Reweighting of the sensory inputs for postural control in patients with cervical spondylotic myelopathy after surgery

The effects of Tai Chi on standing balance control in older adults may be attributed to the improvement of sensory reweighting and complexity rather than reduced sway velocity or amplitude

Introduction

Tai Chi has proved to be an effective therapy for balance performance and cognition. However, non-consistency exists in the results of the effect of Tai Chi training on standing balance control in older adults. This study aimed to use traditional and non-traditional methods to investigate the effect of Tai Chi on standing balance in older adults.

Methods

Thirty-six Tai Chi practitioners (TC group) and thirty-six older adults with no Tai Chi practice (control group) were recruited in this study. A Nintendo Wii Balance Board was used to record the center of pressure (COP) during standing balance over 20 s in the condition of eyes closed with three repetitions. The wavelet analysis, multiscale entropy, recurrence quantification analysis, and traditional methods were used to evaluate the standing balance control in the anterior-posterior (AP) and mediolateral (ML) directions.

Results

(1) Greater sway mean velocity in the AP direction and sway Path length were found in the TC group compared with the control group; (2) lower Very-low frequency band (0.10-0.39 Hz) and higher Moderate frequency band (1.56-6.25 Hz) in the AP and ML directions were found in the TC group compared with the control group; (3) greater complexity index (CI) and lower determinism (DET) in the AP and ML directions were observed in the TC group compared with control group; (4) greater path length linked with smaller Very-low frequency band in the AP and ML directions and higher Moderate frequency band in the AP direction in both groups; (5) greater path length linked with lower DET and higher CI in the AP direction only in the TC group.

Conclusion

Long-term Tai Chi practice improved sensory reweighting (more reliance on the proprioception system and less reliance on the vestibular system) and complexity of standing balance control in older adults. In addition, greater sway velocity may be as an exploratory role in standing balance control of TC older adults, which correlated with greater complexity, but no such significant relationship in the control group. Therefore, the effects of Tai Chi practice on standing balance control in older adults may be attributed to the improvement of sensory reweighting and complexity rather than reduced sway velocity or amplitude.

Quantifying unsupported sitting posture impairments in humans with cervical spinal cord injury using a head-mounted IMU sensor

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To evaluate unsupported sitting posture impairments and identify postural regulatory strategies in cervical spinal cord injury (cSCI) participants via a head-mounted IMU sensor.

SETTING

A research lab in the United States of America.

METHODS

cSCI participants and controls maintained postural stability during unsupported sitting with eyes either open or closed. The head-mounted IMU sensor recorded accelerometer data to calculate cumulative sway motion. The postural regulatory strategy was analyzed by assessing the normalized power spectral density (PSD) in four frequency bands: 0-0.1 Hz (visual regulation), 0.1-0.5 Hz (vestibular regulation), 0.5-1 Hz (cerebellar regulation), and >1 Hz (proprioception and muscle control).

RESULTS

Significant increases in postural sway were observed in cSCI participants compared to controls during unsupported sitting. For cSCI participants, normalized PSD significantly increased in the low-frequency bands (0-0.1 Hz and 0.1-0.5 Hz) but decreased in the high-frequency band (>1 Hz) compared to controls.

CONCLUSIONS

cSCI participants were more reliant on visual and vestibular systems for sitting balance, while depending less on proprioception and muscle control compared to controls. These findings suggest that the altered postural regulatory strategy is ineffective in maintaining postural stability during unsupported sitting, emphasizing the importance of proprioception and muscle control for seated postural stability in cSCI participants.

Beneficial Effect of Repetitive Transcranial Magnetic Stimulation Combined With Physiotherapy After Cervical Spondylotic Myelopathy Surgery

PURPOSE

Cervical spondylotic myelopathy (CSM) is one of the most notable causes of spinal cord impairment among elderly people worldwide. Little is written about the influence of postoperative rehabilitation on recovery of function in patients with CSM. In this study, we assessed the combined effects of repetitive transcranial magnetic stimulation (rTMS) combined with physiotherapy and physiotherapy alone on motor and sensory improvement assessed after spinal cord decompression in patients with CSM.

METHODS

This prospective study comprised 52 patients with CSM; they were divided into two randomized groups after spinal cord decompression. The first group (group Ι) includes 26 patients, received a combination of rTMS and physiotherapy. The second group (group ΙΙ) of 26 patients underwent only physiotherapy. The neurologic assessment measures, including American Spinal Cord Injury Association score, modified Japanese Orthopaedic Association score, Ashworth scale, and Nurick grade, were recorded before and after rehabilitation interventions for each patient.

