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Jayapalli Rajiv Bapuraj, Amy K. Bruzek, Jamaal K. Tarpeh, Lindsey Pelissier, Hugh J. L. Garton, Richard C. E. Anderson, Bin Nan, Tianwen Ma and Cormac O. Maher

OBJECTIVE

Current understanding of how the pediatric craniocervical junction develops remains incomplete. Measurements of anatomical relationships at the craniocervical junction can influence clinical and surgical decision-making. The purpose of this analysis was to quantitatively define clinically relevant craniocervical junction measurements in a population of children with CT scans that show normal anatomy.

METHODS

A total of 1458 eligible patients were identified from children between 1 and 18 years of age who underwent cervical spine CT scanning at a single institution. Patients were separated by both sex and age in years into 34 groups. Following this, patients within each group were randomly selected for inclusion until a target of 15 patients in each group had been reached. Each patient underwent measurement of the occipital condyle–C1 interval (CCI), pB–C2, atlantodental interval (ADI), basion-dens interval (BDI), basion-opisthion diameter (BOD), basion-axial interval (BAI), dens angulation, and canal diameter at C1. Mean values were calculated in each group. Each measurement was performed by two teams and compared for intraclass correlation coefficient (ICC).

RESULTS

The data showed that CCI, ADI, BDI, and dens angulation decrease in magnitude throughout childhood, while pB–C2, PADI, BAI, and BOD increase throughout childhood, with an ICC of fair to good (range 0.413–0.912). Notably, CCI decreases continuously on coronal CT scans, whereas on parasagittal CT scans, CCI does not decrease until after age 9, when it shows a continuous decline similar to measurements on coronal CT scans.

CONCLUSIONS

These morphometric analyses establish parameters for normal pediatric craniocervical spine growth for each year of life up to 18 years. The data should be considered when evaluating children for potential surgical intervention.

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Victor E. Staartjes, Costanza M. Zattra, Kevin Akeret, Nicolai Maldaner, Giovanni Muscas, Christiaan Hendrik Bas van Niftrik, Jorn Fierstra, Luca Regli and Carlo Serra

OBJECTIVE

Although rates of postoperative morbidity and mortality have become relatively low in patients undergoing transnasal transsphenoidal surgery (TSS) for pituitary adenoma, cerebrospinal fluid (CSF) fistulas remain a major driver of postoperative morbidity. Persistent CSF fistulas harbor the potential for headache and meningitis. The aim of this study was to investigate whether neural network–based models can reliably identify patients at high risk for intraoperative CSF leakage.

METHODS

From a prospective registry, patients who underwent endoscopic TSS for pituitary adenoma were identified. Risk factors for intraoperative CSF leaks were identified using conventional statistical methods. Subsequently, the authors built a prediction model for intraoperative CSF leaks based on deep learning.

RESULTS

Intraoperative CSF leaks occurred in 45 (29%) of 154 patients. No risk factors for CSF leaks were identified using conventional statistical methods. The deep neural network–based prediction model classified 88% of patients in the test set correctly, with an area under the curve of 0.84. Sensitivity (83%) and specificity (89%) were high. The positive predictive value was 71%, negative predictive value was 94%, and F1 score was 0.77. High suprasellar Hardy grade, prior surgery, and older age contributed most to the predictions.

CONCLUSIONS

The authors trained and internally validated a robust deep neural network–based prediction model that identifies patients at high risk for intraoperative CSF. Machine learning algorithms may predict outcomes and adverse events that were previously nearly unpredictable, thus enabling safer and improved patient care and better patient counseling.

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Kazuaki Morizane, Mitsuru Takemoto, Masashi Neo, Shunsuke Fujibayashi, Bungo Otsuki, Shimei Tanida, Takayoshi Shimizu, Hiromu Ito and Shuichi Matsuda

OBJECTIVE

Dyspnea and/or dysphagia is a life-threatening complication after occipitocervical fusion. The occiput-C2 angle (O-C2a) is useful for preventing dyspnea and/or dysphagia because O-C2a affects the oropharyngeal space. However, O-C2a is unreliable in atlantoaxial subluxation (AAS) because it does not reflect the translational motion of the cranium to C2, another factor affecting oropharyngeal area in patients with rheumatoid arthritis (RA) who have reducible AAS. The authors previously proposed the occipital and external acoustic meatus to axis angle (O-EAa; i.e., the angle made by McGregor’s line and a line joining the external auditory canal and the middle point of the endplate of the axis [EA line]) as a novel, useful, and powerful predictor of the anterior-posterior narrowest oropharyngeal airway space (nPAS) distance in healthy subjects. The aim of the present study was to elucidate the validity of O-EAa as an indicator of oropharyngeal airway space in RA patients with AAS.

