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Letter to the Editor. Tetrad issues exist regarding spinal fusion with pedicle screws and adjacent-segment disease

Jun Zhang, Chi-Jiao Ma, and Hai-Qiang Wang

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Letter to the Editor: Acute motor-sensory axonal neuropathy and Helicobacter pylori infections

Xu Wang, Hong-Liang Zhang, Chi Ma, Jiang Wu, and Jie Zhu

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A novel surgical planning system using an AI model to optimize planning of pedicle screw trajectories with highest bone mineral density and strongest pull-out force

Chi Ma, Da Zou, Huan Qi, Chentian Li, Cheng Zhang, Kedi Yang, Feng Zhu, Weishi Li, and William W. Lu


The purpose of this study was to evaluate the ability of a novel artificial intelligence (AI) model in identifying optimized transpedicular screw trajectories with higher bone mineral density (BMD) as well as higher pull-out force (POF) in osteoporotic patients.


An innovative pedicle screw trajectory planning system called Bone’s Trajectory was developed using a 3D graphic search and an AI-based finite element analysis model. The preoperative CT scans of 21 elderly osteoporotic patients were analyzed retrospectively. The AI model automatically calculated the number of alternative transpedicular trajectories, the trajectory BMD, and the estimated POF of L3–5. The highest BMD and highest POF of optimized trajectories were recorded and compared with AO standard trajectories.


The average patient age and average BMD of the vertebral bodies were 69.6 ± 7.8 years and 55.9 ± 17.1 mg/ml, respectively. On both sides of L3–5, the optimized trajectories showed significantly higher BMD and POF than the AO standard trajectories (p < 0.05). On average, the POF of optimized trajectory screws showed at least a 2.0-fold increase compared with AO trajectory screws.


The novel AI model performs well in enabling the selection of optimized transpedicular trajectories with higher BMD and POF than the AO standard trajectories.

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Validation of the radiosurgery-based arteriovenous malformation score in a large linear accelerator radiosurgery experience

Clinical article

Scott J. Raffa, Yueh-Yun Chi, Frank J. Bova, and William A. Friedman


The radiosurgery-based arteriovenous malformation (AVM) score (RBAS) is a grading system designed to predict patient outcomes after Gamma Knife surgery for AVMs. This study seeks to validate independently the predictive nature of the RBAS, not only after single treatment but for retreatment, and to assess the overall outcome regardless of number of radiosurgeries.


The authors analyzed 403 patients treated with linear accelerator (LINAC) radiosurgery for AVMs between May 1988 and June 2008. The AVM scores were determined by the following equation: AVM score = (0.1 × volume in cm3) + (0.02 × age in years) + (0.3 × location). The location values are as follows: frontal/temporal = 0, parietal/occipital/corpus callosum/cerebellar = 1, and basal ganglia/thalamus/brainstem = 2.


Testing demonstrated that the RBAS correlated with excellent outcomes after single or repeat radiosurgery (p < 0.001 for both variables). One hundred sixty-two (49%) of 330 patients had excellent outcomes (obliteration without deficit) after a single treatment. Excellent outcomes were achieved in 74, 64, 50, and 11% of patients with AVM scores of < 1.0 (Group 1), between 1.0 and < 1.8 (Group 2), between 1.8 and < 2.5 (Group 3), and ≥ 2.5 (Group 4), respectively. Fifty-one patients (70%) obtained radiosurgical cure and 46 (63%) achieved excellent outcomes after repeat radiosurgery. Of these, 100% achieved excellent outcomes in Group 1, 70% did so in Group 2, 47% in Group 3, and 14% in Group 4. The RBAS correlated with excellent outcomes after overall treatment (p < 0.001). Two hundred seventy-seven patients (69%) obtained AVM obliteration, and 62% achieved excellent outcomes. In Group 1, 87% achieved excellent outcomes, 75% did so in Group 2, 61% in Group 3, and 24% in Group 4.


The RBAS is a good predictor of patient outcomes after LINAC radiosurgery.

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Effects of silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model

Yong-Jun Cho, Chi Hern Lee, Dae Won Kim, Ki-Yeon Yoo, Won Sik Eum, Min Jea Shin, Hyo Sang Jo, Jinseu Park, Kyu Hyung Han, Keun Wook Lee, and Soo Young Choi

The authors investigated the effects of a silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model. They found that it significantly reduced postlaminectomy dural adhesion formation and inflammation. Dural adhesion formation, thought to be an inevitable consequence of laminectomy, is one of the most common complications following spinal surgery, and the authors' results indicate that the silk solution might be a potential novel therapeutic agent for dural adhesion formation.

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Letter to the Editor: Pontine hemorrhage

Yu-Chi Tsai, Fang-Chen Liu, Chao-Ming Chang, Che-Hsien Chang, Yin-Hsien Liao, Tse-Bing Yang, and Dueng-Yuan Hueng

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Oral Presentations 2014 AANS Annual Scientific Meeting San Francisco, California • April 5–9, 2014

Published online June 1, 2015; DOI: 10.3171/2015.6.JNS.AANS2014abstracts

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Oral Presentations 2015 AANS Annual Scientific Meeting Washington, DC • May 2–6, 2015

Published online August 1, 2015; DOI: 10.3171/2015.8.JNS.AANS2015abstracts

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AANS/CNS Cerebrovascular Section Meeting February 2011

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Abstracts of the 2014 Annual Meeting of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves Orlando, Florida • March 5–8, 2014