RESULTS

According to the neurologic assessment measures, physiotherapy with/without rTMS after surgical decompression corresponded to significant improvement of motor function ( P < 0. 01) without significant restoration of sensory function ( P > 0. 01). Recovery rates of motor function were significantly better in group Ι than in group ΙΙ ( P < 0. 01). There was no significant difference between two groups with respect to age ( P = 0.162) and sex ( P = 1.00).

CONCLUSIONS

Although physiotherapy with/without rTMS improves motor function recovery after CSM surgery, rTMS in combination with physiotherapy leads to a more rapid motor function recovery than physiotherapy alone.

Brain MRI changes in degenerative cervical myelopathy: a systematic review

BACKGROUND

Degenerative cervical myelopathy (DCM) is the most common cause of adult spinal cord dysfunction globally. Associated neurological symptoms and signs have historically been explained by pathobiology within the cervical spine. However, recent advances in imaging have shed light on numerous brain changes in patients with DCM, and it is hypothesised that these changes contribute to DCM pathogenesis. The aetiology, significance, and distribution of these supraspinal changes is currently unknown. The objective was therefore to synthesise all current evidence on brain changes in DCM.

METHODS

A systematic review was performed. Cross-sectional and longitudinal studies with magnetic resonance imaging on a cohort of patients with DCM were eligible. PRISMA guidelines were followed. MEDLINE and Embase were searched to 28th August 2023. Duplicate title/abstract screening, data extraction and risk of bias assessments were conducted. A qualitative synthesis of the literature is presented as per the Synthesis Without Meta-Analysis (SWiM) reporting guideline. The review was registered with PROSPERO (ID: CRD42022298538).

FINDINGS

Of the 2014 studies that were screened, 47 studies were identified that used MRI to investigate brain changes in DCM. In total, 1500 patients with DCM were included in the synthesis, with a mean age of 53 years. Brain alterations on MRI were associated with DCM both before and after surgery, particularly within the sensorimotor network, visual network, default mode network, thalamus and cerebellum. Associations were commonly reported between brain MRI alterations and clinical measures, particularly the Japanese orthopaedic association (JOA) score. Risk of bias of included studies was low to moderate.

INTERPRETATION

The rapidly expanding literature provides mounting evidence for brain changes in DCM. We have identified key structures and pathways that are altered, although there remains uncertainty regarding the directionality and clinical significance of these changes. Future studies with greater sample sizes, more detailed phenotyping and longer follow-up are now needed.

FUNDING

ODM is supported by an Academic Clinical Fellowship at the University of Cambridge. BMD is supported by an NIHR Clinical Doctoral Fellowship at the University of Cambridge (NIHR300696). VFJN is supported by an NIHR Rosetrees Trust Advanced Fellowship (NIHR302544). This project was supported by an award from the Rosetrees Foundation with the Storygate Trust (A2844).

Change in sensory integration and regularity of postural sway with the suspensory strategy during static standing balance

Background and aim

The suspensory strategy, a method for controlling postural balance in the vertical direction of the center of mass (COM), is considered by the elderly as a means of balance control. The vertical COM control might alter the sensory integration and regularity of postural sway, which in turn impacts balance. However, to date, this was not confirmed. Thus, this study aimed at investigating the influence of the suspensory strategy achieved through knee flexion on the static standing balance.

Methods

Nineteen participants were monitored at knee flexion angles of 0°, 15°, and 65°. Time-frequency analysis and sample entropy were employed to analyze the COM data. Time-frequency analysis was utilized to assess the energy content across various frequency bands and corresponding percentage of energy within each frequency band. The outcomes of time-frequency are hypothesized to reflect the balance-related sensory input and sensory weights. Sample entropy was applied to evaluate the regularity of the COM displacement patterns.

Results

Knee flexion led to a decreased COM height. The highest energy content was observed at 65° knee flexion, in contrast with the lowest energy observed at 0° in both the anterior-posterior (AP) and medial-lateral (ML) directions. Additionally, the ultra-low-frequency band was more pronounced at 65° than that at 0° or 15° in the ML direction. Furthermore, the COM amplitudes were notably higher at 65° than those at 0° and 15° in the AP and ML directions, respectively. The sample entropy values were lower at 65° and 15° than those at 0° in the ML direction, with the lowest value observed at 65° in the vertical direction.

Conclusion

The suspensory strategy could enhance the sensory input and cause sensory reweighting, culminating in a more regular balance control. Such suspensory strategy-induced postural control modifications may potentially provide balance benefits for people with declining balance-related sensory, central processing, and musculoskeletal system functions.

