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John S. Sarzier, Avery J. Evans and David W. Cahill

Object. The authors conducted a biomechanical study to evaluate pedicle screw pullout strength in osteoporotic cadaveric spines. Nonaugmented hemivertebrae were compared with pressurized polymethylmethacrylate (PMMA)—augmented hemivertebrae.

Methods. Six formalin-fixed cadaveric thoracolumbar spines at least two standard deviations below the mean bone mineral density (BMD) for age were obtained. Radiographic and BMD studies were correlated to grades I, II, and III osteoporosis according to the Jekei scale. Each of the 21 vertebrae underwent fluoroscopic placement of 6-mm transpedicular screws with each hemivertebra serving as the control for the contralateral PMMA-augmented hemivertebra. Pedicle screws were then evaluated for biomechanical axial pullout resistance.

Augmented hemivertebrae axial pullout forces were increased (p = 0.0005). The mean increase in pullout force was 181% for Grade I, 206% for Grade II, and 213% for Grade III osteoporotic spines. Augmented Grade I osteoporotic spines demonstrated axial pullout forces near those levels reported in the literature for nonosteoporotic specimens. Augmented Grade II osteoporotic specimens demonstrated increases to levels found in nonaugmented vertebrae with low-normal BMD. Augmented Grade III osteoporotic specimens had increases to levels equal to those found in nonaugmented Grade I vertebrae.

Conclusions. Augmentation of osteoporotic vertebrae in PMMA-assisted vertebroplasty can significantly increase pedicle screw pullout forces to levels exceeding the strength of cortical bone. The maximum attainable force appears to be twice the pullout force of the nonaugmented pedicle screw for each osteoporotic grade.

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John A. Jane, Joseph P. Evans and Lester E. Fisher

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Sonia G. Teufack, Peter Campbell, Pascal Jabbour, Mitchell Maltenfort, James Evans and John K. Ratliff

Object

The Centers for Medicare and Medicaid Services (CMS) have moved to limit hospital augmentation of diagnosis-related group billing for “never events” (adverse events that are serious, largely preventable, and of concern to the public and health care providers for the purpose of public accountability) and certain hospital-acquired conditions (HACs). Similar restrictions may be applied to physician billing. The financial impact of these restrictions may fall on academic medical centers, which commonly have populations of complex patients with a higher risk of HACs. The authors sought to quantify the potential financial impact of restrictions in never events and periprocedural HAC billing on a tertiary neurosurgery facility.

Methods

Operative cases treated between January 2008 and June 2008 were reviewed after searching a prospectively maintained database of perioperative complications. The authors assessed cases in which there was a 6-month lag time to allow for completion of hospital and physician billing. They speculated that other payers would soon adopt the present CMS restrictions and that procedure-related HACs would be expanded to cover common neurosurgery procedures. To evaluate the impact on physician billing and to directly contrast physician and hospital billing impact, the authors focused on periprocedural HACs, as opposed to entire admission HACs. Billing records were compiled and a comparison was made between individual event data and simultaneous cumulative net revenue and net receipts. The authors assessed the impact of the present regulations, expansion of CMS restrictions to other payers, and expansion to rehospitalization and entire hospitalization case billing due to HACs and never events.

Results

A total of 1289 procedures were completed during the examined period. Twenty-five procedures (2%) involved patients in whom HACs developed; all were wound infections. Twenty-nine secondary procedures were required for this cohort. Length of stay was significantly higher in patients with HACs than in those without (11.6 ± 11.5 vs 5.9 ± 7.0 days, respectively). Fifteen patients required readmission due to HACs. Following present never event and HAC restrictions, hospital and physician billing was minimally affected (never event billing as percent total receipts was 0.007% for hospitals and 0% for physicians). Nonpayment for rehospitalization and reoperation for HACs by CMS and private payers yielded greater financial impact (CMS only, percentage of total receipts: 0.14% hospital, 0.2% physician; all payers: 1.56% hospital, 3.0% physician). Eliminating reimbursement for index procedures yielded profound reductions (CMS only as percentage of total receipts: 0.62% hospital, 0.8% physician; all payers: 5.73% hospital, 8.9% physician).

Conclusions

The authors found potentially significant reductions in physician and facility billing. The expansion of never event and HACs reimbursement nonpayment may have a substantial financial impact on tertiary care facilities. The elimination of never events and reduction in HACs in current medical practices are worthy goals. However, overzealous application of HACs restrictions may remove from tertiary centers the incentive to treat high-risk patients.

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Hunt Bobo, Jimmy D. Miller, Owen B. Evans and John P. Kapp

✓ The authors report development of a delayed intracerebral hematoma following use of a subarachnoid bolt for intracranial pressure monitoring. This complication has not been previously reported.

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Mueez Waqar, Susan Huson, D. Gareth Evans, John Ealing, Konstantina Karabatsou, K. Joshi George and Calvin Soh

OBJECTIVE

C2 nerve root neurofibromas have been reported frequently in patients with neurofibromatosis type 1 (NF1), although their genetic and imaging characteristics are unexplored. The aim of this study was to characterize genetic and spinal imaging findings in a large cohort of NF1 patients with C2 neurofibromas.

