Garrett T. Venable

An analysis of publication productivity for 1225 academic neurosurgeons and 99 departments in the United States

OBJECT Bibliometrics is defined as the study of statistical and mathematical methods used to quantitatively analyze scientific literature. The application of bibliometrics in neurosurgery is in its infancy. The authors calculate a number of publication productivity measures for almost all academic neurosurgeons and departments within the US. METHODS The h-index, g-index, m-quotient, and contemporary h-index (hc-index) were calculated for 1225 academic neurosurgeons in 99 (of 101) programs listed by the Accreditation Council for Graduate Medical Education in January 2013. Three currently available citation databases were used: Google Scholar, Scopus, and Web of Science. Bibliometric profiles were created for each surgeon. Comparisons based on academic rank (that is, chairperson, professor, associate, assistant, and instructor), sex, and subspecialties were performed. Departments were ranked based on the summation of individual faculty h-indices. Calculations were carried out from January to February 2013. RESULTS The median h-index, g-index, hc-index, and m-quotient were 11, 20, 8, and 0.62, respectively. All indices demonstrated a positive relationship with increasing academic rank (p < 0.001). The median h-index was 11 for males (n = 1144) and 8 for females (n = 81). The h-index, g-index and hc-index significantly varied by sex (p < 0.001). However, when corrected for academic rank, this difference was no longer significant. There was no difference in the m-quotient by sex. Neurosurgeons with subspecialties in functional/epilepsy, peripheral nerve, radiosurgery, neuro-oncology/skull base, and vascular have the highest median h-indices; general, pediatric, and spine neurosurgeons have the lowest median h-indices. By summing the manually calculated Scopus h-indices of all individuals within a department, the top 5 programs for publication productivity are University of California, San Francisco; Barrow Neurological Institute; Johns Hopkins University; University of Pittsburgh; and University of California, Los Angeles. CONCLUSIONS This study represents the most detailed publication analysis of academic neurosurgeons and their programs to date. The results for the metrics presented should be viewed as benchmarks for comparison purposes. It is our hope that organized neurosurgery will adopt and continue to refine bibliometric profiling of individuals and departments.

Five-year institutional bibliometric profiles for 103 US neurosurgical residency programs

OBJECT Various bibliometric indices based on the citations accumulated by scholarly articles, including the h-index, g-index, e-index, and Googles i10-index, may be used to evaluate academic productivity in neurological surgery. The present article provides a comprehensive assessment of recent academic publishing output from 103 US neurosurgical residency programs and investigates intradepartmental publishing equality among faculty members. METHODS Each institution was considered a single entity, with the 5-year academic yield of every neurosurgical faculty member compiled to compute the following indices: ih(5), cumulative h, ig(5), ie(5), and i10(5) (based on publications and citations from 2009 through 2013). Intradepartmental comparison of productivity among faculty members yielded Gini coefficients for publications and citations. National and regional comparisons, institutional rankings, and intradepartmental publishing equality measures are presented. RESULTS The median numbers of departmental faculty, total publications and citations, ih(5), summed h, ig(5), ie(5), i10(5), and Gini coefficients for publications and citations were 13, 82, 716, 12, 144, 23, 16, 17, 0.57, and 0.71, respectively. The top 5 most academically productive neurosurgical programs based on ih(5)-index were University of California, San Francisco, University of California, Los Angeles, University of Pittsburgh, Brigham & Womens Hospital, and Johns Hopkins University. The Western US region was most academically productive and displayed greater intradepartmental publishing equality (median ih[5]-index = 18, median Ginipub = 0.56). In all regions, large departments with relative intradepartmental publishing equality tend to be the most academically productive. Multivariable logistic regression analysis identified the ih(5)-index as the only independent predictor of intradepartmental publishing equality (Ginipub ≤ 0.5 [OR 1.20, 95% CI 1.20-1.40, p = 0.03]). CONCLUSIONS The ih(5)-index is a novel, simple, and intuitive metric capable of accurately comparing the recent scholarly efforts of neurosurgical programs and accurately predicting intradepartmental publication equality. The ih(5)-index is relatively insensitive to factors such as isolated highly productive and/or no longer academically active senior faculty, which tend to distort other bibliometric indices and mask the accurate identification of currently productive academic environments. Institutional ranking by ih(5)-index may provide information of use to faculty and trainee applicants, research funding institutions, program leaders, and other stakeholders.