Impaired foot vibration sensitivity is related to altered plantar pressures during walking in people with multiple sclerosis

BACKGROUND

Balance and mobility impairment are two of the most common and debilitating symptoms among people with multiple sclerosis (MS). Somatosensory symptoms, including reduced plantar cutaneous sensation, have been identified in this cohort. Given the importance of the somatosensory system in gait, it is likely that impaired plantar sensation may play a role in the walking adaptations commonly observed in people with MS, including decreased stride length and increased stride width and dual support time, often described as a cautious gait strategy. Understanding the contributions of plantar sensation to these alterations may provide targets for interventions that seek to improve sensory feedback and normalize gait patterns. This cross-sectional study determined whether individuals with MS who demonstrate reduced sensitivity of the plantar surfaces also demonstrate altered plantar pressure distributions during walking compared to a control cohort.

METHODS

Twenty individuals with MS and twenty age- and sex-matched control participants walked barefoot at preferred and three matched speeds. Participants walked across a walkway with an embedded pressure plate used to quantify pressures within ten plantar zones. In addition, vibration perception thresholds were assessed at four sites on the plantar surface.

RESULTS

Individuals with MS demonstrated increased peak total plantar pressures compared to control participants, that increased with walking speed. For the MS group, plantar pressures were higher on the less sensitive foot, although pressures on both feet exceeded those of the control cohort. Positive correlations between vibration perception threshold and peak total pressure were evident, although generally stronger in the MS cohort.

CONCLUSION

A relationship between plantar vibration sensitivity and pressure could indicate that individuals with MS seek to increase plantar sensory feedback during walking. However, because proprioception may also be impaired, increased plantar pressure could result from inaccurate foot placement. Interventions targeting improved somatosensation may have the potential to normalize gait patterns and should be investigated.

The effect of modified optic flow gain on quiet stance

Visual feedback provides critical information to support postural stability. Previous work has shown that magnifying visual feedback, such as by presenting individuals with biofeedback during balance tasks, can improve postural control. When studies manipulate the availability of optic flow directly, the conditions are often restricted to include an absence of visual feedback or sway referenced paradigms. Therefore, the aim of this study was to understand how manipulating the gain of optic flow contributes to quiet standing balance control among healthy adults. Optic flow was amplified or reduced relative to head motion using a virtual reality head-mounted display while participants stood quietly on either a firm or foam surface. Overall, when there was an increased reliance placed on the visual system by standing on foam, a tighter control of upright stance was observed as the gain of optic flow increased. Further, this study provided evidence that visual contributions to balance control may extend to higher frequencies of postural sway than previously theorized (greater than 0.1 Hz).

A novel balance training approach: Biomechanical study of virtual reality-based skateboarding

Introduction: The use of virtual reality (VR) technology in training and rehabilitation gained increasing attention in recent years due to its potential to provide immersive and interactive experiences. We developed a novel VR-based balance training, VR-skateboarding, for improving balance. It is important to investigate the biomechanical aspects of this training, as it would have benefited both health professionals and software engineers. Aims: This study aimed to compare the biomechanical characteristics of VR-skateboarding with those of walking. Materials and Methods: Twenty young participants (10 males and 10 females) were recruited. Participants underwent VR-skateboarding and walking at the comfortable walking speed, with the treadmill set at the same speed for both tasks. The motion capture system and electromyography were used to determine joint kinematics and muscle activity of the trunk and legs, respectively. The force platform was also used to collect the ground reaction force. Results: Participants demonstrated increased trunk flexion angles and muscle activity of trunk extensor during VR-skateboarding than during walking (p < 0.01). For the supporting leg, participants' joint angles of hip flexion and ankle dorsiflexion, as well as muscle activity of knee extensor, were higher during VR-skateboarding than during walking (p < 0.01). For the moving leg, only hip flexion increased in VR-skateboarding when compared to walking (p < 0.01). Furthermore, participants increased weight distribution in the supporting leg during VR-skateboarding (p < 0.01). Conclusion: VR-skateboarding is a novel VR-based balance training that has been found to improve balance through increased trunk and hip flexion, facilitated knee extensor muscles, and increased weight distribution on the supporting leg compared to walking. These differences in biomechanical characteristics have potential clinical implications for both health professionals and software engineers. Health professionals may consider incorporating VR-skateboarding into training protocols to improve balance, while software engineers may use this information to design new features in VR systems. Our study suggests that the impact of VR-skateboarding particularly manifest when focusing on the supporting leg.

