The Relationship Between Lumbar Lateral Listhesis and Radiculopathy in Adult Scoliosis.

STUDY DESIGN: Retrospective review and prospective validation study. OBJECTIVE: To develop a classification system of lumbar lateral listhesis that suggests different likelihoods of having radiculopathy in adult scoliosis. SUMMARY OF BACKGROUND DATA: The association of lumbar lateral listhesis with radiculopathy remains uncertain. METHODS: A retrospective cohort of patients with adult scoliosis enrolled from 2011 to 2015 was studied to develop a classification system of lateral listhesis that can stratify the likelihood of having radiculopathy. Four radiological aspects of lateral listhesis, including Nash and Moe vertebral rotation, L4-L5 lateral listhesis, the number of consecutive listheses, and the presence of a contralateral lateral listhesis at the thoracolumbar junction above a caudal listhesis, were evaluated on radiographs. Their associations with the presence of radicular leg pain were evaluated using multivariable logistic regression. The classification system of lateral listhesis was thus developed using the most influential radiological factors and then validated in a prospective cohort from 2016 to 2017. RESULTS: The retrospective cohort included 189 patients. Vertebral rotation is more than or equal to grade 2 (odds ratio [OR] = 9.45, 95% confidence interval [CI]: 4.07-25.14) and L4-5 listhesis (OR = 4.56, 95%CI: 1.85-12.35) were the two most influential listhesis factors associated with radiculopathy. The classification system of lateral listhesis was thus built based on the combinations of their respective presence: Type 0, 1, 2, 3 were defined as not having listhesis at all, none of the two factors present, one of the two presents, and both present, respectively. This classification significantly stratified the probability of radiculopathy, in both the retrospective cohort (0%, 6.4%, 33.8%, and 68.4% in Type 0, 1, 2, and 3, respectively; P < 0.001) and a prospective cohort of 105 patients (0%, 16.7%, 46.9%, and 72.7%; P < 0.001). CONCLUSION: Lumbar lateral listhesis is associated with the presence of radiculopathy in adult scoliosis. Types 2 and 3 lateral listhesis on radiographs may alert surgeons treating patients with spinal deformity. LEVEL OF EVIDENCE: 2.

An Extreme Learning Machine-Based Neuromorphic Tactile Sensing System for Texture Recognition.

Despite significant advances in computational algorithms and development of tactile sensors, artificial tactile sensing is strikingly less efficient and capable than the human tactile perception. Inspired by efficiency of biological systems, we aim to develop a neuromorphic system for tactile pattern recognition. We particularly target texture recognition as it is one of the most necessary and challenging tasks for artificial sensory systems. Our system consists of a piezoresistive fabric material as the sensor to emulate skin, an interface that produces spike patterns to mimic neural signals from mechanoreceptors, and an extreme learning machine (ELM) chip to analyze spiking activity. Benefiting from intrinsic advantages of biologically inspired event-driven systems and massively parallel and energy-efficient processing capabilities of the ELM chip, the proposed architecture offers a fast and energy-efficient alternative for processing tactile information. Moreover, it provides the opportunity for the development of low-cost tactile modules for large-area applications by integration of sensors and processing circuits. We demonstrate the recognition capability of our system in a texture discrimination task, where it achieves a classification accuracy of 92% for categorization of ten graded textures. Our results confirm that there exists a tradeoff between response time and classification accuracy (and information transfer rate). A faster decision can be achieved at early time steps or by using a shorter time window. This, however, results in deterioration of the classification accuracy and information transfer rate. We further observe that there exists a tradeoff between the classification accuracy and the input spike rate (and thus energy consumption). Our work substantiates the importance of development of efficient sparse codes for encoding sensory data to improve the energy efficiency. These results have a significance for a wide range of wearable, robotic, prosthetic, and industrial applications.

Prospective assessment of the safety and early outcomes of sublaminar band placement for the prevention of proximal junctional kyphosis.

