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Aaron J. Clark, Michael M. Safaee, Nickalus R. Khan, Matthew T. Brown and Kevin T. Foley

OBJECTIVE

Microendoscopic discectomy is a minimally invasive surgery technique that was initially described in 1997. It allows surgeons to work with 2 hands through a small-diameter, operating table–mounted tubular retractor, and to apply standard microsurgical techniques in which a small skin incision and minimal muscle dissection are used. Whether the surgeon chooses to use an endoscope or a microscope for visualization, the technique uses the same type of retractor and is thus called tubular microdiscectomy. The goal in this study was to review the current literature, examine the level of evidence supporting tubular microdiscectomy, and describe surgical techniques for complication avoidance.

METHODS

The authors performed a systematic PubMed review using the terms “microdiscectomy trial,” “tubular and open microdiscectomy,” “microendoscopic open discectomy,” and “minimally invasive open microdiscectomy OR microdiskectomy.” Of 317 references, 10 manuscripts were included for analysis based on study design, relevance, and appropriate comparison of open to tubular discectomy.

RESULTS

Similar and very favorable clinical outcomes can be expected from tubular and standard microdiscectomy. Studies have demonstrated equivalent operating times for both procedures, with lower blood loss and shorter hospital stays associated with tubular microdiscectomy. Furthermore, postoperative analgesic usage has been shown to be significantly lower after tubular microdiscectomy. Overall rates of complications are no different for tubular and standard microdiscectomy.

CONCLUSIONS

Prospective randomized trials have been used to evaluate outcomes of common minimally invasive lumbar spine procedures. For lumbar discectomy, Level I evidence supports equivalently good outcomes for tubular microdiscectomy compared with standard microdiscectomy. Likewise, Level I data indicate similar safety profiles and may indicate lower blood loss for tubular microdiscectomy. Future studies should examine the comparative value of these procedures.

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Berkeley G. Bate, Nickalus R. Khan, Brent Y. Kimball, Kyle Gabrick and Jason Weaver

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.

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Abhaya V. Kulkarni

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Nickalus R. Khan, Prayash G. Patel, John P. Sharpe, Siang Liao Lee and Jeffrey Sorenson

OBJECTIVE

Venous thromboembolism (VTE) is a common and potentially life-threatening complication. The risk of serious hemorrhagic complications when starting chemical prophylaxis for VTE prevention is a substantial concern for neurosurgeons. The objective of this study was to perform an updated systematic review and meta-analysis to determine if the rates of VTE and bleeding complications are different in patients undergoing chemoprophylaxis compared with placebo or mechanical prophylaxis alone following cranial or spinal procedures.

METHODS

In February 2016 a systematic literature review was performed identifying 3944 articles from 4 different databases. A random-effects meta-analysis was performed after identifying the articles that met inclusion criteria.

RESULTS

Nine articles that met the inclusion criteria were included. The quality of the studies was good, with all of them being classified as Level 2 evidence, with moderate Jadad scores. A meta-analysis comparing chemoprophylaxis with placebo in the prevention of deep venous thrombosis showed a significant benefit to chemical prophylaxis (OR 0.51, 95% CI 0.37–0.71; p < 0.0001). No significant increase in major intracranial hemorrhage (p = 0.60), major extracranial hemorrhage (p = 0.98), or minor bleeding complications (p = 0.60) was found.

CONCLUSIONS

Based on moderate-to-good quality of evidence, chemoprophylaxis is beneficial in preventing VTE, with no significant increase in either major or minor bleeding complications in patients undergoing cranial and spinal procedures. Further research is needed to determine whether this conclusion holds true for more specific subpopulations.

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Nickalus R. Khan, Zachary Smalley, Cody L. Nesvick, Siang Liao Lee and L. Madison Michael II

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.

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Nickalus R. Khan, Kenneth Moore, Jaafar Basma, David S. Hersh, Asim F. Choudhri, Brandy Vaughn and Paul Klimo Jr.

OBJECTIVE

An ischemic stroke following an elective craniotomy in a child is perceived to be a rare event. However, to date there are few papers on this topic. The purpose of this study was to investigate the occurrence of stroke following elective intracranial surgery at a children’s hospital.

