Multi-institutional review of characteristics and management of gunshot wounds to the spine.

BACKGROUND CONTEXT: Gunshot wounds (GSWs) to the vertebral column represent an important cause of morbidity and mortality in the United States, constituting approximately 20% of all spinal injuries. The management of these injuries is an understudied and controversial topic, given its heterogeneity and lack of follow-up data. PURPOSE: To characterize the management and follow-up of GSWs to the spine. STUDY DESIGN/SETTING: A multi-institutional retrospective review of the experience of two urban Level 1 trauma centers. PATIENT SAMPLE: Patients with GSWs to the spine between 2010-2021. OUTCOME MEASURES: Measures included work status, follow-up healthcare utilization, and pain management were collected. METHODS: Charts were reviewed for demographics, injury characteristics, surgery and medical management, and follow-up. Statistical analysis included T-tests and ANOVA for comparisons of continuous variables and chi-square testing for categorical variables. All statistics were performed on SPSS v24 (IBM, Armonk, NY). RESULTS: A total of 271 patients were included for analysis. The average age was 28 years old, 82.7% of patients were black, 90% were male, and 76.4% had Medicare/Medicaid. The thoracic spine (35%) was most commonly injured followed by lumbar (33.9%) and cervical (25.6%). Cervical GSW was associated with higher mortality (p<.001); 8.7% of patients developed subsequent osteomyelitis/discitis, 71.3% received prophylactic antibiotics, and 56.1% of cervical GSW had a confirmed vertebral or carotid artery injury. ASIA scores at presentation were most commonly A (26.9%), D (20.7%), or E (19.6%), followed by C (7.4%) and B (6.6%). 18.8% of patients were unable to be assessed at presentation. ASIA score declined in only 2 patients, while 15.5% improved over their hospital stay. Those who improved were more likely to have ASIA B injury (p<.001). Overall, 9.2% of patients underwent spinal surgery. Of these, 33% presented as ASIA A, 21% as ASIA B, 29% as ASIA C, and 13% as ASIA D. Surgery was not associated with an improvement in ASIA score. CONCLUSIONS: Given the ubiquitous and heterogeneous experience with GSWs to the spine, rigorous attempts should be made to define this population and its clinical and surgical outcomes. Here, we present an analysis of 11 years of patients presenting to two large trauma centers to elucidate patterns in presentation, management, and follow-up. We highlight that GSWs to the cervical spine are most often seen in young black male patients. They were associated with high mortality and high rates of injury to vertebral arteries and that surgical intervention did not alter rates of discitis/osteomyelitis or propensity for neurologic recovery; moreover, there was no incidence of delayed spinal instability in the study population.

Plasma ctDNA liquid biopsy of IDH1, TERTp, and EGFRvIII mutations in glioma.

Background: Circulating tumor DNA has emerging clinical applications in several cancers; however, previous studies have shown low sensitivity in glioma. We investigated if 3 key glioma gene mutations IDH1, TERTp, and EGFRvIII could be reliably detected in plasma by droplet digital polymerase chain reaction (ddPCR) thereby demonstrating the potential of this technique for glioma liquid biopsy. Methods: We analyzed 110 glioma patients from our biobank with a total of 359 plasma samples (median 4 samples per patient). DNA was isolated from plasma and analyzed for IDH1, TERTp, and EGFRvIII mutations using ddPCR. Results: Total cfDNA was significantly associated with tumor grade, tumor volume, and both overall and progression-free survival for all gliomas as well as the grade 4 glioblastoma subgroup, but was not reliably associated with changes in tumor volume/progression during the patients' postoperative time course. IDH1 mutation was detected with 84% overall sensitivity across all plasma samples and 77% in the preoperative samples alone; however, IDH1 mutation plasma levels were not associated with tumor progression or survival. IDH1m plasma levels were not associated with pre- or postsurgery progression or survival. The TERTp C228T mutation was detected in the plasma ctDNA in 88% but the C250T variant in only 49% of samples. The EGFRvIII mutation was detected in plasma in 5 out of 7 patients (71%) with tissue EGFRvIII mutations in tumor tissue. Conclusions: Plasma ctDNA mutations detected with ddPCR provide excellent diagnostic sensitivity for IDH1, TERTp-C228T, and EGFRvIII mutations in glioma patients. Total cfDNA may also assist with prognostic information. Further studies are needed to validate these findings and the clinical role of ctDNA in glioma.