OBJECTIVE Proximal junctional kyphosis (PJK) can progress to proximal junctional failure (PJF), a widely recognized early and serious complication of multisegment spinal instrumentation for the treatment of adult spinal deformity (ASD). Sublaminar band placement has been suggested as a possible technique to prevent PJK and PJF but carries the theoretical possibility of a paradoxical increase in these complications as a result of the required muscle dissection and posterior ligamentous disruption. In this study, the authors prospectively assess the safety as well as the early clinical and radiological outcomes of sublaminar band insertion at the upper instrumented vertebra (UIV) plus 1 level (UIV+1). METHODS Between August 2015 and February 2017, 40 consecutive patients underwent either upper (T2-4) or lower (T8-10) thoracic sublaminar band placement at the UIV+1 during long-segment thoracolumbar arthrodesis surgery. Outcome measures were prospectively collected and uploaded to a web-based REDCap database specifically designed to include demographic, clinical, and radiological data. All patients underwent clinical assessment, as well as radiological assessment with anteroposterior and lateral 36-inch whole-spine standing radiographs both pre- and postoperatively. RESULTS Forty patients (24 women and 16 men) were included in this study. Median age at surgery was 64.0 years with an IQR of 57.7-70.0 years. Median follow-up was 12 months (IQR 6-15 months). Three procedure-related complications were noted, including 2 intraoperative cerebrospinal spinal fluid leaks and 1 transient neurological deficit. Median visual analog scale (VAS) scores for back pain significantly improved after surgery (preoperatively: 8.0, IQR 6.0-10.0; 1-year follow-up: 2.0, IQR 0.0-6.0; p = 0.001). Median Oswestry Disability Index (version 2.1a) scores also significantly improved after surgery (preoperatively: 56.0, IQR 45.0-64.0; 1-year follow-up: 46.0, IQR 22.2-54.0; p < 0.001). Sagittal vertical axis (preoperatively: 9.0 cm, IQR 5.3-11.6 cm; final follow-up: 4.7 cm, IQR 2.0-6.6 cm; p < 0.001), pelvic incidence-lumbar lordosis mismatch (24.7°, IQR 11.2°-31.2°; 7.7°, IQR -1.2° to 19.5°; p < 0.001), and pelvic tilt (28.7°, IQR 20.4°-32.6°; 17.1°, IQR 10.8°-25.2°; p < 0.001) were all improved at the final follow-up. While proximal junctional (PJ) Cobb angles increased overall at the final follow-up (preoperatively: 4.2°, IQR 1.9°-7.4°; final follow-up: 8.0°, IQR 5.8°-10.3°; p = 0.002), the significant increase was primarily noted starting at the immediate postoperative time point (7.2°, IQR 4.4°-11.8°; p = 0.001) and not beyond. Three patients (7.5%) developed radiological PJK (mean ΔPJ Cobb 15.5°), while there were no instances of PJF in this cohort. CONCLUSIONS Sublaminar band placement at the UIV+1 during long-segment thoracolumbar instrumented arthrodesis is relatively safe and is not associated with an increased rate of PJK. Moreover, no subjects developed PJF. Prospective large-scale and long-term analysis is needed to define the potential benefit of sublaminar bands in reducing the incidence of PJK and PJF following surgery for ASD. Clinical trial registration no.: NCT02411799 (clinicaltrials.gov).

Impact of Admission Imaging Findings on Neurological Outcomes in Acute Cervical Traumatic Spinal Cord Injury.

Variable and unpredictable spontaneous recovery can occur after acute cervical traumatic spinal cord injury (tSCI). Despite the critical clinical and interventional trial planning implications of this tSCI feature, baseline measures to predict neurologic recovery accurately are not well defined. In this study, we used data derived from 99 consecutive patients (78 male, 21 female) with acute cervical tSCIs to assess the sensitivity and specificity of various clinical and radiological factors in predicting recovery at one year after injury. Categorical magnetic resonance imaging parameters included maximum canal compromise (MCC), maximum spinal cord compression (MSCC), longitudinal length of intramedullary lesion (IML), Brain and Spinal Injury Center (BASIC) score, and a novel derived Combined Axial and Sagittal Score (CASS). Logistic regression analysis of the area under the receiver operating characteristic curve (AUC) was applied to assess the differential predictive value of individual imaging markers. Admission American Spinal Injury Association Impairment Scale (AIS) grade, presence of a spinal fracture, and central cord syndrome were predictive of AIS conversion at one year. Both BASIC and IML were stronger predictors of AIS conversion compared with MCC and MSCC (p = 0.0002 and p = 0.04). The BASIC score demonstrated the highest overall predictive value for AIS conversion at one year (AUC 0.94). We conclude that admission intrinsic cord signal findings are robust predictive surrogate markers of neurologic recovery after cervical tSCI. Direct comparison of imaging parameters in this cohort of patients indicates that the BASIC score is the single best acute predictor of the likelihood of AIS conversion.

