Minimizing pneumocephalus during deep brain stimulation surgery

BACKGROUND

Deep brain stimulation (DBS) surgery is an effective treatment for movement disorders. Introduction of intracranial air following dura opening in DBS surgery can result in targeting inaccuracy and suboptimal outcomes. We develop and evaluate a simple method to minimize pneumocephalus during DBS surgery.

METHODS

A retrospective analysis of prospectively collected data was performed on patients undergoing DBS surgery at our institution from 2014 to 2022. A total of 172 leads placed in 89 patients undergoing awake or asleep DBS surgery were analyzed. Pneumocephalus volume was compared between leads placed with PMT and leads placed with standard dural opening. (112 PMT vs. 60 OPEN). Immediate post-operative high-resolution CT scans were obtained for all leads placed, from which pneumocephalus volume was determined through a semi-automated protocol with ITK-SNAP software. Awake surgery was conducted with the head positioned at 15-30°, asleep surgery was conducted at 0°.

RESULTS

PMT reduced pneumocephalus from 11.2 cm3±9.2 to 0.8 cm3±1.8 (P<0.0001) in the first hemisphere and from 7.6 cm3 ± 8.4 to 0.43 cm3 ± 0.9 (P<0.0001) in the second hemisphere. No differences in adverse events were noted between PMT and control cases. Lower rates of post-operative headache were observed in PMT group.

CONCLUSION

We present and validate a simple yet efficacious technique to reduce pneumocephalus during DBS surgery.

The Evolving Role of Postgraduate Year 7 in Neurological Surgery Residency

BACKGROUND AND OBJECTIVES

In 2013, all neurosurgery programs were mandated to adopt a 7-year structure. We sought to characterize how programs use the seventh year of training (postgraduate year 7 [PGY7]).

METHODS

We surveyed all accredited neurosurgery programs in the United States regarding the PGY7 residents' primary role and the availability of enfolded fellowships. We compiled responses from different individuals in each program: chair, program director, program coordinator, and current chiefs.

RESULTS

Of 120 accredited neurological surgery residency programs within the United States, 91 (76%) submitted responses. At these programs, the primary roles of the PGY7 were chief of service (COS, 71%), enfolded fellowships (EFF, 18%), transition to practice (10%), and elective time (1%). Most residencies have been 7-year programs for >10 years (52, 57%). Sixty-seven programs stated that they offer some form of EFF (73.6%). The most common EFFs were endovascular (57, 62.6%), spine (49, 53.9%), critical care (41, 45.1%), and functional (37, 40.7%). These were also the most common specialties listed as Committee on Advanced Subspecialty Training accredited by survey respondents. Spine and endovascular EFFs were most likely to be restricted to PGY7 (24.2% and 23.1%, respectively), followed by neuro-oncology (12, 13.2%). The most common EFFs reported as Committee on Advanced Subspecialty Training accredited but not restricted to PGY7 were endovascular (24, 26.4%) and critical care (23, 25.3%).

CONCLUSION

Most accredited neurological surgery training programs use the COS as the primary PGY7 role. Programs younger in their PGY7 structure seem to maintain the traditional COS role. Those more established seem to be experimenting with various roles the PGY7 year can fill, including enfolded fellowships and transition-to-practice years, predominantly. Most programs offer some form of enfolded fellowship. This serves as a basis for characterization of how neurological surgery training may develop in years to come.

Surgical Strategies in the Treatment of Giant Pituitary Adenomas

BACKGROUND AND OBJECTIVES

The management of giant pituitary adenomas (GPAs) is challenging due to associated endocrinopathies and the close proximity of these tumors to critical structures, such as the optic nerves, structures of the cavernous sinus, and hypothalamus. The objective of this review article was to summarize the current management strategies for giant pituitary adenomas, including the role of open and endoscopic surgical approaches and the role of medical and radiation therapy in conjunction with surgery.

METHODS

We conducted a retrospective review of GPAs operated at our institute between January 2010 and March 2023. Surgical approaches, extent of resection, and associated complications were documented. Furthermore, we conducted a thorough literature review to identify relevant studies published in the past decade, which were incorporated along with insights gained from our institutional case series of GPAs to analyze and integrate both the existing knowledge base and our institution's firsthand experience in the management of GPAs.

RESULTS

A total of 46 giant pituitary adenomas (GPAs) were operated on, using various surgical approaches. Transsphenoidal approach was used in 25 cases and a staged approach using transsphenoidal and pterional was used in 15 cases. Other approaches included transcortical-transventricular, transcallosal, pterional/orbitozygomatic, and subfrontal approaches. Complications and technical nuances were reported.

CONCLUSION

The management of giant pituitary adenomas remains complex, often involving several modalities-open or endoscopic resection, radiosurgery, and medical management of both the tumor and associated endocrinopathies. Surgical resections are often challenging procedures that require careful consideration of several factors, including patient characteristics, tumor location, and size, and the experience and skill of the surgical team.

Transotic Approach for Resection of Expansile Endolymphatic Sac Tumor

Objectives and Design Endolymphatic sac tumors (ELSTs) are rare and indolent tumors that arise from the endolymphatic sac in the posterior petrous ridge. We present a video case report illustrating the use of a transotic approach for resection of an expansile ELST.

Setting and Participants  A 25-year-old male presented with a multiyear history of worsening left-sided hearing loss, vertigo, and headaches. Otoscopy revealed a red mass behind an intact tympanic membrane. Computed tomography revealed a large, locally aggressive mass centered in the posterior petrous temporal bone. Magnetic resonance imaging demonstrated a heterogeneously enhancing 2.4 × 3.1 × 2.4 cm tumor that exerted mass effect on the cerebellar surface with extension into the jugular foramen, tympanic cavity, internal auditory canal, and cistern of the cerebellopontine angle. A transotic approach was planned to obtain the necessary generous exposure.