Bibliometric evaluation of pediatric neurosurgery in North America

OBJECT The application of bibliometric techniques to academic neurosurgery has been the focus of several recent publications. The authors provide here a detailed analysis of all active pediatric neurosurgeons in North America and their respective departments. METHODS Using Scopus and Google Scholar, a bibliometric profile for every known active pediatric neurosurgeon in North America was created using the following citation metrics: h-, contemporary h-, g-, and e-indices and the m-quotient. Various subgroups were compared. Departmental productivity from 2008 through 2013 was measured, and departments were ranked on the basis of cumulative h- and e-indices and the total number of publications and citations. Lorenz curves were created, and Gini coefficients were calculated for all departments with 4 or more members. RESULTS Three hundred twelve pediatric neurosurgeons (260 male, 52 female) were included for analysis. For the entire group, the median h-index, m-quotient, contemporary h-, g-, and e-indices, and the corrected g- and e-indices were 10, 0.59, 7, 18, 17, 1.14, and 1.01, respectively; the range for each index varied widely. Academic pediatric neurosurgeons associated with fellowship programs (compared with unassociated neurosurgeons), academic practitioners (compared with private practitioners), and men (compared with women) had superior measurements. There was no significant difference between American and Canadian pediatric neurosurgeons. The mean Gini coefficient for publications was 0.45 (range 0.18-0.70) and for citations was 0.53 (range 0.25-0.80). CONCLUSIONS This study represents the most exhaustive evaluation of academic productivity for pediatric neurosurgeons in North America to date. These results should serve as benchmarks for future studies.

Recurrent craniopharyngioma after conformal radiation in children and the burden of treatment

OBJECT In this paper the authors present their experience treating children with recurrent craniopharyngioma who were initially managed with surgery followed by conformal radiation therapy (CRT). METHODS A departmental oncology information system was queried to identify all children (< 18 years old) who received CRT for a craniopharyngioma between 1998 and 2010 (inclusive) and specifically those who experienced tumor progression. For each patient, the authors recorded the type of recurrence (solid, cystic, or both), the time interval to first progression and each subsequent progression, the associated treatment complications, and disease status at last follow-up evaluation. RESULTS Among the 97 patients that met criteria for entry into this study, 18 (18.6%) experienced tumor progression (9 cystic, 3 solid, 6 cystic and solid). The median time to first recurrence was 4.62 years (range 1.81-9.11 years). The subgroup included 6 female and 12 male patients with a median age of 7.54 years (range 3.61-13.83 years). Ten patients experienced first progression within 5 years of CRT. The 5- and 10-year treatment-free survival rates for the entire cohort were 89.0% (95% confidence interval [CI] 80.5%-93.9%) and 76.2% (95% CI 64%-85%), respectively. Seven patients had a single episode of progression and 11 had more than 1. The time interval between each subsequent progression was progressively shorter. The 18 patients underwent 38 procedures. The median follow-up duration for this group was 9.32 years (range 4.04-19.0 years). Three patients died, including 1 from perioperative complications. CONCLUSIONS Craniopharyngioma progression after prior irradiation is exceedingly difficult to treat and local control is challenging despite repeated surgical procedures. Given our results, gross-total resection may need to be the surgical goal at the time of first recurrence, if possible. Decompressing new cyst formation alone has a low rate of long-term success.