The Effects of Interactive Virtual Reality in Patients with Chronic Musculoskeletal Disorders: A Systematic Review and Meta-Analysis

Objective: Interactive virtual reality (iVR) has been widely used for treatment purposes in patients with chronic musculoskeletal disorders. However, no consensus has been reached on the effects of iVR on pain, psychological distress, and functional disability. Therefore, this study aims to investigate the effects of iVR on pain, psychological distress, and functional disability in patients with chronic musculoskeletal disorders compared with no rehabilitation and conventional rehabilitation. Methods: Five electronic databases (PubMed, Cochrane CENTRAL, Scopus, EMBASE, and Web of Science) were searched from January 2016 to December 2021. All randomized controlled trials using iVR for treating pain, psychological distress, and functional disability in patients with chronic musculoskeletal disorders were included. A subgroup analysis was conducted to compare the effects of nonimmersive and immersive types of iVR on the outcomes of interest. Results: Our study provides good quality evidence that iVR reduced overall pain by 9.28 points as compared with no rehabilitation and by 8.09 points as compared with conventional rehabilitation. In the subgroup analysis, nonimmersive iVR showed a reduction in psychological distress (standardized mean differences = -0.35) as compared with no rehabilitation. However, no statistically significant difference in the outcomes existed between nonimmersive and immersive iVR. Furthermore, there were no statistically significant differences in the outcomes of functional disability. Conclusions: iVR is recommended for reducing pain intensity more than no rehabilitation or conventional rehabilitation. Meanwhile, nonimmersive iVR has been proposed for psychological distress improvement, with effects similar to those of conventional rehabilitation. However, iVR may not be an effective intervention in the case of functional disability.

The effect of limited sensory information on exoskeleton performance in people with complete spinal cord injury

Despite the absence of somatosensory information from the lower extremities, people with complete spinal cord injury (SCI) can maintain postural stability in an exoskeleton. This is partly because humans are able to reweigh the relative dependence on each of the senses. However, when the sensory environment is changed, people with complete SCI are limited in their ability to reweigh their sensory organization towards more dependence on somatosensory information. The aim of this study was to investigate the effect of limited visual and/or auditory information on exoskeleton performance in people with complete SCI. Three experienced exoskeleton users performed twelve walking trials in the ReWalk exoskeleton. In each trial, the presence or absence of visual and/or auditory information was varied. Exoskeleton performance was operationalized as the walking distance covered and the amount of crutch loading. In one participant, the distance covered decreased when visual information was limited. The other two participants did not show substantial differences in distance covered between sensory conditions. Two participants decreased crutch loading when visual information was restricted, and one participant decreased crutch loading when auditory information was limited. The current study suggests a limited influence of the presence or absence of visual and auditory information on the distance covered in people with complete SCI walking in an exoskeleton. Interestingly, crutch loading seemed to decrease rather than increase when visual or auditory information was limited.

A novel optimization-based convolution neural network to estimate the contribution of sensory inputs to postural stability during quiet standing

Adequate postural control is maintained by integrating signals from the visual, somatosensory, and vestibular systems. The purpose of this study is to propose a novel convolutional neural network (CNN)-based protocol that can evaluate the contributions of each sensory input for postural stability (calculated a sensory analysis index) using center of pressure (COP) signals in a quiet standing posture. Raw COP signals in the anterior/posterior and medial/lateral directions were extracted from 330 patients in a quiet standing with their eyes open for 20 seconds. The COP signals augmented using jittering and pooling techniques were transformed into the frequency domain. The sensory analysis indices were used as the output information from the deep learning models. A ResNet-50 CNN was combined with the k-nearest neighbor, random forest, and support vector machine classifiers for the training model. Additionally, a novel optimization process was proposed to include an encoding design variable that can group outputs into sub-classes along with hyperparameters. The results of optimization considering only hyperparameters showed low performance, with an accuracy of 55% or less and F-1 scores of 54% or less in all models. However, when optimization was performed using the encoding design variable, the performance was markedly increased in the CNN-classifier combined models (r = 0.975). These results suggest it is possible to evaluate the contribution of sensory inputs for postural stability using COP signals during a quiet standing. This study will facilitate the expanded dissemination of a system that can quantitatively evaluate the balance ability and rehabilitation progress of patients with dizziness.

Clinical Efficacy and Safety of Anterior Cervical Decompression versus Segmental Fusion and Posterior Expansive Canal Plasty in the Treatment of Multilevel Cervical Spondylotic Myelopathy

Objective

To compare the clinical efficacy and safety of anterior cervical decompression and segmental fusion and posterior expansive canal plasty in the treatment of multisegment cervical myelopathy.

Methods

Retrospective analysis was performed of 56 cases of multisegment cervical myelopathy patients admitted from July 2018 to June 2021, 32 male patients and 24 females, aged 56.9 ± 12.8 years with an average duration of 10.6 ± 3.2 years. All patients' preoperative imaging examination revealed multiple-segmented cervical disc herniation and had clinical manifestations of cervical myelopathy.

