Isaac O. Karikari

Minimally invasive transforaminal lumbar interbody fusion: a review of techniques and outcomes.

Study Design. Review of published literature. Objective. To review the available medical literature reporting results after minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) and evaluate functional and radiographic outcomes with those following open TLIF and open posterior lumbar interbody fusion (PLIF) procedures. Summary of Background Data. Minimally invasive spine techniques aim to reduce approach-related surgical morbidity without compromising operative and clinical outcomes. MIS TLIF is increasingly being used for the management of various lumbar degenerative diseases. Despite the limited number of well-designed clinical studies, the available published data suggest potential advantages over its open posterior-approach lumbar interbody fusion counterparts. Such benefits include less intraoperative blood loss, less need for blood transfusions, shorter hospital course, and less postoperative pain. Methods. Literature examining posterior-approach interbody fusion techniques (PLIF, TLIF, and MIS TLIF) was collected using the National Center for Biotechnology Information database and PubMed/MEDLINE, and summarized for discussion. Results. Literature reports of MIS TLIF generally show comparable or improved clinical outcomes when compared with those following open posterior interbody fusion techniques. Additionally, significantly less blood loss, hospital stay, and complications were generally reported, despite slightly longer duration of surgery, especially during early cases in a surgeons experience. Conclusion. More studies designed to provide class I or II data will be needed in the future to further solidify the favorable results observed so far with the MIS TLIF procedure.

2012 Young Investigator Award winner: The distribution of body mass as a significant risk factor for lumbar spinal fusion postoperative infections.

Study Design. A retrospective review. Objective. The purpose of this study was to determine the role in body habitus and weight distribution on developing a surgical site infection (SSI). Summary of Background Data. SSI after lumbar spine surgery remains a significant cause of morbidity. The literature demonstrates an increased risk of postoperative infections associated with obesity, diabetes, and multilevel surgeries. Methods. A retrospective review was performed on a consecutive cohort of 298 adult patients who underwent lumbar spine fusion surgeries between 2006 and 2008 at the Duke University Medical Center. Previously identified risk factors (i.e., number of levels, diabetes, body mass index [BMI]) were collected, as well as the horizontal distance from the lamina to the skin surface (measured at L4) and thickness of subcutaneous fat at the surgical site. Results. Among the 298 patients, 24 (8%) had postoperative infections. Of the previously identified risk factors, number of levels (P = 0.0078) was found to be significantly associated with infections, whereas BMI (P = 0.16) and diabetes (P = 0.13) were found not to be statistically significant. Obesity (BMI ≥30) (P = 0.025), skin to lamina distance (P = 0.046), and thickness of the subcutaneous fat (P = 0.035) were found to be significant risk factors for SSI. Conclusion. Our findings suggest that in obese patients, the distribution of body mass is more predictive of SSI than the absolute BMI and deserves attention in preoperative evaluation.

Extreme lateral interbody fusion approach for isolated thoracic and thoracolumbar spine diseases: initial clinical experience and early outcomes.

Study Design Retrospective review of prospective collected data on 22 patients. Objective To describe our initial clinical experience and outcomes with the extreme lateral interbody fusion (XLIF) approach for spinal diseases requiring access to the thoracic cavity. Summary of Background Data Minimally invasive anterior approaches to the thoracic spine have traditionally consisted of thoracoscopic and mini-open thoracotomy techniques. We present our initial experience with employing the XLIF technique to treat thoracic spine diseases. Methods Clinical, radiographic, operative, postoperative, and functional outcomes were analyzed. Results A total of 22 patients (15 females, 7 males, average age 64.6 y) with isolated thoracic and thoracolumbar spine diseases were treated between 2005 and 2009. The indications for surgery included degenerative scoliosis (11), pathological fractures from tumors (2), adjacent level disease from prior fusions (5), thoracic disc herniations (3), and discitis/osteomyelitis (1). A total of 47 levels were treated. In the subset of patients treated for degenerative scoliosis, the mean preoperative and postoperative coronal Cobb angles were 22 and 14, respectively. The mean preoperative and postoperative sagittal angles were 39 and 44, respectively. The average estimated blood loss and length of stay were 227.5 mL and 4.8 d, respectively. Three complications consisting of wound infection, subsidence, and adjacent level disease requiring additional procedures were encountered. There were no neural, vascular, visceral injuries, or death. At a mean follow-up of 16.4 months (range, 3-50), we observed a 95.5% substantial clinical benefit. All patients who had reached a minimum of 6 months (95.5%) demonstrated radiographic evidence of fusion. Conclusions The XLIF technique can be expanded to treat diseases in the thoracic spine. Although the magnitude of deformity correction achieved is less than that of the traditional open approaches, the lesser invasiveness of this technique may be tolerable for the elderly and in patients with significant medical comorbidities.