Main Outcome Measures and Results  Preoperative angiography revealed arterial supply via the ascending pharyngeal and tumor embolization with Onyx was performed. Surgical resection began with a blind-sac closure created from the external auditory canal. The tympanic membrane and malleus were removed and the incustapedial joint was transected. A subtotal petrosectomy was performed for partial tumor exposure. The facial canal and sigmoid sinus were carefully skeletonized and a labrynthectomy was performed. The tumor was resected using a combination of bipolar cautery and blunt and sharp dissection. For closure, an abdominal fat graft was secured with overlying resorbable mesh followed by sequential closure of all skin layers. Histopathologic analysis revealed an ELST.

Conclusion  The transotic approach offers wide exposure and facilitates large, complex tumor removal.

The link to the video can be found at https://youtu.be/YvhyN8iVi44 .

Are ape gestures like words? Outstanding issues in detecting similarities and differences between human language and ape gesture

Opinion piece: ape gestures are made intentionally, inviting parallels with human language; but how similar are their gestures to words? Here we ask this in three ways, considering: flexibility and ambiguity, first- and second-order intentionality, and usage in interactive exchanges. Many gestures are used to achieve several, often very distinct, goals. Such apparent ambiguity in meaning is potentially disruptive for communication, but-as with human language-situational and interpersonal context may largely resolve the intended meaning. Our evidence for first-order intentional use of gesture is abundant, but how might we establish a case for the second-order intentional use critical to language? Finally, words are rarely used in tidy signal-response sequences but are exchanged in back-and-forth interaction. Do gestures share this property? In this paper, we examine these questions and set out ways in which they can be resolved, incorporating data from wild chimpanzees. This article is part of the theme issue 'Cognition, communication and social bonds in primates'.

The Scope and Impact of the COVID-19 Pandemic on Neuroemergent Patient Transfers, Clinical Care and Patient Outcomes

Introduction

The SARS-CoV-2 (COVID-19) pandemic continues to substantially alter previously established clinical practice patterns and has transformed patient care in American healthcare. However, studies to evaluate the impact of COVID-19 on neuroemergent patient care and associated clinical outcomes are limited. Herein, we describe the impact of COVID-19 on the Neuroemergency Transfer Program (NTP) - a novel, urban, high volume interhospital patient transfer program.

Objective

To evaluate and describe the clinical impact of the COVID-19 pandemic on the NTP.

Study Design

A single-center retrospective study of prospectively collected consecutive neuroemergent patient transfer data between 2018–2021 was analyzed. Adult patients were divided based upon transfer date into a Pre-COVID (PCOV) or COVID cohort. Patient demographics, transfer characteristics and clinical data and outcomes were analyzed.

Results

3,096 patients were included for analysis. Mean age at transfer in the PCOV and COVID cohorts were 62.4 ± 0.36 and 61.1 ± 0.6 years. A significant decrease in mean transfers per month was observed between cohorts (PCOV = 97.8 vs. COV = 68.2 transfers/month, p < 0.01). Total transfer time in the PCOV cohort was 155.1 ± 3.4 min which increased to 169.3 ± 12.8 min in the COVID cohort (p = 0.13). Overall mean transfer distance was significantly longer in the PCOV cohort at 22.0 ± 0.4 miles vs. 20.3 ± 0.67 miles in the COV cohort (p = 0.03). The relative frequency of transfer diagnoses was unchanged between cohorts. A significant increase in mean inpatient length of stay was noted, 7.9 ± 0.15 days to 9.6 ± 0.33 days in the PCOV vs. COVID cohorts (p < 0.01). Ultimately, no difference in the frequency of good vs. poor clinical outcome were noted between the PCOV (79.8% and 19.4%) vs. COV (78.8% and 20.4%) cohorts.

Conclusion

The impact of COVID-19 on current healthcare dynamics are far reaching. Here, we show a significant decrease in interhospital patient transfers and increased length of stay between a Pre-COVID and COVID cohort. Further work to better elucidate the specific interplay of clinical contributors to account for these changes is indicated.

Socioecology of the Australian Tree Skink (Egernia striolata)

There is great diversity in social behavior across the animal kingdom. Understanding the factors responsible for this diversity can help inform theory about how sociality evolves and is maintained. The Australian Tree Skink (Egernia striolata) exhibits inter- and intra-population variability in sociality and is therefore a good system for informing models of social evolution. Here, we conducted a multi-year study of a Tree Skink population to describe intra-population variation in the social organization and mating system of this species. Skinks aggregated in small groups of 2–5 individuals, and these aggregations were typically associated with shared shelter sites (crevices and hollows within rocks and trees). Aggregations were typically made up of one or more adult females and, often, one male and/or juvenile(s). Social network and spatial overlap analyses showed that social associations were strongly biased toward kin. Tree skinks also exhibited high site fidelity regardless of age or sex. There were high levels of genetic monogamy observed with most females (87%) and males (68%) only breeding with a single partner. Our results indicate that Tree Skinks reside in small family groups and are monogamous, which corresponds with existing research across populations. Similar to previous work, our study area consisted of discrete habitat patches (i.e., rock outcrops, trees, or both), which likely limits offspring dispersal and promotes social tolerance between parents and their offspring. Our study clearly demonstrates that there is intra-population variability in Tree Skink social behavior, but it also provides evidence that there is a high degree of inter-population consistency in sociality across their geographic range. We also highlight promising possible avenues for future research, specifically discussing the importance of studying the nature and extent of Tree Skink parental care and quantifying the fitness outcomes of kin-based sociality in this species, which are topics that will further our understanding of the mechanisms underlying variation in vertebrate social behavior.

Sperm Storage in a Family-Living Lizard, the Tree Skink (Egernia striolata)

The ability to produce viable offspring without recently mating, either through sperm storage or parthenogenesis, can provide fitness advantages under a suite of challenging ecological scenarios. Using genetic analysis, we demonstrate that 3 wild-caught female Tree Skinks (Egernia striolata) reproduced in captivity with no access to males for over a year, and that this is best explained by sperm storage. To the best of our knowledge, this is the first time female sperm storage has been documented in any monogamous family-living reptile, including social Australian egerniine skinks (from the subfamily Egerniinae). Furthermore, by using paternal reconstruction of genotypes we show that captive-born offspring produced by the same females in the preceding year, presumably without sperm storage, were sired by different males. We qualitatively compared aspects of these females' mates and offspring between years. The parents of each litter were unrelated, but paternal and offspring genotypes from litters resulting from stored sperm were more heterozygous than those inferred to be from recent matings. Family-living egerniine skinks generally have low rates of multiple paternity, yet our study suggests that female sperm storage, potentially from outside social partners, offers the real possibility of benefits. Possible benefits include increasing genetic compatibility of mates and avoiding inbreeding depression via cryptic female choice. Sperm storage in Tree Skinks, a family-living lizard with a monogamous mating system, suggests that females may bet-hedge through extra-pair copulation with more heterozygous males, reinforcing the idea that females could have more control on reproductive outcomes than previously thought.