An application of Bradford’s law: identification of the core journals of pediatric neurosurgery and a regional comparison of citation density

PurposeBradford’s law describes the number of core journals in a given field or subject and has recently been applied to neurosurgery. The objective of this study was to use currently accepted formulations of Bradford’s law to identify core journals of pediatric neurosurgery. An additional analysis was completed to compare regional dependence on citation density among North American and European neurosurgeons.MethodsAll original research publications from 2009 to 2013 were analyzed for the 25 top publishing pediatric neurosurgeons in North America and Europe, which were sampled to construct regional citation databases of all journal references. Regional differences were compared with each database. Egghe’s formulation and the verbal formulation of Bradford’s law were applied to create specific citation density zones and identify the core journals.ResultsRegional comparison demonstrated a preference for the Journal of Neurosurgery and Child’s Nervous System, respectively, but four of the top five journals were common to both groups. Applying the verbal formulation of Bradford’s law to the North American citation database, a pattern of citation density was identified across the first three zones. Journals residing in the most highly cited first zone are presented as the core journals.ConclusionBradford’s law can be applied to identify the core journals of neurosurgical subspecialties. While regional differences exist between the most highly cited and most frequently published in journals among North American and European pediatric neurosurgeons, there is commonality between the top five core journals in both groups.

Bradford’s law: identification of the core journals for neurosurgery and its subspecialties

OBJECTIVE Bradfords law describes the scatter of citations for a given subject or field. It can be used to identify the most highly cited journals for a field or subject. The objective of this study was to use currently accepted formulations of Bradfords law to identify core journals of neurosurgery and neurosurgical subspecialties. METHODS All original research publications from 2009 to 2013 were analyzed for the top 25 North American academic neurosurgeons from each subspecialty. The top 25 were chosen from a ranked career h-index list identified from previous studies. Egghes formulation and the verbal formulation of Bradfords law were applied to create specific citation density zones and identify the core journals for each subspecialty. The databases were then combined to identify the core journals for all of academic neurosurgery. RESULTS Using Bradfords verbal law with 4 zone models, the authors were able to identify the core journals of neurosurgery and its subspecialties. The journals found in the most highly cited first zone are presented here as the core journals. For neurosurgery as a whole, the core included the following journals: Journal of Neurosurgery, Neurosurgery, Spine, Stroke, Neurology, American Journal of Neuroradiology, International Journal of Radiation Oncology Biology Physics, and New England Journal of Medicine. The core journals for each subspecialty are presented in the manuscript. CONCLUSIONS Bradfords law can be used to identify the core journals of neurosurgery and its subspecialties. The core journals vary for each neurosurgical subspecialty, but Journal of Neurosurgery and Neurosurgery are among the core journals for each neurosurgical subspecialty.

Five-Year Institutional Bibliometric Profiles for 119 North American Neurosurgical Residency Programs: An Update

BACKGROUND We recently performed a comprehensive bibliometric analysis of 103 U.S. neurosurgical departments and found the ih(5)-index as meaningful and reproducible using public data. The present report expands this analysis by adding 14 Canadian and 2 additional U.S. programs. METHODS Departments were included if listed in the American Association of Neurological Surgeons Residency Directory. Each institution was considered a single entity, and original research articles with authors who were neurosurgeon faculty were counted only once per institution, although a single article may have been credited toward multiple institutions, if applicable. The following bibliometric indices were calculated and used to rank departments: ih(5), ig(5), ie(5), and i10(5). In addition, intradepartmental comparison of productivity among faculty members was analyzed by computing Gini coefficients for publications and citations. RESULTS The top 5 most academically productive North American neurosurgical programs based on ih(5)-index were found to be the University of Toronto, University of California at San Francisco, University of California at Los Angeles, University of Pittsburgh, and Brigham and Womens Hospital. The top 5 Canadian programs were the University of Toronto, University of Calgary, McGill University, University of Sherbrooke, and University of British Columbia. The median ih(5)-index for U.S. and Canadian programs was 12 and 10.5, respectively. CONCLUSIONS This is the most accurate comprehensive analysis to date of contemporary bibliometrics among North American neurosurgery departments. Using the ih(5)-index for institutional ranking allows for informative comparison of recent scholarly efforts.