Plasma ctDNA enables early detection of temozolomide resistance mutations in glioma.

Background: Liquid biopsy based on circulating tumor DNA (ctDNA) is a novel tool in clinical oncology, however, its use has been limited in glioma to date, due to low levels of ctDNA. In this study, we aimed to demonstrate that sequencing techniques optimized for liquid biopsy in glioma patients can detect ctDNA in plasma with high sensitivity and with potential clinical utility. Methods: We investigated 10 glioma patients with tumor tissue available from at least 2 surgical operations, who had 49 longitudinally collected plasma samples available for analysis. Plasma samples were sequenced with CAPP-seq (AVENIO) and tissue samples with TSO500. Results: Glioma-derived ctDNA mutations were detected in 93.8% of plasma samples. 25% of all mutations detected were observed in plasma only. Mutations of the mismatch repair (MMR) genes MSH2 and MSH6 were the most frequent circulating gene alterations seen after temozolomide treatment and were frequently observed to appear in plasma prior to their appearance in tumor tissue at the time of surgery for recurrence. Conclusions: This pilot study suggests that plasma ctDNA in glioma is feasible and may provide sensitive and complementary information to tissue biopsy. Furthermore, plasma ctDNA detection of new MMR gene mutations not present in the initial tissue biopsy may provide an early indication of the development of chemotherapy resistance. Additional clinical validation in larger cohorts is needed.

Intraoperative Monitoring of the External Urethral Sphincter Reflex: A Novel Adjunct to Bulbocavernosus Reflex Neuromonitoring for Protecting the Sacral Neural Pathways Responsible for Urination, Defecation and Sexual Function.

PURPOSE: Intraoperative bulbocavernosus reflex neuromonitoring has been utilized to protect bowel, bladder, and sexual function, providing a continuous functional assessment of the somatic sacral nervous system during surgeries where it is at risk. Bulbocavernosus reflex data may also provide additional functional insight, including an evaluation for spinal shock, distinguishing upper versus lower motor neuron injury (conus vs. cauda syndromes) and prognosis for postoperative bowel and bladder function. Continuous intraoperative bulbocavernosus reflex monitoring has been utilized to provide the surgeon with an ongoing functional assessment of the anatomical elements involved in the S2-S4 mediated reflex arc including the conus, cauda equina and pudendal nerves. Intraoperative bulbocavernosus reflex monitoring typically includes the electrical activation of the dorsal nerves of the genitals to initiate the afferent component of the reflex, followed by recording the resulting muscle response using needle electromyography recordings from the external anal sphincter. METHODS: Herein we describe a complementary and novel technique that includes recording electromyography responses from the external urethral sphincter to monitor the external urethral sphincter reflex. Specialized foley catheters embedded with recording electrodes have recently become commercially available that provide the ability to perform intraoperative external urethral sphincter muscle recordings. RESULTS: We describe technical details and the potential utility of incorporating external urethral sphincter reflex recordings into existing sacral neuromonitoring paradigms to provide redundant yet complementary data streams. CONCLUSIONS: We present two illustrative neurosurgical oncology cases to demonstrate the utility of the external urethral sphincter reflex technique in the setting of the necessary surgical sacrifice of sacral nerve roots.

Association of Do-Not-Resuscitate orders and in-hospital mortality among patients undergoing cranial neurosurgery.

