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Alex B. Valadka, Jaclyn S. Valadka, Patrick R. Valadka and Patricia C. Valadka

The theme of the 2018 American Association of Neurological Surgeons Annual Meeting was “The Privilege of Service.” In the current climate of rapid change in healthcare delivery and increasing pressure on physicians, this theme was chosen to remind us of our true priorities and of the amazing opportunities that we have as neurosurgeons. In parallel to the classic triple-threat practitioner who excels in teaching, research, and clinical care, future neurosurgeons will need to acquire mastery in three areas of service, which have been summarized as the three A’s: administration, advocacy, and altruism. The blessings that we enjoy afford us a platform from which we can take advantage of the many opportunities to experience the privilege of serving others.

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Arnaud Dagain, Olivier Aoun, Aurore Sellier, Nicolas Desse, Christophe Joubert, Nathan Beucler, Cédric Bernard, Mathilde Fouet, Jean-Marc Delmas and Renaud Dulou

This article aims to describe the French concept regarding combat casualty neurosurgical care from the theater of operations to a homeland hospital. French military neurosurgeons are not routinely deployed to all combat zones. As a consequence, general surgeons initially treat neurosurgical wounds. The principle of this medical support is based on damage control. It is aimed at controlling intracranial hypertension spikes when neuromonitoring is lacking in resource-limited settings. Neurosurgical damage control permits a medevac that is as safe as can be expected from a conflict zone to a homeland medical treatment facility. French military neurosurgeons can occasionally be deployed within an airborne team to treat a military casualty or to complete a neurosurgical procedure performed by a general surgeon in theaters of operation. All surgeons regardless of their specialty must know neurosurgical damage control. General surgeons must undergo the required training in order for them to perform this neurosurgical technique.

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Yixuan Zhai, Jiwei Bai, Shuai Wang, Hua Gao, Mingxuan Li, Chuzhong Li, Songbai Gui and Yazhuo Zhang

OBJECTIVE

In this study, the authors’ aim was to research clinical features and prognostic factors in patients harboring clival chordomas and explore the relationship between platelet-derived growth factor receptor-β (PDGFR-β) expression and tumor invasion and prognosis of clival chordoma.

METHODS

A total of 242 patients were retrospectively analyzed. Clinical information, including extent of resection, Al-Mefty classification, postoperative complications, and postoperative radiotherapy, was reviewed. Kaplan-Meier analysis was used to estimate survival time. Immunohistochemical analysis, quantitative reverse transcription polymerase chain reaction, and Western blotting were used to measure the expression level of proteins or mRNA. Transwell assaying was performed to measure the invasive ability of the tumor cells.

RESULTS

According to the Al-Mefty classification, there were 37, 112, and 93 type I, II, and III tumors, respectively. Gross-total resection (GTR) was achieved in 86 cases (35.5%), subtotal resection (STR) in 63 cases (26.0%), and partial resection (PR) in 93 cases (38.4%). The 5-year progression-free survival (PFS) and overall survival (OS) rates in the GTR group were significantly higher than those in the non–total resection (NTR; i.e., STR and PR) group (p < 0.001). The 5-year PFS and OS rates for patients with type I tumors were significantly higher than those for patients harboring types II and III tumors (p < 0.001). In the NTR group, the median PFS and OS of patients with lower PDGFR-β expression were significantly longer than those of patients with higher PDGFR-β expression. Reduction of PDGFR-β suppressed the invasion ability of cells in vitro. In addition, reduction of PDGFR-β can obviously downregulate the expression levels of mammalian target of rapamycin (mTOR) or phospho-mTOR.

CONCLUSIONS

Extent of resection, Al-Mefty classification, primary tumor, postoperative radiotherapy, and PDGFR-β expression level are valuable prognostic factors in patients with clival chordomas. PDGFR-β could regulate invasion through the mTOR pathway in clival chordoma cells.

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Arthur Carminucci, Ke Nie, Joseph Weiner, Eric Hargreaves and Shabbar F. Danish

OBJECTIVE

The Leksell Gamma Knife Icon (GK Icon) radiosurgery system can utilize cone-beam computed tomography (CBCT) to evaluate motion error. This study compares the accuracy of frame-based and frameless mask-based fixation using the Icon system.