METHODS

The authors investigated 64 patients with RA. The authors collected lateral cervical radiographs at neutral position, flexion, extension, protrusion, and retraction and measured the O-C2a, C2-C6, O-EAa, anterior atlantodental interval (AADI), and nPAS. Patients were classified into 2 groups according to the presence of AAS and its mobility: group N, patients without AAS; and group R, patients with reducible AAS during dynamic cervical movement.

RESULTS

Group N had a significantly lower AADI and O-EAa than group R in all but the extension position. The O-EAa was a better predictor for nPAS than O-C2a according to the mixed-effects models in both groups (marginal R2: 0.510 and 0.575 for the O-C2a and O-EAa models in group N, and 0.250 and 0.390 for the same models, respectively, in group R).

CONCLUSIONS

O-EAa was superior to O-C2a in predicting nPAS, especially in the case of AAS, because it affects both O-C2a and cranial translational motion. O-EAa would be a useful parameter for surgeons performing occipitocervical fusion in patients with AAS.

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Sonia Ajmera, Ryan P. Lee, Andrew Schultz, David S. Hersh, Jacob Lepard, Raymond Xu, Hassan Saad, Olutomi Akinduro, Melissa Justo, Brittany D. Fraser, Mustafa Motiwala, Pooja Dave, Brian Jimenez, David A. Wallace, Olufemi Osikoya, Sebastian Norrdahl, Jennings H. Dooley, Nickalus R. Khan, Brandy N. Vaughn, Cormac O. Maher and Paul Klimo Jr.

OBJECTIVE

The objective of this study was to analyze the publication output of postgraduate pediatric neurosurgery fellows for a 10-year period as well as identify 25 individual highly productive pediatric neurosurgeons. The correlation between academic productivity and the site of fellowship training was studied.

METHODS

Programs certified by the Accreditation Council for Pediatric Neurosurgery Fellowships that had 5 or more graduating fellows from 2006 to 2015 were included for analysis. Fellows were queried using Scopus for publications during those 10 years with citation data through 2017. Pearson correlation coefficients were calculated, comparing program rankings of faculty against fellows using the revised Hirsch index (r-index; primary) and Hirsch index (h-index; secondary). A list of 25 highly accomplished individual academicians and their fellowship training locations was compiled.

RESULTS

Sixteen programs qualified with 152 fellows from 2006 to 2015; 136 of these surgeons published a total of 2009 articles with 23,735 citations. Most publications were pediatric-specific (66.7%) clinical articles (93.1%), with middle authorship (55%). Co-investigators were more likely from residency than fellowship. There was a clustering of the top 7 programs each having total publications of around 120 or greater, publications per fellow greater than 12, more than 1200 citations, and adjusted ir10 (revised 10-year institutional h-index) and ih10 (10-year institutional h-index) values of approximately 2 or higher. Correlating faculty and fellowship program rankings yielded correlation coefficients ranging from 0.53 to 0.80. Fifteen individuals (60%) in the top 25 (by r5 index) list completed their fellowship at 1 of these 7 institutions.

CONCLUSIONS

Approximately 90% of fellowship-trained pediatric neurosurgeons have 1 or more publications, but the spectrum of output is broad. There is a strong correlation between where surgeons complete their fellowships and postgraduate publications.

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Sebastian Butscheidt, Marielle Ernst, Tim Rolvien, Jan Hubert, Jozef Zustin, Michael Amling and Tobias Martens

OBJECTIVE

Primary intraosseous meningioma (PIM) is a rare manifestation of meningioma, a benign, neoplastic lesion of the meninges. Its characteristic appearance is hyperostosis, while no or only minimal dural changes can be observed. This study aims to characterize this rare entity from both a clinical and histopathological point of view in order to improve clinical management.

METHODS

In the years 2009–2017, 26 cases of PIM were diagnosed using MRI and CT scans. In 16 cases the indication for resection was given, and specimens were further examined using a multilevel approach, including histological and immunohistochemical analyses. Additionally, the local database was searched for all cases of meningiomas, as well as osteosclerotic differential diagnoses—i.e., fibrous dysplasia, Paget’s disease of bone, and other benign osteosclerotic lesions.

RESULTS

In this study, PIM represented 2.4% of all meningiomas with a predominant occurrence in females (85%). Regarding the initial manifestation, PIMs show a slightly earlier onset than meningiomas. While most PIMs are located in the sphenoid bone, associated calcifications were visible in 58% of the cases on CT scans. Most of the cases were classified as WHO grade I (93%) and meningotheliomatous meningiomas (91%). Tumor growth was associated with an increased bone resorption followed by massive osteoid deposition and consecutive sclerosis. The frequently observed frayed appearance results from multiple bony canals, which contain blood vessels for the blood supply of the highly vascularized tumor tissue.

