Faculty Bibliography

OBJECTIVE Smoking is a known risk factor for aneurysm development and aneurysmal subarachnoid hemorrhage, as well as subsequent vasospasm in both untreated individuals and patients who have undergone surgical clipping of cerebrovascular aneurysms. However, there is a lack of data in the current scientific literature about the long-term effects that smoking has on the integrity of endovascular repairs of cerebral aneurysms. This study was designed to determine if any smoking history increased the risk of poorer outcomes and/or aneurysm recurrence in patients who have had endovascular repair of cerebral aneurysms. METHODS The authors retrospectively analyzed the medical records of patients admitted to the University of Michigan Health System from January 1999 to December 2011 with coiled aneurysms and angiography, CT angiography, or MR angiography follow-up. Patients were identified and organized based on many criteria including age, sex, smoking history, aneurysm recurrence, aneurysm location, and Hunt and Hess grade. Analysis was targeted to the patient population with a history of smoking. Bivariate chi-square tests were used to analyze the association between a positive smoking history and documented aneurysm recurrence and were adjusted for potential confounders by fitting multivariate logistic regression models of recurrence. RESULTS A total of 247 patients who had undergone endovascular treatment of 296 documented cerebral aneurysms were included in this study. The recurrence rate among all patients treated with endovascular repair was 24.3%, and the average time to the most recent follow-up imaging studies was 1.62 years. Smokers accounted for 232 aneurysms and were followed up for an average of 1.57 years, with a recurrence rate of 26.3%. Never smokers accounted for the remaining 64 aneurysms and were followed up for an average of 1.82 years, with a recurrence rate of 17.2%. Multivariate analysis revealed that, after controlling for potential confounders, a history of smoking-whether current or former-was associated with a significantly increased risk of aneurysm recurrence. The odds ratios for aneurysm recurrence for current and former smokers were 2.739 (95% CI 1.127-7.095, p = 0.0308) and 2.698 (95% CI 1.078-7.212, p = 0.0395), respectively, compared with never smokers. CONCLUSIONS A positive smoking history is associated with a significantly increased risk of aneurysm recurrence in patients who have undergone endovascular repair of a cerebral aneurysm, compared with the risk in patients who have never smoked.

OBJECTIVE Proximal junctional kyphosis (PJK) is a well-recognized, yet incompletely defined, complication of adult spinal deformity surgery. There is no standardized definition for PJK, but most studies describe PJK as an increase in the proximal junctional angle (PJA) of greater than 10°-20°. Ligament augmentation is a novel strategy for PJK reduction that provides strength to the upper instrumented vertebra (UIV) and adjacent segments while also reducing junctional stress at those levels. METHODS In this study, ligament augmentation was used in a consecutive series of adult spinal deformity patients at a single institution. Patient demographics, including age; sex; indication for surgery; revision surgery; surgical approach; and use of 3-column osteotomies, vertebroplasty, or hook fixation at the UIV, were collected. The PJA was measured preoperatively and at last follow-up using 36-inch radiographs. Data on change in PJA and need for revision surgery were collected. Univariate and multivariate analyses were performed to identify factors associated with change in PJA and proximal junctional failure (PJF), defined as PJK requiring surgical correction. RESULTS A total of 200 consecutive patients were included: 100 patients before implementation of ligament augmentation and 100 patients after implementation of this technique. The mean age of the ligament augmentation cohort was 66 years, and 67% of patients were women. Over half of these cases (51%) were revision surgeries, with 38% involving a combined anterior or lateral and posterior approach. The mean change in PJA was 6° in the ligament augmentation group compared with 14° in the control group (p < 0.001). Eighty-four patients had a change in PJA of less than 10°. In a multivariate linear regression model, age (p = 0.016), use of hook fixation at the UIV (p = 0.045), and use of ligament augmentation (p < 0.001) were associated with a change in PJA. In a separate model, only ligament augmentation (OR 0.193, p = 0.012) showed a significant association with PJF. CONCLUSIONS Ligament augmentation represents a novel technique for the prevention of PJK and PJF. Compared with a well-matched historical cohort, ligament augmentation is associated with a significant decrease in PJK and PJF. These data support the implementation of ligament augmentation in surgery for adult spinal deformity, particularly in patients with a high risk of developing PJK and PJF.