METHODS

A retrospective cohort study was conducted to evaluate patients who had undergone radiosurgery with the GK Icon system between June and December 2017. Patients were immobilized in either a stereotactic head frame or a noninvasive thermoplastic mask with stereotactic infrared (IR) camera monitoring. Setup error was defined as displacement of the skull in the stereotactic space upon setup as noted on pretreatment CBCT compared to its position in the stereotactic space defined by planning MRI for frame patients and defined as skull displacement on planning CBCT compared to its position on pretreatment CBCT for mask patients. For frame patients, the intrafractionation motion was measured by comparing pretreatment and posttreatment CBCT. For mask patients, the intrafractionation motion was evaluated by comparing pretreatment CBCT and additional CBCT obtained during the treatment. The translational and rotational errors were recorded.

RESULTS

Data were collected from 77 patients undergoing SRS with the GK Icon. Sixty-four patients underwent frame fixation, with pre- and posttreatment CBCT studies obtained. Thirteen patients were treated using mask fixation to deliver a total of 33 treatment fractions. Mean setup and intrafraction translational and rotation errors were small for both fixation systems, within 1 mm and 1° in all axes. Yet mask fixation demonstrated significantly larger intrafraction errors than frame fixation. Also, there was greater variability in both setup and intrafraction errors for mask fixation than for frame fixation in all translational and rotational directions. Whether the GK treatment was for metastasis or nonmetastasis did not influence motion uncertainties between the two fixation types. Additionally, monitoring IR-based intrafraction motion for mask fixation—i.e., the number of treatment stoppages due to reaching the IR displacement threshold—correlated with increasing treatment time.

CONCLUSIONS

Compared to frame-based fixation, mask-based fixation demonstrated larger motion variations. The variability in motion error associated with mask fixation must be taken into account when planning for small lesions or lesions near critical structures.

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Veronika Paštyková, Josef Novotný Jr., Tomáš Veselský, Dušan Urgošík, Roman Liščák and Josef Vymazal

OBJECTIVE

The aim of this study was to compare 3 different methods to assess the geometrical distortion of two 1.5-T and one 3-T magnetic resonance (MR) scanners and to evaluate co-registration accuracy. The overall uncertainty of each particular method was also evaluated.

METHODS

Three different MR phantoms were used: 2 commercial CIRS skull phantoms and PTGR known target phantom and 1 custom cylindrical Perspex phantom made in-house. All phantoms were fixed in the Leksell stereotactic frame and examined by a Siemens Somatom CT unit, two 1.5-T Siemens (Avanto and Symphony) MRI systems, and one 3-T Siemens (Skyra) MRI system. The images were evaluated using Leksell GammaPlan software, and geometrical deviation of the selected points from the reference values were determined. The deviations were further investigated for both definitions including fiducial-based and co-registration–based in the case of the CIRS phantom images. The same co-registration accuracy assessment was also performed for a clinical case. Patient stereotactic imaging was done on 3-T Skyra, 1.5-T Avanto, and CT scanners.

RESULTS

The accuracy of the CT scanner was determined as 0.10, 0.30, and 0.30 mm for X, Y, and Z coordinates, respectively. The total estimated uncertainty in distortion measurement in one coordinate was determined to be 0.32 mm and 0.14 mm, respectively, for methods using and not using CT as reference imaging. Slightly more significant distortions were observed when using the 3-T than either 1.5-T MR units. However, all scanners were comparable within the estimated measurement error. Observed deviation/distortion for individual X, Y, and Z stereotactic coordinates was typically within 0.50 mm for all 3 scanners and all 3 measurement methods employed. The total radial deviation/distortion was typically within 1.00 mm. Maximum total radial distortion was observed when the CIRS phantom was used; 1.08 ± 0.49 mm, 1.15 ± 0.48 mm, and 1.35 ± 0.49 mm for Symphony, Avanto, and Skyra, respectively. The co-registration process improved image stereotactic definition in a clinical case in which fiducial-based stereotactic definition was not accurate; this was demonstrated for 3-T stereotactic imaging in this study. The best results were shown for 3-T MR image co-registration with CT images improving image stereotactic definition by about 0.50 mm. The results obtained with patient data provided a similar trend of improvement in stereotactic definition by co-registration.

