Breaking the Intrinsic Strength-Ductility Tradeoff in Graphene-Metal Composites.

Small carbon materials, such as graphene, offer excellent mechanical strength. Micro/nano carbon materials are often dispersed into a metal matrix to form bulk composites with mechanical enhancement. Despite technical progress, such composites intrinsically suffer from a trade-off condition between strength and ductility because the load transfer path forms between mechanically strong yet chemically inert micro/nano carbon materials or between the carbon-metal interfaces. In other words, conventional carbon and metal composites become stronger with increasing carbon contents, but the weak interfaces also increase, leading to premature failure. In this regard, crucial advances are presented toward breaking the strength-ductility trade-off condition by utilizing Axially bi-Continuous Graphene-Nickel (ACGN) wires. This innovative ACGN achieves excellent combined strength and ductility-the highest among the current Ni-, Al-, and Cu-based carbon-enhanced metal matrix composites. For example, the ultimate strength and failure strain of 25-µm-diameter ACGN wires are improved by 71.76% and 58.24%, compared to their counterparts. The experimental and theoretical analyses indicate that the graphene-nickel interplay via their axially bi-continuous structure is the main underlying mechanism for the superb mechanical behavior. In specific, the continuous graphene, in addition to effective load-sharing, passivates the free surface of fine wire, forming dislocation pileups along the graphene-nickel interface and, therefore, hindering localized necking.

Topographical depth reveals contact guidance mechanism distinct from focal adhesion confinement.

Cellular response to the topography of their environment, known as contact guidance, is a crucial aspect to many biological processes yet remains poorly understood. A prevailing model to describe cellular contact guidance involves the lateral confinement of focal adhesions (FA) by topography as an underlying mechanism governing how cells can respond to topographical cues. However, it is not clear how this model is consistent with the well-documented depth-dependent contact guidance responses in the literature. To investigate this model, we fabricated a set of contact guidance chips with lateral dimensions capable of confining focal adhesions and relaxing that confinement at various depths. We find at the shallowest depth of 330 nm, the model of focal adhesion confinement is consistent with our observations. However, the cellular response at depths of 725 and 1000 nm is inadequately explained by this model. Instead, we observe a distinct reorganization of F-actin at greater depths in which topographically induced cell membrane deformation alters the structure of the cytoskeleton. These results are consistent with an alternative curvature-hypothesis to explain cellular response to topographical cues. Together, these results indicate a confluence of two molecular mechanisms operating at increased induced membrane curvature that govern how cells sense and respond to topography.

Facial electromyogram-based facial gesture recognition for hands-free control of an AR/VR environment: optimal gesture set selection and validation of feasibility as an assistive technology.

The rapid expansion of virtual reality (VR) and augmented reality (AR) into various applications has increased the demand for hands-free input interfaces when traditional control methods are inapplicable (e.g., for paralyzed individuals who cannot move their hands). Facial electromyogram (fEMG), bioelectric signals generated from facial muscles, could solve this problem. Discriminating facial gestures using fEMG is possible because fEMG signals vary with these gestures. Thus, these signals can be used to generate discrete hands-free control commands. This study implemented an fEMG-based facial gesture recognition system for generating discrete commands to control an AR or VR environment. The fEMG signals around the eyes were recorded, assuming that the fEMG electrodes were embedded into the VR head-mounted display (HMD). Sixteen discrete facial gestures were classified using linear discriminant analysis (LDA) with Riemannian geometry features. Because the fEMG electrodes were far from the facial muscles associated with the facial gestures, some similar facial gestures were indistinguishable from each other. Therefore, this study determined the best facial gesture combinations with the highest classification accuracy for 3-15 commands. An analysis of the fEMG data acquired from 15 participants showed that the optimal facial gesture combinations increased the accuracy by 4.7%p compared with randomly selected facial gesture combinations. Moreover, this study is the first to investigate the feasibility of implementing a subject-independent facial gesture recognition system that does not require individual user training sessions. Lastly, our online hands-free control system was successfully applied to a media player to demonstrate the applicability of the proposed system. Supplementary Information: The online version contains supplementary material available at 10.1007/s13534-023-00277-9.