Management of a spontaneous spinal epidural abscess: a single-center 10-year experience.

OBJECTIVEThere is significant debate in the literature regarding the optimal management of patients with the diagnosis of a spinal epidural abscess (SEA). Although some have advocated conservative treatment with intravenous antibiotics alone in select patients, recent studies have shown that patients treated without early surgery are more likely to have poor outcomes. METHODSIn this study, we review patients treated at a tertiary medical center with a spontaneous SEA. A total of 104 patients had a diagnosis of an SEA over a 10-year period. More than half of these patients presented with back pain alone and no objective motor weakness. Sixty-four patients (61.5%) were treated conservatively with computed tomography-guided aspiration or antibiotics alone based on blood cultures, whereas 40 patients (38.5%) underwent surgical decompression. RESULTSOf the patients managed nonoperatively, 11% improved, 64% remained stable, and 17% died. Conversely, of the patients treated with surgery, 25% improved, 43% remained stable, and 23% died. Review of the imaging studies revealed that 65.4% of patients had a ventral SEA, whereas 34.6% had a dorsal SEA. Although there were no statistically significant differences between these 2 groups in terms of management or outcome, 30.6% of the patients with a dorsal SEA were paraplegic or quadriplegic, and only 7.3% of the patients with a ventral SEA were paraplegic or quadriplegic (P = 0.003). CONCLUSIONOur data do not support the hypothesis that patients treated without early surgery are more likely to have a poor outcome. Furthermore, we propose that the anatomy of the SEA (ventral or dorsal) should play an important role in determining the treatment plan.

Impact of tumor histology on resectability and neurological outcome in primary intramedullary spinal cord tumors: a single-center experience with 102 patients.

BACKGROUND Surgical outcomes for intramedullary spinal cord tumors are affected by many variables including tumor histology and preoperative neurological function. OBJECTIVE To analyze the impact of tumor histology on neurological outcome in primary intramedullary spinal cord tumors. METHODS A retrospective review of 102 consecutive patients with intramedullary spinal cord tumors treated at a single institution between January 1998 and March 2009. RESULTS Ependymomas were the most common tumors with 55 (53.9%), followed by 21 astrocytomas (20.6%), 12 hemangioblastomas (11.8%), and 14 miscellaneous tumors (13.7%). Gross total resection was achieved in 50 ependymomas (90.9%), 3 astrocytomas (14.3%), 11 hemangioblastomas (91.7%), and 12 miscellaneous tumors (85.7%). At a mean follow-up of 41.8 months (range, 1-132 months), we observed recurrences in 4 ependymoma cases (7.3%), 10 astrocytoma cases (47.6%), 1 miscellaneous tumor case (7.1%), and no recurrence in hemangioblastoma cases. When analyzed by tumor location, there was no difference in neurological outcomes (P = .66). At the time of their last follow-up visit, 11 patients (20%) with an ependymoma improved, 38 (69%) remained the same, and 6 (10.9%) worsened. In patients with an astrocytoma, 1 (4.8%) improved, 10 (47.6%) remained the same, and 10 (47.6%) worsened. One patient (8.3%) with a hemangioblastoma improved and 11 (91.7%) remained the same. No patient with a hemangioblastoma worsened. In the miscellaneous tumor group, 2 (14.3%) improved, 10 (71.4%) remained the same, and 2 (14.3%) worsened. Preoperative neurological status (P = .02), tumor histology (P = .005), and extent of resection (P < .0001) were all predictive of functional neurological outcomes. CONCLUSION Tumor histology is the most important predictor of neurological outcome after surgical resection because it predicts resectability and recurrence.