Results

No neurovascular complications occurred in both groups, and 24 to 36 months of follow-up (mean 28.6 months) were obtained. The height of the cervical spondylosis segment was higher than that 2 weeks after surgery (p < 0.05), and the curvature of the cervical spine was significantly lower than that before surgery. There was no statistical significance in the height of the anterior column and curvature of the cervical vertebra at 2 weeks after surgery and at the last follow-up (p > 0.05). There were statistically significant differences in anterior curvature of the cervical spine between the two groups at 2 weeks after surgery and the last follow-up (p < 0.05). Japanese Orthopaedic Association (JOA) scores in both groups recovered significantly after surgery. At 3 months and the last follow-up, the improvement rate of JOA score in the anterior approach group was significantly higher than that in the posterior approach group (p < 0.05), and the improvement rate of JOA score in the anterior approach group was also better than that in the posterior approach group (p < 0.05).

Conclusion

This segmented anterior fusion procedure can effectively restore the anterior cervical column height and can significantly improve spinal cord function compared with posterior spinal canal enlargement plasty, thus could be considered an effective option for the treatment of multisegment cervical myelopathy.

Recovery of Supraspinal Microstructural Integrity and Connectivity in Patients Undergoing Surgery for Degenerative Cervical Myelopathy

BACKGROUND

It remains unknown if the progressive loss of axonal conduction along sensorimotor tracts can be recovered after surgery in patients with degenerative cervical myelopathy (DCM) and if subsequent adaptive microstructural changes are associated with the neurological improvement.

OBJECTIVE

To investigate the upstream recovery of microstructural integrity and reorganization of microstructural connectivity that occurs in patients with DCM after surgical decompression.

METHODS

Preoperative and postoperative cerebral diffusion tensor imaging and diffusion spectrum imaging data were collected for 22 patients with DCM (age = 56.9 ± 9.1 years). Paired t-tests were used to identify significant microstructural changes within cohorts, and correlation analysis was used to identify whether those changes are associated with neurological improvement.

RESULTS

Before surgery, higher structural connectivity (SC) was observed in the prefrontal/frontal lobes, anterior cingulate, the internal and external capsules, and the anterior, posterior, and superior regions of the corona radiata fibers. Following surgery, an increased modified Japanese Orthopaedic Association score was associated with increased SC from the primary sensorimotor regions to the posterior cingulate and precuneus; increased SC between the cerebellum and the bilateral lingual gyri; and decreased SC from areas of the limbic system to the basal ganglia and the frontal lobe. In addition, increased fractional anisotropy and normalized quantitative anisotropy values along white matter fibers responsible for conveying sensory information and motor coordination and planning were associated with neurological improvement of patients with DCM after surgery.

CONCLUSION

Recovery of microstructural integrity along the corticospinal tract and other sensorimotor pathways, together with supraspinal reorganization of microstructural connectivity within sensory and motor-related regions, was associated with neurological improvement after surgical decompression.

Degenerative cervical myelopathy delays responses to lateral balance perturbations regardless of predictability

The aim of this study was to quantify balance impairments in standing in people with degenerative cervical myelopathy (PwDCM) in response to external perturbations. PwDCM have damage to their spinal cord due to degeneration of the cervical vertebral column, but little is known about balance. Balance was quantified by capturing kinetics, kinematic, and electromyographic data during standing in response to lateral waist pulls. Participants received pulls during predictable and unpredictable contexts in three stance widths at two magnitudes. In response to lateral waist pulls, PwDCM had larger center of mass excursion (P < 0.001) and delayed gluteus medius electromyography onset (P < 0.001) and peak (P < 0.001) timing. These main effects of history of myelopathy were consistent across predictability, stance width, and magnitude. A multilinear regression determined that gluteus medius peak timing + tibialis anterior peak timing most strongly predicted center of mass excursion (R² = 0.50, P < 0.001). These data suggest that PwDCM have delays in generating voluntary and reactive motor commands, contributing to balance impairments. Future rehabilitation strategies should focus on generating rapid muscular contractions. Additionally, frontal plane postural control is regulated by the gluteus medius and the tibialis anterior, whereas other muscles (e.g. gluteus minimus, ankle invertors/evertors) not studied here may also contribute.NEW & NOTEWORTHY Frontal plane reactive postural control is impaired in persons with degenerative cervical myelopathy because of delayed muscle responses. Additionally, postural control varies across stance width, predictability, and perturbation magnitude.

Developing Peri-Operative Rehabilitation in Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 6]: An Unexplored Opportunity?

STUDY DESIGN

Narrative review.

