Faculty Bibliography

BACKGROUND:Mesh cages have commonly been used for reconstruction after corpectomy. Recently, expandable cages have become a popular alternative. Regardless of cage type, subsidence is a concern following cage placement. OBJECTIVE:To assess whether subsidence rates differ between static and expandable cages, and identify independent risk factors for subsidence and extent of subsidence when present. METHODS:A consecutive population of patients who underwent corpectomy between 2006 and 2009 was identified. Subsidence was assessed via x-ray at 1-month and 1-year follow-ups. In addition to cage type, demographic, medical, and cage-related covariates were recorded. Multivariate models were used to assess independent associations with rate, odds, and extent of subsidence. RESULTS:Of 91 patients, 44.0% had expandable cages and 56.0% had static cages. One-month subsidence rate was 36.3%, and the 1-year subsidence rate was 51.6%. Expandable cages were independently associated with higher rates and odds of subsidence in comparison with static cages. Infection, trauma, and footplate-to-vertebral body endplate ratio of less than 0.5 were independent risk factors for subsidence. The presence of prongs on cages and posterior fusion 2 or more levels above and below corpectomy level had lower rates and odds of subsidence. Infection and cage placement in the thoracic or lumbar region had greater extent of subsidence when subsidence was present. CONCLUSION/CONCLUSIONS:Expandable cages had higher rates and risk of subsidence in comparison with static cages. When subsidence was present, expandable cages had greater magnitudes of subsidence. Other factors including footplate-to-vertebral body endplate ratio, prongs, extent of supplemental posterior fusion, spinal region, and diagnosis also impacted subsidence.

OBJECT/OBJECTIVE:A reported risk factor for adjacent-segment disease is injury to the superior facet joint from pedicle screw placement. Given that the facet joint is not typically visualized during percutaneous pedicle screw insertion, there is a concern for increased facet violation (FV) in minimally invasive fusion procedures. The purpose of this study was to analyze and compare the incidence of FV among patients undergoing minimally invasive transforaminal lumbar interbody fusion (MITLIF) and open transforaminal lumbar interbody fusion (TLIF). The impact of O-arm navigation compared with traditional fluoroscopy on FV in MITLIF is also assessed, as are risk factors for FV. METHODS:The authors identified a consecutive population of patients who underwent MITLIF with percutaneous pedicle screw placement, as well as a matched cohort of patients who underwent open TLIF. Postoperative CT imaging was assessed to determine intraarticular FV due to pedicle screw placement. Patients were stratified into minimally invasive and open TLIF groups. Within the MITLIF group, the authors performed a subanalysis of image guidance methods used in cases of FV. Two-tailed Student t-test, ANOVA, chi-square testing, and logistic regression were used for statistical analysis. RESULTS:A total of 282 patients were identified, with a total of 564 superior pedicle screw placements. The MITLIF group consisted of 142 patients with 284 screw insertions. The open TLIF group consisted of 140 patients with 280 screw insertions. Overall, 21 (7.4%) of 282 patients experienced FV. A total of 21 screws violated a facet joint for a screw-based FV rate of 3.7% (21 of 564 screws). There were no significant differences between the MITLIF and open TLIF groups in the percentage of patients with FV (6.3% vs 8.6%) and or the percentage of screws with FV (3.2% vs 4.3%) (p = 0.475 and p = 0.484, respectively). Further stratifying the MI group into O-arm navigation and fluoroscopic guidance subgroups, the patient-based rates of FV were 10.8% (4 of 37 patients) and 4.8% (5 of 105 patients), respectively, and the screw-based rates of FV were 5.4% (4 of 74 screws) and 2.4% (5 of 210 screws), respectively. There was no significant difference between the subgroups with respect to patient-based or screw-based FV rates (p = 0.375 and p = 0.442, respectively). The O-arm group had a significantly higher body mass index (BMI) (p = 0.021). BMI greater than 29.9 was independently associated with higher FV (OR 2.36, 95% CI 1.65-8.53, p = 0.039). CONCLUSIONS:The findings suggest that minimally invasive pedicle screw placement is not associated with higher rates of FV. Overall violation rates were similar in MITLIF and open TLIF. Higher BMI, however, was a risk factor for increased FV. The use of O-arm fluoroscopy with computer-assisted guidance did not significantly decrease the rate of FV.

