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Tomasz Matys, Tariq Ali, Fulvio Zaccagna, Damiano G. Barone, Ramez W. Kirollos and Tarik F. Massoud

OBJECTIVE

Ossification of pterygoalar and pterygospinous ligaments traversing the superior aspect of the infratemporal fossa results in formation of osseous bars that can obstruct percutaneous needle access to the trigeminal ganglion through the foramen ovale (FO), interfere with lateral mandibular nerve block, and impede transzygomatic surgical approaches. Presence of these ligaments has been studied on dry skulls, but description of their radiological anatomy is scarce, in particular on cross-sectional imaging. The aim of this study was to describe visualization of pterygoalar and pterygospinous bars on computed tomography (CT) and to review their prevalence and clinical significance.

METHODS

The authors retrospectively reviewed 200 helical sinonasal CT scans by analyzing 0.75- to 1.0-mm axial images, maximum intensity projection (MIP) reconstructions, and volume rendered (VR) images, including views along the anticipated axis of the needle in percutaneous Hartel and submandibular approaches to the FO.

RESULTS

Ossified pterygoalar and pterygospinous ligaments were readily identifiable on CT scans. An ossified pterygoalar ligament was demonstrated in 10 patients, including 1 individual with bilateral complete ossification (0.5%), 4 patients with unilateral complete ossification (2.0%), and 5 with incomplete unilateral ossification (2.5%). Nearly all patients with pterygoalar bars were male (90%, p < 0.01). An ossified pterygospinous ligament was seen in 35 patients, including 2 individuals with bilateral complete (1.0%), 8 with unilateral complete (4%), 8 with bilateral incomplete (4.0%), 12 with bilateral incomplete (6.0%) ossification, and 5 (2.5%) with mixed ossification (complete on one side and incomplete on the contralateral side). All pterygoalar bars interfered with a hypothetical needle access to the FO using the Hartel approach but not the submandibular approach. In contrast, 54% of complete and 24% of incomplete pterygospinous bars impeded the submandibular approach to the FO, without affecting the Hartel approach.

CONCLUSIONS

This study provides the first detailed description of cross-sectional radiological and applied surgical anatomy of pterygoalar and pterygospinous bars. Our data are clinically useful during skull base imaging to predict potential obstacles to percutaneous cannulation of the FO and assist in the choice of approach, as these two variants differentially impede the Hartel and submandibular access routes. Our results can also be useful in planning surgical approaches to the skull base through the infratemporal fossa.

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Jin Wook Kim, Hee-Won Jung, Yong Hwy Kim, Chul-Kee Park, Hyun-Tai Chung, Sun Ha Paek, Dong Gyu Kim and Sang Hyung Lee

OBJECTIVE

A thorough investigation of the long-term outcomes and chronological changes of multimodal treatments for petroclival meningiomas is required to establish optimal management strategies. The authors retrospectively reviewed the long-term clinical outcomes of patients with petroclival meningioma according to various treatments, including various surgical approaches, and they suggest treatment strategies based on 30 years of experience at a single institution.

METHODS

Ninety-two patients with petroclival meningiomas were treated surgically at the authors’ institution from 1986 to 2015. Patient demographics, overall survival, local tumor control rates, and functional outcomes according to multimodal treatments, as well as chronological change in management strategies, were evaluated. The mean clinical and radiological follow-up periods were 121 months (range 1–368 months) and 105 months (range 1–348 months), respectively.

RESULTS

A posterior transpetrosal approach was most frequently selected and was followed in 44 patients (48%); a simple retrosigmoid approach, undertaken in 30 patients, was the second most common. The initial extent of resection and following adjuvant treatment modality were classified into 3 subgroups: gross-total resection (GTR) only in 13 patients; non-GTR treatment followed by adjuvant radiosurgery or radiation therapy (non-GTR+RS/RT) in 56 patients; and non-GTR without adjuvant treatment (non-GTR only) in 23 patients. The overall progression-free survival rate was 85.8% at 5 years and 81.2% at 10 years. Progression or recurrence rates according to each subgroup were 7.7%, 12.5%, and 30.4%, respectively.

CONCLUSIONS

The authors’ preferred multimodal treatment strategy, that of planned incomplete resection and subsequent adjuvant radiosurgery, is a feasible option for the management of patients with large petroclival meningiomas, considering both local tumor control and postoperative quality of life.