Suction Drain Tip Cultures in Predicting a Surgical Site Infection.

STUDY DESIGN: Retrospective study. PURPOSE: This study aimed to evaluate the prognostic value of drain tip culture after spinal surgery with a large number of participants. OVERVIEW OF LITERATURE: The routine culture of suction drain tips that are placed in the surgical site of spinal surgeries has been performed in many institutions to detect surgical site infection (SSI). However, few reports have evaluated drain tip culture as a prognostic for SSI after spinal surgery. Materials and. METHODS: This study retrospectively included 1,415 consecutive patients who underwent spinal surgery between January 2016 and December 2021. Patients diagnosed with infectious diseases were excluded. Prophylactic antibiotics were administered intraoperatively and 24 hours postoperatively. Drains were removed when the volume of postoperative fluid drainage was <50 mL and <100 mL in patients who underwent cervical and thoracic surgery and lumbar surgery in the preceding 24 hours, respectively, and cultures were made. We evaluated the correlation between the results of positive drain tip culture and SSI. RESULTS: Positive drain tip cultures were found in 51 cases (3.6%). SSI was identified in 34 cases (2.4%). The most frequently isolated microorganism was methicillin-resistant Staphylococcus epidermidis (61.8%). The sensitivity, specificity, and positive, and negative predictive values of drain tip culture were 50.0%, 97.4%, 32.1%, and 98.8%, respectively. The same bacteria were isolated from the surgical lesion in 16 of 17 SSI cases with a positive drain tip culture, thereby giving a bacteria matching rate between tissue culture and drain tip culture of 94.1%. The number of surgery levels, drain remaining period, and drain tip culture positivity were significantly increased in the SSI group. CONCLUSIONS: Drain tip cultures might be useful for predicting SSI. Drain tip culture had a high positivity rate in the SSI group, and the coincidence rate for the causative pathogen was high.

Facial Motion Capture System Based on Facial Electromyogram and Electrooculogram for Immersive Social Virtual Reality Applications.

With the rapid development of virtual reality (VR) technology and the market growth of social network services (SNS), VR-based SNS have been actively developed, in which 3D avatars interact with each other on behalf of the users. To provide the users with more immersive experiences in a metaverse, facial recognition technologies that can reproduce the user's facial gestures on their personal avatar are required. However, it is generally difficult to employ traditional camera-based facial tracking technology to recognize the facial expressions of VR users because a large portion of the user's face is occluded by a VR head-mounted display (HMD). To address this issue, attempts have been made to recognize users' facial expressions based on facial electromyogram (fEMG) recorded around the eyes. fEMG-based facial expression recognition (FER) technology requires only tiny electrodes that can be readily embedded in the HMD pad that is in contact with the user's facial skin. Additionally, electrodes recording fEMG signals can simultaneously acquire electrooculogram (EOG) signals, which can be used to track the user's eyeball movements and detect eye blinks. In this study, we implemented an fEMG- and EOG-based FER system using ten electrodes arranged around the eyes, assuming a commercial VR HMD device. Our FER system could continuously capture various facial motions, including five different lip motions and two different eyebrow motions, from fEMG signals. Unlike previous fEMG-based FER systems that simply classified discrete expressions, with the proposed FER system, natural facial expressions could be continuously projected on the 3D avatar face using machine-learning-based regression with a new concept named the virtual blend shape weight, making it unnecessary to simultaneously record fEMG and camera images for each user. An EOG-based eye tracking system was also implemented for the detection of eye blinks and eye gaze directions using the same electrodes. These two technologies were simultaneously employed to implement a real-time facial motion capture system, which could successfully replicate the user's facial expressions on a realistic avatar face in real time. To the best of our knowledge, the concurrent use of fEMG and EOG for facial motion capture has not been reported before.

Toxicological and molecular adverse effect of Illicium verum fruit constituents toward Bradysia procera.