OBJECTIVE

Degenerative cervical myelopathy is one of the most frequent impairments of the spinal cord encountered internationally in adults. Currently, surgical decompression is the recommended treatment for people with DCM (PwCM) presenting with moderate to severe symptoms or neurological deficits. However, despite surgical intervention, not all patients make a complete recovery due to the irreversible tissue damage within the spinal cord. The objective of this review is to describe the state and gaps in the current literature on rehabilitation for PwCM and possible innovative rehabilitation strategies.

METHODS

Literature search.

RESULTS

In other neurological disorders such as stroke and acute traumatic spinal cord injury (SCI), timely and strategic rehabilitation has been shown to be indispensable for maximizing functional outcomes, and it is imperative that appropriate perioperative rehabilitative interventions accompany surgical approaches in order to enable the best outcomes. In this review, the current state of knowledge regarding rehabilitation for PwCM is described. Additionally, various therapies that have shown to improve outcomes in comparable neurological conditions such as stroke and SCI which may be translated to DCM will be reviewed.

CONCLUSIONS

We conclude that locomotor training and arm/hand therapy may benefit PwCM. Further, we conclude that body weight support, robotic assistance, and virtual/augmented reality therapies may be beneficial therapeutic analogs to locomotor and hand therapies.

Activation of the Prefrontal Cortex and Improvement of Cognitive Performance with Standing on One Leg

The prefrontal cortex (PFC) is involved in attention, motor planning, and executive functions. In addition, it is known that postural control and cognitive performance are affected during dual-task paradigms, suggesting that postural control and cognition use common areas of the brain. Although postural control and cognition have been used as interfering dual tasks, the neuronal mechanisms underlying interference are not fully understood. We simultaneously performed postural and cognitive tasks in healthy young adults and evaluated activity in the PFC using near-infrared spectrometry. The displacement of the center of pressure (COP) is reduced by cognitive tasks. Difficult postural tasks increased the relative proportion and amplitude of postural sway in the high-frequency bandwidth, related to the adjustment of postural sway. Although the cognitive tasks did not affect the relative proportion of each frequency bandwidth, the amplitudes were selectively reduced. The postural task-dependent change in PFC activity was correlated with the relative proportion and amplitude of postural sway in the high-frequency bandwidth of the COP movement. Cognitive task-dependent changes in PFC activity were not correlated with postural sway. Cognitive performance was better in unipedal standing than bipedal standing. These findings suggest that postural tasks affect cognitive performance via the activation of the PFC, but cognitive tasks affect postural control through a different mechanism.

Phybrata Sensors and Machine Learning for Enhanced Neurophysiological Diagnosis and Treatment

Concussion injuries remain a significant public health challenge. A significant unmet clinical need remains for tools that allow related physiological impairments and longer-term health risks to be identified earlier, better quantified, and more easily monitored over time. We address this challenge by combining a head-mounted wearable inertial motion unit (IMU)-based physiological vibration acceleration (“phybrata”) sensor and several candidate machine learning (ML) models. The performance of this solution is assessed for both binary classification of concussion patients and multiclass predictions of specific concussion-related neurophysiological impairments. Results are compared with previously reported approaches to ML-based concussion diagnostics. Using phybrata data from a previously reported concussion study population, four different machine learning models (Support Vector Machine, Random Forest Classifier, Extreme Gradient Boost, and Convolutional Neural Network) are first investigated for binary classification of the test population as healthy vs. concussion (Use Case 1). Results are compared for two different data preprocessing pipelines, Time-Series Averaging (TSA) and Non-Time-Series Feature Extraction (NTS). Next, the three best-performing NTS models are compared in terms of their multiclass prediction performance for specific concussion-related impairments: vestibular, neurological, both (Use Case 2). For Use Case 1, the NTS model approach outperformed the TSA approach, with the two best algorithms achieving an F1 score of 0.94. For Use Case 2, the NTS Random Forest model achieved the best performance in the testing set, with an F1 score of 0.90, and identified a wider range of relevant phybrata signal features that contributed to impairment classification compared with manual feature inspection and statistical data analysis. The overall classification performance achieved in the present work exceeds previously reported approaches to ML-based concussion diagnostics using other data sources and ML models. This study also demonstrates the first combination of a wearable IMU-based sensor and ML model that enables both binary classification of concussion patients and multiclass predictions of specific concussion-related neurophysiological impairments.