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Thiago Augusto Hernandes Rocha, Cyrus Elahi, Núbia Cristina da Silva, Francis M. Sakita, Anthony Fuller, Blandina T. Mmbaga, Eric P. Green, Michael M. Haglund, Catherine A. Staton and Joao Ricardo Nickenig Vissoci

OBJECTIVE

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, with a disproportionate burden of this injury on low- and middle-income countries (LMICs). Limited access to diagnostic technologies and highly skilled providers combined with high patient volumes contributes to poor outcomes in LMICs. Prognostic modeling as a clinical decision support tool, in theory, could optimize the use of existing resources and support timely treatment decisions in LMICs. The objective of this study was to develop a machine learning–based prognostic model using data from Kilimanjaro Christian Medical Centre in Moshi, Tanzania.

METHODS

This study is a secondary analysis of a TBI data registry including 3138 patients. The authors tested nine different machine learning techniques to identify the prognostic model with the greatest area under the receiver operating characteristic curve (AUC). Input data included demographics, vital signs, injury type, and treatment received. The outcome variable was the discharge score on the Glasgow Outcome Scale–Extended.

RESULTS

The AUC for the prognostic models varied from 66.2% (k-nearest neighbors) to 86.5% (Bayesian generalized linear model). An increasing Glasgow Coma Scale score, increasing pulse oximetry values, and undergoing TBI surgery were predictive of a good recovery, while injuries suffered from a motor vehicle crash and increasing age were predictive of a poor recovery.

CONCLUSIONS

The authors developed a TBI prognostic model with a substantial level of accuracy in a low-resource setting. Further research is needed to externally validate the model and test the algorithm as a clinical decision support tool.

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Bailey A. Dyck, Christopher S. Bailey, Chris Steyn, Julia Petrakis, Jennifer C. Urquhart, Ruheksh Raj and Parham Rasoulinejad

OBJECTIVE

This proof-of-concept study was conducted to determine whether negative-pressure wound therapy, through the use of incisional vacuum-assisted closure (VAC), is associated with a reduction in surgical site infections (SSIs) when compared to standard wound dressings in patients undergoing open posterior spinal fusion who have a high risk of infection.

METHODS

A total of 64 patients were examined; 21 patients received incisional VAC application (VAC group) versus 43 diagnosis-matched patients who received standard wound dressings (control group). Patients in the VAC group were prospectively enrolled in a consecutive series between March 2013 and March 2014 if they met the following diagnostic criteria for high risk of infection: posterior open surgery across the cervicothoracic junction; thoracic kyphosis due to metastatic disease; high-energy trauma; or multilevel revision reconstructive surgery. Patients in the VAC group also met one or more comorbidity criteria, including body mass index ≥ 35 or < 18.5, diabetes, previous radiation at surgical site, chemotherapy, steroid use, bedridden state, large traumatic soft-tissue disruption, or immunocompromised state. Consecutive patients in the control group were retrospectively selected from the previous year by the same high-risk infection diagnostic criteria as the VAC group. All surgeries were conducted by the same surgeon at a single site. The primary outcome was SSI. All patients had 1 year of follow-up after their surgery. Baseline demographics, intraoperative parameters, and postoperative wound infection rates were compared between groups.

RESULTS

Patient demographics including underlying comorbidities were similar, with the exception that VAC-treated patients were malnourished (p = 0.020). VAC-treated patients underwent longer surgeries (p < 0.001) and required more postoperative ICU admissions (p = 0.039). The median length of hospital stay was not different between groups. In total, 9 control patients (21%) developed an SSI, versus 2 VAC-treated patients (10%).

CONCLUSIONS

Patients in this cohort were selected to have an increased risk of infection; accordingly, the rate of SSI was high. However, negative-pressure wound therapy through VAC application to the postoperative incision resulted in a 50% reduction in SSI. No adverse effects were noted secondary to VAC application. The preliminary data confirm the authors’ proof of concept and strongly support the need for a prospective randomized trial.

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Georg Widhalm, Jonathan Olson, Jonathan Weller, Jaime Bravo, Seunggu J. Han, Joanna Phillips, Shawn L. Hervey-Jumper, Susan M. Chang, David W. Roberts and Mitchel S. Berger

OBJECTIVE

In patients with suspected diffusely infiltrating low-grade gliomas (LGG), the prognosis is dependent especially on extent of resection and precision of tissue sampling. Unfortunately, visible 5-aminolevulinic acid (5-ALA) fluorescence is usually only present in high-grade gliomas (HGGs), and most LGGs cannot be visualized. Recently, spectroscopic probes were introduced allowing in vivo quantitative analysis of intratumoral 5-ALA–induced protoporphyrin IX (PpIX) accumulation. The aim of this study was to intraoperatively investigate the value of visible 5-ALA fluorescence and quantitative PpIX analysis in suspected diffusely infiltrating LGG.