METHODS

The authors performed a retrospective review of all patients who developed a perioperative stroke following an elective craniotomy from 2010 through 2017. Data were collected using an institutional database that contained demographic, medical, radiological, and outcome variables.

RESULTS

A total of 1591 elective craniotomies were performed at the authors’ institution during the study period. Of these, 28 (1.8%) were followed by a perioperative stroke. Radiographic diagnosis of the infarction occurred at a median of 1.7 days (range 0–9 days) from the time of surgery, and neurological deficits were apparent within 24 hours of surgery in 18 patients (62.5%). Infarcts tended to occur adjacent to tumor resection sites (86% of cases), and in a unilateral (89%), unifocal (93%), and supratentorial (93%) location. Overall, 11 (39.3%) strokes were due to a perforating artery, 10 (35.7%) were due to a large vessel, 4 (14.3%) were venous, and 3 (10.7%) were related to hypoperfusion or embolic causes. Intraoperative MRI (iMRI) was used in 11 of the 28 cases, and 6 (55%) infarcts were not detected, all of which were deep.

CONCLUSIONS

The incidence of stroke following an elective craniotomy is low, with nearly all cases (86%) occurring after tumor resection. Perforator infarcts were most common but may be missed on iMRI.

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Garrett T. Venable, Nicholas B. Rossi, G. Morgan Jones, Nickalus R. Khan, Zachary S. Smalley, Mallory L. Roberts and Paul Klimo Jr.

OBJECTIVE

Shunt surgery consumes a large amount of pediatric neurosurgical health care resources. Although many studies have sought to identify risk factors for shunt failure, there is no consensus within the literature on variables that are predictive or protective. In this era of “quality outcome measures,” some authors have proposed various metrics to assess quality outcomes for shunt surgery. In this paper, the Preventable Shunt Revision Rate (PSRR) is proposed as a novel quality metric.

METHODS

An institutional shunt database was queried to identify all shunt surgeries performed from January 1, 2010, to December 31, 2014, at Le Bonheur Children's Hospital. Patients' records were reviewed for 90 days following each “index” shunt surgery to identify those patients who required a return to the operating room. Clinical, demographic, and radiological factors were reviewed for each index operation, and each failure was analyzed for potentially preventable causes.

RESULTS

During the study period, there were 927 de novo or revision shunt operations in 525 patients. A return to the operating room occurred 202 times within 90 days of shunt surgery in 927 index surgeries (21.8%). In 67 cases (33% of failures), the revision surgery was due to potentially preventable causes, defined as inaccurate proximal or distal catheter placement, infection, or inadequately secured or assembled shunt apparatus. Comparing cases in which failure was due to preventable causes and those in which it was due to nonpreventable causes showed that in cases in which failure was due to preventable causes, the patients were significantly younger (median 3.1 vs 6.7 years, p = 0.01) and the failure was more likely to occur within 30 days of the index surgery (80.6% vs 64.4% of cases, p = 0.02). The most common causes of preventable shunt failure were inaccurate proximal catheter placement (33 [49.3%] of 67 cases) and infection (28 [41.8%] of 67 cases). No variables were found to be predictive of preventable shunt failure with multivariate logistic regression.

CONCLUSIONS

With economic and governmental pressures to identify and implement “quality measures” for shunt surgery, pediatric neurosurgeons and hospital administrators must be careful to avoid linking all shunt revisions with “poor” or less-than-optimal quality care. To date, many of the purported risk factors for shunt failure and causes of shunt revision surgery are beyond the influence and control of the surgeon. We propose the PSRR as a specific, meaningful, measurable, and—hopefully—modifiable quality metric for shunt surgery in children.

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Nicholas B. Rossi, Nickalus R. Khan, Tamekia L. Jones, Jacob Lepard, Joseph H. McAbee and Paul Klimo Jr.

OBJECT

Ventricular shunts for pediatric hydrocephalus continue to be plagued with high failure rates. Reported risk factors for shunt failure are inconsistent and controversial. The raw or global shunt revision rate has been the foundation of several proposed quality metrics. The authors undertook this study to determine risk factors for shunt revision within their own patient population.

