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Nan-Xiang Xiong and Hong-Yang Zhao

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Bing Zhao, Hua Yang, Kuang Zheng, Zequn Li, Ye Xiong, Xianxi Tan, Ming Zhong and the AMPAS Study Group

OBJECTIVE

An increasing number of patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH) have received endovascular treatment. Endovascular treatment of poor-grade aSAH, however, is based on single-center retrospective studies, and predictors of long-term outcome have not been well defined. Using results from a multicenter prospective registry, the authors aimed to develop preoperative and postoperative prognostic models to predict poor outcome after endovascular treatment of poor-grade aSAH.

METHODS

A Multicenter Poor-grade Aneurysm Study (AMPAS) was a prospective and observational registry of consecutive patients with poor-grade aSAH. From October 2010 to March 2012, 366 patients were enrolled in the registry, and 136 patients receiving endovascular treatment were included in this study. Outcome was assessed by modified Rankin Scale (mRS) score at 12 months, and poor outcome was defined as an mRS score of 4, 5, or 6. Prognostic models were developed in multivariate logistic regression models. The area under receiver operating characteristic curves (AUC) was used to assess the model's discriminatory ability, and Hosmer-Lemeshow goodness-of-fit tests were used to assess the calibration.

RESULTS

At 12 months, 64 patients (47.0%) had a poor outcome: 9 (6.6%) had an mRS score of 4, 6 (4.4%) had an mRS score of 5, and 49 (36.0%) had died. Univariate analyses showed that older age (p = 0.001), female sex (p = 0.044), lower Glasgow Coma Scale score (p < 0.001), a World Federation of Neurosurgical Societies (WFNS) grade of V (p < 0.001), higher Fisher grade (p < 0.001), modified Fisher grade (p < 0.001), and wider neck aneurysm (p = 0.026) were associated with a poor outcome. There was a trend toward a worse outcome in patients with anterior communicating artery aneurysms (p = 0.080) and in those with incompletely occluded aneurysms (p = 0.063). After endovascular treatment, the presence of cerebral infarction (p = 0.039), symptomatic vasospasm (p = 0.039), and pneumonia (p = 0.006) were associated with a poor outcome. Multivariate analyses showed that the preoperative prognostic model including age, a WFNS grade of V, modified Fisher grade, and aneurysm neck size had excellent discrimination with an AUC of 0.86 (95% CI 0.80–0.92, p < 0.001), and a postoperative model that included these predictors as well as postoperative pneumonia had excellent discrimination (AUC = 0.87, 95% CI 0.81–0.93, p < 0.001). Both models had good calibration (p = 0.941 and p = 0.653, respectively).

CONCLUSIONS

Older age, WFNS Grade V, higher modified Fisher grade, wider neck aneurysm, and postoperative pneumonia were independent predictors of poor outcome after endovascular treatment of poor-grade aSAH. The preoperative model had almost the same discrimination as the postoperative model. Endovascular treatment should be carefully considered in patients with poor-grade aSAH with ruptured wide-neck aneurysms.

▪ CLASSIFICATION OF EVIDENCE Type of question: prognostic; study design: retrospective cohort trial; evidence: Class I.

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Quan-chang Tan, Jian-wei Wu, Fei Peng, Yuan Zang, Yang Li, Xiong Zhao, Wei Lei and Zi-xiang Wu

OBJECTIVE

This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw.

METHODS

Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter.

RESULTS

The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p < 0.0001). All FPS-B groups had a higher pullout strength than the FPS-A groups.

CONCLUSIONS

The diameter of the perforations affects the distribution of PMMA cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study results indicated 1.5-ml of PMMA was a conservative volume for PMMA augmentation; more cement injection would significantly increase the risk of cement leakage.