In silico modeling of electric field modulation by transcranial direct current stimulation in stroke patients with skull burr holes: Implications for safe clinical application.

Background: Transcranial direct current stimulation (tDCS) has emerged as a promising tool for stroke rehabilitation, supported by evidence demonstrating its beneficial effects on post-stroke recovery. However, patients with skull defects, such as burr holes, have been excluded from tDCS due to limited knowledge regarding the effect of skull defects on the electric field.

Objective: We investigated the effect of burr holes on the electric field induced by tDCS and identified the electrode location that modulates the electric field.

Tract-specific magnetization transfer ratio provides insights into the severity of degenerative cervical myelopathy.

Study Design: Cross-sectional study.

Objectives: This study's goal is to report whether Magnetization Transfer Ratio (MTR) can evaluate the severity of white matter (WM) injury in degenerative cervical myelopathy (DCM).

Setting: Laureate Institute of Brain Research, USA; Department of Neurosurgery, University of Oklahoma Health Sciences Center, USA.

Cervical spinal cord morphometrics in degenerative cervical myelopathy: quantification using semi-automated normalized technique and correlation with neurological dysfunctions.

Background Context: Degenerative cervical myelopathy (DCM) is characterized by spinal cord atrophy. Accurate estimation of spinal cord atrophy is key to the understanding of neurological diseases, including DCM. However, its clinical application is hampered by difficulties in its precise and consistent estimation due to significant variability in spinal cord morphometry along the cervical spine, both within and between individuals.

The hormonal profile in women using combined monophasic oral contraceptive pills varies across the pill cycle: a temporal analysis of serum endogenous and exogenous hormones using liquid chromatography with tandem mass spectroscopy.

Oral contraceptive pills, of all types, are used by approximately 151 million women worldwide; however, a clear understanding of the concentrations of endogenous and exogenous hormones across a 28-day combination monophasic oral contraceptive pill pack is not well described. In our study of 14 female participants taking various combination monophasic oral contraceptive pills, we found significant fluctuations in endogenous and exogenous hormone levels throughout the pill cycle. Our analysis revealed significantly greater levels of ethinyl estradiol on the 20th and 21st days of active pill ingestion, compared with (active) and (inactive pill ingestion).

17β-Estradiol Effects in Skeletal Muscle: A P MR Spectroscopic Imaging (MRSI) Study of Young Females during Early Follicular (EF) and Peri-Ovulation (PO) Phases.

The natural variation in estrogen secretion throughout the female menstrual cycle impacts various organs, including estrogen receptor (ER)-expressed skeletal muscle. Many women commonly experience increased fatigue or reduced energy levels in the days leading up to and during menstruation, when blood estrogen levels decline. Yet, it remains unclear whether endogenous 17β-estradiol, a major estrogen component, directly affects the energy metabolism in skeletal muscle due to the intricate and fluctuating nature of female hormones.

Myoelectric interface for neurorehabilitation conditioning to reduce abnormal leg co-activation after stroke: a pilot study.

Background: The ability to walk is an important factor in quality of life after stroke. Co-activation of hip adductors and knee extensors has been shown to correlate with gait impairment. We have shown previously that training with a myoelectric interface for neurorehabilitation (MINT) can reduce abnormal muscle co-activation in the arms of stroke survivors.

Sex hormone mediated change on flexion reflex.

It has been shown that estrogen and progesterone receptors are expressed in the spinal cord; therefore, fluctuation in their concentrations may affect the spinal network and modulate the control of movement. Herein, we assessed the neuro-modulatory effect of sex hormones on the polysynaptic spinal network by using a flexion reflex network as a model system. Twenty-four healthy eumenorrheic women (age 21-37 years) were tested every other day for one menstrual cycle.

Effect of Non-invasive Spinal Stimulation on Self-sustained Firing Motoneuron Model: In-Silico Study Using Human Body Model.

Transcutaneous spinal electrical stimulation (tSCS) is a non-invasive neuromodulation approach using a low intensity direct current. Recent developments in the technique have opened the possibility that tSCS can help restore motor function after spinal cord injury (SCI). However, the exact mechanism of action tSCS has on the spinal circuits is still unknown.