METHODS

Patients with radiologically suspected diffusely infiltrating LGG were prospectively recruited, and 5-ALA was preoperatively administered. During resection, visual fluorescence and absolute tissue PpIX concentration (CPpIX) measured by a spectroscopic handheld probe were determined in different intratumoral areas. Subsequently, corresponding tissue samples were safely collected for histopathological analysis. Tumor diagnosis was established according to the World Health Organization 2016 criteria. Additionally, the tumor grade and percentage of tumor cells were investigated in each sample.

RESULTS

All together, 69 samples were collected from 22 patients with histopathologically confirmed diffusely infiltrating glioma. Visible fluorescence was detected in focal areas in most HGGs (79%), but in none of the 8 LGGs. The mean CPpIX was significantly higher in fluorescing samples than in nonfluorescing samples (0.693 μg/ml and 0.008 μg/ml, respectively; p < 0.001). A significantly higher mean percentage of tumor cells was found in samples with visible fluorescence compared to samples with no fluorescence (62% and 34%, respectively; p = 0.005), and significant correlation of CPpIX and percentage of tumor cells was found (r = 0.362, p = 0.002). Moreover, high-grade histology was significantly more common in fluorescing samples than in nonfluorescing samples (p = 0.001), whereas no statistically significant difference in mean CPpIX was noted between HGG and LGG samples. Correlation between maximum CPpIX and overall tumor grade was highly significant (p = 0.005). Finally, 14 (40%) of 35 tumor samples with no visible fluorescence and 16 (50%) of 32 LGG samples showed significantly increased CPpIX (cutoff value: 0.005 μg/ml).

CONCLUSIONS

Visible 5-ALA fluorescence is able to detect focal intratumoral areas of malignant transformation, and additional quantitative PpIX analysis is especially useful to visualize mainly LGG tissue that usually remains undetected by conventional fluorescence. Thus, both techniques will support the neurosurgeon in achieving maximal safe resection and increased precision of tissue sampling during surgery for suspected LGG.

Clinical trial registration no.: NCT01116661 (clinicaltrials.gov)

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Patrick W. Hitchon, Jonathan M. Mahoney, Jonathan A. Harris, Mir M. Hussain, Noelle F. Klocke, John C. Hao, Doniel Drazin and Brandon S. Bucklen

OBJECTIVE

Posterior reduction with pedicle screws is often used for stabilization of unstable spondylolisthesis to directly reduce misalignment or protect against micromotion while fusion of the affected level occurs. Optimal treatment of spondylolisthesis combines consistent reduction with a reduced risk of construct failure. The authors compared the reduction achieved with a novel anterior integrated spacer with a built-in reduction mechanism (ISR) to the reduction achieved with pedicle screws alone, or in combination with an anterior lumbar interbody fusion (ALIF) spacer, in a cadaveric grade I spondylolisthesis model.

METHODS

Grade I slip was modeled in 6 cadaveric L5–S1 segments by creation of a partial nucleotomy and facetectomy and application of dynamic cyclic loading. Following the creation of spondylolisthesis, reduction was performed under increasing axial loads, simulating muscle trunk forces between 50 and 157.5 lbs, in the following order: bilateral pedicle screws (BPS), BPS with an anterior spacer (BPS+S), and ISR. Percent reduction and reduction failure load—the axial load at which successful reduction (≥ 50% correction) was not achieved—were recorded along with the failure mechanism. Corrections were evaluated using lateral fluoroscopic images.

RESULTS

The average loads at which BPS and BPS+S failed were 92.5 ± 6.1 and 94.2 ± 13.9 lbs, respectively. The ISR construct failed at a statistically higher load of 140.0 ± 27.1 lbs. Reduction at the largest axial load (157.5 lbs) by the ISR device was tested in 67% (4 of 6) of the specimens, was successful in 33% (2 of 6), and achieved 68.3 ± 37.4% of the available reduction. For the BPS and BPS+S constructs, the largest axial load was 105.0 lbs, with average reductions of 21.3 ± 0.0% (1 of 6) and 32.4 ± 5.7% (3 of 6) respectively.