BACKGROUND: Bradysia procera, a ginseng stem fungus gnat, is one of the most serious insect pests of Korean ginseng (Panax ginseng), causing significant damage to plant growth. The goal of this study was to determine the toxicity and mechanism of action of phenylpropanoids (trans-anethole and estragole) isolated from the methanol extract and hydrodistillate of Illicium verum fruit against third-instar larvae and eggs of Bradysia procera. RESULTS: The filter-paper mortality bioassay revealed that estragole [median lethal concentration (LC50 ) = 4.68 g/cm2 ] has a significant fumigant effect, followed by trans-anethole (LC50 = 43.92 g/cm2 ). However, estragole had the lowest toxic effect when compared to commercially available insecticides. After 7 days, estragole and trans-anethole at 75 g/cm2 inhibited egg hatchability up to 97% and 93%, respectively. At 0.09 g/cm2 , insecticides had an inhibitory effect on egg-hatching ability ranging from 88% to 94%. Furthermore, in both closed and open containers, these active constituents were able to consistently induce vapor-phased toxicity. Both estragole and trans-anethole have the ability to inhibit acetylcholinesterase (AChE), which is involved in neurotransmitter function. However, the active constituent estragole from I. verum fruit acted as a potent AChE inhibitor and had a slightly lower effect on cyclic adenosine monophosphate (AMP) than octopamine alone. CONCLUSION: This finding suggests that estragole may influence Bradysia procera neurotransmitter function via both the AChE and octopaminergic receptors. More research is needed to demonstrate the potential applications of I. verum fruit-derived products as potential larvicides and ovicides for Bradysia procera population control. © 2022 Society of Chemical Industry.

Cavitation nucleation and its ductile-to-brittle shape transition in soft gels under translational mechanical impact.

Cavitation bubbles in the human body, when subjected to impact, are being increasingly considered as a possible brain injury mechanism. However, the onset of cavitation and its complex dynamics in biological materials remain unclear. Our experimental results using soft gels as a tissue simulant show that the critical acceleration (acr) at cavitation nucleation monotonically increases with increasing stiffness of gelatin A/B, while acr for agarose and agar initially increases but is followed by a plateau or even decrease after stiffness reach to ∼100 kPa. Our image analyses of cavitation bubbles and theoretical work reveal that the observed trends in acr are directly linked to how bubbles grow in each gel. Gelatin A/B, regardless of their stiffness, form a localized damaged zone (tens of nanometers) at the gel-bubble interface during bubble growth. In contrary, the damaged zone in agar/agarose becomes significantly larger (> 100 times) with increasing shear modulus, which triggers the transition from formation of a small, damaged zone to activation of crack propagation. STATEMENT OF SIGNIFICANCE: We have studied cavitation nucleation and bubble growth in four different types of soft gels (i.e., tissue simulants) under translational impact. The critical linear acceleration for cavitation nucleation has been measured in the simulants by utilizing a recently developed method that mimics acceleration profiles of typical head blunt events. Each gel type exhibits significantly different trends in the critical acceleration and bubble shape (e.g., A gel-specific sphere-to-saucer transition) with increasing gel stiffness. Our theoretical framework, based on the concepts of a damaged zone and crack propagation in each gel, explains underlying mechanisms of the experimental observations. Our in-depth studies shed light on potential links between traumatic brain injuries and cavitation bubbles induced by translational acceleration, the overlooked mechanism in the literature.

An Axially Continuous Graphene-Copper Wire for High-Power Transmission: Thermoelectrical Characterization and Mechanisms.

The demand for high-power electrical transmission continues to increase with technical advances in electric vehicles, unmanned drones, portable devices, and deployable military applications. In this study, significantly enhanced electrical properties (i.e., a 450% increase in the current density breakdown limit) are demonstrated by synthesizing axially continuous graphene layers on microscale-diameter wires. To elucidate the underlying mechanisms of the observed enhancements, the electrical properties of pure copper wires and axially continuous graphene-copper (ACGC) wires with three different diameters are characterized while controlling the experimental conditions, including ambient temperature, gases, and pressure. The study reveals that the main mechanism that allows the application of extremely large current densities (>400 000 A cm-2 ) through the ACGC wires is threefold: the continuous graphene layers considerably improve: 1) surface heat dissipation (224% higher), 2) electrical conductivity (41% higher), and 3) thermal stability (41.2% lower resistivity after thermal cycles up to 450 °C), compared with pure copper wires. In addition, it is observed, through the use of high-speed camera images, that the ACGC wires exhibit very different failure behavior near the current density limit, compared with the pure copper wires.