METHODS

In this single-center retrospective cohort study, a database was created of all ventricular shunt operations performed at the authors’ institution from January 1, 2010, through December 2013. For each index shunt surgery, demographic, clinical, and procedural variables were assembled. An “index surgery” was defined as implantation of a new shunt or the revision or augmentation of an existing shunt system. Bivariate analyses were first performed to evaluate individual effects of each independent variable on shunt failure at 90 days and at 180 days. A final multivariate model was chosen for each outcome by using a backward model selection approach.

RESULTS

There were 466 patients in the study accounting for 739 unique (“index”) operations, for an average of 1.59 procedures per patient. The median age for the cohort at the time of the first shunt surgery was 5 years (range 0–35.7 years), with 53.9% males. The 90- and 180-day shunt failure rates were 24.1% and 29.9%, respectively. The authors found no variable—demographic, clinical, or procedural—that predicted shunt failure within 90 or 180 days.

CONCLUSIONS

In this study, none of the risk factors that were examined were statistically significant in determining shunt failure within 90 or 180 days. Given the negative findings and the fact that all other risk factors for shunt failure that have been proposed in the literature thus far are beyond the control of the surgeon (i.e., nonmodifiable), the use of an institution’s or individual’s global shunt revision rate remains questionable and needs further evaluation before being accepted as a quality metric.

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Nickalus R. Khan, Brittany D. Fraser, Vincent Nguyen, Kenneth Moore, Scott Boop, Brandy N. Vaughn and Paul Klimo Jr.

OBJECTIVE

Despite established risk factors, abusive head trauma (AHT) continues to plague our communities. Cerebrovascular accident (CVA), depicted as areas of hypodensity on CT scans or diffusion restriction on MR images, is a well-known consequence of AHT, but its etiology remains elusive. The authors hypothesize that a CVA, in isolation or in conjunction with other intracranial injuries, compounds the severity of a child’s injury, which in turn leads to greater health care utilization, including surgical services, and an increased risk of death.

METHODS

The authors conducted a retrospective observational study to evaluate data obtained in all children with AHT who presented to Le Bonheur Children’s Hospital (LBCH) from January 2009 through August 2016. Demographic, hospital course, radiological, cost, and readmission information was collected. Children with one or more CVA were compared with those without a CVA.

RESULTS

The authors identified 282 children with AHT, of whom 79 (28%) had one or more CVA. Compared with individuals without a CVA, children with a stroke were of similar overall age (6 months), sex (61% male), and race (56% African-American) and had similar insurance status (81% public). Just under half of all children with a stroke (38/79, 48%) were between 1–6 months of age. Thirty-five stroke patients (44%) had a Grade II injury, and 44 (56%) had a Grade III injury. The majority of stroke cases were bilateral (78%), multifocal (85%), associated with an overlying subdural hematoma (86%), and were watershed/hypoperfusion in morphology (73%). Thirty-six children (46%) had a hemispheric stroke. There were a total of 48 neurosurgical procedures performed on 28 stroke patients. Overall median hospital length of stay (11 vs 3 days), total hospital charges ($13.8 vs $6.6 million), and mean charges per patient ($174,700 vs $32,500) were significantly higher in the stroke cohort as a whole, as well as by injury grade (II and III). Twenty children in the stroke cohort (25%) died as a direct result of their AHT, whereas only 2 children in the nonstroke cohort died (1%). There was a 30% readmission rate within the first 180-day postinjury period for patients in the stroke cohort, and of these, approximately 50% required additional neurosurgical intervention(s).

CONCLUSIONS

One or more strokes in a child with AHT indicate a particularly severe injury. These children have longer hospital stays, greater hospital charges, and a greater likelihood of needing a neurosurgical intervention (i.e., bedside procedure or surgery). Stroke is such an important predictor of health care utilization and outcome that it warrants a subcategory for both Grade II and Grade III injuries. It should be noted that the word “stroke” or “CVA” should not automatically imply arterial compromise in this population.

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Nickalus R. Khan, Clinton J. Thompson, Douglas R. Taylor, Garrett T. Venable, R. Matthew Wham, L. Madison Michael II and Paul Klimo Jr.

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.