BACKGROUND: Previous studies identified pre-existing DNR orders as a predictor of mortality after surgery. We sought to evaluate mortality of patients receiving cranial neurosurgery with DNR orders placed at the time of, or within 24 h of admission. METHODS: We performed a retrospective cohort study using the California State Inpatient Database, January 2018 to December 2020. We used International Classification of Diseases, 10th Revision (ICD-10) codes to identify emergent hospitalizations with principal diagnosis of brain injury, including traumatic brain injury [TBI], ischemic stroke [IS], intracerebral hemorrhage [ICH], subarachnoid hemorrhage [SAH], or malignant brain tumor [mBT]. We used procedure and Diagnosis Related Group codes to identify cranial neurosurgery. Patients with DNR were one-to-one matched to non-DNR controls based on diagnosis (exact matching), age, sex, Elixhauser comorbidity index, and organ failure (coarsened matching). The primary outcome was inpatient mortality. RESULTS: In California, 30,384 patients underwent cranial neurosurgery, 2018-2020 (n = 3,112, 10% DNR). DNR patients were older, more often female, more often White, with greater comorbidity and organ system dysfunction. There were 2,505 patients with DNR orders 1:1 matched to controls. Patients with DNR had greater inpatient mortality (56% vs. 23%, p < 0.001; Hazard Ratio 3.11, 95% CI 2.50-3.86), received tracheostomy (Odds Ratio [OR] 0.37, 95% CI 0.24-0.57) and gastrostomy less (OR 0.48, 95% CI 0.39-0.58) compared to controls. Multivariable analysis of the unmatched cohort demonstrated similar results. CONCLUSION: Patients undergoing cranial neurosurgery with early or pre-existing DNR have high inpatient mortality compared to clinically similar non-DNR patients; 1 in 2 died during their hospitalization.

Treatment of hydrocephalus in an ovine model with an intraparenchymal stent.

OBJECTIVE: While CSF diversion is highly effective at treating hydrocephalus, shunting is unfortunately associated with a very high revision rate. Studies have demonstrated that proximal catheter obstruction is a major cause of failure. A novel proximal access device was developed, and pilot testing was performed in a sheep model of hydrocephalus. METHODS: Hydrocephalus was induced in 8 sheep using a cisternal injection of 4 ml of 25% kaolin, and the sheep were randomized to either a standard ventricular catheter or a novel intraparenchymal stent (IPS). Both groups received identical valves and distal catheters. The novel device included a 3D-printed stainless steel port and a 6 × 40-mm covered peripheral vascular stent. Animals were euthanized for signs of hydrocephalus or at a time point of 2 months. MRI was performed to determine ventricular size. Time to failure and Evans indices were compared using the Wilcoxon rank-sum test. RESULTS: All 4 experimental devices were placed without difficulty into the right lateral ventricle. There was a trend toward longer survival in the experimental group (40 vs 26 days, p = 0.24). Within the IPS group, 3 of the 4 sheep did not experience clinical symptoms of shunt failure and had an average of 37% decrease in Evans index. While 3 of 4 traditional proximal catheters demonstrated debris within the inlet holes, there was no obstructive material found in the IPSs. CONCLUSIONS: An IPS was successfully used to treat hydrocephalus in a sheep model. While statistical significance was not achieved, there were clear benefits to using a stent, including a decreased clog rate and the ability to perform a percutaneous revision. Further testing is needed to ensure efficacy and safety prior to human application.

Novel Standalone Motion-Sparing Pelvic Fixation Prevents Short-Term Insufficiency Fractures After Midsacrectomies Without Sacrificing Normal, Mobile Lumbar Segments Traditionally Used for Stabilization.