Mechanically Induced Cavitation in Biological Systems.

Cavitation bubbles form in soft biological systems when subjected to a negative pressure above a critical threshold, and dynamically change their size and shape in a violent manner. The critical threshold and dynamic response of these bubbles are known to be sensitive to the mechanical characteristics of highly compliant biological systems. Several recent studies have demonstrated different biological implications of cavitation events in biological systems, from therapeutic drug delivery and microsurgery to blunt injury mechanisms. Due to the rapidly increasing relevance of cavitation in biological and biomedical communities, it is necessary to review the current state-of-the-art theoretical framework, experimental techniques, and research trends with an emphasis on cavitation behavior in biologically relevant systems (e.g., tissue simulant and organs). In this review, we first introduce several theoretical models that predict bubble response in different types of biological systems and discuss the use of each model with physical interpretations. Then, we review the experimental techniques that allow the characterization of cavitation in biologically relevant systems with in-depth discussions of their unique advantages and disadvantages. Finally, we highlight key biological studies and findings, through the direct use of live cells or organs, for each experimental approach.

Subclinical gait disturbance and postoperative gait improvement in patients with degenerative cervical myelopathy.

This study aimed to evaluate the subclinical gait abnormalities and the postoperative gait improvements in patients with degenerative cervical myelopathy using three-dimensional gait analysis. We reviewed the gait analysis of 62 patients who underwent surgical treatment for degenerative cervical myelopathy. The asymptomatic gait group included 30 patients and the gait disturbance group included 32 patients who can walk on their own slowly or need assistive device on stairs. The step width (17.2 cm vs. 15.9 cm, P = 0.003), stride length (105.2 cm vs. 109.1 cm, P = 0.015), and double-limb support duration (13.4% vs. 11.7%, P = 0.027) improved only in the asymptomatic gait group. Preoperatively, the asymptomatic gait group exhibited better maximum knee flexion angle (60.5° vs. 54.8°, P = 0.001) and ankle plantarflexion angle at push-off (- 12.2° vs. - 6.5°, P = 0.001) compared to the gait disturbance group. Postoperatively, maximum knee flexion angle (62.3° vs. 58.2°, P = 0.004) and ankle plantarflexion angle at push-off (- 12.8° vs. - 8.3°, P = 0.002) were still better in the asymptomatic gait group, although both parameters improved in the gait disturbance group (P = 0.005, 0.039, respectively). Kinematic parameters could improve in patients with gait disturbance. However, temporospatial parameters improvement may be expected when the operative treatment is performed before apparent gait disturbance.

Comparison of Early Surgical Treatment With Conservative Treatment of Incomplete Cervical Spinal Cord Injury Without Major Fracture or Dislocation in Patients With Pre-existing Cervical Spinal Stenosis.