Neurosurgery residency and fellowship education in the United States: 2 decades of system development by the One Neurosurgery Summit organizations

The purpose of this report is to chronicle a 2-decade period of educational innovation and improvement, as well as governance reform, across the specialty of neurological surgery. Neurological surgery educational and professional governance systems have evolved substantially over the past 2 decades with the goal of improving training outcomes, patient safety, and the quality of US neurosurgical care. Innovations during this period have included the following: creating a consensus national curriculum; standardizing the length and structure of neurosurgical training; introducing educational outcomes milestones and required case minimums; establishing national skills, safety, and professionalism courses; systematically accrediting subspecialty fellowships; expanding professional development for educators; promoting training in research; and coordinating policy and strategy through the cooperation of national stakeholder organizations. A series of education summits held between 2007 and 2009 restructured some aspects of neurosurgical residency training. Since 2010, ongoing meetings of the One Neurosurgery Summit have provided strategic coordination for specialty definition, neurosurgical education, public policy, and governance. The Summit now includes leadership representatives from the Society of Neurological Surgeons, the American Association of Neurological Surgeons, the Congress of Neurological Surgeons, the American Board of Neurological Surgery, the Review Committee for Neurological Surgery of the Accreditation Council for Graduate Medical Education, the American Academy of Neurological Surgery, and the AANS/CNS Joint Washington Committee. Together, these organizations have increased the effectiveness and efficiency of the specialty of neurosurgery in advancing educational best practices, aligning policymaking, and coordinating strategic planning in order to meet the highest standards of professionalism and promote public health.

The Materials Utilized in Cranial Reconstruction: Past, Current, and Future

BACKGROUND

Cranioplasty (CP) is associated with high complication rates compared to other common neurosurgical procedures. Several graft materials are used for CP, which may contribute to the high complication rates, but data in the literature regarding the influence of graft material on post-CP outcomes are inconsistent making it difficult to determine if, when, and to what extent the graft material impacts the rate of perioperative complications. There is an increased demand to identify and develop superior graft materials.

OBJECTIVE

To review and compare the indications, risks, complications, and patient results associated with the use of different graft materials for cranial reconstructions.

DESIGN

A search through EBSCOhost was conducted using the keywords "craniectomy" or "decompressive craniectomy," "cranioplasty," and "materials." The search was limited to literature published in the English language from 2005 until the present. Ultimately, 69 articles were included in this review. Due to the heterogeneity of the study populations, results, statistical analyses, and collecting methods, no statistical analyses could be performed.

CONCLUSIONS

Several graft materials have been adapted for use in cranial reconstructions with inconsistent results making it unclear if or when one material may be indicated over others. Advances in computer-aided design have led to improved patient-specific implants, but the ideal graft material is still being sought after in ongoing research efforts. Reviewing materials currently available, as well as those in clinical trials, is important to identify the limitations associated with different implants and to guide future research.

Laparoscopic-Assisted Versus Mini-Open Laparotomy for Ventriculoperitoneal Shunt Placement in the Medicare Population

BACKGROUND

Placement of the distal shunt catheter into the peritoneum during ventriculoperitoneal shunt (VPS) surgery can be done with either laparoscopic assistance or laparotomy.

OBJECTIVE

To compare outcomes in laparoscopic-assisted vs laparotomy for placement of VPS in the Medicare population.

METHODS

Patients undergoing VPS placement, between 2004 and 2014, were identified by International Classification of Disease, Ninth Revision and Current Procedural Terminology codes in the Medicare database. Demographic data including age, sex, comorbidities, and indications were collected. Six- and twelve-month complication rates were analyzed.

RESULTS

A total of 1966 (3.2%) patients underwent laparoscopic-assisted VPS and 60 030 (96.8%) patients underwent nonlaparoscopic-assisted VPS placement. Compared with traditional open VPS placement, the laparoscopic approach was associated with decreased odds of distal revision at 6- and 12-mo postoperatively (6 mo: odds ratio [OR] = 0.41, 95% confidence interval [CI]: 0.21-0.74; 12 mo: OR = 0.60, 95% CI: 0.39-0.94). At 6- and 12-mo postoperatively, multivariable regression analysis demonstrated increased odds of distal revision in patients with a body mass index (BMI) > 30 Kg/M2, history of open abdominal surgery, and history of laparoscopic abdominal surgery. Additionally, history of prior abdominal surgery and BMI > 30 Kg/M2 were significantly associated with increase odds of shunt infection at 6 and 12-mo, respectively.

CONCLUSION

In the largest retrospective analysis to date, patients with a history of abdominal surgery and obesity were found to be at increased risk of infection and distal revision after VPS placement. However, the laparoscopic approach for abdominal placement of the distal catheter was associated with reduced rates of distal revision in this population, suggesting an avenue for reducing complications in well-selected patients.

Using natural travel paths to infer and compare primate cognition in the wild

Within comparative psychology, the evolution of animal cognition is typically studied either by comparing indirect measures of cognitive abilities (e.g., relative brain size) across many species or by conducting batteries of decision-making experiments among (typically) a few captive species. Here, we propose a third, complementary approach: inferring and comparing cognitive abilities through observational field records of natural information gradients and the associated variation in decision-making outcomes, using the ranging behavior of wild animals. To demonstrate the feasibility of our proposal, we present the results of a global survey assessing the availability of long-term ranging data sets from wild primates and the willingness of primatologists to share such data. We explore three ways in which such ranging data, with or without the associated behavioral and ecological data often collected by primatologists, might be used to infer and compare spatial cognition. Finally, we suggest how ecological complexity may be best incorporated into comparative analyses.