A Saccade Based Framework for Real-Time Motion Segmentation Using Event Based Vision Sensors.

Motion segmentation is a critical pre-processing step for autonomous robotic systems to facilitate tracking of moving objects in cluttered environments. Event based sensors are low power analog devices that represent a scene by means of asynchronous information updates of only the dynamic details at high temporal resolution and, hence, require significantly less calculations. However, motion segmentation using spatiotemporal data is a challenging task due to data asynchrony. Prior approaches for object tracking using neuromorphic sensors perform well while the sensor is static or a known model of the object to be followed is available. To address these limitations, in this paper we develop a technique for generalized motion segmentation based on spatial statistics across time frames. First, we create micromotion on the platform to facilitate the separation of static and dynamic elements of a scene, inspired by human saccadic eye movements. Second, we introduce the concept of spike-groups as a methodology to partition spatio-temporal event groups, which facilitates computation of scene statistics and characterize objects in it. Experimental results show that our algorithm is able to classify dynamic objects with a moving camera with maximum accuracy of 92%.

Discrimination of Dynamic Tactile Contact by Temporally Precise Event Sensing in Spiking Neuromorphic Networks.

This paper presents a neuromorphic tactile encoding methodology that utilizes a temporally precise event-based representation of sensory signals. We introduce a novel concept where touch signals are characterized as patterns of millisecond precise binary events to denote pressure changes. This approach is amenable to a sparse signal representation and enables the extraction of relevant features from thousands of sensing elements with sub-millisecond temporal precision. We also proposed measures adopted from computational neuroscience to study the information content within the spiking representations of artificial tactile signals. Implemented on a state-of-the-art 4096 element tactile sensor array with 5.2 kHz sampling frequency, we demonstrate the classification of transient impact events while utilizing 20 times less communication bandwidth compared to frame based representations. Spiking sensor responses to a large library of contact conditions were also synthesized using finite element simulations, illustrating an 8-fold improvement in information content and a 4-fold reduction in classification latency when millisecond-precise temporal structures are available. Our research represents a significant advance, demonstrating that a neuromorphic spatiotemporal representation of touch is well suited to rapid identification of critical contact events, making it suitable for dynamic tactile sensing in robotic and prosthetic applications.

Encapsulation of Piezoelectric Transducers for Sensory Augmentation and Substitution with Wearable Haptic Devices.

The integration of polymeric actuators in haptic displays is widespread nowadays, especially in virtual reality and rehabilitation applications. However, we are still far from optimizing the transducer ability in conveying sensory information. Here, we present a vibrotactile actuator characterized by a piezoelectric disk embedded in a polydimethylsiloxane (PDMS) shell. An original encapsulation technique was performed to provide the stiff active element with a compliant cover as an interface towards the soft human skin. The interface stiffness, together with the new geometry, generated an effective transmission of vibrotactile stimulation and made the encapsulated transducer a performant component for the development of wearable tactile displays. The mechanical behavior of the developed transducer was numerically modeled as a function of the driving voltage and frequency, and the exerted normal forces were experimentally measured with a load cell. The actuator was then tested for the integration in a haptic glove in single-finger and bi-finger condition, in a 2-AFC tactile stimulus recognition test. Psychophysical results across all the tested sensory conditions confirmed that the developed integrated haptic system was effective in delivering vibrotactile information when the frequency applied to the skin is within the 200⁻700 Hz range and the stimulus variation is larger than 100 Hz.

CONE: Convex-Optimized-Synaptic Efficacies for Temporally Precise Spike Mapping.