Profiling of CD4+, CD8+, and CD4+CD25+CD45RO+FoxP3+ T Cells in Patients with Malignant Glioma Reveals Differential Expression of the Immunologic Transcriptome Compared with T Cells from Healthy Volunteers

Purpose: Analyses of T-cell mRNA expression profiles in glioblastoma multiforme has not been previously reported but may help to define and characterize the immunosuppressed phenotype in patients with this type of cancer. Experimental Design: We did microarray studies that have shown significant and fundamental differences in the expression profiles of CD4+ and CD8+ T cells and immunosuppressive CD4+CD25+CD45RO+FoxP3+ regulatory T cells (Treg) from normal healthy volunteers compared with patients with newly diagnosed glioblastoma multiforme. For these investigations, we isolated total RNA from enriched CD4+ and CD8+ T cell or Treg cell populations from age-matched individuals and did microarray analyses. Results: ANOVA and principal components analysis show that the various T cell compartments exhibit consistently similar mRNA expression profiles among individuals within either healthy or brain tumor groups but reflect significant differences between these groups. Compared with healthy volunteers, CD4+ and CD8+ T cells from patients with glioblastoma multiforme display coordinate down-regulation of genes involved in T cell receptor ligation, activation, and intracellular signaling. In contrast, Tregs from patients with glioblastoma multiforme exhibit increased levels of transcripts involved in inhibiting host immunity. Conclusion: Our findings support the notion that key differences between expression profiles in T-cell populations from patients with glioblastoma multiforme results from differential expression of the immunologic transcriptome, such that a limited number of genes are principally important in producing the dysregulated T-cell phenotype.

Minimally Invasive Lumbar Interbody Fusion in Patients Older Than 70 Years of Age: Analysis of Peri- and Postoperative Complications

BACKGROUND:The number of spine operations performed in the elderly population is rising. OBJECTIVE:To identify and describe perioperative and postoperative complications in patients 70 years and older who have undergone minimally invasive lumbar interbody spine fusion. METHODS:A retrospective analysis was performed on 66 consecutive patients aged 70 years or older who underwent a minimally invasive interbody lumbar fusion. Electronic medical records were analyzed for patient demographics, procedures, and perioperative and postoperative complications. RESULTS:Between 2000 and 2009, 66 patients with an average age of 74.9 years (range, 70-86 years) underwent 68 lumbar interbody fusions procedures. The mean follow-up was 14.7 months (range, 1.5-50 months). The minimally invasive approaches included 41 cases of extreme lateral interbody fusion and 27 minimally invasive transforaminal lumbar interbody fusions. We observed 5 major (7.4%) and 17 minor (25%) complications. The 5 major complications consisted of 4 cases of interbody graft subsidence and 1 adjacent level disease. There were no intraoperative medical complications. There were no myocardial infarctions, pulmonary embolisms, hardware complications requiring removal, wound infections, major visceral, vascular, neural injuries, or death in the study period. CONCLUSION:Minimally invasive interbody fusions can be performed in the elderly (ages 70 years and older) with an overall low rate of major complications. Graft subsidence in this population when not supplemented with posterior instrumentation is a concern. Age should not be a deterrent to performing complex minimally invasive interbody fusions in the elderly.

Cancer after spinal fusion: the role of bone morphogenetic protein.

BACKGROUND Bone morphogenetic protein (BMP) is used in tens of thousands of spinal fusions each year. A trial evaluating a high-dose BMP formulation demonstrated that its use may be associated with an increased risk of cancer. OBJECTIVE To evaluate whether BMP, as commonly used today, is associated with an increased risk of cancer or benign tumors. METHODS We performed a retrospective study using the Thomson Reuter MarketScan database. We retained all patients who had no previous diagnosis of cancer or benign tumor and had at least 2 years of uninterrupted enrollment in the database before and after their operations. A propensity score--matched cohort was created to ensure greater covariate balance between treatment groups. RESULTS Within the propensity score--matched cohort (n = 4698), BMP-exposed patients had a nonsignificant increase in the rate of cancer diagnosis (9.37% vs 7.92%; P = .08). After adjustment for covariates, BMP exposure was associated with a 31% increased risk of benign tumor diagnosis (odds ratio, 1.31; 95% confidence interval, 1.02-1.68; P < .05). When the benign tumor diagnoses were stratified by organ type, BMP patients had significantly more diagnoses of benign nervous system tumors (0.81% vs 0.34%; P = .03), and within this group, benign tumors of the spinal meninges were much more common in the BMP-treated group (0.13% vs 0.02%; P = .002). CONCLUSION The results of this large, independent, propensity-matched study suggest that the use of BMP in lumbar fusions is associated with a significantly higher rate of benign neoplasms but not malignancies.

Thickness of subcutaneous fat as a risk factor for infection in cervical spine fusion surgery.