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Comparing animal ranging decisions in natural habitats has untapped potential

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How decisions vary with natural information gradients reveals wild animal cognition

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Ranging data on at least 164 populations of 105 wild primate species are available

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We present three thought analyses to compare cognition and explain its evolution

Structural and Functional Imaging in Glioma Management

The goal of glioma surgery is maximal safe resection in order to provide optimal tumor control and survival benefit to the patient. There are multiple imaging modalities beyond traditional contrast-enhanced magnetic resonance imaging (MRI) that have been incorporated into the preoperative workup of patients presenting with gliomas. The aim of these imaging modalities is to identify cortical and subcortical areas of eloquence, and their relationship to the lesion. In this article, multiple modalities are described with an emphasis on the underlying technology, clinical utilization, advantages, and disadvantages of each. functional MRI and its role in identifying hemispheric dominance and areas of language and motor are discussed. The nuances of magnetoencephalography and transcranial magnetic stimulation in localization of eloquent cortex are examined, as well as the role of diffusion tensor imaging in defining normal white matter tracts in glioma surgery. Lastly, we highlight the role of stimulated Raman spectroscopy in intraoperative histopathological diagnosis of tissue to guide tumor resection. Tumors may shift the normal arrangement of functional anatomy in the brain; thus, utilization of multiple modalities may be helpful in operative planning and patient counseling for successful surgery.

Responsive Neurostimulation of the Mesial Temporal White Matter in Bilateral Temporal Lobe Epilepsy

BACKGROUND

Responsive neuromodulation (RNS) is a treatment option for patients with medically refractory bilateral mesial temporal lobe epilepsy (MTLE). A paucity of data exists on the feasibility and clinical outcome of hippocampal-sparing bilateral RNS depth lead placements within the parahippocampal white matter or temporal stem.

OBJECTIVE

To evaluate seizure reduction outcomes with at least a 1-yr follow-up in individuals with bilateral MTLE undergoing hippocampus-sparing implantation of RNS depth leads.

METHODS

A retrospective analysis of prospectively collected data was performed on patients at our institution with bilateral MTLE who were implanted with RNS depth leads along the longitudinal extent of bitemporal parahippocampal white matter or temporal stem. Baseline and postoperative seizure frequency, previous surgical interventions, and postimplantation electrocorticography and stimulation data were analyzed.

RESULTS

Ten patients were included in the study (7 male, 3 female). Overall seizure frequency declined by a median 44.25% at 3.13 yr (standard deviation 3.31) postimplantation. Four patients (40%) achieved 50% responder rate at latest follow-up. Two of four patients with focal onset bilateral tonic-clonic seizures became completely seizure-free. Forty percent of patients were previously implanted with a vagus nerve stimulator, and 20% underwent a prior temporal lobectomy. All depth lead placements were confirmed as radiographically located in the parahippocampal white matter or temporal stem without hippocampus violation. There were no cases of lead malposition.

CONCLUSION

Extrahippocampal or temporal stem white matter targeting during RNS surgery for bitemporal MTLE is feasible and allows for electrographic seizure detection. Larger controlled studies with longer follow-up are needed to validate these preliminary findings.

Trends in United States neurosurgery residency education and training over the last decade (2009-2019)

OBJECTIVE

Postgraduate training in medicine has been under scrutiny in the last 10 years, with a focus on improving residents' education. The aim of this study was to quantify trends in neurosurgery residency (NSR) training and education over the last 10 years.

METHODS

The authors assessed Accreditation Council for Graduate Medical Education (ACGME), National Resident Matching Program, and American Board of Neurological Surgeons records and searched PubMed to collate 2009-2019 data. Analyzed trends included residents' demographic data, programs' characteristics, graduation and attrition rates, match data, resident case logs, and qualitative educational curriculum changes.

RESULTS

Significant increases in residents' demographic data (p < 0.05) included the number of female residents (from 12.7% to 17.6%) and the absolute number of residents (from 1112 to 1462). Age (mean 28.8 years), ethnicity, and number of residents per program (mean 13 residents per program) were unchanged. There were 16 new ACGME NSR programs, with currently 115 programs nationwide. The number of applicants per year (324 applicants per year) and the matching rate (mean 64%) remained stable. The mean attrition rate of 2.6% (range 2%-4%) was higher than the mean 2.1% ACGME attrition rate, a rate that decreased from 3% in 2009 to 1.6% in 2019. Education curriculum changes aimed at the standardization of training across the US included residents' boot camp (2009), the Milestones project (2012), and mandatory 7-year training initiated in 2013. An increase in endovascular, functional, trauma, and spine resident caseload was noted. The number of yearly publications about US NSR education has significantly increased (p < 0.05).

CONCLUSIONS

NSR education has received greater attention over the last decade in the US. Standardization of training has been implemented. A steady number of students remain interested in neurosurgery, with an increased number of women entering the field. Attention to wellness, in addition to high-quality education, should be further assessed as a factor to improve the overall NSR training and retention rate.

Outcomes and Patterns of Care in Elderly Patients with Glioblastoma Multiforme

BACKGROUND

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults, with an increased incidence among the elderly. However, the optimal treatment strategy in elderly patients remains unclear. This study seeks to investigate the effect of patient selection and treatment strategies on survival trends in these patients.

METHODS

Patients with diagnosis codes specific for GBM were queried from the National Cancer Database during 2004-2016. Univariate and multivariate Cox regression analysis was performed to investigate outcomes. Survival curves and 5-year survival were also generated based on patient-specific factors.