Spiking neural networks are well suited to perform time-dependent pattern recognition problems by encoding the temporal dimension in precise spike times. With an appropriate set of weights, a spiking neuron can emit precisely timed action potentials in response to spatiotemporal input spikes. However, deriving supervised learning rules for spike mapping is nontrivial due to the increased complexity. Existing methods rely on heuristic approaches that do not guarantee a convex objective function and, therefore, may not converge to a global minimum. In this paper, we present a novel technique to obtain the weights of spiking neurons by formulating the problem in a convex optimization framework, rendering it be compatible with the established methods. We introduce techniques to influence the weight distribution and membrane trajectory, and then study how these factors affect robustness in the presence of noise. In addition, we show how the existence of a solution can be determined and assess memory capacity limits of a neuron model using synthetic examples. The practical utility of our technique is further assessed by its application to gait-event detection using the experimental data.

Spontaneous Spinal Epidural Hematoma Report.

We report a case of spontaneous spinal epidural hematoma in a 12-year-old female, who presented with significant upper and lower extremities weakness preceded by pain around the neck and shoulder girdle. Magnetic resonance imaging revealed epidural hematoma extending from C6-T2 with characteristic heterogeneously hyperintensity on T2 and homogenously isointensity on T1. Emergent spinal decompression was performed. However, the patient remained substantially weak in her lower extremities and was wheelchair bound at 3 months postoperatively. We have discussed clinical features, predisposing events, pathogenesis and treatment guidelines described in the literature. We also aim to reinforce the notion of keeping a high degree of clinical suspicion to identify and intervene at the earliest stage to prevent the physically and socially challenging consequences of SSEH.

Impact of associated injuries in conjunction with fracture of the axis vertebra on inpatient outcomes and postoperative complications: a Nationwide Inpatient Sample analysis from 2002 to 2011.

BACKGROUND CONTEXT: There are limited data available on the impact of associated spinal (other spinal injuries [OSIs]) and extra-spinal injuries (ESIs) occurring in conjunction with fractures of the axis vertebra (C2) on clinical outcomes. PURPOSE: This study aimed to compare outcomes in patients with isolated C2 fractures versus patients with associated injuries in conjunction with C2 fractures. STUDY DESIGN/SETTING: A retrospective cohort study. PATIENT SAMPLE: A total of 30,472 adult patients with C2 fractures (International Classification of Diseases, Ninth Revision, Clinical Modification code 805.02) registered in the Nationwide Inpatient Sample (NIS) database (2002-2011) comprised the patient sample. OUTCOME MEASURES: Inpatient mortality, unfavorable discharge, prolonged length of stay (LOS) and high-end hospital charges in the non-operative and operative cohorts, and postoperative complications (deep venous thrombosis [DVT]; acute renal failure [ARF]; respiratory complications and wound infections) for the operative cohort were the outcome measures. METHODS: Patients were stratified into four categories based on injury type: (1) isolated C2 fracture (n=10,135; 33.3%); (2) C2 fracture+OSI (8.7%); (3) C2 fracture+ESI (37.2%); and (4) C2 fracture+OSI+ESI (20.8%). Multivariable logistic regression fitted with generalized estimating equations using the sandwich variance-covariance matrix estimator to account for clustering of similar outcomes within hospitals was used to examine the association of primary endpoints for each of the associated injury categories with reference to isolated C2 fractures. RESULTS: Mean age of the cohort was 66.27±21.67 years and 52% were female. Of the cohort, 52% underwent surgical intervention for C2 fracture. In a pooled regression analysis involving the operative cohort, the risks for inpatient mortality (odds ratio [OR]: 3.77; 95% confidence interval [CI]: 3.02-4.70; p<.001), unfavorable discharge (OR: 1.83; 95% CI: 1.66-2.01; p<.001), prolonged LOS (OR: 1.33; 95% CI: 1.18-1.50; p<.001), high hospital charges (OR: 1.49; 95% CI: 1.31-2.69; p<.001), DVT (OR: 2.08; 95% CI: 1.61-2.68; p<.001), and ARF (OR: 1.46; 95% CI: 1.16-1.83; p=.001) were significantly higher in patients with additional injuries when compared with patients with C2 fractures alone. Likewise, increased chances of inpatient mortality (OR: 1.40; 95% CI: 1.21-1.62; p<.001), unfavorable discharge (OR: 1.24; 95% CI: 1.15-1.34; p<.001) and high hospital charges (OR: 1.31; 95% CI: 1.21-1.43; p<.001) were observed in a pooled analysis of patients with concomitant associated injuries in the non-operative cohort. CONCLUSIONS: Associated injuries occurring concomitantly with C2 fractures adversely influence postoperative outcomes. In comparison to isolated C2 fractures, patients with associated injuries tend to have a greater propensity for higher health-care resource use because of more complicated and longer hospital inpatient stay.