BACKGROUND AND OBJECTIVES: Sacrectomy is often the treatment of choice to provide the greatest chance of progression-free and overall survival for patients with primary malignant bone tumors of the sacrum. After midsacrectomy, the stability of the sacropelvic interface is diminished, resulting in insufficiency fractures. Traditional stabilization involves lumbopelvic fixation but subjects normal mobile segments to fusion. The purpose of this study was to determine whether standalone intrapelvic fixation is a safe adjunct to midsacrectomy, avoiding both sacral insufficiency fractures and the morbidity of instrumenting into the mobile spine. METHODS: A retrospective study identified all patients who underwent resection of sacral tumors at 2 comprehensive cancer centers between June 2020 and July 2022. Demographic, tumor-specific, operative characteristics and outcome data were collected. The primary outcome was presence of sacral insufficiency fractures. A retrospective data set of patients undergoing midsacrectomy without hardware placement was collected as a control. RESULTS: Nine patients (5 male, 4 female), median age 59 years, underwent midsacrectomy with concomitant placement of standalone pelvic fixation. No patients developed insufficiency fractures during the 216 days of clinical and 207 days of radiographic follow-up. There were no adverse events attributable to the addition of standalone pelvic fixation. In our historical cohort of partial sacrectomies without stabilization, there were 4/25 patients (16%) with sacral insufficiency fractures. These fractures appeared between 0 and 5 months postoperatively. CONCLUSION: A novel standalone intrapelvic fixation after partial sacrectomy is a safe adjunct to prevent postoperative sacral insufficiency fractures in patients undergoing midsacrectomy for tumor. Such a technique may allow for long-term sacropelvic stability without sacrificing mobile lumbar segments.

Meningitis due to intra-abdominal cerebrospinal fluid fistula following gunshot wound successfully treated with antibiotics and blood patch: A case report and literature review.

Background: Penetrating spinal cord injury (PSCI) represents an average of 5.5% of all SCIs among civilians in the United States. The formation of a cerebrospinal fluid (CSF) fistula following PSCI occurs in approximately 9% of cases. Intra-abdominal CSF fistulae are rarely reported. Case Description: We present the case of a 28-year-old Caucasian female who suffered a single gunshot wound to the abdomen with a missile fragment lodged within the left L2 pedicle and transverse process without obvious canal compromise. The patient developed bacterial meningitis 13 days after the initial injury, treated with IV antibiotics. CT myelogram demonstrated intra-abdominal ventral CSF fistula from the left L2-L3 neuroforamen. The patient was successfully treated with fluoroscopy-guided dorsal autologous blood patch graft. Conclusion: This case highlights a rare complication of PSCI successfully managed with the use of a blood patch graft.

Credentialing, Certification, and Peer Review Essentials for the Neurosurgeon.

Credentialing and certification are essential processes during hiring to ensure that the physician is competent and possesses the qualifications and skill sets claimed. Peer review ensures the continuing evolution of these skills to meet a standard of care. We have provided an overview and discussion of these processes in the United States. Credentialing is the process by which a physician is determined to be competent and able to practice, used to ensure that medical staff meets specific standards, and to grant operative privileges at an institution. Certification is a standardized affirmation of a physician's competence on a nationwide basis. Although not legally required to practice in the United States, many institutions emphasize certification for full privileges on an ongoing basis at a hospital. In the United States, peer review of adverse events is a mandatory prerequisite for accreditation. The initial lack of standardization led to the development of the Health Care Quality Improvement Act, which protects those involved in the peer review process from litigation, and the National Provider Databank, which was established as a national database to track misconduct. A focus on quality improvement in the peer review process can lead to improved performance and patient outcomes. A thorough understanding of the processes of credentialing, certification, and peer review in the United States will benefit neurosurgeons by allowing them to know what institutions are looking for as well and their rights and responsibilities in any given situation. It could also be useful to compare these policies and practices in the United States to those in other countries.

Workplace Violence and Neurosurgery: Insights from a Nationwide Survey.