CONCLUSIONS

All 3 methods/phantoms used were evaluated as satisfactory for the image distortion measurement. The method using the PTGR phantom had the lowest uncertainty as no reference CT imaging was needed. Image co-registration can improve stereotactic image definition when fiducial-based definition is not accurate.

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Stacy A. Shackelford, Deborah J. del Junco, Michael C. Reade, Randy Bell, Tyson Becker, Jennifer Gurney, Randall McCafferty and Donald W. Marion

OBJECTIVE

In combat and austere environments, evacuation to a location with neurosurgery capability is challenging. A planning target in terms of time to neurosurgery is paramount to inform prepositioning of neurosurgical and transport resources to support a population at risk. This study sought to examine the association of wait time to craniectomy with mortality in patients with severe combat-related brain injury who received decompressive craniectomy.

METHODS

Patients with combat-related brain injury sustained between 2005 and 2015 who underwent craniectomy at deployed surgical facilities were identified from the Department of Defense Trauma Registry and Joint Trauma System Role 2 Registry. Eligible patients survived transport to a hospital capable of diagnosing the need for craniectomy and performing surgery. Statistical analyses included unadjusted comparisons of postoperative mortality by elapsed time from injury to start of craniectomy, and Cox proportional hazards modeling adjusting for potential confounders. Time from injury to craniectomy was divided into quintiles, and explored in Cox models as a binary variable comparing early versus delayed craniectomy with cutoffs determined by the maximum value of each quintile (quintile 1 vs 2–5, quintiles 1–2 vs 3–5, etc.). Covariates included location of the facility at which the craniectomy was performed (limited-resource role 2 facility vs neurosurgically capable role 3 facility), use of head CT scan, US military status, age, head Abbreviated Injury Scale score, Injury Severity Score, and injury year. To reduce immortal time bias, time from injury to hospital arrival was included as a covariate, entry into the survival analysis cohort was defined as hospital arrival time, and early versus delayed craniectomy was modeled as a time-dependent covariate. Follow-up for survival ended at death, hospital discharge, or hospital day 16, whichever occurred first.

RESULTS

Of 486 patients identified as having undergone craniectomy, 213 (44%) had complete date/time values. Unadjusted postoperative mortality was 23% for quintile 1 (n = 43, time from injury to start of craniectomy 30–152 minutes); 7% for quintile 2 (n = 42, 154–210 minutes); 7% for quintile 3 (n = 43, 212–320 minutes); 19% for quintile 4 (n = 42, 325–639 minutes); and 14% for quintile 5 (n = 43, 665–3885 minutes). In Cox models adjusted for potential confounders and immortal time bias, postoperative mortality was significantly lower when time to craniectomy was within 5.33 hours of injury (quintiles 1–3) relative to longer delays (quintiles 4–5), with an adjusted hazard ratio of 0.28, 95% CI 0.10–0.76 (p = 0.012).

CONCLUSIONS

Postoperative mortality was significantly lower when craniectomy was initiated within 5.33 hours of injury. Further research to optimize craniectomy timing and mitigate delays is needed. Functional outcomes should also be evaluated.

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Da Liu, Jun Sheng, Hong-hua Wu, Xia Kang, Qing-yun Xie, Yang Luo, Jiang-jun Zhou and Wei Zheng

OBJECTIVE

The purpose of this study was to compare stability of injectable hollow pedicle screws with different numbers of holes using different volumes of polymethylmethacrylate (PMMA) in severely osteoporotic lumbar vertebrae and analyze the relationship between screw stability and distribution and volume of PMMA.