CONCLUSIONS

PIM is a rare but important differential diagnosis for osteosclerotic lesions of the skull, especially in women. Tumor-induced, cellular-mediated bone resorption and formation may play a central role in the underlying pathogenesis.

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Thomas J. Buell, Ching-Jen Chen, James H. Nguyen, Peter A. Christiansen, Saikiran G. Murthy, Avery L. Buchholz, Chun-Po Yen, Mark E. Shaffrey, Christopher I. Shaffrey and Justin S. Smith

OBJECTIVE

Prior reports have demonstrated the efficacy of surgical correction for adult lumbar scoliosis. Many of these reports focused on mild to moderate scoliosis. The authors’ objective was to report their experience and to assess outcomes and complications after deformity correction for severe adult scoliosis.

METHODS

The authors retrospectively analyzed consecutive adult scoliosis patients with major thoracolumbar/lumbar (TL/L) curves ≥ 75° who underwent deformity correction at their institution. Those eligible with a minimum 2 years of follow-up were included. Demographic, surgical, coronal and sagittal plane radiographic measurements, and health-related quality of life (HRQL) scores were analyzed.

RESULTS

Among 26 potentially eligible patients, 22 (85%) had a minimum 2 years of follow-up (range 24–89 months) and were included in the study (mean age 57 ± 11 years; 91% women). The cohort comprised 16 (73%), 4 (18%), and 2 (9%) patients with adult idiopathic scoliosis, de novo degenerative scoliosis, and iatrogenic scoliosis, respectively. The surgical approach was posterior-only and multistage anterior-posterior in 18 (82%) and 4 (18%) patients, respectively. Three-column osteotomy was performed in 5 (23%) patients. Transforaminal and anterior lumbar interbody fusion were performed in 14 (64%) and 4 (18%) patients, respectively. All patients had sacropelvic fixation with uppermost instrumented vertebra in the lower thoracic spine (46% [10/22]) versus upper thoracic spine (55% [12/22]). The mean fusion length was 14 ± 3 levels. Preoperative major TL/L and lumbosacral fractional (L4–S1) curves were corrected from 83° ± 8° to 28° ± 13° (p < 0.001) and 34° ± 8° to 13° ± 6° (p < 0.001), respectively. Global coronal and sagittal balance significantly improved from 5 ± 4 cm to 1 ± 1 cm (p = 0.001) and 9 ± 8 cm to 2 ± 3 cm (p < 0.001), respectively. Pelvic tilt significantly improved from 33° ± 9° to 23° ± 10° (p < 0.001). Significant improvement in HRQL measures included the following: Scoliosis Research Society (SRS) pain score (p = 0.009), SRS appearance score (p = 0.004), and SF-12/SF-36 physical component summary (PCS) score (p = 0.026). Transient and persistent neurological deficits occurred in 8 (36%) and 2 (9%) patients, respectively. Rod fracture/pseudarthrosis occurred in 6 (27%) patients (supplemental rods were utilized more recently in 23%). Revisions were performed in 7 (32%) patients.

CONCLUSIONS

In this single-center surgical series for severe adult scoliosis (major curves ≥ 75°), a posterior-only or multistage anterior-posterior approach provided major curve correction of 66% and significant improvements in global coronal and sagittal spinopelvic alignment. Significant improvements were also demonstrated in HRQL measures (SRS pain, SRS appearance, and SF-12/SF-36 PCS). Complications and revisions were comparable to those of other reports involving less severe scoliosis. The results of this study warrant future prospective multicenter studies to further delineate outcomes and complication risks for severe adult scoliosis correction.

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Matthew F. Gornet, Todd H. Lanman, J. Kenneth Burkus, Randall F. Dryer, Jeffrey R. McConnell, Scott D. Hodges and Francine W. Schranck

OBJECTIVE

The authors assessed the 10-year clinical safety and effectiveness of cervical disc arthroplasty (CDA) to treat degenerative cervical spine disease at 2 adjacent levels compared to anterior cervical discectomy and fusion (ACDF).

METHODS

A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted comparing the low-profile titanium ceramic composite–based Prestige LP Cervical Disc (n = 209) at two levels with ACDF (n = 188). Ten-year follow-up data from a postapproval study were available on 148 CDA and 118 ACDF patients and are reported here. Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative follow-up intervals for up to 10 years. The primary endpoint was overall success, a composite variable that included key safety and efficacy considerations. Ten-year follow-up rates were 86.0% for CDA and 84.9% for ACDF.

