Nickalus R. Khan

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.

Optimal Outcomes for Patients with Blunt Cerebrovascular Injury (BCVI): Tailoring Treatment to the Lesion

BACKGROUND Blunt cerebrovascular injuries (BCVI) once went unrecognized until cerebral ischemia or death occurred. We previously demonstrated that screening of high-risk asymptomatic patients and early treatment improved outcomes. However, major dissections, pseudoaneurysms, and fistulas rarely heal with antithrombotic therapy alone. Endovascular therapy in these lesions has increased without reports of outcomes. We sought to determine ischemic stroke and death rates after BCVI with and without endovascular treatment. STUDY DESIGN Patients with BCVI during a 53-month period ending May 2009 were identified. Antithrombotic therapy with heparin (goal partial thromboplastin time 40-60 s) or antiplatelets (aspirin and/or clopidogrel) was instituted after diagnosis of BCVI. Endovascular treatment was performed in patients with pseudoaneurysms, major dissections, and fistulas, whereas minor dissections and occluded vessels were treated with medical therapy alone. Outcomes evaluated were ischemic stroke and mortality, both in hospital and long term. RESULTS A total of 222 patients had 263 BCVI (115 carotid, 148 vertebral injuries); 22 patients had ischemic strokes before their angiographic diagnosis (17 present on arrival, 5 before angiography); 41% of patients underwent endovascular treatment for their BCVI, 50% were placed on heparin drips, and 76% and 52% were given aspirin and clopidogrel, respectively. Seven patients developed infarcts after BCVI diagnosis for a postdiagnosis rate of 4%. Follow-up was achieved in 85% of patients at a mean of 22 months. In-hospital mortality was 11%, and overall mortality rate was 16% at last follow-up. CONCLUSIONS Endovascular therapy of appropriate lesions in conjunction with medical therapy leads to the lowest ischemic stroke rates reported. Despite being used for more severe lesions with higher potential for ischemia, endovascular therapy had outcomes similar to medical therapy. Aggressive screening and treatment of BCVI leads to the lowest reported mortality and stroke rates.

Stereotactic radiosurgery for spinal metastases with or without separation surgery

OBJECT In patients with significant epidural spinal cord compression, initial surgical decompression and stabilization of spinal metastases, as opposed to radical oncological resection, provides a margin around the spinal cord that facilitates subsequent treatment with high-dose adjuvant stereotactic radiosurgery (SRS). If a safe margin exists between tumor and spinal cord on initial imaging, then high-dose SRS may be used as the primary therapy, eliminating the need for surgery. Selecting the appropriate approach has shown greater efficacy of tumor control, neurological outcome, and duration of response when compared with external beam radiotherapy, regardless of tumor histology. This study evaluates the efficacy of this treatment approach in a series of 57 consecutive patients. METHODS Patients treated for spinal metastases between 2007 and 2011 using the Varian Trilogy Linear Accelerator were identified retrospectively. Each received SRS, with or without initial surgical decompression and instrumentation. Medical records were reviewed to assess neurological outcome and surgical or radiation-induced complications. Magnetic resonance images were obtained for each patient at 3-month intervals posttreatment, and radiographic response was assessed as stability/regression or progression. End points were neurological outcome and local radiographic disease control at death or latest follow-up. RESULTS Fifty-seven patients with 69 lesions were treated with SRS for spinal metastases. Forty-eight cases (70%) were treated with SRS alone, and 21 (30%) were treated with surgery prior to SRS. A single fraction was delivered in 38 cases (55%), while a hypofractionated scheme was used in 31 (45%). The most common histological entities were renal cell, breast, and lung carcinomas. Radiographically, local disease was unchanged or regressed in 63 of 69 tumors (91.3%). Frankel score improved or remained stable in 68 of 69 cases (98.6%). CONCLUSIONS SRS, alone or as an adjunct following surgical decompression, provides durable local radiographic disease control while preserving or improving neurological function. This less-invasive alternative to radical spinal oncological resection appears to be effective regardless of tumor histology without sacrificing durability of radiographic or clinical response.

Understanding bibliometric parameters and analysis.

Bibliometric parameters have become an important part of modern assessment of academic productivity. These parameters exist for the purpose of evaluating authors (publication count, citation count, h-index, m-quotient, hc-index, e-index, g-index, i-10 [i-n] index) and journals (impact factor, Eigenfactor, article influence score, SCImago journal rank, source-normalized impact per paper). Although in recent years there has been a proliferation of bibliometric parameters, the true meaning and appropriate use of these parameters is generally not well understood. Effective use of existing and emerging bibliometric tools can aid in assessment of academic productivity, including readiness for promotions and other awards. However, if not properly understood, the data can be misinterpreted and may be subject to manipulation. Familiarity with bibliometric parameters will aid in their effective implementation in the review of authors-whether individuals or groups-and journals, as well as their possible use in the promotions review process, maximizing the effectiveness of bibliometric analysis.