Detection of compensatory balance responses using wearable electromyography sensors for fall-risk assessment.

Loss of balance is prevalent in older adults and populations with gait and balance impairments. The present paper aims to develop a method to automatically distinguish compensatory balance responses (CBRs) from normal gait, based on activity patterns of muscles involved in maintaining balance. In this study, subjects were perturbed by lateral pushes while walking and surface electromyography (sEMG) signals were recorded from four muscles in their right leg. To extract sEMG time domain features, several filtering characteristics and segmentation approaches are examined. The performance of three classification methods, i.e., k-nearest neighbor, support vector machines, and random forests, were investigated for accurate detection of CBRs. Our results show that features extracted in the 50-200Hz band, segmented using peak sEMG amplitudes, and a random forest classifier detected CBRs with an accuracy of 92.35%. Moreover, our results support the important role of biceps femoris and rectus femoris muscles in stabilization and consequently discerning CBRs. This study contributes towards the development of wearable sensor systems to accurately and reliably monitor gait and balance control behavior in at-home settings (unsupervised conditions), over long periods of time, towards personalized fall risk assessment tools.

Medicare payment data for spine reimbursement; important but flawed data for evaluating utilization of resources.

BACKGROUND: Medicare data showing physician-specific reimbursement for 2012 were recently made public in the mainstream media. Given the ongoing interest in containing healthcare costs, we analyze these data in the context of the delivery of spinal surgery. METHODS: Demographics of 206 leading surgeons were extracted including state, geographic area, residency training program, fellowship training, and academic affiliation. Using current procedural terminology (CPT) codes, information was evaluated regarding the number of lumbar laminectomies, lumbar fusions, add-on laminectomy levels, and anterior cervical fusions reimbursed by Medicare in 2012. RESULTS: In 2012 Medicare reimbursed the average neurosurgeon slightly more than an orthopedic surgeon for all procedures ($142,075 vs. $110,920), but this was not found to be statistically significant (P = 0.218). Orthopedic surgeons had a statistical trend illustrating increased reimbursement for lumbar fusions specifically, $1187 versus $1073 (P = 0.07). Fellowship trained spinal surgeons also, on average, received more from Medicare ($125,407 vs. $76,551), but again this was not statistically significant (P = 0.112). A surgeon in private practice, on average, was reimbursed $137,495 while their academic counterparts were reimbursed $103,144 (P = 0.127). Surgeons performing cervical fusions in the Centers for Disease Control West Region did receive statistically significantly less reimbursement for that procedure then those surgeons in other parts of the country (P = 0.015). Surgeons in the West were reimbursed on average $849 for CPT code 22,551 while those in the Midwest received $1475 per procedure. CONCLUSION: Medicare reimbursement data are fundamentally flawed in determining healthcare expenditure as it shows a bias toward delivery of care in specific patient demographics. However, neurosurgeons, not just policy makers, must take ownership to analyze, investigate, and interpret these data as it will affect healthcare reimbursement and delivery moving forward.

Occipitocervical Fusion Surgery: Review of Operative Techniques and Results.

Objective Varying types of clinicoradiologic presentations at the craniovertebral junction (CVJ) influence the decision process for occipitocervical fusion (OCF) surgery. We discuss the operative techniques and decision-making process in OCF surgery based on our clinical experience and a literature review. Material and Methods A total of 49 consecutive patients who underwent OCF participated in the study. Sagittal computed tomography images were used to illustrate and measure radiologic parameters. We measured Wackenheim clivus baseline (WCB), clivus-canal angle (CCA), atlantodental distance (ADD), and Powers ratio (PR) in all the patients. Results Clinical improvement on Nurick grading was recorded in 36 patients. Patients with better preoperative status (Nurick grades 1-3) had better functional outcomes after the surgery (p = 0.077). Restoration of WCB, CCA, ADD, and PR parameters following the surgery was noted in 39.2%, 34.6%, 77.4%, and 63.3% of the patients, respectively. Complications included deep wound infections (n = 2), pseudoarthrosis (n = 2), and deaths (n = 4). Conclusion Conventional wire-based constructs are superseded by more rigid screw-based designs. Odontoidectomy is associated with a high incidence of perioperative complications. The advent of newer implants and reduction techniques around the CVJ has obviated the need for this procedure in most patients.

