivariate analysis, older age was an independent predictor of decreased likelihood of local recurrence. Melanoma was the only cancer type independently associated with higher risk for recurrence. Patients with recurrence had significantly higher 1- and 2-year survival rates than patients without recurrence. Median length of survival was longer in the recurrent group as well. CONCLUSIONS:Other than melanoma, covariates significantly associated with recurrence were factors likely associated with increased survival, including less-extensive spinal disease and radiotherapy. Thus, longer survival time following surgery likely results in a greater chance for local recurrence. As advancements in treatment provide prolonged survival, local recurrence rates will likely increase.

Cigarette smoking is a common health risk behavior among the general adult population, and is the leading preventable cause of morbidity and mortality in the US. The surgical literature shows that active tobacco smoking is a major risk factor for perioperative morbidity and complications, and that preoperative smoking cessation is an effective measure to lower these risks associated with active smoking. However, few studies have examined the effects of smoking and perioperative complications following neurosurgical procedures. The goal of this review was to highlight the scientific data that do exist regarding the impact of smoking on neurosurgical outcomes, to promote awareness of the need for further work in the specific neurosurgical context, and to suggest ways that neurosurgeons can promote smoking cessation in their patients and lead efforts nationally to emphasize the importance of preoperative smoking cessation. This review indicates that there is limited but good evidence that smoking is associated with higher rates of perioperative complications following neurosurgical intervention. Specific research is needed to understand the effects of smoking and perioperative complications. Neurosurgeons should encourage preoperative smoking cessation as part of their clinical practice to mitigate perioperative morbidity associated with active smoking.

Desmoplastic fibroma (DF) is a rare bone tumor that accounts for about 0.1%-0.3% of all bone tumors. It is typically characterized as slow growing, but in rare cases it can proliferate extensively and exhibit locally aggressive characteristics. It is found most commonly in the appendicular skeleton and rarely in the axial skeleton. The authors present the cases of 2 women in their 20s with DF originating from the cervicothoracic spine. Both tumors intimately involved the brachial plexus and caused significant impingement of the mediastinum resulting in cardiopulmonary compromise. Both patients underwent hemiclamshell thoracotomies for tumor resection, and in both cases subtotal resection was performed given the encasement of the brachial plexus. Although DF is a benign process, it can be locally aggressive and proliferate at extensive rates. The authors describe these 2 cases, review the literature, and discuss management.