Prospects of cell replacement therapy for the treatment of degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) presents insidiously during middle-age with deterioration in neurological function. It accounts for the most common cause of non-traumatic spinal cord injury in developed countries and disease prevalence is expected to rise with the aging population. Whilst surgery can prevent further deterioration, biological therapies may be required to restore neurological function in advanced disease. Cell replacement therapy has been inordinately focused on treatment of traumatic spinal cord injury yet holds immense promise in DCM. We build upon this thesis by reviewing the pathophysiology of DCM as revealed by cadaveric and molecular studies. Loss of oligodendrocytes and neurons occurs via apoptosis. The tissue microenvironment in DCM prior to end-stage disease is distinct from that following acute trauma, and in many ways more favourable to receiving exogenous cells. We highlight clinical considerations for cell replacement in DCM such as selection of cell type, timing and method of delivery, as well as biological treatment adjuncts. Critically, disease models often fail to mimic features of human pathology. We discuss directions for translational research towards clinical application.

Physiological Vibration Acceleration (Phybrata) Sensor Assessment of Multi-System Physiological Impairments and Sensory Reweighting Following Concussion

Objective

To assess the utility of a head-mounted wearable inertial motion unit (IMU)-based physiological vibration acceleration (“phybrata”) sensor to support the clinical diagnosis of concussion, classify and quantify specific concussion-induced physiological system impairments and sensory reweighting, and track individual patient recovery trajectories.

Methods

Data were analyzed from 175 patients over a 12-month period at three clinical sites. Comprehensive clinical concussion assessments were first completed for all patients, followed by testing with the phybrata sensor. Phybrata time series data and spatial scatter plots, eyes open (Eo) and eyes closed (Ec) phybrata powers, average power (Eo+Ec)/2, Ec/Eo phybrata power ratio, time-resolved phybrata spectral density (TRPSD) distributions, and receiver operating characteristic (ROC) curves are compared for individuals with no objective impairments and those clinically diagnosed with concussions and accompanying vestibular impairment, other neurological impairment, or both vestibular and neurological impairments. Finally, pre- and post-injury phybrata case report results are presented for a participant who was diagnosed with a concussion and subsequently monitored during treatment, rehabilitation, and return-to-activity clearance.

Results

Phybrata data demonstrate distinct features and patterns for individuals with no discernable clinical impairments, diagnosed vestibular pathology, and diagnosed neurological pathology. ROC curves indicate that the average power (Eo+Ec)/2 may be utilized to support clinical diagnosis of concussion, while Eo and Ec/Eo may be utilized as independent measures to confirm accompanying neurological and vestibular impairments, respectively. All 3 measures demonstrate area under the curve (AUC), sensitivity, and specificity above 90% for their respective diagnoses. Phybrata spectral analyses demonstrate utility for quantifying the severity of concussion-induced physiological impairments, sensory reweighting, and subsequent monitoring of improvements throughout treatment and rehabilitation.

Conclusion

Phybrata testing assists with objective concussion diagnosis and provides an important adjunct to standard concussion assessment tools by objectively ascertaining neurological and vestibular impairments, guiding targeted rehabilitation strategies, monitoring recovery, and assisting with return-to-sport/work/learn decision-making.

White Matter Microstructure of the Cerebellar Peduncles Is Associated with Balance Performance during Sensory Re-Weighting in People with Multiple Sclerosis

People with multiple sclerosis (PwMS) exhibit impaired balance during different sensory environments and poor cerebellar peduncle microstructure. We aimed to examine associations between microstructures of the superior, middle and inferior cerebellar peduncles (CP) with visual, vestibular, and proprioceptive-based balance in PwMS. Twenty-seven PwMS and twenty-nine healthy controls (HC) underwent MRI and balance assessments. We assessed CP microstructure with radial diffusivity (RD) and fractional anisotropy (FA) and balance with center of pressure-derived measures of path length and root mean square of sway during proprioceptive (C2), visual (C3), and vestibular (C4) balance conditions of the modified clinical test of sensory integration on balance (mCTSIB). PwMS exhibited significantly lower FA (p < 0.001) and greater RD (p < 0.001) across all CP and greater path length (p < 0.05) in the mCTSIB compared with HC. In PwMS, significant associations were detected between inferior CP white matter microstructure and proprioceptive-based balance control (rho = -0.43, p < 0.05) and middle CP white matter microstructure and visual-based balance control (rho = 0.39, p < 0.05). PwMS may rely more on cerebellar-regulated proprioceptive- and visual-based balance control than HC.