RESULTS

Among 104,456 patients with GBM identified, elderly patients were less likely to receive radiotherapy (61.3% vs. 77.8%; P < 0.001) or chemotherapy (47.2% vs. 62.9%; P < 0.001) or to undergo surgical resection (68.3% vs. 81.8; P < 0.001). Mean overall survival was 9.1 months (standard deviation, 10.0) and 5-year survival was 5.3%. Multivariate analysis showed age 75-84 years (hazard ratio [HR], 1.39; 95% confidence interval [CI], 1.12-1.73; P = 0.003) and lower Karnofsky Performance Status (50-70: HR, 1.68, 95% CI, 1.35-2.08, P < 0.001; ≤40: HR, 1.79, 95% CI 1.18-2.72, P = 0.006) were associated with decreased overall survival, whereas surgical resection (subtotal resection: HR, 0.52, 95% CI, 0.38-0.71, P < 0.001; gross total resection: HR, 0.29, 95% CI, 0.21-0.41, P < 0.001), radiotherapy (HR, 0.65; 95% CI, 0.47-0.91; P = 0.012), and chemotherapy (HR, 0.65; 95% CI, 0.48-0.88; P = 0.006) were associated with increased overall survival in elderly patients.

CONCLUSIONS

In an analysis of 104,456 patients with GBM, all treatment modalities were found to be used less frequently in elderly patients. Increasing age and poor performance status were associated with worsened survival. Gross total resection was associated with the greatest survival benefit, and chemotherapy and radiotherapy also improved survival outcomes. These treatment options improved outcomes regardless of performance status. Although maximal treatment strategies may improve survival in elderly patients with GBM, these treatment strategies must be balanced against patient-specific factors and quality-of-life concerns.

Resection of vestibular schwannomas after stereotactic radiosurgery: a systematic review

OBJECTIVE

Multiple short series have evaluated the efficacy of salvage microsurgery (MS) after stereotactic radiosurgery (SRS) for treatment of vestibular schwannomas (VSs); however, there is a lack of a large volume of patient data available for interpretation and clinical adaptation. The goal of this study was to provide a comprehensive review of tumor characteristics, management, and surgical outcomes of salvage of MS after SRS for VS.

METHODS

The Medline/PubMed, Scopus, CINAHL, Cochrane Library, and Google Scholar databases were queried according to PRISMA guidelines. All English-language and translated publications were included. Studies lacking adequate study characteristics and outcomes were excluded. Cases involving neurofibromatosis type 2, previous MS, or malignant transformation were excluded when possible.

RESULTS

Twenty studies containing 297 cases met inclusion criteria. Three additional cases from Rush University Medical Center were added for 300 total cases. Tumor growth with or without symptoms was the primary indication for salvage surgery (92.3% of cases), followed by worsening of symptoms without growth (4.6%) and cystic enlargement (3.1%). The average time to MS after SRS was 39.4 months. The average size and volume of tumor at surgery were 2.44 cm and 5.92 cm3, respectively. The surgical approach was retrosigmoid (42.8%) and translabyrinthine (57.2%); 59.5% of patients had a House-Brackmann (HB) grade of I or II. The facial nerve was preserved in 91.5% of cases. Facial nerve preservation and HB grades were lower for the translabyrinthine versus retrosigmoid approach (p = 0.31 and p = 0.18, respectively); however, fewer complications were noted in the translabyrinthine approach (p = 0.29). Gross-total resection (GTR) was completed in 55.7% of surgeries. Studies that predominantly used subtotal resection (STR) were associated with a lower rate of facial nerve injury (5.3% vs 11.3%, p = 0.07) and higher rate of HB grade I or II (72.9% vs 48.0%, p = 0.00003) versus those using predominantly GTR. However, majority STR was associated with a recurrence rate of 3.6% as compared to 1.4% for majority GTR (p = 0.29).

CONCLUSIONS

This study showed that the leading cause of MS after SRS was tumor growth at an average of 39.4 months after radiation. There were no significant differences in outcomes of facial nerve preservation, postoperative HB grade, or complication rate based on surgical approach. Patients who underwent STR showed statistically significant better HB outcomes compared with GTR. MS after SRS was considered by most authors to be more difficult than primary MS. These data support the notion that the surgical goals of salvage surgery are debulking of tumor mass, decreasing compression of the brainstem, and not necessarily pursuing GTR.

Surgical Resection of Clinoidal Meningiomas without Routine Use of Clinoidectomy

OBJECTIVE

Meningiomas of the anterior clinoid process (ACP) present significant surgical challenges given their anatomic relation to critical neurovascular structures. Routine anterior clinoidectomy is often described as a critical step in the resection of these tumors to reduce recurrence and improve visual outcomes. Anterior clinoidectomy, however, is not without risk and its benefits have not been clearly delineated. We present the outcomes of our series of surgically managed ACP meningiomas in which an anterior clinoidectomy was not routinely employed.

METHODS

A retrospective review of all ACP meningiomas operated on between August 1997 and March 2019 was conducted. Patients with a recurrent tumor or with <6 months of follow-up were excluded. Resection was typically carried out via a frontotemporal craniotomy followed by intradural removal of the tumor. Anterior clinoidectomy was only performed if hyperostosis of the ACP caused mass effect on the optic nerve.

RESULTS

Twenty-nine patients were included in this study. Anterior clinoidectomy was performed in 3 patients (10.3%). Gross total resection was achieved in 22 patients (75.9%). Of the 21 patients (72.4%) who presented with visual deficits, vision improved in 18 patients (85.7%) and worsened in 2 (9.5%). Tumor recurrence occurred in 5 patients (17.2%) at a mean follow-up of 64.9 months. Perioperative morbidity was 10.3%. Permanent morbidity and mortality were 6.9% (vision deterioration) and 0%, respectively.

CONCLUSIONS

Resection of ACP meningiomas without routine anterior clinoidectomy minimizes potential risk while achieving gross total resection, recurrence, and visual improvement rates comparable with those in previously reported series.