STUDY DESIGN: This was a retrospective comparative study. OBJECTIVE: The objective of this study was to evaluate the clinical outcomes of early surgical treatment (<24 h) and conservative treatment of incomplete cervical spinal cord injury (CSCI) without major fracture or dislocation in patients with pre-existing cervical spinal canal stenosis (CSCS). SUMMARY OF BACKGROUND DATA: The relative benefits of surgery, especially early surgical treatment, and conservative treatment for CSCI without major fracture or dislocation in patients with pre-existing CSCS remain unclear. Animal models of CSCI have demonstrated that early surgical decompression immediately after the initial insult may prevent or reverse secondary injury. However, the clinical outcomes of early surgery for incomplete CSCI in patients with pre-existing CSCS are still unclear. MATERIALS AND METHODS: The medical records and radiographic data of 54 patients admitted to our facility between 2005 and 2015 with American Spinal Injury Association (ASIA) impairment scale grade B or C and pre-existing CSCS without major fracture or dislocation were retrospectively reviewed. Thirty-three patients (mean age, 57.4±14.0 y) underwent early surgical treatment within 24 hours after initial trauma (S group), and 21 patients (mean age, 56.9±13.6 y) underwent conservative treatment (C group) performed by 2 spinal surgeons in accordance with their policies. The primary outcome was the degree of improvement in ASIA grade after 2 years. RESULTS: During the 2-year follow-up period, higher percentages of patients in the S group than in the C group showed ≥1 grade (90.9% vs. 57.1%, P=0.0051) and 2 grade (30.3% vs. 9.5%) improvements in ASIA grade. Multivariate analysis showed that treatment type, specifically early surgical treatment, was the only factor significantly associated with ASIA grade improvement after 2 years (P=0.0044). CONCLUSIONS: Early surgery yielded better neurological outcomes than conservative treatment in patients with incomplete CSCI without major fracture or dislocation and pre-existing CSCS. LEVEL OF EVIDENCE: Level III.

Mechanisms of cell damage due to mechanical impact: an in vitro investigation.

The dynamic response of cells when subjected to mechanical impact has become increasingly relevant for accurate assessment of potential blunt injuries and elucidating underlying injury mechanisms. When exposed to mechanical impact, a biological system such as the human skin, brain, or liver is rapidly accelerated, which could result in blunt injuries. For this reason, an acceleration of greater than > 150 g is the most commonly used criteria for head injury. To understand the main mechanism(s) of blunt injury under such extreme dynamic threats, we have developed an innovative experimental method that applies a well-characterized and -controlled mechanical impact to live cells cultured in a custom-built in vitro setup compatible with live cell microscopy. Our studies using fibroblast cells as a model indicate that input acceleration ([Formula: see text]) alone, even when it is much greater than the typical injury criteria, e.g., [Formula: see text] g, does not result in cell damage. On the contrary, we have observed a material-dependent critical pressure value above which a sudden decrease in cell population and cell membrane damage have been observed. We have unambiguously shown that (1) this critical pressure is associated with the onset of cavitation bubbles in a cell culture chamber and (2) the dynamics of cavitation bubbles in the chamber induces localized compressive/tensile pressure cycles, with an amplitude that is considerably greater than the acceleration-induced pressure, to cells. More importantly, the rate of pressure change with time for cavitation-induced pressure is significantly faster (more than ten times) than acceleration-induced pressure. Our in vitro study on the dynamic response of biological systems due to mechanical impact is a crucial step towards understanding potential mechanism(s) of blunt injury and implementing novel therapeutic strategies post-trauma.

Cadaveric device-injected very high-viscosity cement during vertebroplasty.

INTRODUCTION: Cement extravasation during vertebroplasty (VP) is the most commonly reported complication. Cement viscosity is considered the single most important predictor of the risk of extravasation. Certainly, injecting high-viscosity cement (HVC) is difficult to utilize in real practice. We invented a new device capable of injecting high-viscosity with ease and at a distance to avoid radiation. The aim of this study is to confirm the efficacy and safety of the new device on cadaveric vertebrae. METHODOLOGY: A 126 osteoporotic vertebral bodies were harvested from cadavers. Eighty vertebrae were included in the study. Computer-randomization software was used to allocate specimens over two main groups, Conventional VP and New Device. Both groups were further subdivided into two subgroups; high-viscosity and low-viscosity. A custom device was used on each vertebra to induce a compression fracture. RESULTS: Injecting HVC was associated with a lower leakage volume compared with low-viscosity cement. HVC was associated with no leakage into the spinal canal. It was also associated with a low incidence of vascular extravasation (P < 0.001). The mean volume of cement leakage in the low-viscosity group was 0.23 and 0.15 cc, for the Conventional VP and New Device, respectively. In both groups, the most common site for leakage was the vertebral end plate, which was exhibited more in the low-viscosity group (71.5%) compared with the high-viscosity group (42.5%). The preset target amount of cement to be injected was reached in 99% of the time when injecting HVC with the New Device, compared with 62% using the Conventional VP. In both groups, there was no correlation between the amount of cement injected and the amount of leakage. CONCLUSION: The new device is capable of injecting HVC easily, with a lower incidence of cement leakage. It also minimized the risk of radiation exposure to the surgeon.