OBJECTIVE There is ample evidence that extent of resection (EOR) is associated with improved outcomes for glioma surgery. However, it is often difficult to accurately estimate EOR intraoperatively, and surgeon accuracy has yet to be reviewed. In this study, the authors quantitatively assessed the accuracy of intraoperative perception of EOR during awake craniotomy for tumor resection. METHODS A single-surgeon experience of performing awake craniotomies for tumor resection over a 17-year period was examined. Retrospective review of operative reports for quantitative estimation of EOR was recorded. Definitive EOR was based on postoperative MRI. Analysis of accuracy of EOR estimation was examined both as a general outcome (gross-total resection [GTR] or subtotal resection [STR]), and quantitatively (5% within EOR on postoperative MRI). Patient demographics, tumor characteristics, and surgeon experience were examined. The effects of accuracy on motor and language outcomes were assessed. RESULTS A total of 451 patients were included in the study. Overall accuracy of intraoperative perception of whether GTR or STR was achieved was 79.6%, and overall accuracy of quantitative perception of resection (within 5% of postoperative MRI) was 81.4%. There was a significant difference (p = 0.049) in accuracy for gross perception over the 17-year period, with improvement over the later years: 1997-2000 (72.6%), 2001-2004 (78.5%), 2005-2008 (80.7%), and 2009-2013 (84.4%). Similarly, there was a significant improvement (p = 0.015) in accuracy of quantitative perception of EOR over the 17-year period: 1997-2000 (72.2%), 2001-2004 (69.8%), 2005-2008 (84.8%), and 2009-2013 (93.4%). This improvement in accuracy is demonstrated by the significantly higher odds of correctly estimating quantitative EOR in the later years of the series on multivariate logistic regression. Insular tumors were associated with the highest accuracy of gross perception (89.3%; p = 0.034), but lowest accuracy of quantitative perception (61.1% correct; p < 0.001) compared with tumors in other locations. Even after adjusting for surgeon experience, this particular trend for insular tumors remained true. The absence of 1p19q co-deletion was associated with higher quantitative perception accuracy (96.9% vs 81.5%; p = 0.051). Tumor grade, recurrence, diagnosis, and isocitrate dehydrogenase-1 (IDH-1) status were not associated with accurate perception of EOR. Overall, new neurological deficits occurred in 8.4% of cases, and 42.1% of those new neurological deficits persisted after the 3-month follow-up. Correct quantitative perception was associated with lower postoperative motor deficits (2.4%) compared with incorrect perceptions (8.0%; p = 0.029). There were no detectable differences in language outcomes based on perception of EOR. CONCLUSIONS The findings from this study suggest that there is a learning curve associated with the ability to accurately assess intraoperative EOR during glioma surgery, and it may take more than a decade to be truly proficient. Understanding the factors associated with this ability to accurately assess EOR will provide safer surgeries while maximizing tumor resection.

Surgery guided by 5-aminolevulinic acid (ALA) fluorescence has become a valuable adjunct in the resection of malignant intracranial gliomas. Furthermore, the fluorescence intensity of biopsied areas of a resection cavity correlates with histological identification of tumor cells. However, in the case of lesions deep within a resection cavity, light penetration may be suboptimal, resulting in less excitation of 5-ALA metabolites, leading to decreased fluorescence emission. To address this obstacle, the authors report on the use of a 400-nm wavelength fiber-optic lighted suction instrument that can be used both during resection of a tumor and to provide direct light to deeper areas of a resection cavity. In the presented case, this wavelength-specific lighted suction instrument improved the fluorescence intensity of patches of malignant tissue within the resection cavity. This technique may further improve the utility of 5-ALA in identifying tumor-infiltrated tissue for deep-seated lesions. Additionally, this tool may have implications for scoring systems that correlate 5-ALA fluorescence intensity with histological identification of malignant cells.