STUDY DESIGN/METHODS:Retrospective case series. OBJECTIVE:To compare perioperative end points and outcomes of single-level versus multilevel corpectomy performed using a modified costotransversectomy approach. SUMMARY OF BACKGROUND DATA/BACKGROUND:Single-level corpectomy via posterolateral approach has been shown to be an effective alternative to the traditional anterior thoracotomy approach. However, there is a paucity of studies that have examined multilevel thoracic corpectomy via posterolateral approach. METHODS:Using electronic medical records, we identified a consecutive population of adult patients who underwent modified costotransversectomy corpectomy in the thoracic region between 2006 and 2009. Patients were stratified by number of corpectomies performed into either a single-level or multilevel group. With the use of baseline descriptive statistics and multivariate analysis, perioperative parameters and follow-up outcomes were assessed between the 2 groups. RESULTS:A total of 40 patients were included in the final analysis, with 25 patients in the single-level group and 15 patients in the multilevel group. Mean follow-up was 16.1 months. Overall complication rate was 37.5%. Between the 2 groups, there were no significant differences in operative time, blood loss, transfusion rate, quantity of blood transfused, length of hospital stay, or complication rates. Also, there were no significant differences in repeat surgery rate, Medical Research Council strength, Nurick score, or pain at most recent follow-up, and all groups gained a comparable magnitude of benefit from surgery. CONCLUSION/CONCLUSIONS:Multilevel corpectomy via modified costotransversectomy approach in the thoracic region is a feasible and effective option that does not seem to be associated with significantly increased morbidity. The degree of clinical improvement also seems comparable with single-level corpectomy.

OBJECT/OBJECTIVE:The surgical Apgar score (SAS) reliably predicts postoperative death and complications and has been validated in a large cohort of general and vascular surgery patients. However, there has been limited study of the utility of the score in the neurosurgical population. The authors tested the hypothesis that the SAS would predict postoperative complications and length of stay after neurosurgical procedures. METHODS:A cohort of 918 intracranial and spine surgery patients treated over a 3-year period were retrospectively evaluated. The 10-point SAS was calculated and postoperative 30-day mortality and complications rates, intensive care unit (ICU) stay, and hospital stay were assessed by 2 independent raters. Univariate analysis and multivariate logistic regression were performed. RESULTS:There were 145 patients (15.8%) with at least 1 complication and 24 patients (2.6%) who died within 30 days of surgery. Surgical Apgar scores were significantly associated with the likelihood of postoperative complications (p < 0.001) and death (p = 0.002); scores varied inversely with postoperative complication and mortality risk in a multivariate analysis. Low SASs also predicted prolonged ICU and hospital stay. Patients with scores of 0-2 stayed a mean of 18.9 days (p < 0.001) and patients with scores of 3-4 stayed an average of 14.3 days (p < 0.001) compared with 4.1 days in patients with scores of 9-10. CONCLUSIONS:The application of the surgical Apgar score to a neurosurgical cohort predicted 30-day postoperative mortality and complication rates as well as extended ICU and hospital stay. This readily calculated score may help neurosurgical teams efficiently direct postoperative care to those at highest risk of death and complications.

Comparative studies evaluating efficacy and safety of minimally invasive spinal fusion between patients with significant obesity (body mass index [BMI]≥35 kg/m(2)) and those of normal weight are scarce. We examined complication rates and outcomes for minimally invasive transforaminal lumbar interbody fusion (MITLIF) in patients with significant obesity and those of normal weight undergoing treatment for symptomatic spondylolisthesis. Patients with a BMI≥35 kg/m(2) or <25 kg/m(2) undergoing elective MITLIF for symptomatic spondylolisthesis for the period 2006-09 were identified. Of the 16 patients identified, nine patients with a mean BMI of 37.4 kg/m(2) were included in the obese group, while seven patients with a mean BMI of 23.4 kg/m(2) comprised the normal weight group. Estimated blood loss (EBL), operative time, complication rate, length of hospital stay, and clinical outcomes were assessed. Outcome measures included patient-reported visual analog scale (VAS) score for pain and the Oswestry Disability Index (ODI) questionnaire completed by the patient. No significant differences were found in blood loss (p=0.436), hospital stay (p=0.606), or number of surgical complications (p=0.920) between the two groups. Mean follow-up intervals were 15.0 months for patients with obesity, and 18.6 months for those of normal weight. Both groups had significant improvements in VAS (obese, p=0.003; normal, p=0.016) and ODI (obese, p=0.020; normal, p=0.034) scores. There were no statistically significant differences between normal weight and obese groups in postoperative VAS (p=0.728) and ODI (p=0.886) scores. Patients with significant obesity experienced clinical improvement similar to that of patients with normal weight, suggesting that obesity does not impact MITLIF outcomes. In addition, both groups experienced similar complication rates, operative times, EBL, and length of hospital stay.