Continuous improvement in patient safety and quality in neurological surgery: the American Board of Neurological Surgery in the past, present, and future

The American Board of Neurological Surgery (ABNS) was incorporated in 1940 in recognition of the need for detailed training in and special qualifications for the practice of neurological surgery and for self-regulation of quality and safety in the field. The ABNS believes it is the duty of neurosurgeons to place a patient's welfare and rights above all other considerations and to provide care with compassion, respect for human dignity, honesty, and integrity. At its inception, the ABNS was the 13th member board of the American Board of Medical Specialties (ABMS), which itself was founded in 1933. Today, the ABNS is one of the 24 member boards of the ABMS. To better serve public health and safety in a rapidly changing healthcare environment, the ABNS continues to evolve in order to elevate standards for the practice of neurological surgery. In connection with its activities, including initial certification, recognition of focused practice, and continuous certification, the ABNS actively seeks and incorporates input from the public and the physicians it serves. The ABNS board certification processes are designed to evaluate both real-life subspecialty neurosurgical practice and overall neurosurgical knowledge, since most neurosurgeons provide call coverage for hospitals and thus must be competent to care for the full spectrum of neurosurgery. The purpose of this report is to describe the history, current state, and anticipated future direction of ABNS certification in the US.

African elephants interpret a trunk gesture as a clue to direction of interest

Orienting to gaze-direction is widespread among animal species, but evidence for spontaneous use of gesture for direction is limited [1]. Remarkably, African elephants (Loxodonta africana) have been found able to follow human pointing, including subtle actions in which the contralateral hand is used, and in which the body silhouette is not broken [2,3]. The natural origin of this ability is puzzling, as the species is not reported to use trunk- or limb-gesture for showing directions [4]. One natural gesture, the 'periscope-sniff' presumed to be used to enhance olfactory sampling by an elephant in circumstances of alarm or curiosity [5], might also betray the elephant's direction of focal attention. Here we investigate what information elephants gain from seeing periscope-sniff. When one elephant in a group gave a periscope-sniff, we recorded the location and orientation of the next periscope-sniff given. Elephants that could not see the first gesturer only gestured themselves if immediately adjacent to the first or closer to the presumed stimulus of interest. In contrast, elephants able to see the first signaller's periscope-sniff were often a considerable distance behind it, further from the stimulus. Focusing on these cases, where making the periscope-sniff was apparently caused by seeing the first gesture, we found its orientation significantly matched the first, suggesting that direction information was gained from seeing the periscope-sniff. Elephants' ability to use a conspecific's periscope-sniff as if it were an ostensive pointing gesture enables them to react to the presence and location of potential dangers.

Preoperative Computed Tomography Imaging of the Sphenoid Sinus: Striving Towards Safe Transsphenoidal Surgery

Introduction  Preoperative high-resolution computed tomography (HRCT) is essential in patients undergoing transsphenoidal surgery to identify potential high-risk anatomic variations. There is no consensus in the literature, as to which grading system to use to describe these variants, leading to inconsistent terminology between studies. In addition, substantial variability exists in the reported incidence of anatomic variants. In this study, we performed an institutional imaging analysis and literature review with the objective of consolidating and clearly defining these sphenoid sinus anatomical variations. In addition, we highlighted their surgical implications and propose a checklist for a systematic assessment of the sphenoid sinus on preoperative CT. Methods  Review of the literature and retrospective analysis assessing several imaging parameters in 81 patients who underwent preoperative HRCT imaging for endoscopic transsphenoidal tumor resection from January 2008 through July 2015 at Rush University Medical Center. Results  The most common sphenoid pneumatization patterns were sellar (45%) and postsellar (49%) types. Anterior clinoid process (ACP) pneumatization was seen in 17% of patients with high concordance of ipsilateral optic nerve (ON) protrusion. ON protrusion and dehiscence was present in 17 and 6% of patients, respectively. Internal carotid artery (ICA) protrusion and dehiscence was present in 30 and 5% of patients, respectively. Dehiscence rates from local bone invasion overlying the ICA and ON occurred in 17 and 4% of cases, respectively. Conclusions  Our study highlights and reviews the key variants that have potential to impact surgical complications and outcomes in a heterogeneous patient population. The proposed preoperative CT checklist for patients, undergoing transsphenoidal surgery, consistently identifies these higher risk anatomical variants.

Symptomatic Primary Tethered Optic Chiasm: Technical Case Report

BACKGROUND AND IMPORTANCE

Symptomatic tethering of the optic nerves and chiasm is a rare occurrence and has been reported following both surgical and medical treatment of pituitary adenoma. Here we present a case of primary optic chiasm tethering in a patient with empty sella syndrome.

CLINICAL PRESENTATION

The patient was a 61-yr-old female who presented with progressively worsening bitemporal hemianopsia. Magnetic resonance imaging (MRI) brain revealed an empty sella with herniation of the optic chiasm into the sella. The patient underwent an endoscopic, endonasal/trans-sphenoidal approach to the sella, where the optic chiasm was then detethered via lysis of arachnoid adhesions and ultimately buttressed with an abdominal fat graft. Postoperatively, the patient did well with subjective and objective improvements in her visual fields.

CONCLUSION

We report a rare case of primary tethered optic chiasm, which was successfully treated via an endoscopic, endonasal approach with abdominal fat graft harvest.

Dural Venous Sinus Thrombosis after Vestibular Schwannoma Surgery: The Anticoagulation Dilemma

Introduction  Dural venous sinus thrombosis (DVST) is a relatively understudied complication of vestibular schwannoma (VS) surgery. Several studies have examined this topic; however, there is limited data on the incidence, clinical progression, and proper management of this patient population. Methods  A retrospective review was performed for patients undergoing surgery for VS at a single institution. All postoperative imaging was reviewed for incidence of DVST. Demographic data were collected including tumor and surgical characteristics along with postoperative course. Results  A total of 63 patients underwent resection of their VS. The incidence of DVST was 34.9%. The operative time was greater in the dural venous sinus thrombosis (DSVT) group, at an average of 6.69 hours versus 4.87 in the no DSVT cohort ( p  = 0.04). Tumor size was correlationally significant ( p  = 0.051) at 2.75 versus 2.12 cm greatest diameter. The translabyrinthine approach was most prevalent (68.2%). The side of the thrombosis was ipsilateral to the tumor and surgery in all patients. The sigmoid sinus was most commonly involved (95.5%). Of them, 85% patients had a codominant or thrombus contralateral to the dominant sinus. All patients were asymptomatic. No patients were treated with anticoagulation. Resolution of thrombus was seen in five (22.7%) of the patients on last follow-up imaging. There were no hemorrhagic complications. Conclusion  The overall incidence of DVST was (34.9%) of 63 patients who underwent VS surgery. All patients were asymptomatic and none were treated with anticoagulation. In our study, continuing to observe asymptomatic patients did not lead to any adverse events.