METHODS

The authors performed a review of national NF1 referrals between 2009 and 2016. Inclusion criteria were at least 1 C2 root neurofibroma and cervical-spine or whole-spine MRI scans available for analysis. Blinded imaging review was performed by a neuroradiologist with an interest in NF1.

RESULTS

Fifty-four patients with 106 C2 neurofibromas were included. The median age was 32.5 years (range 15–61 years), and there were slightly more male patients (33 vs 21 female patients). Splice-site (30%) and missense (20%) variants were frequent. Spinal neurofibromas were distributed in all spine regions (65%) or in the cervical spine alone (22%). Most (93%) C2 neurofibromas were visible on MRI scans of the head. Intradural invasion and cord compression in the cervical spine included the C2 level in 95% and 80% of patients, respectively. Compared with all other cervical spine neurofibromas in these patients, C2 neurofibromas had higher rates of intraspinal extension (75% vs 32%; OR 6.20, 95% CI 3.85–9.97; p < 0.001), intradural invasion (53% vs 26%; OR 3.20, 95% CI 2.08–4.92; p < 0.001), and cord compression (25% vs 13%; OR 2.26, 95% CI 1.35–3.79; p = 0.002). However, C2 neurofibromas had lower rates of extraforaminal growth beyond the transverse process (12% vs 62%; OR 0.09, 95% CI 0.05–0.16; p < 0.001).

CONCLUSIONS

C2 neurofibromas are associated with an aggressive intraspinal phenotype, limited growth outside the spinal canal, and an uncommon genetic profile. These observations require future study.

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Editorial

“Never events” come to neurosurgery

Joseph H. Piatt Jr.

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James J. Evans, Sin-Soo Jeun, Joung H. Lee, Jyoti A. Harwalkar, Yigal Shoshan, John K. Cowell and Mladen Golubic

Object. The neurofibromatosis Type 2 (NF2) gene is the only tumor suppressor gene that has been clearly implicated in the development of benign meningiomas. Interestingly, previous data obtained by the authors indicate that reduced NF2 protein expression seldom occurs in meningothelial meningiomas, the most common histological type of meningioma. The goal of the current study was to explore further the hypothesis of NF2 gene-independent tumorigenesis of meningothelial meningiomas.

Methods. The authors performed a mutational analysis of all 17 exons of the NF2 gene by using single-stranded conformational polymorphism (SSCP). In addition, expression levels of the NF2 protein and (µ-calpain, a protease suggested to inactivate the NF2 protein, were determined by immunoblotting analysis of 27 meningiomas (20 meningothelial and seven nonmeningothelial). Mutations of the NF2 gene were found in only one (5%) of 20 meningothelial meningiomas and three (43%) of seven nonmeningothelial tumors (Fisher's exact test, p = 0.042). The levels of NF2 protein were severely reduced in six (28.5%) of 21 meningothelial meningiomas, in contrast to six (86%) of seven nonmeningothelial meningiomas (Fisher's exact test, p = 0.023). Activation of (µ-calpain did not correlate with the status of NF2 protein expression in the meningiomas analyzed, demonstrating that (µ-calpain activation does not account for the loss of NF2 protein in meningiomas with apparently normal NF2 genes.

Conclusions. These results clearly demonstrate that NF2 gene mutations and decreased NF2 protein expression rarely occur in meningothelial meningiomas compared with other histological types of meningiomas. The clinical behavior of meningothelial meningiomas, however, is similar to that of other benign meningiomas. It is likely, therefore, that the tumorigenesis of meningothelial meningiomas is the result of deleterious alterations of genes that have final phenotypical effects similar to inactivation of the NF2 gene.

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Christopher R. Durst, Robert M. Starke, John R. Gaughen Jr., Scott Geraghty, K. Derek Kreitel, Ricky Medel, Nicholas Demartini, Kenneth C. Liu, Mary E. Jensen and Avery J. Evans

Object

The endovascular treatment of wide-necked aneurysms can be technically challenging due to distal coil migration or impingement of the parent vessel. In this paper, the authors illustrate an alternative method for the treatment of wide-necked intracranial aneurysms using a dual microcatheter technique.

Methods

The authors' first 100 consecutive patients who underwent coil embolization of a wide-necked aneurysm using a dual microcatheter technique are reported. With this technique, 2 microcatheters are used to introduce coils into the aneurysm. The coils are deployed either sequentially or concurrently to form a stable construct and prevent coil herniation or migration. Angiographic and clinical outcomes are reported.

Results

The technical success rate of the dual microcatheter technique is 91% with a morbidity and mortality of 1% and 2%, respectively. Clinical outcomes are excellent with 93% of patients demonstrating a modified Rankin Scale score of 0–2 at long-term follow-up regardless of their score at presentation. Retreatment rates are 18%.

Conclusions

The dual microcatheter technique may be a safe and efficacious first line of treatment for widenecked aneurysms.