Objective : To determine if autologous fat grafting to the posterior pharynx can reduce hypernasality in patients with cleft palate and mild velopharyngeal insufficiency (VPI). Design : Retrospective case series. Setting : Tertiary care center. Patients : Eleven patients with cleft palate status after palatoplasty (with or without secondary speech surgery) with nasendoscopic evidence of VPI. Interventions : Autologous fat was harvested and injected into the posterior pharynx under general anesthesia. Main Outcome Measures : Pre- and postoperative subjective, nasometry, and nasendoscopy data. Apnea-hypopnea indices (AHIs) were also assessed. Comparisons were made using Fisher's exact test, Student's t tests, and relative risk (RR) assessments. Results : An average of 13.1 mL of fat was injected (range: 5 to 22 mL). Mean follow-up was 17.5 months (range: 12 to 25 months). Statistically significant improvements in speech resonance were identified in nasometry (Zoo passage; p  =  .027) and subjective hypernasality assessment (p  =  .035). Eight of the patients (73%) demonstrated normal speech resonance after posterior pharyngeal fat grafting (PPFG) on subjective or objective assessment (p  =  .001). All five patients with previous secondary speech surgeries demonstrated normal speech resonance on similar assessment (RR  =  1.8; p  =  .13). Complete velopharyngeal closure was observed in seven patients on postoperative nasendoscopy. No changes in AHIs were observed (p  =  .581). Conclusion : PPFG may be best used as an adjunct to secondary speech surgery. In this series, PPFG was not accompanied by the negative sequelae of hyponasality, sleep apnea, or airway compromise.

Cervical fractures can result in severe neurological compromise and even death. One of the most commonly injured segments is the C2 vertebrae, which most frequently involves the odontoid process. In this report, we present the unusual case of a 28-year-old female who sustained a C2 vertebral body fracture (comminuted transverse fracture through the body and both transverse processes) that had both a significant distractive and rotational component, causing the fracture to be highly unstable. Application of halo bracing was unsuccessful. The patient subsequently required a C1-C4 posterior spinal fusion. Follow-up computer tomography imaging confirmed fusion and the patient did well clinically thereafter.

OBJECT/OBJECTIVE:Surgery for spinal metastasis is considered palliative, and postoperative survival is often less than a year. Recurrence of metastatic lesions is quite common, and it remains unclear whether repeat surgery is effective. In this study, the authors assessed independent predictors for survival at 6 months, 1 year, and 2 years after surgery, and examined whether repeat surgery for recurrence of spinal metastasis influenced survival rates. METHODS:Retrospective review of the electronic medical records was performed to identify a consecutive population of adult patients who underwent surgery for spinal metastasis during the period 2005-2011. Utilizing a Cox proportional hazard regression model, the authors assessed independent predictors and risk factors for survival at 6 months, 1 year, and 2 years after surgery. In addition, the impact of repeat surgery on survival was specifically assessed via multivariable analysis. RESULTS:A total of 99 patients were included in the final analysis. The overall mean postoperative duration of survival was 9.6 months. In addition to previously identified predictors of survival (preoperative ambulation, Karnofsky Performance Status [KPS], radiotherapy, primary cancer type, presence of extraspinal metastasis, and number of spinal segments with metastasis), pain on presentation and body mass index (BMI) of 25-30 were both independently associated with survival. Patients with recurrence who underwent repeat surgery had longer mean survival times than patients with recurrence who did not undergo repeat surgery (19.6 months vs 12.8 months, respectively). Repeat surgery was also independently associated with higher survival rates on multivariate analysis. Follow-up KPS was significantly higher in patients who underwent repeat surgery as well. CONCLUSIONS:In addition to confirming previously identified predictors of survival following surgery for spinal metastasis, the authors identified BMI and pain on presentation as independent predictors of survival. They also found that repeat surgery may be a viable option in patients with metastatic recurrence and may offer prolonged survival, likely due to improved functionality, mitigating complications associated with immobility.