What Is the Fate of Pseudarthrosis Detected 1 Year After Anterior Cervical Discectomy and Fusion?

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To investigate the consequences and appropriate management of pseudarthrosis after anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: Pseudarthrosis is a frequent complication of ACDF and causes unsatisfactory results. Little is known about long-term prognosis of detecting pseudarthrosis 1 year after ACDF. METHODS: Eighty-nine patients with a minimum 2-year follow-up were included. ACDF surgery using allograft and plating was performed: single-level in 51 patients, two-level in 26 patients, and three-level in 12 patients. Presence of pseudarthrosis was evaluated 1 year postoperatively and then the nonunion segments were re-evaluated 2 years postoperatively. Demographic data were assessed to identify the risk factors associated with pseudarthrosis. A visual analogue scale for neck/arm pain and the Neck Disability Index were analyzed preoperatively and at 1 and 2 years postoperatively. RESULTS: Pseudarthrosis was detected in 29 patients (32.6%) 1 year postoperatively: 15of 51 patients after single-level surgery, 9 of 26 patients after two-level surgery, and 5 of 12 patients after three-level surgery. Only eight patients showed persistent nonunion at 2 years: 3 of 15 patients after single-level surgery, 3 of 9 after two-level surgery, and 2 of 5 after three-level surgery. The remaining 21 patients (72.4%) achieved bony fusion 2 years postoperatively without any intervention. Patients who underwent two-level or three-level ACDF had a significantly higher pseudarthrosis rate than those who underwent single-level ACDF, with odds ratios of 1.844 and 3.147, respectively. The improvements in visual analogue scale for neck pain and Neck Disability Index scores in the persistent nonunion group were significantly lower than those in the final union group at 2 years. CONCLUSION: Patients with pseudarthrosis detected 1 year postoperatively may be observed without any intervention because approximately 70% of them will eventually fuse by the 2-year point. Early revision could, however, be considered if the pseudarthrosis is associated with considerable neck pain after multilevel ACDF. LEVEL OF EVIDENCE: 3.

Multilevel posterior foraminotomy with laminoplasty versus laminoplasty alone for cervical spondylotic myelopathy with radiculopathy: a comparative study.

BACKGROUND CONTEXT: Conventional laminoplasty is useful for expanding a stenotic spinal canal. However, it has limited use for the decompression of accompanying neural foraminal stenosis. As such, an additional posterior foraminotomy could be simultaneously applied, although this procedure carries a risk of segmental kyphosis and instability. PURPOSE: The aim of this study was to elucidate the long-term surgical outcomes of additional posterior foraminotomy with laminoplasty (LF) for cervical spondylotic myelopathy (CSM) with radiculopathy. STUDY DESIGN/SETTING: A retrospective comparative study was carried out. PATIENT SAMPLE: Ninety-eight consecutive patients who underwent laminoplasty for CSM with radiculopathy between January 2006 and December 2012 were screened for eligibility. This study included 66 patients, who were treated with a laminoplasty of two or more levels and followed up for more than 2 years after surgery. OUTCOME MEASURES: The Neck Disability Index (NDI), Japanese Orthopedic Association (JOA) scores, JOA recovery rates, and visual analog scale (VAS) were used to evaluate clinical outcomes. The C2-C7 sagittal vertical axis distance, cervical lordosis, range of motion (ROM), and angulation and vertebral slippage at the foraminotomy level were used to measure radiological outcomes using the whole spine anterioposterior or lateral and dynamic lateral radiographs. METHODS: Sixty-six patients with CSM with radiculopathy involving two or more levels were consecutively treated with laminoplasty and followed up for more than 2 years after surgery. The first 26 patients underwent laminoplasty alone (LA group), whereas the next 40 patients underwent an additional posterior foraminotomy at stenotic neural foramens with radiating symptoms in addition to laminoplasty (LF group). In the LF group, the foraminotomy with less resection than 50% of facet joint to avoid segmental kyphosis and instability was performed at 78 segments (unilateral-to-bilateral ratio=57:21) and 99 sites. Clinical and radiographic data were assessed preoperatively and at 2-year follow-up and compared between the groups. RESULTS: The NDI, JOA scores, JOA recovery rates, and VAS for neck and arm pain were improved significantly in both groups after surgery. The improvement in the VAS for arm pain was significantly greater in the LF group (from 5.55±2.52 to 1.85±2.39) than the LA group (from 5.48±2.42 to 3.40±2.68) (p<.001). Although cervical lordosis and ROM decreased postoperatively in both groups, there were no significant differences in the degree of reduction between the LF and LA groups. Although the postoperative focal angulation and slippage were slightly increased in the LF group, this was not to a significant degree. Furthermore, segmental kyphosis and instability were not observed in the LF group, regardless of whether the patient underwent a unilateral or bilateral foraminotomy. CONCLUSIONS: Additional posterior foraminotomy with laminoplasty is likely to improve arm pain more significantly than laminoplasty alone by decompressing nerve roots. Also, performing posterior foraminotomy via multiple levels or bilaterally did not significantly affect segmental malalignment and instability. Therefore, when a laminoplasty is performed for CSM with radiculopathy, an additional posterior foraminotomy could be an efficient and safe treatment that improves both myelopathy symptoms and radicular arm pain.