Association of risk factors with unfavorable outcomes after resection of adult benign intradural spine tumors and the effect of hospital volume on outcomes: an analysis of 18, 297 patients across 774 US hospitals using the National Inpatient Sample (2002-2011).

OBJECT Because of the limited data available regarding the associations between risk factors and the effect of hospital case volume on outcomes after resection of intradural spine tumors, the authors attempted to identify these associations by using a large population-based database. METHODS Using the National Inpatient Sample database, the authors performed a retrospective cohort study that involved patients who underwent surgery for an intradural spinal tumor between 2002 and 2011. Using national estimates, they identified associations of patient demographics, medical comorbidities, and hospital characteristics with inpatient postoperative outcomes. In addition, the effect of hospital volume on unfavorable outcomes was investigated. Hospitals that performed fewer than 14 resections in adult patients with an intradural spine tumor between 2002 and 2011 were labeled as low-volume centers, whereas those that performed 14 or more operations in that period were classified as high-volume centers (HVCs). These cutoffs were based on the median number of resections performed by hospitals registered in the National Inpatient Sample during the study period. RESULTS Overall, 18,297 patients across 774 hospitals in the United States underwent surgery for an intradural spine tumor. The mean age of the cohort was 56.53 ± 16.28 years, and 63% were female. The inpatient postoperative risks included mortality (0.3%), discharge to rehabilitation (28.8%), prolonged length of stay (> 75th percentile) (20.0%), high-end hospital charges (> 75th percentile) (24.9%), wound complications (1.2%), cardiac complications (0.6%), deep vein thrombosis (1.4%), pulmonary embolism (2.1%), and neurological complications, including durai tears (2.4%). Undergoing surgery at an HVC was significantly associated with a decreased chance of inpatient mortality (OR 0.39; 95% CI 0.16-0.98), unfavorable discharge (OR 0.86; 95% CI 0.76-0.98), prolonged length of stay (OR 0.69; 95% CI 0.62-0.77), high-end hospital charges (OR 0.67; 95% CI 0.60-0.74), neurological complications (OR 0.34; 95% CI 0.26-0.44), deep vein thrombosis (OR 0.65; 95% CI 0.45-0.94), wound complications (OR 0.59; 95% CI 0.41-0.86), and gastrointestinal complications (OR 0.65; 95% CI 0.46-0.92). CONCLUSIONS The results of this study provide individualized estimates of the risks of postoperative complications based on patient demographics and comorbidities and hospital characteristics and shows a decreased risk for most unfavorable outcomes for those who underwent surgery at an HVC. These findings could be used as a tool for risk stratification, directing presurgical evaluation, assisting with surgical decision making, and strengthening referral systems for complex cases.

Complications of Anterior Cervical Fusion using a Low-dose Recombinant Human Bone Morphogenetic Protein-2.

OBJECTIVE: There are several reports, which documented a high incidence of complications following the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in anterior cervical fusions (ACFs). The objective of this study is to share our experience with low-dose rhBMP-2 in anterior cervical spine. METHODS: We performed a retrospective analysis of 197 patients who underwent anterior cervical fusion (ACF) with the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) during 2007-2012. A low-dose rhBMP-2 (0.7mg/level) sponge was placed exclusively within the cage. In 102 patients demineralized bone matrix (DBM) was filled around the BMP sponge. Incidence and severity of dysphagia was determined by 5 points SWAL-QOL scale. RESULTS: Two patients had prolonged hospitalization due to BMP unrelated causes. Following the discharge, 13.2%(n=26) patients developed dysphagia and 8.6%(n=17) patients complained of neck swelling. More than half of the patients (52.9%, n=9) with neck swelling also had associated dysphagia; however, only 2 of these patients necessitated readmission. Both of these patients responded well to the intravenous dexamethasone. The use of DBM did not affect the incidence and severity of complications (p>0.05). Clinico-radiological evidence of fusion was not observed in 2 patients. CONCLUSION: A low-dose rhBMP-2 in ACFs is not without risk. However, the incidence and severity of complications seem to be lower with low-dose BMP placed exclusively inside the cage. Packing DBM putty around the BMP sponge does not affect the safety profile of rhBMP-2 in ACFs.