OBJECTIVE: Workplace violence (WPV) against neurosurgeons is an understudied phenomenon, as previous research has focused on high-risk specialties like emergency medicine and psychiatry. We sought to fill in this gap in the literature by determining the frequency and type of WPV that neurosurgeons experience. METHODS: We sent a 26-question online survey to members of the American Association of Neurological Surgery via SurveyMonkey. This survey contained questions about WPV experienced over the previous two years, as well as questions about security measures and workplace protocols for WPV. RESULTS: We received 107 responses of 4757 surveys disseminated, a response rate of 2.25%. Although small, this response rate is representative of historical survey response rates. In total, 53.3% of our sample reported WPV, and 4.7% reported at least one physical assault. In total, 50.5% of respondents were afraid of becoming a victim of WPV, and 40.4% felt less secure today than when they began practicing. A total of 17.8% of respondents reported that they had obtained a weapon or a concealed weapon permit due to a perceived threat. Tests for association revealed that early career and female neurosurgeons were significantly more likely to receive verbal threats than other neurosurgeons (P = 0.049 and 0.01, respectively). CONCLUSIONS: WPV is prevalent in neurosurgery at rates comparable with a range of other specialties. Many neurosurgeons feel unsafe in the workplace, with some taking significant actions such as weapon acquisition. An opportunity for education and resources regarding WPV exists, especially among early career and female neurosurgeons.

Sepsis and septic shock after craniotomy: Predicting a significant patient safety and quality outcome measure.

OBJECTIVES: Sepsis and septic shock are important quality and patient safety metrics. This study examines incidence of Sepsis and/or septic shock (S/SS) after craniotomy for tumor resection, one of the most common neurosurgical operations. METHODS: Multicenter, prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database was used to identify patients undergoing craniotomy for tumor (CPT 61510, 61521, 61520, 61518, 61526, 61545, 61546, 61512, 61519, 61575) from 2012-2015. Univariate and multivariate logistic regression models were used to identify risk factors for S/SS. RESULTS: There were 18,642 patients that underwent craniotomy for tumor resection. The rate of sepsis was 1.35% with a mortality rate of 11.16% and the rate of septic shock was 0.65% with a 33.06% mortality rate versus an overall mortality rate of 2.46% in the craniotomy for tumor cohort. The 30-day readmission rate was 50.54% with S/SS vs 10.26% in those without S/SS. Multiple factors were identified as statistically significant (p <0.05) for S/SS including ascites (OR = 33.0), ventilator dependence (OR = 4.5), SIRS (OR = 2.8), functional status (OR = 2.3), bleeding disorders (OR = 1.7), severe COPD (OR = 1.6), steroid use (OR = 1.6), operative time >310 minutes (OR = 1.5), hypertension requiring medication (OR = 1.5), ASA class ≥ 3 (OR = 1.4), male sex (OR = 1.4), BMI >35 (OR = 1.4) and infratentorial location. CONCLUSIONS: The data indicate that sepsis and septic shock, although uncommon after craniotomy for tumor resection, carry a significant risk of 30-day unplanned reoperation (35.60%) and mortality (18.21%). The most significant risk factors are ventilator dependence, ascites, SIRS and poor functional status. By identifying the risk factors for S/SS, neurosurgeons can potentially improve outcomes. Further investigation should focus on the creation of a predictive score for S/SS with integration into the electronic health record for targeted protocol initiation in this unique neurosurgical patient population.

Descriptive Analysis of 1972 Cervical Corpectomy Patients and 30-Day Postoperative Outcomes.

BACKGROUND: There exists no large, multi-institutional analysis of patients undergoing cervical corpectomy for common degenerative spinal disease, including patient demographics and comorbidities as well as postoperative complications. METHODS: Using Current Procedural Terminology and International Classification of Diseases codes, 1972 patients who underwent a cervical corpectomy for degenerative spinal disease were identified from the American College of Surgeons National Surgical Quality Improvement Program data sets from 2012 to 2015. A descriptive analysis of the patients who underwent the procedure as well as 30-day outcomes and adverse events were collected. Multivariate logistic regression models were used to determine the effect of any preoperative factors identified from a univariate logistic regression analysis (variables with P < .10) of complications. RESULTS: The total complication rate, defined as major or minor adverse event, mortality, unplanned readmission, unplanned reoperation, or admission >30 days, was 13.28%. The percentage of patients who had ≥1 major or minor adverse events was 5.02%. Several factors commonly associated with an increased risk of perioperative complications, including smoking and diabetes, were found not to be independently associated with complications in this cohort. CONCLUSIONS: This study is the largest analysis of cervical corpectomies. The results of the multivariate analysis provide guidance on risk factors associated with perioperative complications. These data could help develop risk-appropriate strategies for minimizing the effects of certain preoperative factors on perioperative complications.