CONCLUSIONS

While both posterior and anterior reduction devices maintained reduction under gravimetric loading, the reduction capacity of the novel anterior ISR device was more effective at greater loads than traditional pedicle screw techniques. Full correction was achieved with pedicle screws, with or without ALIF, but under significantly lower axial loads. The anterior ISR may prove useful when higher reduction forces are required; however, additional clinical studies will be needed to evaluate the effectiveness of anterior devices with built-in reduction mechanisms.

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Christian Scheller, Stefan Rampp, Marcos Tatagiba, Alireza Gharabaghi, Kristofer F. Ramina, Oliver Ganslandt, Barbara Bischoff, Cordula Matthies, Thomas Westermaier, Maria Teresa Pedro, Veit Rohde, Kajetan von Eckardstein and Christian Strauss

OBJECTIVE

Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery.

METHODS

A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine.

RESULTS

Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House-Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group.

CONCLUSIONS

Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.

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Nobuo Senbokuya, Hideyuki Yoshioka, Takashi Yagi, Yuji Owada and Hiroyuki Kinouchi

OBJECTIVE

Elucidating the mechanisms of neuronal injury is crucial for the development of spinal cord injury (SCI) treatments. Brain-type fatty acid–binding protein 7 (FABP7) is expressed in the adult rodent brain, especially in astrocytes, and has been reported to play a role in astrocyte function in various types of brain damage; however, its role after SCI has not been well studied. In this study, the authors evaluated the expression change of FABP7 after SCI using a mouse spinal cord compression model and observed the effect of FABP7 gene knockout on neuronal damage and functional recovery after SCI.

METHODS

Female FABP7 knockout (KO) mice with a C57BL/6 background and their respective wild-type littermates were subjected to SCI with a vascular clip. The expression of FABP7, neuronal injury, and functional recovery after SCI were analyzed in both groups of mice.

RESULTS

Western blot analysis revealed upregulation of FABP7 in the wild-type mice, which reached its peak 14 days after SCI, with a significant difference in comparison to the control mice. Immunohistochemistry also showed upregulation of FABP7 at the same time points, mainly in proliferative astrocytes. The number of surviving ventral neurons in the FABP7-KO mice at 28 days after SCI was significantly lower than that observed in the wild-type mice. In addition, motor functional recovery in the FABP7-KO mice was significantly worse than that of the wild-type mice.

CONCLUSIONS

The findings of this study indicate that FABP7 could have a neuroprotective role that might be associated with modulation of astrocytes after SCI. FABP7 could potentially be a therapeutic target in the treatment of SCI.

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Nikolaos Mouchtouris, Michael J. Lang, Kaitlyn Barkley, Guilherme Barros, Justin Turpin, Ahmad Sweid, Robert M. Starke, Nohra Chalouhi, Pascal Jabbour, Robert H. Rosenwasser and Stavropoula Tjoumakaris

OBJECTIVE

The authors sought to determine the predictors of late neurological and hospital-acquired medical complications (HACs) in patients with low-grade aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

The authors conducted a retrospective study of 424 patients with low-grade aSAH admitted to their institution from 2008 to 2015. Data collected included patient comorbidities, Hunt and Hess (HH) grade, ICU length of stay (LOS), and complications. A logistic regression analysis was performed to determine the predictors for neurological and hospital-associated complications.

RESULTS

Out of 424 patients, 50 (11.8%) developed neurological complications after the first week, with a mean ICU stay of 16.3 ± 6.5 days. Of the remaining 374 patients without late neurological complications, 83 (22.2%) developed late HACs with a mean LOS of 15.1 ± 7.6 days, while those without medical complications stayed 11.8 ± 6.2 days (p = 0.001). Of the 83 patients, 55 (66.3%) did not have any HACs in the first week. Smoking (p = 0.062), history of cardiac disease (p = 0.043), HH grade III (p = 0.012), intraventricular hemorrhage (IVH) (p = 0.012), external ventricular drain (EVD) placement (p = 0.002), and early pneumonia/urinary tract infection (UTI)/deep vein thrombosis (DVT) (p = 0.001) were independently associated with late HACs. Logistic regression showed early pneumonia/UTI/DVT (p = 0.026) and increased HH grade (p = 0.057) to be significant risk factors for late medical complications.

CONCLUSIONS

While an extended ICU admission allows closer monitoring, low-grade aSAH patients develop HACs despite being at low risk for neurological complications. The characteristics of low-grade aSAH patients who would benefit from early discharge are reported in detail.