RESULTS

From 2 to 10 years, CDA demonstrated statistical superiority over ACDF for overall success, with rates at 10 years of 80.4% versus 62.2%, respectively (posterior probability of superiority [PPS] = 99.9%). Neck Disability Index (NDI) success was also superior, with rates at 10 years of 88.4% versus 76.5% (PPS = 99.5%), as was neurological success (92.6% vs 86.1%; PPS = 95.6%). Improvements from preoperative results in NDI and neck pain scores were consistently statistically superior for CDA compared to ACDF. All other study effectiveness measures were at least noninferior for CDA compared to ACDF through the 10-year follow-up period, including disc height. Mean angular ranges of motion at treated levels were maintained in the CDA group for up to 10 years. The rates of grade IV heterotopic ossification (HO) at the superior and inferior levels were 8.2% and 10.3%, respectively. The rate of severe HO (grade III or IV) did not increase significantly from 7 years (42.4%) to 10 years (39.0%). The CDA group had fewer serious (grade 3–4) implant-related or implant/surgical procedure–related adverse events (3.8% vs 8.1%; posterior mean 95% Bayesian credible interval [BCI] of the log hazard ratio [LHR] −0.92 [−1.88, −0.01]). The CDA group also had statistically fewer secondary surgical procedures at the index levels (4.7%) than the ACDF group (17.6%) (LHR [95% BCI] −1.39 [−2.15, −0.61]) as well as at adjacent levels (9.0% vs 17.9%).

CONCLUSIONS

The Prestige LP Cervical Disc, implanted at two adjacent levels, maintains improved clinical outcomes and segmental motion 10 years after surgery and is a safe and effective alternative to fusion.

Clinical trial registration no.: NCT00637156 (clinicaltrials.gov)

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Rinchen Phuntsok, Chase W. Provost, Andrew T. Dailey, Douglas L. Brockmeyer and Benjamin J. Ellis

OBJECTIVE

Prior studies have provided conflicting evidence regarding the contribution of key ligamentous structures to atlantoaxial (AA) joint stability. Many of these studies employed cadaveric techniques that are hampered by the inherent difficulties of testing isolated-injury scenarios. Analysis with validated finite element (FE) models can overcome some of these limitations. In a previous study, the authors completed an FE analysis of 5 subject-specific craniocervical junction (CCJ) models to investigate the biomechanics of the occipitoatlantal joint and identify the ligamentous structures essential for its stability. Here, the authors use these same CCJ FE models to investigate the biomechanics of the AA joint and to identify the ligamentous structures essential for its stability.

METHODS

Five validated CCJ FE models were used to simulate isolated- and combined ligamentous–injury scenarios of the transverse ligament (TL), tectorial membrane (TM), alar ligament (AL), occipitoatlantal capsular ligament, and AA capsular ligament (AACL). All models were tested with rotational moments (flexion-extension, axial rotation, and lateral bending) and anterior translational loads (C2 constrained with anterior load applied to the occiput) to simulate physiological loading and to assess changes in the atlantodental interval (ADI), a key radiographic indicator of instability.

RESULTS

Isolated AACL injury significantly increased range of motion (ROM) under rotational moment at the AA joint for flexion, lateral bending, and axial rotation, which increased by means of 28.0% ± 10.2%, 43.2% ± 15.4%, and 159.1% ± 35.1%, respectively (p ≤ 0.05 for all). TL removal simulated under translational loads resulted in a significant increase in displacement at the AA joint by 89.3% ± 36.6% (p < 0.001), increasing the ADI from 2.7 mm to 4.5 mm. An AACL injury combined with an injury to any other ligament resulted in significant increases in ROM at the AA joint, except when combined with injuries to both the TM and the ALs. Similarly, injury to the TL combined with injury to any other CCJ ligament resulted in a significant increase in displacement at the AA joint (significantly increasing ADI) under translational loads.

CONCLUSIONS

Using FE modeling techniques, the authors showed a significant reliance of isolated- and combined ligamentous–injury scenarios on the AACLs and TL to restrain motion at the AA joint. Isolated injuries to other structures alone, including the AL and TM, did not result in significant increases in either AA joint ROM or anterior displacement.