METHODS

Forty-eight severely osteoporotic cadaveric lumbar vertebrae were randomly divided into 3 groups—groups A, B, and C (16 vertebrae per group). The screws used in group A had 4 holes (2 pairs of holes, with the second hole of each pair placed 180° further along the thread than the first). The screws used in group B had 6 holes (3 pairs of holes, placed with the same 180° difference in position). Unmodified conventional screws were used in group C. Each group was randomly divided into subgroups 0, 1, 2, and 3, with different volumes of PMMA used in each subgroup. Type A and B pedicle screws were directly inserted into the vertebrae in groups A and B, respectively, and then different volumes of PMMA were injected through the screws into the vertebrae in subgroups 0, 1, 2, and 3. The pilot hole was filled with different volumes of PMMA followed by insertion of screws in groups C0, C1, C2, and C3. Distributions of PMMA were evaluated radiographically, and axial pull-out tests were performed to measure the maximum axial pullout strength (Fmax).

RESULTS

Radiographic examination revealed that PMMA surrounded the anterior third of the screws in the vertebral bodies (VBs) in groups A1, A2, and A3; the middle third of screws in the junction area of the vertebral body (VB) and pedicle in groups B1, B2, and B3; and the full length of screws evenly in both VB and pedicle in groups C1, C2, and C3. In addition, in groups A3 and B3, PMMA from each of the screws (left and right) was in contact with PMMA from the other screw and the PMMA was closer to the posterior wall and pedicle than in groups A1, A2, B1, and B2. One instance of PMMA leakage was found (in group B3). Two-way analysis of variance revealed that 2 factors—distribution and volume of PMMA—significantly influenced Fmax (p < 0.05) but that they were not significantly correlated (p = 0.078). The Fmax values in groups in which screws were augmented with PMMA were significantly better than those in groups in which no PMMA was used (p < 0.05).

CONCLUSIONS

PMMA can significantly improve stability of different injectable pedicle screws in severely osteoporotic lumbar vertebrae, and screw stability is significantly correlated with distribution and volume of PMMA. The closer the PMMA is to the pedicle and the greater the quantity of injected PMMA used, the greater the pedicle screw stability is. Injection of 3.0 mL PMMA through screws with 4 holes (2 pair of holes, with the screws in each pair placed on opposite sides of the screw) produces optimal stability in severely osteoporotic lumbar vertebrae.

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Thara Tunthanathip, Kanutpon Khocharoen and Nakornchai Phuenpathom

OBJECTIVE

In the ongoing conflict in southern Thailand, the improvised explosive device (IED) has been a common cause of blast-induced traumatic brain injury (bTBI). The authors investigated the particular characteristics of bTBI and the factors associated with its clinical outcome.

METHODS

A retrospective cohort study was conducted on all patients who had sustained bTBI between 2009 and 2017. Collected data included clinical characteristics, intracranial injuries, and outcomes. Factors analysis was conducted using a forest plot.

RESULTS

During the study period, 70 patients met the inclusion criteria. Fifty individuals (71.4%) were military personnel. One-third of the patients (32.9%) suffered moderate to severe bTBI, and the rate of intracerebral injuries on brain CT was 65.7%. Coup contusion was the most common finding, and primary blast injury was the most common mechanism of blast injury. Seventeen individuals had an unfavorable outcome (Glasgow Outcome Scale score 1–3), and the overall mortality rate for bTBI was 11.4%. In the univariate analysis, factors associated with an unfavorable outcome were preoperative coagulopathy, midline shift of the brain ≥ 5 mm, basal cistern effacement, moderate to severe TBI, hypotension, fixed and dilated pupils, surgical site infection, hematocrit < 30% on admission, coup contusion, and subdural hematoma. In the multivariable analysis, midline shift ≥ 5 mm (OR 29.1, 95% CI 2.5–328.1) and coagulopathy (OR 28.7, 95% CI 4.5–180.3) were the only factors predicting a poor outcome of bTBI.

CONCLUSIONS

bTBIs range from mild to severe. Midline shift and coagulopathy are treatable factors associated with an unfavorable outcome. Hence, in cases of bTBI, reversing an abnormal coagulogram is required as soon as possible to improve clinical outcomes. The management of brain shift needs further study.

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Manabu Sasaki, Shunji Asamoto, Masao Umegaki and Katsumi Matsumoto

OBJECTIVE

This study aimed to investigate the characteristics of cervical degeneration in Japanese professional wrestlers and its relationship with the risk of cervical spine injury (CSI).