Lead Toxicity From Intradiscal Retained Bullet Fragment: Management Considerations and Recommendations.

BACKGROUND: Lead toxicity (plumbism) secondary to retained lead missiles in synovial joint spaces is a rare complication after gunshot injuries. Management of lead missiles in the intradiscal space regarding potential lead toxicity is less certain. CASE DESCRIPTION: We reviewed the literature regarding lead toxicity secondary to intradiscal bullets particularly concerning incidence, management, and outcomes. A lack of high-quality published data precludes a meta-analysis from taking place. Only four reports of lead toxicity secondary to missiles in the intradiscal space have been published. Including an additional case presented in this report, our review of the literature has led us to make several management recommendations, largely based on both the available literature and our current report. CONCLUSIONS: First, there is insufficient evidence for removing retained lead missiles solely to mitigate the risk of lead toxicity. Second, chelation therapy in addition to surgical removal of the lead source is a valuable adjunct in the perioperative period and should be undertaken with the assistance of medical toxicology. Third, a retained missile does not mandate a simultaneous stabilization procedure in lieu of other indications based on the data available at this time.

Comparative Analysis of Decompression Versus Decompression and Fusion for Surgical Management of Lumbar Spondylolisthesis.

OBJECTIVE: When lumbar stenosis involves spondylolisthesis, many surgeons include fixation. Two recent trials have shown no consensus to definitive treatment. We aimed to add to the discourse of fusion versus decompression in patients with lumbar spondylolisthesis by providing a large-scale generalizable study. METHODS: We used multicenter, prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Program database to compare 30-day outcomes for decompression alone versus combination decompression and fusion in the treatment of lumbar spondylolisthesis. Logistic regression models were used to analyze the effect of surgical type on multiple characteristics. Univariate 2-tailed χ2 analyses were used to identify further outcome differences. RESULTS: In total, 9606 patients with treated lumbar spondylolisthesis were identified (907 decompression only, 8699 decompression and fusion). The fusion group tended to be younger (P < 0.001) and was more likely to be smokers (P = 0.01). Unplanned return to surgery was 3.02% in the fusion group, compared with 1.02% (P = 0.011). Minor adverse events occurred in 12.8% of the fusion group versus 4.9% (P < 0.001). Major adverse events occurred in 4.5% of the fusion group versus 3.1% (P = 0.0498). There was no significant difference in 30-day mortality, prolonged admission, or 30-day readmission. CONCLUSIONS: Unplanned return to the operating room and major and minor adverse events were greater for patients undergoing fusion. This could influence future decision-making in lumbar spondylolisthesis. This study indicates that further investigation is warranted but that decompression may be associated with less morbidity in the properly selected patient.

Trends in Interhospital Transfers and Mechanical Thrombectomy for United States Acute Ischemic Stroke Inpatients.