Impact of elective versus emergent admission on perioperative complications and resource utilization in lumbar fusion.

BACKGROUND: The notion of higher complication rate and mortality in emergency surgeries is well established. There is a paucity of literature demonstrating the impact of emergent versus elective admissions for spinal surgery on the perioperative outcomes. We aim to evaluate the influence of the type of admission (elective or emergent) and day of surgery (same day versus other days within the emergent group) on the incidence, pattern of perioperative complications and hospital charges in the patients undergoing lumbar fusion for degenerative spine disease. METHODS: Data was obtained from the Nationwide Inpatient Sample (NIS) database between 2002 and 2011. We performed multivariate analysis to evaluate the impact of admission type and day of surgery on perioperative outcomes. RESULTS: A total of 266439 patients were identified. The majority of the admissions were elective (92.6%). Emergent admission comprised 7.4% of the total admission. Mean Charlson comorbidity index (CCI) was significantly higher in emergent and 'other days' (<0.001) groups. Emergent admission and surgery performed on the 'other days' were the independent risk factors for the higher incidence of the venous thromboembolic events, surgical site infection and wound dehiscence. The patients in the emergent and 'other days' surgery groups had a longer stay in the hospital (P<0.001). The mean total hospital charges were higher in the emergent admission and 'other days' surgery groups (P<0.001). CONCLUSIONS: 'Emergent admission' and surgery performed on the 'other days' in lumbar fusion are independent risk factors for the higher incidence of perioperative complications. Complicated hospital course and longer stay of the patients in the emergent admission and 'other days' group seems to be associated with higher total hospital charges.

Predictors of reoperation-free survival following decompression-alone lumbar spine surgery for on-the-job injuries.

INTRODUCTION: Workers' compensation patients are known to be associated with inferior outcomes following lumbar surgery. We investigated demographics and clinical characteristics between the reoperative and non-reoperative group of patients undergoing decompression-alone lumbar surgery (discectomy and/or laminectomy) for on-the-job injuries (OJI) at our institute, and evaluated its possible impact on the reoperation-free survival (RFS). METHODS: A retrospective analysis of patients undergoing lumbar surgery for OJI between 2003 through 2010 by a single surgeon (A.N.) was performed. A comparison of baseline clinical and demographic parameters between the two groups was compared using Fisher's exact test for the categorical variables and the independent t-test (2-tailed) for the continuous variables. Overall, RFS was presented in Kaplan-Meier curves and the RFS difference was compared using log-rank (Mantel-Cox) test. Cox proportional hazard model was used for the univariate and multivariate analysis and hazard ratios with 95% confidence intervals were reported. RESULTS: About 92 patients with mean age 48.07 ± 10.10 years and mean follow-up of 36.4 (range 24.3-66.0) months were included. About 38 (41.3%) patients underwent reoperation for failed decompression-alone procedures whereas the non-reoperative cohort comprises 54 (58.7%) patients. Female gender (p = 0.015) and history of previous surgery (p = 0.05) were associated with a higher chance of reoperation. Majority of the reoperations (20/38, 52.6%) were performed within the first 2 years, with a RFS at the end of 2 years being 78.3% (n = 72) and 58.9% (n = 53) at 5 years. Cox-regression analysis did not demonstrate any influence of patients and treatment-related factors on the RFS. CONCLUSION: There is a substantial risk of redo surgeries following decompression-alone lumbar procedures for OJI. As patient and treatment-related factors did not influence the reoperation rates and RFS in this study, it appears that workman compensation status of patients is inherently associated with poor outcomes following spine surgeries.

National trends of incidence, treatment, and hospital charges of isolated C-2 fractures in three different age groups.