INTRODUCTION:Brachytherapy is a major adjuvant modality for neoplasms, but few have trialed its use for spinal tumors. This study examines perioperative and oncologic outcomes of patients with malignant spinal tumors who underwent resection with intraoperative phosphorous-32 (P32) brachytherapy. METHODS:Consecutive adult patients who underwent P32 brachytherapy during malignant spinal tumor resection were retrospectively identified from 2014 to 2015. Complications, tumor recurrence, and survival were reviewed. A comprehensive review of the literature was performed. RESULTS:A total of 8 patients were included. Average age was 54.3 years, and 25.0% were males. Tumor types included metastatic leiomyosarcoma, chordoma, multifocal recurrent ependymomas, breast metastasis, malignant meningioma, and myxofibrosarcoma. One-half of patients underwent en bloc tumor resection. P32 plaques were applied to 2 sites per patient for mean 13.1 minutes per site with a goal penetration of 10 Gy to 1-mm depth. Perioperative complications occurred in 3 patients (37.5%), including a persistent cerebral spinal fluid leak, deep infection requiring reoperation, and sacral insufficiency fracture. At a mean 25.6 months follow-up, local recurrence rate was 25.0%, and overall survival was 75.0%. Mean time to recurrence was 14.4 months. Survival at 6, 12, 18, and 24 months was 100.0%, 100.0%, 85.7%, and 71.4%, respectively. CONCLUSIONS:The use of P32 is safe and feasible. P32 intraoperative brachytherapy does not seem to increase the rate of complications. The sample size of this series is small with heterogeneity in tumor type, but recurrence and survival outcomes seem promising compared with previous reports. Further clinical trials are needed.

Pedicle aplasia is an uncommon congenital anomaly most frequently involving the absence of a single pedicle at a single vertebral level. Bilateral pedicle aplasia at multiple levels is exceedingly rare and has only been described once previously in the literature. While single-level pedicle aplasia is often asymptomatic and discovered incidentally, pedicle aplasia of multiple levels may produce severe spinal deformities and neurological deficits. Due to the rarity of this condition, optimal management remains uncertain. In this case report, the authors describe the surgical management of a healthy 9-year-old boy who presented with frequent falls, difficulty running, and severe thoracic kyphotic deformity and was found to have bilateral pedicle aplasia from T3 to T9. A review of the literature regarding pedicle aplasia is also presented.

BACKGROUND:Patient safety is foundational to neurosurgical care. Postprocedural "debrief" checklists have been proposed to improve patient safety, but data about their use in neurosurgery are limited. Here, we implemented an initiative to routinely perform postoperative debriefs and evaluated the impact of debriefing on operating room (OR) safety culture. METHODS:A 10-question safety attitude questionnaire (SAQ) was sent to neurosurgical OR staff at a major academic medical center before and 18 months after the implementation of a postoperative debriefing initiative. Rates of debrief compliance and changes in attitudes before and after the survey were evaluated. The survey used a Likert scale and analyzed with standard statistical methods. RESULTS:After the debrief initiative, the rate of debriefing increased from 51% to 86% of cases for the neurosurgery service. Baseline SAQ responses found that neurosurgeons had a more favorable perception of OR safety than did anesthesiologists and nurses. After implementation of the postoperative debriefing process, perceptions of OR safety significantly improved for neurosurgeons, anesthesiologists, and nurses. Furthermore, the disparity between nurses and surgeons was no longer significant. After debrief implementation, neurosurgical OR staff had improved perceptions of patient safety compared with surgical services that did not commonly perform debriefing. Debriefing identified OR efficiency concerns in 26.9% of cases, and prevention of potential adverse events/near misses was reported in 8% of cases. CONCLUSIONS:Postoperative debriefing can be effectively introduced into the OR and improves the safety culture after implementation. Debriefing is an effective tool to identify OR inefficiencies and potential adverse events.

Choroid plexus papillomas (CPPs) are typically benign tumors that can occur in any age group but are more commonly found in pediatric patients. Although these tumors are benign, there are several reports in adult patients of distant metastases present either at the time of diagnosis or occurring months to years after initial resection. Here, the authors report the case of a 14-year-old boy who presented with symptoms of elevated intracranial pressure due to obstructive hydrocephalus that was caused by a large fourth ventricular mass. Preoperative imaging included a full MRI of the spine, which revealed an intradural lesion that encased the distal sacral nerve roots at the tip of the thecal sac and was concerning for a drop metastasis. The patient underwent gross-total resection of both the fourth ventricular and sacral tumors with histology of both lesions consistent with benign CPP (WHO Grade I). In addition, the authors review prior reports of both pediatric and adult patients in whom benign CPPs have metastasized with either benign or atypical pathology found at a distant site. Taking into account this unusual case and reports in the literature, patients with even benign CPPs may warrant initial and routine follow-up imaging of the total neural axis in search of the rare, but possible, occurrence of drop metastasis.