BACKGROUND Surgical site infections increase the incidence of morbidity and mortality as well as health-care expenses. The cost of care increases threefold to fourfold as a consequence of surgical site infection after spinal surgery. The aim of the present study was to determine the role of subcutaneous fat thickness in the development of surgical site infection following cervical spine fusion surgery. METHODS We performed a retrospective review of a consecutive cohort of 213 adult patients who underwent posterior cervical spine fusion between 2006 and 2008 at Duke University Medical Center. The horizontal distance from the lamina to the skin surface at the C5 level and the thickness of subcutaneous fat were measured, and the ratio of the fat thickness to the total distance at the surgical site was determined. Previously identified risk factors for the development of surgical site infection were also recorded. RESULTS Twenty-two of the 213 patients developed a postoperative infection. Obesity (body mass index ≥ 30 kg/m2) was not a significant risk factor for surgical site infection; the body mass index (and 95% confidence interval) was 29.4 ± 1.2 kg/m2 in the patients who developed a surgical site infection compared with 28.9 ± 0.94 kg/m2 in the patients without an infection. However, the thickness of subcutaneous fat and the ratio of the fat thickness to the lamina-to-skin distance were both significant risk factors for infection. The thickness of subcutaneous fat was 27.0 ± 2.5 mm in the patients who developed a surgical site infection group compared with 21.4 ± 0.88 mm in the patients without an infection (p = 0.042). The ratio of fat thickness to total thickness was 0.42 ± 0.019 in the patients who developed a surgical site infection compared with 0.35 ± 0.01 in the patients without an infection (p = 0.020). Multivariate analysis revealed this ratio to be an independent risk factor for developing a postoperative infection (odds ratio, 3.18; 95% confidence interval, 1.02 to 9.97). CONCLUSIONS The study demonstrated that the thickness of subcutaneous fat at the surgical site is a factor in the development of surgical site infection following cervical spine fusion and deserves assessment in the preoperative evaluation.

Glioblastoma in the elderly: the effect of aggressive and modern therapies on survival

OBJECTIVE The prognosis of elderly patients with glioblastoma (GBM) is universally poor. Currently, few studies have examined postoperative outcomes and the effects of various modern therapies such as bevacizumab on survival in this patient population. In this study, the authors evaluated the effects of various factors on overall survival in a cohort of elderly patients with newly diagnosed GBM. METHODS A retrospective review was performed of elderly patients (≥ 65 years old) with newly diagnosed GBM treated between 2004 and 2010. Various characteristics were evaluated in univariate and multivariate stepwise models to examine their effects on complication risk and overall survival. RESULTS A total of 120 patients were included in the study. The median age was 71 years, and sex was distributed evenly. Patients had a median Karnofsky Performance Scale (KPS) score of 80 and a median of 2 neurological symptoms on presentation. The majority (53.3%) of the patients did not have any comorbidities. Tumors most frequently (43.3%) involved the temporal lobe, followed by the parietal (35.8%), frontal (32.5%), and occipital (15.8%) regions. The majority (57.5%) of the tumors involved eloquent structures. The median tumor size was 4.3 cm. Every patient underwent resection, and 63.3% underwent gross-total resection (GTR). The vast majority (97.3%) of the patients received the postoperative standard of care consisting of radiotherapy with concurrent temozolomide. The majority (59.3%) of patients received additional agents, most commonly consisting of bevacizumab (38.9%). The median survival for all patients was 12.0 months; 26.7% of patients experienced long-term (≥ 2-year) survival. The extent of resection was seen to significantly affect overall survival; patients who underwent GTR had a median survival of 14.1 months, whereas those who underwent subtotal resection had a survival of 9.6 months (p = 0.038). Examination of chemotherapeutic effects revealed that the use of bevacizumab compared with no bevacizumab (20.1 vs 7.9 months, respectively; p < 0.0001) and irinotecan compared with no irinotecan (18.0 vs 9.7 months, respectively; p = 0.027) significantly improved survival. Multivariate stepwise analysis revealed that older age (hazard ratio [HR] 1.06 [95% CI1.02-1.10]; p = 0.0077), a higher KPS score (HR 0.97 [95% CI 0.95-0.99]; p = 0.0082), and the use of bevacizumab (HR 0.51 [95% CI 0.31-0.83]; p = 0.0067) to be significantly associated with survival. CONCLUSION This study has demonstrated that GTR confers a modest survival benefit on elderly patients with GBM, suggesting that safe maximal resection is warranted. In addition, bevacizumab significantly increased the overall survival of these elderly patients with GBM; older age and preoperative KPS score also were significant prognostic factors. Although elderly patients with GBM have a poor prognosis, they may experience enhanced survival after the administration of the standard of care and the use of additional chemotherapeutics such as bevacizumab.