What is the risk of a shunt malfunction after elective intradural surgery

OBJECT Surgery for CSF diversion is the most common procedure performed by pediatric neurosurgeons. The failure rates for shunts remain frustratingly high, resulting in a burden to patients, families, providers, and healthcare systems. The goal of this study was to quantify the risk of a shunt malfunction in patients with an existing shunt who undergo an elective intradural operation. METHODS All elective intradural surgeries (cranial and spinal) at Le Bonheur Childrens Hospital from January 2010 through June 2014 were reviewed to identify those patients who had a functional ventricular shunt at the time of surgery. Patient records were reviewed to collect demographic, surgical, clinical, radiological, and pathologic data, including all details related to any subsequent shunt revision surgery. The primary outcome was all-cause shunt revision (i.e., malfunction or infection) within 90 days of elective intradural surgery. RESULTS One hundred and fifty elective intradural surgeries were identified in 109 patients during the study period. There were 14 patients (12.8%, 13 male) who experienced 16 shunt malfunctions (10.7%) within 90 days of elective intradural surgery. These 14 patients underwent 13 craniotomies, 2 endoscopic fenestrations for loculated hydrocephalus, and 1 laminectomy for dorsal rhizotomy. Median time to failure was 9 days, with the shunts in half of our patients failing within 5 postoperative days. Those patients with failed shunts were younger (median 4.2 years [range 0.33-26 years] vs median 10 years [range 0.58-34 years]), had a shorter time interval from their previous shunt surgery (median 11 months [range 0-81 months] vs median 20 months [range 0-238 months]), and were more likely to have had intraventricular surgery (80.0% vs. 60.3%). CONCLUSIONS This is the first study to quantify the risk of a shunt malfunction after elective intradural surgery. The 90-day all-cause shunt failure rate (per procedure) was 10.7%, with half of the failures occurring within the first 5 postoperative days. Possible risk factors for shunt malfunction after elective intradural surgeries are intraventricular surgical approach, shorter time since last shunt-related surgery, and young age.

Image-guided Convection-enhanced Delivery into Agarose Gel Models of the Brain

Convection-enhanced delivery (CED) has been proposed as a treatment option for a wide range of neurological diseases. Neuroinfusion catheter CED allows for positive pressure bulk flow to deliver greater quantities of therapeutics to an intracranial target than traditional drug delivery methods. The clinical utility of real time MRI guided CED (rCED) lies in the ability to accurately target, monitor therapy, and identify complications. With training, rCED is efficient and complications may be minimized. The agarose gel model of the brain provides an accessible tool for CED testing, research, and training. Simulated brain rCED allows practice of the mock surgery while also providing visual feedback of the infusion. Analysis of infusion allows for calculation of the distribution fraction (Vd/Vi) allowing the trainee to verify the similarity of the model as compared to human brain tissue. This article describes our agarose gel brain phantom and outlines important metrics during a CED infusion and analysis protocols while addressing common pitfalls faced during CED infusion for the treatment of neurological disease.

The Impact of a Pediatric Shunt Surgery Checklist on Infection Rate at a Single Institution

BACKGROUND Shunt infections remain a significant challenge in pediatric neurosurgery. Numerous surgical checklists have been introduced to reduce infection rates. OBJECTIVE To introduce an evidence-based shunt surgery checklist and its impact on our shunt infection rate. METHODS Between January 1, 2008 and December 31, 2015, pediatric patients who underwent shunt surgery at our institution were indexed in a prospectively maintained database. All definitive shunt procedures were included. Shunt infection was defined according to the Center for Disease Control and Preventions National Hospital Safety Network surveillance definition for surgical site infection. Clinical and procedural variables were abstracted per procedure. Infection data were compared for the 4 year before and 4 year after protocol implementation. Compliance was calculated from retrospective review of our checklists. RESULTS Over the 8-year study period, 1813 procedures met inclusion criteria with a total of 37 shunt infections (2%). Prechecklist (2008-2011) infection rate was 3.03% (28/924) and decreased to 1.01% (9/889; P = .003) postchecklist (2012-2015), representing an absolute risk reduction of 2.02% and relative risk reduction of 66.6%. One shunt infection was prevented for every 50 times the checklist was used. Those patients who developed an infection after protocol implementation were younger (0.95 years vs 3.40 years (P = .027)), but there were no other clinical or procedural variables, including time to infection, that were significantly different between the cohorts. Average compliance rate among required checklist components was 97% (range 85%-100%). CONCLUSION Shunt surgery checklist implementation correlated with lower infection rates that persisted in the 4 years after implementation.