OBJECTIVE Adult spinal deformity (ASD) develops in the setting of asymmetrical arthritic degeneration, and can also be due to iatrogenic causes, such as prior surgery. Many patients who present with ASD have undergone prior spine surgery with instrumentation. Unfortunately, contemporary studies that evaluate the effect of prior surgery or instrumentation on perioperative outcomes, readmission rates, and need for reoperation are lacking. METHODS All ASD patients who underwent a 3-column osteotomy performed by the senior author at the authors' institution for correction of thoracolumbar spinal deformity between 2006 and 2016 were identified. The authors compared surgical outcomes between primary (first-time) and revision cases. Further subgroup analysis was conducted to investigate the effect of the number of prior surgeries (0, 1, 2, 3, 4, and 5 or more) and the presence of spinal instrumentation on outcomes. Multivariate analysis was used to adjust for relevant and significant confounders. RESULTS A total of 300 patients were included; 38.3% of patients were male. The overall perioperative complication rate was 24.7%, and the mean length of hospitalization was 8.2 days. The 90-day readmission rate was 9.0%, and the overall follow-up reoperation rate was 26.7%. There were no significant differences in complication rates (26.6% vs 24.0%, p = 0.645), length of hospitalization (8.7 vs 7.9 days, p = 0.229), readmission rates (11.4% vs 8.1%, p = 0.387), or reoperation rates (26.6% vs 26.7%, p = 0.984) between primary and revision cases. There was no significant difference in wound complications (infections/dehiscence) requiring reoperation (5.1% vs 6.3%, p = 0.683). Subgroup analysis conducted to evaluate the effect of the number of prior spinal surgeries or the presence of spinal instrumentation did not reveal significant differences for the aforementioned surgical outcomes. In adjusted multivariate analysis, there were no significant associations between history of prior surgery (number of prior surgeries and prior instrumentation) and all of the surgical outcomes of interest. CONCLUSIONS The findings from this study suggest that patients who have undergone prior spine surgery with or without instrumentation are not at increased risk for perioperative complications, need for readmission, or reoperation following 3-column osteotomy of the thoracolumbar spine.

OBJECTIVE During the mini-open posterior corpectomy, percutaneous instrumentation without fusion is performed above and below the corpectomy level. In this study, the authors' goal was to compare the perioperative and long-term implant failure rates of patients who underwent nonfused percutaneous instrumentation with those of patients who underwent traditional open instrumented fusion. METHODS Adult patients who underwent posterior thoracic corpectomies with cage reconstruction between 2009 and 2014 were identified. Patients who underwent mini-open corpectomy had percutaneous instrumentation without fusion, and patients who underwent open corpectomy had instrumented fusion above and below the corpectomy site. The authors compared perioperative outcomes and rates of implant failure requiring reoperation between the open (fused) and mini-open (unfused) groups. RESULTS A total of 75 patients were identified, and 53 patients (32 open and 21 mini-open) were available for followup. The mean patient age was 52.8 years, and 56.6% of patients were male. There were no significant differences in baseline variables between the 2 groups. The overall perioperative complication rate was 15.1%, and there was no significant difference between the open and mini-open groups (18.8% vs 9.5%; p = 0.359). The mean hospital stay was 10.5 days. The open group required a significantly longer stay than the mini-open group (12.8 vs 7.1 days; p < 0.001). Overall implant failure rates requiring reoperation were 1.9% at 6 months, 9.1% at 1 year, and 14.7% at 2 years. There were no significant differences in reoperation rates between the open and mini-open groups at 6 months (3.1% vs 0.0%, p = 0.413), 1 year (10.7% vs 6.2%, p = 0.620), and 2 years (18.2% vs 8.3%, p = 0.438). The overall mean follow-up was 29.2 months. CONCLUSIONS These findings suggest that percutaneous instrumentation without fusion in mini-open transpedicular corpectomies offers similar implant failure and reoperation rates as open instrumented fusion as far out as 2 years of follow-up.