Large exotropia after retrobulbar anesthesia.

A 67-year-old woman complained of horizontal diplopia shortly following bilateral cataract surgery with intraocular lens implantation performed under retrobulbar anesthesia. Retrobulbar anesthesia was administered at an inferotemporal injection site using 1 cc lidocaine hydrochloride 2% mixed with bupivacaine hydrochloride 0.5%. The initial ophthalmologic evaluation showed a 12-prism diopter (PD) exotropia, and ocular motility evaluation revealed marked limitation of adduction without vertical limitation. One year after cataract surgery, the exodeviation increased up to 60 PD. The patient underwent an 8.0-mm recession of the right lateral rectus and a 6.0-mm recession of the left lateral rectus. Both lateral rectus muscles were biopsied, and biopsy revealed dense fibrous connective tissue without viable muscular cells. The lateral rectus muscle might be injured by retrobulbar anesthesia, and it could induce large exotropia.

The use of magnetic resonance imaging to predict the clinical outcome of non-surgical treatment for lumbar intervertebral disc herniation.

OBJECTIVE: We wanted to investigate the relationship between the magnetic resonance (MR) findings and the clinical outcome after treatment with non-surgical transforaminal epidural steroid injections (ESI) for lumbar herniated intervertebral disc (HIVD) patients. MATERIALS AND METHODS: Transforaminal ESI were performed in 91 patients (50 males and 41 females, age range: 13-78 yrs) because of lumbosacral HIVD from March 2001 to August 2002. Sixty eight patients whose MRIs and clinical follow-ups were available were included in this study. The medical charts were retrospectively reviewed and the patients were divided into two groups; the successful (responders, n = 41) and unsatisfactory (non-responders, n = 27) outcome groups. A successful outcome required a patient satisfaction score greater than two and a pain reduction score greater than 50%. The MR findings were retrospectively analyzed and compared between the two groups with regard to the type (protrusion, extrusion or sequestration), hydration (the T2 signal intensity), location (central, right/left central, subarticular, foraminal or extraforaminal), and size (volume) of the HIVD, the grade of nerve root compression (grade 1 abutment, 2 displacement and 3 entrapment), and an association with spinal stenosis. RESULTS: There was no significant difference between the responders and non-responders in terms of the type, hydration and size of the HIVD, or an association with spinal stenosis (p > 0.05). However, the location of the HIVD and the grade of nerve root compression were different between the two groups (p < 0.05). CONCLUSION: MRI could play an important role in predicting the clinical outcome of non-surgical transforaminal ESI treatment for patients with lumbar HIVD.