OBJECTIVE: Stroke care in the US is increasingly regionalized. Many patients undergo interhospital transfer to access specialized, time-sensitive interventions such as mechanical thrombectomy. METHODS: Using a stratified survey design of the US Nationwide Inpatient Sample (2009-2014) we examined trends in interhospital transfers for ischemic stroke resulting in mechanical thrombectomy. International Classification of Disease-Ninth Revision (ICD-9) codes were used to identify stroke admissions and inpatient procedures within endovascular-capable hospitals. Regression analysis was used to identify factors associated with patient outcomes. RESULTS: From 2009-2014, 772,437 ischemic stroke admissions were identified. Stroke admissions that arrived via interhospital transfer increased from 12.5% to 16.8%, 2009-2014 (P-trend < .001). Transfers receiving thrombectomy increased from 4.0% to 5.2%, 2009-2014 (P-trend = .016), while those receiving tissue plasminogen activator increased from 16.0% to 20.0%, 2009-2014 (P-trend < .001). One in 4 patients receiving thrombectomy were transferred from another acute care facility (n = 6,014 of 24,861). Compared to patients arriving via the hospital "front door" receiving mechanical thrombectomy, those arriving via transfer were more often from rural areas and received by teaching hospitals with greater frequency of thrombectomy. Those arriving via interhospital transfer undergoing thrombectomy had greater odds of symptomatic intracranial hemorrhage (adjusted odds ratio [AOR] 1.19, 95% CI: 1.01-1.42) versus "front door" arrivals. There were no differences in inpatient mortality (AOR 1.11, 95% CI: .93-1.33). CONCLUSIONS: From 2009 to 2014, interhospital stroke transfers to endovascular-capable hospitals increased by one-third. For every ∼15 additional transfers over the time period one additional patient received thrombectomy. Optimization of transfers presents an opportunity to increase access to thrombectomy.

Risk Factors and Associated Complications of Symptomatic Venous Thromboembolism in Patients with Craniotomy for Meningioma.

OBJECTIVE: Patients undergoing surgical resection of meningioma are at increased risk for developing venous thromboembolism (VTE). The aim of this study was to assess occurrence of VTE in patients who underwent surgical resection of meningioma to determine risk factors and associated complications of VTE. METHODS: The American College of Surgeons National Surgical Quality Improvement Project database from 2012 to 2015 was reviewed for patients who had undergone meningioma resection according to primary Current Procedural Terminology codes and International Classification of Diseases, Ninth Revision. RESULTS: The study included 5036 patients with meningioma. Rate of VTE was 3.38%, with pulmonary embolism rate of 1.47% and deep venous thrombosis rate of 2.42%. During the first 30 days after surgery, patients with VTE had a mortality rate of 5.88% compared with 1.15% for patients without VTE. Multivariate binary logistic regression analysis determined 5 risk factors for VTE,: age ≥60 years, American Society of Anesthesiologists classification III, operative time ≥310 minutes, ventilator dependence, and preoperative transfusions. Univariate analysis revealed a number of complications significantly associated with VTE occurrence, including unplanned intubation, ventilator use for >48 hours, stroke, sepsis, septic shock, pneumonia, urinary tract infection, and transfusions. CONCLUSIONS: Risk factors of VTE and associated complications were identified. Understanding these risk factors provides physicians with further insight in managing this subgroup of patients in a personalized fashion in the perioperative period to minimize the incidence and morbidity of VTE.

Network dynamics of human face perception.

Prevailing theories suggests that cortical regions responsible for face perception operate in a serial, feed-forward fashion. Here, we utilize invasive human electrophysiology to evaluate serial models of face-processing via measurements of cortical activation, functional connectivity, and cortico-cortical evoked potentials. We find that task-dependent changes in functional connectivity between face-selective regions in the inferior occipital (f-IOG) and fusiform gyrus (f-FG) are bidirectional, not feed-forward, and emerge following feed-forward input from early visual cortex (EVC) to both of these regions. Cortico-cortical evoked potentials similarly reveal independent signal propagations between EVC and both f-IOG and f-FG. These findings are incompatible with serial models, and support a parallel, distributed network underpinning face perception in humans.

Category specific spatial dissociations of parallel processes underlying visual naming.

The constituent elements and dynamics of the networks responsible for word production are a central issue to understanding human language. Of particular interest is their dependency on lexical category, particularly the possible segregation of nouns and verbs into separate processing streams. We applied a novel mixed-effects, multilevel analysis to electrocorticographic data collected from 19 patients (1942 electrodes) to examine the activity of broadly disseminated cortical networks during the retrieval of distinct lexical categories. This approach was designed to overcome the issues of sparse sampling and individual variability inherent to invasive electrophysiology. Both noun and verb generation evoked overlapping, yet distinct nonhierarchical processes favoring ventral and dorsal visual streams, respectively. Notable differences in activity patterns were noted in Broca's area and superior lateral temporo-occipital regions (verb > noun) and in parahippocampal and fusiform cortices (noun > verb). Comparisons with functional magnetic resonance imaging (fMRI) results yielded a strong correlation of blood oxygen level-dependent signal and gamma power and an independent estimate of group size needed for fMRI studies of cognition. Our findings imply parallel, lexical category-specific processes and reconcile discrepancies between lesional and functional imaging studies.