BACKGROUND:Incidence and predictors of neurosurgical interventions following nonsevere traumatic brain injury (TBI) with mildly abnormal head computed tomographic (CT) findings are poorly defined. Despite this, neurosurgical consultation is routinely requested in this patient population. Our objective was to determine incidence of neurosurgical intervention in this patient population and identify clinical and radiographic features predicting the subsequent need for these interventions. METHODS:We identified all consecutive adult patients with nonsevere TBI admitted from January 1, 2001, through December 31, 2010. The definitions of "mildly abnormal initial head CT findings" and "neurosurgical interventions" were determined a priori by author consensus. Cumulative incidence of neurosurgical interventions was determined, and multivariate logistic regression was used to identify independent predictors of neurosurgical intervention. RESULTS:Of 677 patients, 51 underwent neurosurgical intervention for a cumulative incidence of 7.5%. Only 1.6% required an intracranial procedure. In adjusted analysis, presence of coagulopathy (odds ratio [OR], 2.21; 95% confidence interval [CI], 1.13-4.3; p = 0.02), suspected cerebrospinal fluid leak (OR, 11.36; 95% CI, 2.83-45.58; p = 0.001), any basal cistern or sylvian fissure subarachnoid hemorrhage (OR, 2.94; 95% CI, 1.56-5.57; p = 0.001), depressed skull fracture (OR, 2.84; 95% CI, 1.29-6.28; p = 0.01), or unstable repeated head CT findings (OR, 2.81; 95% CI, 1.52-5.2; p = 0.001) remained an independent predictor of the need for subsequent neurosurgical intervention. CONCLUSION/CONCLUSIONS:Among patients with nonsevere TBI and mildly abnormal head imaging findings in which routine neurosurgical consultation is obtained, there is a low incidence of neurosurgical interventions. Our findings suggest that routine early neurosurgical consultation in this patient population may not be necessary; however, this should be tested in a prospective, comparative study. LEVEL OF EVIDENCE/METHODS:Prognostic study, level III; therapeutic study, level IV.

OBJECT/OBJECTIVE:The extent of resection (EOR) is a known prognostic factor in patients with glioblastoma. However, gross-total resection (GTR) is not always achieved. Understanding the factors that prevent GTR is helpful in surgical planning and when counseling patients. The goal of this study was to identify demographic, tumor-related, and technical factors that influence EOR and to define the relationship between the surgeon's impression of EOR and radiographically determined EOR. METHODS:The authors performed a retrospective review of the electronic medical records to identify all patients who underwent craniotomy for glioblastoma resection between 2006 and 2009 and who had both preoperative and postoperative MRI studies. Forty-six patients were identified and were included in the study. Image analysis software (FIJI) was used to perform volumetric analysis of tumor size and EOR based on preoperative and postoperative MRI. Using multivariate analysis, the authors assessed factors associated with EOR and residual tumor volume. Perception of resectability was described using bivariate statistics, and survival was described using the log-rank test and Kaplan-Meier curves. RESULTS:The EOR was less for tumors in eloquent areas (p = 0.014) and those touching ventricles (p = 0.031). Left parietal tumors had significantly greater residual volume (p = 0.042). The average EOR was 91.0% in this series. There was MRI-demonstrable residual tumor in 69.6% of cases (16 of 23) in which GTR was perceived by the surgeon. Expert reviewers agreed that GTR could be safely achieved in 37.0% of patients (17 of 46) in this series. Among patients with safely resectable tumors, radiographically complete resection was achieved in 23.5% of patients (4 of 17). An EOR greater than 90% was associated with a significantly greater 1-year survival (76.5%) than an EOR less than 90% (p = 0.005). CONCLUSIONS:The authors' findings confirm that tumor location affects EOR and suggest that EOR may also be influenced by the surgeon's ability to judge the presence of residual tumor during surgery. The surgeon's ability to judge completeness of resection during surgery is commonly inaccurate. The authors' study confirms the impact of EOR on 1-year survival.