Myoelectric interface for neurorehabilitation conditioning to reduce abnormal leg co-activation after stroke: a pilot study.

Background: The ability to walk is an important factor in quality of life after stroke. Co-activation of hip adductors and knee extensors has been shown to correlate with gait impairment. We have shown previously that training with a myoelectric interface for neurorehabilitation (MINT) can reduce abnormal muscle co-activation in the arms of stroke survivors.

Identifying spinal tracts transmitting distant effects of trans-spinal magnetic stimulation.

Estimating the state of tract-specific inputs to spinal motoneurons is critical to understanding movement deficits induced by neurological injury and potential pathways to recovery but remains challenging in humans. In this study, we explored the capability of trans-spinal magnetic stimulation (TSMS) to modulate distal reflex circuits in young adults. TSMS was applied over the thoracic spine to condition soleus H-reflexes involving sacral-level motoneurons.

Low-Grade Inflammatory Mediators and Metalloproteinases Yield Synchronous and Delayed Responses to Mechanical Joint Loading.

Objective: Mechanical loading is an essential factor for the maintenance of joint inflammatory homeostasis and the sensitive catabolic-anabolic signaling cascade involved in maintaining cartilage tissue health. However, abnormal mechanical loading of the joint structural tissues can propagate joint metabolic dysfunction in the form of low-grade inflammation. To date, few studies have attempted to delineate the early cascade responsible for the initiation and perpetuation of stress-mediated inflammation and cartilage breakdown in human joints.

Isolating Neurologic Deficits in Cervical Spondylotic Myelopathy: A Case-Controlled Study, Using the NIH Toolbox Motor Battery.

Background And Objectives: Patients with cervical spondylotic myelopathy (CSM) have motor impairments, including weakness, imbalance, and loss of dexterity. The reliable assessment of these symptoms is critical for treatment decisions. This study aimed to determine, for the first time, the use of the NIH Toolbox motor battery (NIHTBm) in the objective assessment of motor deficits in patients with CSM.

Sex hormone-mediated change on muscle activation deactivation dynamics in young eumenorrheic women.

The goal of the study was to characterize muscle activation/deactivation dynamics across the menstrual cycle in healthy young women. Twenty-two healthy eumenorrheic women (age: 27.0 ± 4.

Surrogate modeling of articular cartilage degradation to understand the synergistic role of MMP-1 and MMP-9: a case study.

A characteristic feature of arthritic diseases is cartilage extracellular matrix (ECM) degradation, often orchestrated by the overexpression of matrix metalloproteinases (MMPs) and other proteases. The interplay between fibril level degradation and the tissue-level aggregate response to biomechanical loading was explored in this work by a computational multiscale cartilaginous model. We considered the relative abundance of collagenases (MMP-1) and gelatinases (MMP-9) in surrogate models, where the diffusion (spatial distribution) of these enzymes and the subsequent, co-localized fibrillar damage were spatially randomized with Latin Hypercube Sampling.

Sexual Dimorphism in the Extracellular and Pericellular Matrix of Articular Cartilage.

Objective: Women have a higher prevalence and burden of joint injuries and pathologies involving articular cartilage than men. Although knee injuries affecting young women are on the rise, most studies related to sexual dimorphism target postmenopausal women. We hypothesize that sexual dimorphism in cartilage structure and mechanics is present before menopause, which can contribute to sex disparities in cartilage pathologies.

Can Increased Locomotor Task Difficulty Differentiate Knee Muscle Forces After Anterior Cruciate Ligament Reconstruction?

Changes in knee mechanics following anterior cruciate ligament (ACL) reconstruction are known to be magnified during more difficult locomotor tasks, such as when descending stairs. However, it is unclear if increased task difficulty could distinguish differences in forces generated by the muscles surrounding the knee. This study examined how knee muscle forces differ between individuals with ACL reconstruction with different graft types (hamstring tendon and patellar tendon autograft) and "healthy" controls when performing tasks with increasing difficulty.

