Unpredictable Hearing Loss after Intratympanic Gentamicin Treatment for Vertigo. A New Theory

A new hypothesis is advanced suggesting that unpredictable cases of profound hearing loss after intratympanic gentamicin treatment (IGT) may be caused by decreased patency of the communication routes between the inner ear and the cerebrospinal fluid, primarily of the cochlear aqueduct. A tympanic displacement analyzer, which can indirectly analyze inner ear and intracranial pressure changes and can also evaluate the efficiency of communication between these two compartments, was used. Two cases are presented: in the first, a patient who became deaf after IGT showed signs of decreased patency of the communication routes with the tympanic membrane displacement (TMD) test; in the second, a patient without hearing damage after IGT had efficient communication evaluated by the TMD test. These preliminary findings are in accordance with the proposed pathophysiology. If future clinical studies confirm the present theory and findings, it may prove possible to predict and prevent deafness after IGT and possibly also after systemic aminoglycoside treatment.     

Gravity assisted reduction of ankle (GARA) fractures: Results of a novel technique for relocating displaced ankle fractures in the emergency setting in comparison to traditional manipulation and reduction (TMR) technique

BackgroundAnkle fracture displacements cause significant discomfort to the patient and can compromise soft tissues including the neurovascular structures. Prompt reduction and plaster splint application are vital in the early management of these potentially limb-threatening conditions. The process can be distressing for the patient often requiring additional personnel or equipment. We have used a novel technique of Gravity Assisted Reduction of Ankle (GARA) fractures and compared the results with the Traditional Manipulation and Reduction (TMR) technique.Material and methodsWith adequate analgesia, the patient turns to lay either in lateral or prone position depending on fracture pattern, thus permitting gravity to gradually aid in reduction and hold the fracture in place while Plaster Of Paris (POP) is applied. We performed a retrospective comparative study of GARA vs TMR using validated radiological parameters to assess the quality of reduction with both techniques.Results21 patients had GARA technique, in comparison with 19 patients in TMR group. All measured radiological parameters showed similar improvement in both the groups, despite the fact that the pronation-external rotation injury pattern was more often seen in the GARA group. Intravenous sedation and monitoring were needed in 10 patients of TMR group, none in GARA group. On an average 4 personnel needed for TMR, but only 2 personnel needed for GARA technique.ConclusionGravity assisted ankle fracture reduction is a simple, effective and reproducible alternative technique to TMR, with no need of intravenous sedation along with fewer people needed to perform the procedure.Level of evidence3b     

Fate of mandibular canals displaced by enlarged cystic lesions: does the inferior alveolar neurovascular bundle relocate to its original position?

Our aim was to identify the positional changes of the inferior alveolar neurovascular bundle and evaluate the relocation of the displaced mandibular canal after enucleation of a cyst. Seventy patients (72 sites) who had had cysts enucleated were divided into three groups based on the degree of encroachment of the cystic lesion into the mandibular canal and whether a bone graft had been inserted after the cyst had been enucleated. The mean (range) of patients’ ages was 45 (18–75) years, and there were 29 male and 41 female patients. Group A comprised cysts with encroachment on the mandibular canal that were enucleated without a bone graft; Group B consisted of cysts with no encroachment of the mandibular canal, but were enucleated without a bone graft; and Group C comprised cysts with encroachment of the mandibular canal that were enucleated with a bone graft. The displacement of the mandibular canal was identified from analysis of computed tomographic (CT) images. Changes in the position of the mandibular canal were measured on panoramic radiographs. The mandibular canal was repositioned superiorly by a mean (SD) of 2.4 (1.65) mm after enucleation of the cyst, which was significant in Group A (p < 0.001), but not in Groups B and C. These results indicate that the displaced inferior alveolar neurovascular bundles that were not surrounded by bony canal tended to relocate towards a supposedly normal position, and after enucleation of the cyst the mandibular canal was remodelled in this new location. This tendency to relocate was blocked by bone grafting. Bone grafts are therefore recommended in cases where enough bony height is required for future insertion of implants.     

Tympanic Displacement Analysis in Healthy Volunteers after Indomethacin Administration

The aim of this study was to investigate whether a tympanic displacement analyser could detect decreases in cerebral blood flow and intracranial pressure after administration of indomethacin in healthy volunteers. In a double-blind crossover study involving 14 healthy volunteers all subjects first underwent a test-retest evaluation to investigate reproducibility followed by tests performed in sitting and supine positions to confirm intracranial-cochlear pressure transfer. In two further sessions tests were performed before and 90 min after subjects were blindly administered a suppository containing either 100 mg of indomethacin or placebo. It was found that tympanic membrane analysis performed 90 min after administration of such a suppository did not mirror the induced reduction in cerebral blood flow after administration of active drug. After administration of indomethacin eight of the subjects experienced discomfort and dizziness; after placebo none experienced subjective symptoms. After administration of indomethacin a statistically significant decrease in heart rate was demonstrated. The exponential form of the intracranial pressure-volume curve may explain why a decrease in intracranial pressure was not detected using the tympanic membrane displacement method, because the measurements were made in subjects with normal intracranial pressure. More significant findings may be found in patients with elevated intracranial pressure.     