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Harry Mushlin, Daina M. Brooks, Joshua Olexa, Bryan J. Ferrick, Stephen Carbine, Gerald M. Hayward II, Brandon S. Bucklen and Charles A. Sansur

OBJECTIVE

The sacroiliac joint (SIJ) is a known source of low-back pain. Randomized clinical trials support sacroiliac fusion over conservative management for SIJ dysfunction. Clinical studies suggest that SIJ degeneration occurs in the setting of lumbosacral fusions. However, there are few biomechanical studies to provide a good understanding of the effect of lumbosacral fusion on the SIJ. In the present study, researchers performed a biomechanical investigation to discern the effect of pelvic versus SIJ fixation on the SIJ in lumbosacral fusion.

METHODS

Seven fresh-frozen human cadaveric specimens were used. There was one intact specimen and six operative constructs: 1) posterior pedicle screws and rods from T10 to S1 (PS); 2) PS + bilateral iliac screw fixation (BIS); 3) PS + unilateral iliac screw fixation (UIS); 4) PS + UIS + 3 contralateral unilateral SIJ screws (UIS + 3SIJ); 5) PS + 3 unilateral SIJ screws (3SIJ); and 6) PS + 6 bilateral SIJ screws (6SIJ). A custom-built 6 degrees-of-freedom apparatus was used to simulate three bending modes: flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Range of motion (ROM) was recorded at L5–S1 and the SIJ.

RESULTS

All six operative constructs had significantly reduced ROM at L5–S1 in all three bending modes compared to that of the intact specimen (p < 0.05). In the FE mode, the BIS construct had a significant reduction in L5–S1 ROM as compared to the other five constructs (p < 0.05). SIJ ROM was greatest in the FE mode compared to LB and AR. Although the FE mode did not show any statistically significant differences in SIJ ROM across the constructs, there were appreciable differences. The PS construct had the highest SIJ ROM. The BIS construct reduced bilateral SIJ ROM by 44% in comparison to the PS construct. The BIS and 6SIJ constructs showed reductions in SIJ ROM nearly equal to those of the PS construct. UIS and 3SIJ showed an appreciable reduction in unfused SIJ ROM compared to PS.

CONCLUSIONS

This investigation demonstrated the effects of various fusion constructs using pelvic and sacroiliac fixation in lumbosacral fusion. This study adds biomechanical evidence of adjacent segment stress in the SIJ in fusion constructs extending to S1. Unilateral pelvic fixation, or SIJ fusion, led to an appreciable but nonsignificant reduction in the ROM of the unfused contralateral SIJ. Bilateral pelvic fixation showed the greatest significant reduction of movement at L5–S1 and was equivalent to bilateral sacroiliac fusion in reducing SIJ motion.

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Victoria L. Morgan, Baxter P. Rogers, Hernán F. J. González, Sarah E. Goodale and Dario J. Englot

OBJECTIVE

Seizure outcome after mesial temporal lobe epilepsy (mTLE) surgery is complex and diverse, even across patients with homogeneous presurgical clinical profiles. The authors hypothesized that this is due in part to variations in network connectivity across the brain before and after surgery. Although presurgical network connectivity has been previously characterized in these patients, the objective of this study was to characterize presurgical to postsurgical functional network connectivity changes across the brain after mTLE surgery.

METHODS

Twenty patients with drug-refractory unilateral mTLE (5 left side, 10 female, age 39.3 ± 13.5 years) who underwent either selective amygdalohippocampectomy (n = 13) or temporal lobectomy (n = 7) were included in the study. Presurgical and postsurgical (36.6 ± 14.3 months after surgery) functional connectivity (FC) was measured with 3-T MRI and compared with findings in age-matched healthy controls (n = 44, 21 female, age 39.3 ± 14.3 years). Postsurgical connectivity changes were then related to seizure outcome, type of surgery, and presurgical disease parameters.

RESULTS

The results demonstrated significant decreases of FC from control group values across the brain after surgery that were not present before surgery, including many contralateral hippocampal connections distal to the surgical site. Postsurgical impairment of contralateral precuneus to ipsilateral occipital connectivity was associated with seizure recurrence. Presurgical impairment of the contralateral precuneus to contralateral temporal lobe connectivity was associated with those who underwent selective amygdalohippocampectomy compared to those who had temporal lobectomy. Finally, changes in thalamic connectivity after surgery were linearly related to duration of epilepsy and frequency of consciousness-impairing seizures prior to surgery.

CONCLUSIONS

The widespread contralateral hippocampal FC changes after surgery may be a reflection of an ongoing epileptogenic progression that has been altered by the surgery, rather than a direct result of the surgery itself. This network evolution may contribute to long-term seizure outcome. Therefore, the combination of presurgical network mapping with the understanding of the dynamic effects of surgery on the networks may ultimately be used to create predictors of the likelihood of long-term seizure recurrence in individual patients after mTLE surgery.