Assessment of the Interrater Reliability of the Congress of Neurological Surgeons Microanastomosis Assessment Scale

BACKGROUND

The potential for simulation-based learning in neurosurgical training has led the Congress of Neurosurgical Surgeons to develop a series of simulation modules. The Northwestern Objective Microanastomosis Assessment Tool (NOMAT) was created as the corresponding assessment tool for the Congress of Neurosurgical Surgeons Microanastomosis Module. The face and construct validity of the NOMAT have been previously established.

OBJECTIVE

To further validate the NOMAT by determining its interrater reliability (IRR) between raters of varying levels of microsurgical expertise.

METHODS

The NOMAT was used to assess residents' performance in a microanastomosis simulation module in 2 settings: Northwestern University and the Society of Neurological Surgeons 2014 Boot Camp at the University of Indiana. At Northwestern University, participants were scored by 2 experienced microsurgeons. At the University of Indiana, participants were scored by 2 postdoctoral fellows and an experienced microsurgeon. The IRR of NOMAT was estimated by computing the intraclass correlation coefficient using SPSS v22.0 (IBM, Armonk, New York).

RESULTS

A total of 75 residents were assessed. At Northwestern University, 21 residents each performed microanastomosis on 2 model vessels of different sizes, one 3 mm and one 1 mm. At the University of Indiana, 54 residents performed a single microanastomosis procedure on 3-mm vessels. The intraclass correlation coefficient of the total NOMAT scores was 0.88 at Northwestern University and 0.78 at the University of Indiana.

CONCLUSION

This study indicates high IRR for the NOMAT. These results suggest that the use of raters with varying levels of expertise does not compromise the precision or validity of the scale. This allows for a wider adoption of the scale and, hence, a greater potential educational impact.

Mapping in Low-Grade Glioma Surgery: Low- and High-Frequency Stimulation

Surgery for lower grade glioma requires the use of brain mapping techniques to identify functional boundaries, which represent the limit of the resection. Two stimulation paradigms are currently available and their use should be tailored to the clinical context to extend tumor removal and decrease the odds of postoperative permanent deficits.

Sensory laterality in affiliative interactions in domestic horses and ponies (Equus caballus)

Many studies have been carried out into both motor and sensory laterality of horses in agonistic and stressful situations. Here we examine sensory laterality in affiliative interactions within four groups of domestic horses and ponies (N = 31), living in stable social groups, housed at a single complex close to Vienna, Austria, and demonstrate for the first time a significant population preference for the left side in affiliative approaches and interactions. No effects were observed for gender, rank, sociability, phenotype, group, or age. Our results suggest that right hemisphere specialization in horses is not limited to the processing of stressful or agonistic situations, but rather appears to be the norm for processing in all social interactions, as has been demonstrated in other species including chicks and a range of vertebrates. In domestic horses, hemispheric specialization for sensory input appears not to be based on a designation of positive versus negative, but more on the perceived need to respond quickly and appropriately in any given situation.

Obstructive Hydrocephalus Due to Intraventricular Hemorrhage After Incidental Durotomy During Lumbar Spine Surgery

STUDY DESIGN

Case report and review of literature.

OBJECTIVE

To present an exceedingly rare occurrence of obstructive hydrocephalus secondary to intraventricular hemorrhage after incidental durotomy during lumbar spine surgery.

SUMMARY OF BACKGROUND DATA

Incidental durotomies are uncommon but well recognized complications associated with spine surgery. Whereas mostly considered benign with no untoward clinical sequele, it can be symptomatic and present with spinal headaches, pseudomeningoceles, wound infection, meningitis and rarely intracerebral hemorrhage.

METHODS

A 76-year-old woman underwent L3-S1 laminectomies and fusion for lumbar spondylosis and stenosis. Intraoperatively, a small incidental durotomy was encountered and primarily repaired.

RESULTS

The patient developed altered mental status on postoperative day 2. Computed tomography of the brain revealed obstructive hydrocephalus and intraventricular hemorrhage. The patient was immediately transferred to the neurosurgery intensive care unit and an external ventricular drain was placed emergently with high opening pressure. Her mental status improved immediately after cerebral spinal fluid diversion. The external ventricular drain was successfully removed after 8 days. The patient made a full recovery and was discharged in stable condition.

CONCLUSION

Obstructive hydrocephalus after intraventricular hemorrhage is an exceptionally rare but potentially life-threatening complication of incidental durotomies. Spine surgeons should be aware of this rare but serious complication.

LEVEL OF EVIDENCE

4.

Bonobo and chimpanzee gestures overlap extensively in meaning

Cross-species comparison of great ape gesturing has so far been limited to the physical form of gestures in the repertoire, without questioning whether gestures share the same meanings. Researchers have recently catalogued the meanings of chimpanzee gestures, but little is known about the gesture meanings of our other closest living relative, the bonobo. The bonobo gestural repertoire overlaps by approximately 90% with that of the chimpanzee, but such overlap might not extend to meanings. Here, we first determine the meanings of bonobo gestures by analysing the outcomes of gesturing that apparently satisfy the signaller. Around half of bonobo gestures have a single meaning, while half are more ambiguous. Moreover, all but 1 gesture type have distinct meanings, achieving a different distribution of intended meanings to the average distribution for all gesture types. We then employ a randomisation procedure in a novel way to test the likelihood that the observed between-species overlap in the assignment of meanings to gestures would arise by chance under a set of different constraints. We compare a matrix of the meanings of bonobo gestures with a matrix for those of chimpanzees against 10,000 randomised iterations of matrices constrained to the original data at 4 different levels. We find that the similarity between the 2 species is much greater than would be expected by chance. Bonobos and chimpanzees share not only the physical form of the gestures but also many gesture meanings.