Cortical surface shift estimation using stereovision and optical flow motion tracking via projection image registration

Stereovision is an important intraoperative imaging technique that captures the exposed parenchymal surface noninvasively during open cranial surgery. Estimating cortical surface shift efficiently and accurately is critical to compensate for brain deformation in the operating room (OR). In this study, we present an automatic and robust registration technique based on optical flow (OF) motion tracking to compensate for cortical surface displacement throughout surgery. Stereo images of the cortical surface were acquired at multiple time points after dural opening to reconstruct three-dimensional (3D) texture intensity-encoded cortical surfaces. A local coordinate system was established with its z-axis parallel to the average surface normal direction of the reconstructed cortical surface immediately after dural opening in order to produce two-dimensional (2D) projection images. A dense displacement field between the two projection images was determined directly from OF motion tracking without the need for feature identification or tracking. The starting and end points of the displacement vectors on the two cortical surfaces were then obtained following spatial mapping inversion to produce the full 3D displacement of the exposed cortical surface. We evaluated the technique with images obtained from digital phantoms and 18 surgical cases – 10 of which involved independent measurements of feature locations acquired with a tracked stylus for accuracy comparisons, and 8 others of which 4 involved stereo image acquisitions at three or more time points during surgery to illustrate utility throughout a procedure. Results from the digital phantom images were very accurate (0.05 pixels). In the 10 surgical cases with independently digitized point locations, the average agreement between feature coordinates derived from the cortical surface reconstructions was 1.7–2.1 mm relative to those determined with the tracked stylus probe. The agreement in feature displacement tracking was also comparable to tracked probe data (difference in displacement magnitude was <1 mm on average). The average magnitude of cortical surface displacement was 7.9 ± 5.7 mm (range 0.3–24.4 mm) in all patient cases with the displacement components along gravity being 5.2 ± 6.0 mm relative to the lateral movement of 2.4 ± 1.6 mm. Thus, our technique appears to be sufficiently accurate and computationally efficiency (typically ∼15 s), for applications in the OR.     

Comparison Between Oblique Pulling Spinal Manipulation and Other Treatments for Lumbar Disc Herniation: A Systematic Review and Meta-Analysis

Objective

The purpose of this review was to compare oblique pulling spinal manipulation with other treatments for lumbar disc herniation.

基于神经网络法反求耳结构弹性模量

目的通过耳结构的位移反算耳结构弹性模量。方法基于Patran软件建立耳结构有限元模型,使用Mat-lab建立计算耳结构反问题的BP神经网络。对耳结构有限元模型进行频率响应分析,得到鼓膜凸和镫骨足板的位移响应;把位移作为BP神经网络的输入、相对应的结构弹性模量作为输出,对网络进行训练。结果利用训练成熟的BP网络反算出耳结构的弹性模量,相对误差非常小。结论反算结果表明,所使用的反问题方法求解耳结构弹性模量是可行的,可为临床提供确定生物结构力学参数简捷有效的方法。     

下颌支矢状骨劈开术数字模型的建立及不同固定方式的稳定性分析

目的:建立下颌支矢状骨劈开术数字模型,探讨3种不同固定方式的应力及位移改变.方法:CT扫描数据导入三维重建软件Mimics以及Geomagic中,建立下颌骨三维实体模型,并进行矢状劈开、坚固内固定,ANSYS进行网格划分,建立三维有限元模型.边界约束后,进行双侧下颌第一磨牙咬合力(132 N)加载.结果:建立了双侧下颌支矢状骨劈开术3种不同固定方式三维有限元模型,获得术前下颌骨及矢状骨劈开后咬合力加载的应力及位移生物力学特点.结论:下颌支矢状骨劈开术倒L形固定应力分布最均匀,劈开处位移最小,与其他2种方式相比,其固定稳定性最佳.     

超声二维应变评价正常人左室扭转和径向位移的初步研究

目的应用超声二维应变技术（2DS）探讨正常左室扭转及径向位移运动特征,构建左室-扭转位移环。方法健康成人志愿者58例,取胸骨旁左室心尖和心底短轴观对各水平旋转及径向位移进行定量分析,计算左室扭转及径向位移,构建左室-扭转位移环,并记录心底部与心尖部旋转角度峰值和左室扭转角度峰值及达峰时间,收缩期及等容舒张期左室径向位移。结果正常人扭转运动主要表现为心底部顺时针旋转和心尖部逆时针旋转,心脏整体表现为心动周期内逆时针方向为主的扭转运动。左室扭转-位移环均呈＂8＂字构型。收缩期及等容舒张期左室扭转与径向位移呈线性相关。结论应用2DS技术可无创性评价正常人左室扭转及径向位移运动特征,构建左室-扭转位移环。