Recursive grid partitioning on a cortical surface model: an optimized technique for the localization of implanted subdural electrodes.

OBJECT: Precise localization of subdural electrodes (SDEs) is essential for the interpretation of data from intracranial electrocorticography recordings. Blood and fluid accumulation underneath the craniotomy flap leads to a nonlinear deformation of the brain surface and of the SDE array on postoperative CT scans and adversely impacts the accurate localization of electrodes located underneath the craniotomy. Older methods that localize electrodes based on their identification on a postimplantation CT scan with coregistration to a preimplantation MR image can result in significant problems with accuracy of the electrode localization. The authors report 3 novel methods that rely on the creation of a set of 3D mesh models to depict the pial surface and a smoothed pial envelope. Two of these new methods are designed to localize electrodes, and they are compared with 6 methods currently in use to determine their relative accuracy and reliability. METHODS: The first method involves manually localizing each electrode using digital photographs obtained at surgery. This is highly accurate, but requires time intensive, operator-dependent input. The second uses 4 electrodes localized manually in conjunction with an automated, recursive partitioning technique to localize the entire electrode array. The authors evaluated the accuracy of previously published methods by applying the methods to their data and comparing them against the photograph-based localization. Finally, the authors further enhanced the usability of these methods by using automatic parcellation techniques to assign anatomical labels to individual electrodes as well as by generating an inflated cortical surface model while still preserving electrode locations relative to the cortical anatomy. RESULTS: The recursive grid partitioning had the least error compared with older methods (672 electrodes, 6.4-mm maximum electrode error, 2.0-mm mean error, p < 10(-18)). The maximum errors derived using prior methods of localization ranged from 8.2 to 11.7 mm for an individual electrode, with mean errors ranging between 2.9 and 4.1 mm depending on the method used. The authors also noted a larger error in all methods that used CT scans alone to localize electrodes compared with those that used both postoperative CT and postoperative MRI. The large mean errors reported with these methods are liable to affect intermodal data comparisons (for example, with functional mapping techniques) and may impact surgical decision making. CONCLUSIONS: The authors have presented several aspects of using new techniques to visualize electrodes implanted for localizing epilepsy. The ability to use automated labeling schemas to denote which gyrus a particular electrode overlies is potentially of great utility in planning resections and in corroborating the results of extraoperative stimulation mapping. Dilation of the pial mesh model provides, for the first time, a sense of the cortical surface not sampled by the electrode, and the potential roles this "electrophysiologically hidden" cortex may play in both eloquent function and seizure onset.

Frequency-specific network connectivity increases underlie accurate spatiotemporal memory retrieval.

The medial temporal lobes, prefrontal cortex and parts of parietal cortex form the neural underpinnings of episodic memory, which includes remembering both where and when an event occurred. However, the manner in which these three regions interact during retrieval of spatial and temporal context remains untested. We employed simultaneous electrocorticographical recordings across multilobular regions in patients undergoing seizure monitoring while they retrieved spatial and temporal context associated with an episode, and we used phase synchronization as a measure of network connectivity. Successful memory retrieval was characterized by greater global connectivity compared with incorrect retrieval, with the medial temporal lobe acting as a hub for these interactions. Spatial versus temporal context retrieval resulted in prominent differences in both the spectral and temporal patterns of network interactions. These results emphasize dynamic network interactions as being central to episodic memory retrieval, providing insight into how multiple contexts underlying a single event can be recreated in the same network.