The Effect of Implanted Functional Electrical Stimulation on Gait Performance in Stroke Survivors: A Systematic Review.

The emerging literature suggests that implantable functional electrical stimulation may improve gait performance in stroke survivors. However, there is no review providing the possible therapeutic effects of implanted functional electrical stimulation on gait performance in stroke survivors. We performed a web-based, systematic paper search using PubMed, the Cochrane Library, and EMBASE.

Sensitivity analysis of the knee ligament forces to the surgical design variation during anterior cruciate ligament reconstruction: a finite element analysis.

The purpose of this study is to understand the effect of essential surgical design parameters on collateral and cruciate ligaments behavior for a Bone-Patellar-Tendon-Bone (BPTB) anterior cruciate ligament reconstruction (ACL-R) surgery. A parametric finite element model of biomechanical experiments depicting the ACL-R surgery associated with a global sensitivity analysis was adopted in this work. The model parameters were six intraoperative variables, two-quadrant coordinates of femoral tunnel placement, femoral tunnel sagittal and coronal angles, graft pretension, and the joint angle at which the BPTB graft is tensioned (fixation angle).

Effect of Surgical Design Variations on the Knee Contact Behavior during Anterior Cruciate Ligament Reconstruction.

In this study, we aimed to develop an in-silico synthesis of the effect of critical surgical design parameters on articular contact behavior for a bone-patellar-tendon-bone anterior cruciate ligament reconstruction (ACL-R) surgery. A previously developed finite element model of the knee joint consisting of all relevant soft tissues was employed. The knee model was further updated with additional features to develop the parametric FE model of the biomechanical experiments that depicted the ACL-R surgery.

Fatty infiltration in cervical flexors and extensors in patients with degenerative cervical myelopathy using a multi-muscle segmentation model.

Background: In patients with degenerative cervical myelopathy (DCM) that have spinal cord compression and sensorimotor deficits, surgical decompression is often performed. However, there is heterogeneity in clinical presentation and post-surgical functional recovery.

Objectives: Primary: a) to assess differences in muscle fat infiltration (MFI) in patients with DCM versus controls, b) to assess association between MFI and clinical disability.

Multi-color and Multi-Material 3D Printing of Knee Joint models.

Objective: This study reports on a new method for the development of multi-color and multi-material realistic Knee Joint anatomical models with unique features. In particular, the design of a fibers matrix structure that mimics the soft tissue anatomy.

Methods: Various Computer-Aided Design (CAD) systems and the PolyJet 3D printing were used in the fabrication of three anatomical models wherein fibers matrix structure is mimicked: (i) Anterior cruciate ligament reconstruction (ACL-R) model used in the previous study.

Computational frame of ligament in situ strain in a full knee model.

The biomechanical function of connective tissues in a knee joint is to stabilize the kinematics-kinetics of the joint by augmenting its stiffness and limiting excessive coupled motion. The connective tissues are characterized by an in vivo reference configuration (in situ strain) that would significantly contribute to the mechanical response of the knee joint. In this work, a novel iterative method for computing the in situ strain at reference configuration was presented.

Magnetization Transfer Ratio and Morphometrics of the Spinal Cord Associates with Surgical Recovery in Patients with Degenerative Cervical Myelopathy.

Objectives: We assessed the prognostic value of the preoperative magnetization transfer ratio (MTR) and morphometrics of the spinal cord in patients with degenerative cervical myelopathy (DCM) in a longitudinal cohort study.

Methods: Thirteen subjects with DCM underwent 3T magnetization transfer imaging. The MTR was calculated for the spinal cord regions and specific white matter tracts.

Assessing the spatial distribution of cervical spinal cord activity during tactile stimulation of the upper extremity in humans with functional magnetic resonance imaging.

Dermatomal maps are a mainstay of clinical practice and provide information on the spatial distribution of the cutaneous innervation of spinal nerves. Dermatomal deficits can help isolate the level of spinal nerve root involvement in spinal conditions and guide clinicians in diagnosis and treatment. Dermatomal maps, however, have limitations, and the spatial distribution of spinal cord sensory activity in humans remains to be quantitatively assessed.