Fibrinolysis for Intraventricular Hemorrhage An Updated Meta-Analysis and Systematic Review of the Literature

Background and Purpose— Intraventricular hemorrhage is associated with high mortality and poor functional outcome. The use of intraventricular fibrinolytic (IVF) therapy as an intervention in intraventricular hemorrhage is an evolving therapy with conflicting reports in the literature. The goal of this study is to investigate the impact of IVF on mortality, functional outcome, ventriculitis, shunt dependence, and rehemorrhage. Methods— During March and April 2014, a systematic literature search was performed identifying 1359 articles. Of these, 24 met inclusion criteria. A random effects meta-analysis was performed using both pooled and subset analysis based on study type. Results— Our meta-analysis demonstrated that IVF reduced mortality in intraventricular hemorrhage by nearly half (relative risk [RR], 0.55; 95% confidence interval [CI], 0.42–0.71; P<0.00001), increased the likelihood of good functional outcome by 66% (RR, 1.66; 95% CI, 1.27–2.19; P=0.0003), and also decreased the rate of shunt dependence (RR, 0.62; 95% CI, 0.42–0.93; P=0.02). IVF was not found to be associated with increased rates of ventriculitis (RR=1.46; 95% CI, 0.77–2.76; P=0.25) or rehemorrhage (RR=1.06; 95% CI, 0.66–1.70; P=0.80). We detected no evidence of publication bias. Conclusions— Our meta-analysis showed that IVF is safe and could be an effective strategy for the treatment of intraventricular hemorrhage. It may reduce mortality, improve functional outcome, and diminish the need for permanent ventricular shunting, while not increasing the risk of ventriculitis or rehemorrhage.

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.

The use of lumbar drains in preventing spinal cord injury following thoracoabdominal aortic aneurysm repair: an updated systematic review and meta-analysis

OBJECTIVE Paraplegia and paraparesis following aortic aneurysm repair occur at a substantially high rate and are often catastrophic to patients, their families, and the overall health care system. Spinal cord injury (SCI) following open thoracoabdominal aortic aneurysm (TAAA) repair is reported to be as high as 20% in historical controls. The goal of this study was to determine the impact of CSF drainage (CSFD) on SCI following TAAA repair. METHODS In August 2015 a systematic literature search was performed using clinicaltrials.gov , the Cochrane Library, PubMed/MEDLINE, and Scopus that identified 3478 articles. Of these articles, 10 met inclusion criteria. Random and fixed-effect meta-analyses were performed using both pooled and subset analyses based on study type. RESULTS The meta-analysis demonstrated that CSFD decreased SCI by nearly half (relative risk 0.42, 95% confidence interval 0.25-0.70; p = 0.0009) in the pooled analysis. This effect remained in the subgroup analysis of early SCI but did not remain significant in late SCI. CONCLUSIONS This meta-analysis showed that CSFD could be an effective strategy in preventing SCI following aortic aneurysm repair. Care should be taken to prevent complications related to overdrainage. No firm conclusions can be drawn about the newer endovascular procedures at the current time.

Image Guidance in Ventricular Cerebrospinal Fluid Shunt Catheter Placement: A Systematic Review and Meta-Analysis.

BACKGROUND Ventricular shunt placement for treating hydrocephalus is one of the most common neurosurgical procedures. The rate of shunt failure, however, has not appreciably changed with time. OBJECTIVE To investigate whether intraoperative image guidance using ultrasound or stereotaxy contributes to accurate shunt catheter placement and survival. METHODS We performed a systematic literature review using PubMed and MEDLINE databases for studies that use ultrasound and frameless stereotaxy for ventricular catheter placement for hydrocephalus. All articles assessed the accuracy of catheter tip placement and/or overall shunt survival, and the rate of accurate shunt catheter placement, the overall failure rate, and the average time to shunt failure were extracted for analysis. RESULTS Although each modality (ultrasound/stereotaxy) did not increase catheter placement accuracy, a combined random-effects meta-analysis of 738 catheters (136 guided by ultrasound, 168 guided by frameless stereotaxy, and 434 freehand) demonstrated a weak benefit of image guidance (risk ratio: 1.19, 95% confidence interval: 1.02-1.39, P = .02), but this result was limited by considerable heterogeneity among studies (I² = 86%, P < .001 by Cochranes Q test). A meta-analysis could not be performed for shunt survival due to heterogeneity in data reporting. CONCLUSION Although image guidance offers a promising solution to lower the risk of inaccurate catheter placement, which could lead to lower premature failure of ventricular shunts, our review demonstrated that there is not yet a clear benefit of these technologies. Current literature is limited to case series and cohort studies, and significant between-study heterogeneity in methodology and reporting currently limits a higher order analysis.

Functional outcomes following blunt cerebrovascular injury.

BACKGROUND There has been much debate on whom to screen, how to screen, and how to treat blunt cerebrovascular injury (BCVI), but there has been little published on long-term functional outcomes following diagnosis and treatment of BCVI. This study was conducted to address those long-term outcomes. METHODS Patients with BCVI during a 53-month period ending June 2009 were identified. Charts were reviewed for demographics, associated injuries, treatments, strokes, and in-hospital mortality. Posthospital discharge follow-up was conducted. A structured telephone interview was performed using a functional independence measurement–functional activity measurement questionnaire consisting of 30 questions in seven categories (self-care, sphincter control, mobility, locomotion, communication, psychosocial, and cognitive). Each question was scored from 1 (requires full assistance) to 7 (fully independent). Outcomes were compared by type of BCVI, associated injuries, and stroke. RESULTS Two hundred twenty-two patients with BCVI were identified. Twenty-four patients died during their initial hospitalization, and an additional 11 patient died after hospital discharge. The 68 patients who completed the interview constituted our study population. Mean follow-up was 35 months. Of a possible 210 points, the mean total score on functional independence measurement and functional activity measurement was 186, 185, and 188 for all patients, carotid artery injuries, and vertebral arteries injuries, respectively. A significant difference was seen when comparing patients with and without strokes (173 and 189, respectively). CONCLUSION This is the first report of functional outcomes following BCVI. We found that carotid and vertebral artery injuries have similar functional outcomes. As would be expected, the development of stroke led to worse outcomes. This underscores the importance of early diagnosis and initiation of therapy. Prevention of stroke in patients with BCVI leads to near-normal functional outcomes. LEVEL OF EVIDENCE Epidemiologic/prognostic study, level III.