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Manish N. Shah, Jeffrey R. Leonard, Gabrielle Inder, Feng Gao, Michael Geske, Devon H. Haydon, Melvin E. Omodon, John Evans, Diego Morales, Ralph G. Dacey, Matthew D. Smyth, Michael R. Chicoine and David D. Limbrick

Object

This study describes the pediatric experience with a dual-multifunction-room IMRIS 1.5-T intraoperative magnetic resonance imaging (iMRI) suite and analyzes its impact on clinical variables associated with neurosurgical resection of intracranial lesions, including safety and efficacy.

Methods

Since the inception of the iMRI–guided resection program in April 2008 at both Barnes-Jewish and St. Louis Children's Hospital, a prospective database recorded the clinical variables associated with demographics and outcome with institutional review board approval. A similarly approved retrospective database was constructed from February 2006 to March 2010 for non–iMRI resections. These databases were retrospectively reviewed for clinical variables associated with resection of pediatric (age 20 months–21 years) intracranial lesions including brain tumors and focal cortical dysplasia. Patient demographics, operative time, estimated blood loss, additional resection, length of stay, pathology, and complications were analyzed.

Results

The authors found that 42 iMRI–guided resections were performed, whereas 103 conventional resections had been performed without the iMRI. The mean patient age was 10.5 years (range 20 months–20 years) in the iMRI group and 9.8 years (range 2–21 years) in the conventional group (p = 0.41). The mean duration of surgery was 350 minutes in the iMRI group and 243 minutes in the conventional group (p < 0.0001). The mean hospital stay was 8.2 days in the iMRI group, and 6.6 days in the conventional group, and this trended toward significance (p = 0.05). In the first 2 weeks postoperatively, there were 8 reoperations (7.77%) in the conventional group compared with none in the iMRI group, which was not significant in a 2-tailed test (p = 0.11) but trended toward significance in a 1-tailed test (p = 0.06). The significant complications included reoperation for hydrocephalus or infection: 6.8% (conventional) versus 4.8% (iMRI).

Conclusions

Intraoperative MR imaging–guided resections resulted in a trend toward reduction in the need for repeat surgery in the immediate 2-week postoperative period compared with conventional pediatric neurosurgical resections for tumor or focal cortical dysplasia. Although there is an increased operative time, the iMRI suite offers a comparable safety and efficacy profile while potentially reducing the per-case cost by diminishing the need for early reoperation.

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Amar S. Shah, Peter T. Sylvester, Alexander T. Yahanda, Ananth K. Vellimana, Gavin P. Dunn, John Evans, Keith M. Rich, Joshua L. Dowling, Eric C. Leuthardt, Ralph G. Dacey, Albert H. Kim, Robert L. Grubb, Gregory J. Zipfel, Mark Oswood, Randy L. Jensen, Garnette R. Sutherland, Daniel P. Cahill, Steven R. Abram, John Honeycutt, Mitesh Shah, Yu Tao and Michael R. Chicoine

OBJECTIVE

Intraoperative MRI (iMRI) is used in the surgical treatment of glioblastoma, with uncertain effects on outcomes. The authors evaluated the impact of iMRI on extent of resection (EOR) and overall survival (OS) while controlling for other known and suspected predictors.

METHODS

A multicenter retrospective cohort of 640 adult patients with newly diagnosed supratentorial glioblastoma who underwent resection was evaluated. iMRI was performed in 332/640 cases (51.9%). Reviews of MRI features and tumor volumetric analysis were performed on a subsample of cases (n = 286; 110 non-iMRI, 176 iMRI) from a single institution.

RESULTS

The median age was 60.0 years (mean 58.5 years, range 20.5–86.3 years). The median OS was 17.0 months (95% CI 15.6–18.4 months). Gross-total resection (GTR) was achieved in 403/640 cases (63.0%). Kaplan-Meier analysis of 286 cases with volumetric analysis for EOR (grouped into 100%, 95%–99%, 80%–94%, and 50%–79%) showed longer OS for 100% EOR compared to all other groups (p < 0.01). Additional resection after iMRI was performed in 104/122 cases (85.2%) with initial subtotal resection (STR), leading to a 6.3% mean increase in EOR and a 2.2-cm3 mean decrease in tumor volume. For iMRI cases with volumetric analysis, the GTR rate increased from 54/176 (30.7%) on iMRI to 126/176 (71.5%) postoperatively. The EOR was significantly higher in the iMRI group for intended GTR and STR groups (p = 0.02 and p < 0.01, respectively). Predictors of GTR on multivariate logistic regression included iMRI use and intended GTR. Predictors of shorter OS on multivariate Cox regression included older age, STR, isocitrate dehydrogenase 1 (IDH1) wild type, no O 6-methylguanine DNA methyltransferase (MGMT) methylation, and no Stupp therapy. iMRI was a significant predictor of OS on univariate (HR 0.82, 95% CI 0.69–0.98; p = 0.03) but not multivariate analyses. Use of iMRI was not associated with an increased rate of new permanent neurological deficits.

CONCLUSIONS

GTR increased OS for patients with newly diagnosed glioblastoma after adjusting for other prognostic factors. iMRI increased EOR and GTR rate and was a significant predictor of GTR on multivariate analysis; however, iMRI was not an independent predictor of OS. Additional supporting evidence is needed to determine the clinical benefit of iMRI in the management of glioblastoma.