METHODS

Since 2012, 27 Japanese male wrestlers belonging to a professional wrestling association have undergone periodical medical examinations of the cervical spine. If neurological symptoms were observed in the wrestlers, the resident trainers urged them to undergo a brief examination at the authors’ institutions. In addition to this prospective research study, the mechanisms of the CSIs that occurred in 5 wrestlers, including 2 with CSI before 2012 and 3 who were independent from the professional wrestling association, were retrospectively investigated by reviewing the circumstances of the injury and the wrestlers’ imaging studies.

RESULTS

The mean age of the wrestlers was 36.9 years (range 23–56 years) at the initial examination. An anterior giant ossifying lesion (AGOL) was observed in the anterior aspect of the cervical spine of 11 wrestlers (41%). The AGOLs tended to grow and spread to multiple spinal levels as the wrestlers aged. Of the 12 wrestlers with osteogenic lesions, 10 older than 40 years of age (83%) had an AGOL, which is frequently accompanied by osseous spinal canal stenosis. Two wrestlers presented with spinal cord compression with intramedullary intensity change on MRI. However, during the follow-up period, no spinal cord injury (SCI) occurred in the wrestlers, although thoracolumbar injury occurred in 2 wrestlers during a match. In examining the 5 wrestlers with CSI, the injury occurred at the spinal levels without an AGOL. The most frequent pathology of CSI (60%) was SCI at the spinal level adjacent to the multilevel AGOL.

CONCLUSIONS

AGOL is a peculiar cervical degeneration of Japanese professional wrestlers, especially in aged wrestlers. The AGOL appears to be a biological reaction to reinforce the anterior aspect of the cervical spine of professional wrestlers, who routinely defend themselves in a flexed neck posture against their opponent. The present results suggest that the risk of CSI is not increased by spinal canal stenosis accompanied by AGOL. Further studies are needed to investigate the relationship between the wrestlers’ cervical degeneration and the risk of CSI in more detail.

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Harri Isokuortti, Grant L. Iverson, Noah D. Silverberg, Anneli Kataja, Antti Brander, Juha Öhman and Teemu M. Luoto

OBJECTIVE

The incidence of intracranial abnormalities after mild traumatic brain injury (TBI) varies widely across studies. This study describes the characteristics of intracranial abnormalities (acute/preexisting) in a large representative sample of head-injured patients who underwent CT imaging in an emergency department.

METHODS

CT scans were systematically analyzed/coded in the TBI Common Data Elements framework. Logistic regression modeling was used to quantify risk factors for traumatic intracranial abnormalities in patients with mild TBIs. This cohort included all patients who were treated at the emergency department of the Tampere University Hospital (between 2010 and 2012) and who had undergone head CT imaging after suffering a suspected TBI (n = 3023), including 2766 with mild TBI and a reference group with moderate to severe TBI.

RESULTS

The most common traumatic lesions seen on CT scans obtained in patients with mild TBIs and those with moderate to severe TBIs were subdural hematomas, subarachnoid hemorrhages, and contusions. Every sixth patient (16.1%) with mild TBI had an intracranial lesion compared with 5 of 6 patients (85.6%) in the group with moderate to severe TBI. The distribution of different types of acute traumatic lesions was similar among mild and moderate/severe TBI groups. Preexisting brain lesions were a more common CT finding among patients with mild TBIs than those with moderate to severe TBIs. Having a past traumatic lesion was associated with increased risk for an acute traumatic lesion but neurodegenerative and ischemic lesions were not. A lower Glasgow Coma Scale score, male sex, older age, falls, and chronic alcohol abuse were associated with higher risk of acute intracranial lesion in patients with mild TBI.

CONCLUSIONS

These findings underscore the heterogeneity of neuropathology associated with the mild TBI classification. Preexisting brain lesions are common in patients with mild TBI, and the incidence of preexisting lesions increases with age. Acute traumatic lesions are fairly common in patients with mild TBI; every sixth patient had a positive CT scan. Older adults (especially men) who fall represent a susceptible group for acute CT-positive TBI.