OBJECT: Incidence of C-2 fracture is increasing in elderly patients. Patient age also influences decision making in the management of these fractures. There are very limited data on the national trends of incidence, treatment interventions, and resource utilization in patients in different age groups with isolated C-2 fractures. The aim of this study is to investigate the incidence, treatment, complications, length of stay, and hospital charges of isolated C-2 fracture in patients in 3 different age groups by using the Nationwide Inpatient Sample (NIS) database. METHODS: The data were obtained from NIS from 2002 to 2011. Data on patients with closed fractures of C-2 without spinal cord injury were extracted using ICD-9-CM diagnosis code 805.02. Patients with isolated C-2 fractures were identified by excluding patients with other associated injuries. The cohort was divided into 3 age groups: < 65 years, 65-80 years, and > 80 years. Incidence, treatment characteristics, inpatient/postoperative complications, and hospital charges (mean and total annual charges) were compared between the 3 age groups. RESULTS: A total of 10,336 patients with isolated C-2 fractures were identified. The majority of the patients were in the very elderly age group (> 80 years; 42.3%) followed by 29.7% in the 65- to 80-year age group and 28% in < 65-year age group. From 2002 to 2011, the incidence of hospitalization significantly increased in the 65- to 80-year and > 80-year age groups (p < 0.001). However, the incidence did not change substantially in the < 65-year age group (p = 0.287). Overall, 21% of the patients were treated surgically, and 12.2% of the patients underwent nonoperative interventions (halo and spinal traction). The rate of nonoperative interventions significantly decreased over time in all age groups (p < 0.001). Regardless of treatment given, patients in older age groups had a greater risk of inpatient/postoperative complications, nonroutine discharges, and longer hospitalization. The mean hospital charges were significantly higher in older age groups (p < 0.001). CONCLUSIONS: The incidence of hospitalization for isolated C-2 fractures is progressively increasing in older age groups. Simultaneously, there has been a steadily decreasing trend in the preference for nonoperative interventions. Due to more complicated hospital stay, longer hospitalizations, and higher rates of nonroutine discharges, the patients in older age groups seem to have a higher propensity for greater health care resource utilization.

Surgical Strategies in the Management of Spinal Nerve Sheath Tumors.

OBJECTIVES: Spinal nerve sheath tumors (SNSTs) are the most common lesions in the extramedullary intradural compartment. Complex and large lesions may pose technical difficulties for the operating surgeons. We discuss the management of SNSTs and technical issues including surgical approaches, spinal fixation, and dural handling with the goal of achieving good clinical outcomes while minimizing the risk of complications. We also propose a new classification for SNSTs to guide surgical treatment of these tumors. METHODS: A retrospective analysis was performed of 61 patients who underwent surgery for SNSTs during the period 1995-2012. The posterior approach was used for removal of most tumors (n = 53). Lesions having a substantial extraforaminal component were accessed from the anterior or lateral approach or a combined approach. Concomitant spinal fixation and fusion was performed in 7 patients. RESULTS: Most of the patients (n = 53) had clinical improvement; clinical status was the same in 4 patients and worse in the remaining 4 patients. One or more complications developed in 18 patients (29.5%). Recurrence was the most common complication (n = 7). Death occurred in 2 patients with malignant peripheral nerve sheath tumors 12 and 8 months, respectively, after surgical resection. CONCLUSIONS: Lesions with large extraforaminal extension pose technical difficulty. Spinal fixation with fusion should be supplemented whenever necessary. Complications related to dura mater may be associated with significant morbidity, and all possible efforts should be made to prevent them.

Julius Caesar Arantius (Giulio Cesare Aranzi, 1530-1589) and the hippocampus of the human brain: history behind the discovery.

Julius Caesar Arantius is one of the pioneer anatomists and surgeons of the 16th century who discovered the different anatomical structures of the human body. One of his prominent discoveries is the hippocampus. At that time, Arantius originated the term hippocampus, from the Greek word for seahorse (hippos ["horse"] and kampos ["sea monster"]). Arantius published his description of the hippocampus in 1587, in the first chapter of his work titled De Humano Foetu Liber. Numerous nomenclatures of this structure, including "white silkworm," "Ammon's horn," and "ram's horn" were proposed by different scholars at that time. However, the term hippocampus has become the most widely used in the literature.