A Survey of the Neuro-Oncology Landscape

The field of neuro-oncology is evolving rapidly. Many important advances have recently been reported, and other promising investigations have the potential to soon make substantial impacts in the field, especially in the areas of high-grade gliomas and brain metastases. We present an overview of the current status of this field, highlighting the key recent advances as well as representative work of key clinical investigations, since these concepts have the potential to influence clinical management if they are demonstrated to be safe and efficacious. This overview includes some work that has only appeared in abstract form in order to provide a timely understanding of how the field is actively changing and what may lie on the horizon. We focus on both medical and surgical neuro-oncology advances in this highly multidisciplinary subspecialty.

Living in stable social groups is associated with reduced brain size in woodpeckers (Picidae)

Group size predicts brain size in primates and some other mammal groups, but no such relationship has been found in birds. Instead, stable pair-bonding and bi-parental care have been identified as correlates of larger brains in birds. We investigated the relationship between brain size and social system within the family Picidae, using phylogenetically controlled regression analysis. We found no specific effect of duration or strength of pair-bonds, but brain sizes were systematically smaller in species living in long-lasting social groups of larger sizes. Group-living may only present a cognitive challenge in groups in which members have individually competitive relationships; we therefore propose that groups functioning for cooperative benefit may allow disinvestment in expensive brain tissue.

Great ape gestures: intentional communication with a rich set of innate signals

Great apes give gestures deliberately and voluntarily, in order to influence particular target audiences, whose direction of attention they take into account when choosing which type of gesture to use. These facts make the study of ape gesture directly relevant to understanding the evolutionary precursors of human language; here we present an assessment of ape gesture from that perspective, focusing on the work of the "St Andrews Group" of researchers. Intended meanings of ape gestures are relatively few and simple. As with human words, ape gestures often have several distinct meanings, which are effectively disambiguated by behavioural context. Compared to the signalling of most other animals, great ape gestural repertoires are large. Because of this, and the relatively small number of intended meanings they achieve, ape gestures are redundant, with extensive overlaps in meaning. The great majority of gestures are innate, in the sense that the species' biological inheritance includes the potential to develop each gestural form and use it for a specific range of purposes. Moreover, the phylogenetic origin of many gestures is relatively old, since gestures are extensively shared between different genera in the great ape family. Acquisition of an adult repertoire is a process of first exploring the innate species potential for many gestures and then gradual restriction to a final (active) repertoire that is much smaller. No evidence of syntactic structure has yet been detected.

Truebeam Radiosurgery for the Treatment of Trigeminal Neuralgia: Preliminary Results at a Single Institution

Introduction

Radiosurgery is now an established method of satisfactory pain control in patients with trigeminal neuralgia (TN). The Varian Truebeam STx (Varian Medical Systems, Palo Alto, CA) linear accelerator (LINAC) system is an arc-based, frameless stereotactic radiosurgery system used for the treatment of TN. To our knowledge, there has been only one published series of patient histories that documents the use of a frameless LINAC system for the treatment of TN. We describe the treatment parameters, patient outcomes, and complications associated with the treatment of TN.

Methods

All patients treated with the Truebeam system for TN between 2012 and 2015, with at least a six-month follow-up, were identified. A dose of 90 Gy was delivered to the isocenter using a 0.5 cm diameter cone. The cisternal segment of the trigeminal nerve was placed at the location of the LINAC isocenter using an ExacTrac™ (Brainlab, Munich, Germany) image guidance system. The radiosurgical dose, Barrow Neurologic Institute pain score (BNI PS), symptom recurrence, magnetic resonance imaging (MRI) radiographic changes, and other complications, including Barrow Neurologic Institute facial numbness score (BNI FN), were analyzed.

Results

A total of 18 patients—15 women and 3 men—with a mean age of 58 years (median: 59 years; range: 22-84 years) were treated at our institution. Fourteen patients (78%) had a BNI PS of IIIb or better, which was considered successful treatment. Twelve patients had excellent (BNI PS I) pain relief and two patients had good (BNI PS II-IIIB; recurrence after one year) pain relief. The pain of four patients recurred after a mean of 10 months.

Conclusion

Truebeam radiosurgery can provide effective and safe treatment for patients suffering from TN. The efficacy appears similar to other frame- and frameless-based systems

Wild chimpanzees' use of single and combined vocal and gestural signals

ABSTRACT

We describe the individual and combined use of vocalizations and gestures in wild chimpanzees. The rate of gesturing peaked in infancy and, with the exception of the alpha male, decreased again in older age groups, while vocal signals showed the opposite pattern. Although gesture-vocal combinations were relatively rare, they were consistently found in all age groups, especially during affiliative and agonistic interactions. Within behavioural contexts rank (excluding alpha-rank) had no effect on the rate of male chimpanzees' use of vocal or gestural signals and only a small effect on their use of combination signals. The alpha male was an outlier, however, both as a prolific user of gestures and recipient of high levels of vocal and gesture-vocal signals. Persistence in signal use varied with signal type: chimpanzees persisted in use of gestures and gesture-vocal combinations after failure, but where their vocal signals failed they tended to add gestural signals to produce gesture-vocal combinations. Overall, chimpanzees employed signals with a sensitivity to the public/private nature of information, by adjusting their use of signal types according to social context and by taking into account potential out-of-sight audiences. We discuss these findings in relation to the various socio-ecological challenges that chimpanzees are exposed to in their natural forest habitats and the current discussion of multimodal communication in great apes.

SIGNIFICANCE STATEMENT

All animal communication combines different types of signals, including vocalizations, facial expressions, and gestures. However, the study of primate communication has typically focused on the use of signal types in isolation. As a result, we know little on how primates use the full repertoire of signals available to them. Here we present a systematic study on the individual and combined use of gestures and vocalizations in wild chimpanzees. We find that gesturing peaks in infancy and decreases in older age, while vocal signals show the opposite distribution, and patterns of persistence after failure suggest that gestural and vocal signals may encode different types of information. Overall, chimpanzees employed signals with a sensitivity to the public/private nature of information, by adjusting their use of signal types according to social context and by taking into account potential out-of-sight audiences.