Upright Balance Control in Individuals with Cervical Myelopathy Following Cervical Decompression Surgery: A Prospective Cohort Study

Patients with cervical myelopathy may manifest impairments in functional activities and balance control caused by compression of the spinal cord. The objective of the current study was to determine long-term changes in the upright balance control of patients with cervical myelopathy who had undergone cervical decompression surgery. This is a prospective cohort study from the preoperative phase to 3 months, 6 months, and 1 year postsurgery. Fifty-three patients with cervical myelopathy were recruited for the cervical myelopathy group and 22 age-matched healthy controls were recruited for the control group. Functional assessments including Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire-Lower Extremity Function (JOACMEQ-LEF) and 10-second step test; as well as balance assessments including postural sway (center-of-pressure: COP) were performed for both groups. The JOACMEQ-LEF (p = 0.036) scores of the myelopathy group improved postoperatively, and a significant decrease in COP variables of postural sway was observed. The upright posture was less stable in the myelopathy group than in the control group (p < 0.05) both before and after surgery. The effect size and standard response mean of the COP variables ranged from −0.49 to 0.03 at 3 months, 6 months, and 1 year postsurgery. The upright balance control had improved significantly 6 months after decompression surgery. However, the balance control of the patients who had undergone decompression surgery remained less stable than that of the age-matched healthy controls. Balance training should be initiated before 6 months postsurgery to accelerate balance control recovery in patients with cervical myelopathy.

Clinical outcomes of epidural and intradural decompression for treatment of degenerative cervical myelopathy

Objective

This study was performed to examine the clinical outcomes of epidural and intradural decompression for degenerative cervical myelopathy.

Methods

The data for 13 patients who underwent epidural and intradural decompression for treatment of degenerative cervical myelopathy (study group) and 20 patients who underwent only cervical laminoplasty, fusion, and epidural decompression (historical control group) were retrospectively reviewed. The preoperative and postoperative neurological status was evaluated using the Japanese Orthopaedic Association (JOA) score.

Results

All patients’ neurological symptoms were significantly improved at the final follow-up. In the study group, the patients’ mean preoperative JOA score was 8.07 ± 1.80, and the final score improved by 70.88% ± 21.18%. The blood loss and operation time were significantly greater in the study group than control group. The recovery time was shorter in the study group than control group. The improvement rate was not significantly different between the two groups.

Conclusions

A pia mater incision with separation of the arachnoid adhesion can significantly improve the cerebrospinal fluid flow and spinal blood flow in degenerative cervical myelopathy. Arachnoid adhesion can lead to intradural spinal scar compression. The surgical intervention described herein can achieve satisfactory neurological outcomes and shorten the recovery time.

Association of Cervical Spondylosis With Peripheral Vertigo: A Case-Control Study

OBJECTIVES/HYPOTHESIS

This study aimed to assess the association of prior cervical spondylosis (CS) with peripheral vertigo.

STUDY DESIGN

Case-control study.

METHODS

Data were retrieved from the Taiwan Longitudinal Health Insurance Database. A total of 2,570 patients who were newly diagnosed with peripheral vertigo were identified. We compared them with a 3:1 ratio of propensity score-matched patients, 7,710 comparison patients from the same dataset. We performed multivariate logistic regressions to estimate the odds ratio for prior CS occurrence among peripheral vertigo patients versus controls.

RESULTS

Of 10,280 sample patients, 1,739 (16.92%) patients had CS prior to the index date. A significant difference in prior CS between peripheral vertigo patients and controls (19.49% vs. 16.06%, P < .001) was observed. Logistic regression analysis shows that the odds of prior CS was 1.285 for peripheral vertigo patients versus controls (95% confidence interval [CI]: 1.143-1.446) after adjusting for age, sex, urbanization level, monthly income, geographic region, hyperlipidemia, diabetes, coronary heart disease, hypertension, and asthma. Prior CS with myelopathy was not associated with peripheral vertigo. Stratified analysis by age showed that the odds of CS were highest among patients with peripheral vertigo in the 45- to 64-year-old age group (1.442, 95% CI: 1.215-1.712).

CONCLUSIONS

CS is associated with subsequent peripheral vertigo in the Taiwan population, with higher risk among those aged 45 to 64 years.

LEVEL OF EVIDENCE

2b Laryngoscope, 131:E625-E630, 2021.

Fatigue changes neck muscle control and deteriorates postural stability during arm movement perturbations in patients with chronic neck pain

BACKGROUND CONTEXT

Multisensory afferent inputs to the cervical spine affect the generation of neck muscle control. Chronic neck pain (CNP) and muscle fatigue are factors that disturb somatosensory function. Whether they affect postural control under self-initiated perturbation in daily activities is still unclear.

PURPOSE

To investigate the effect of CNP and neck flexor muscle fatigue on muscle control strategy and postural control in young patients performing voluntary shoulder flexion movements.

STUDY DESIGN

Cross-sectional case-control study.

PATIENT SAMPLE

Twenty-five patients with CNP and 25 age-matched asymptomatic controls.

OUTCOME MEASURES

The postural sway, muscle onset time, and activation level of the erector spinae, rectus abdominal, semispinalis capitis (SSC), and sternocleidomastoid (SCM) muscles were recorded and analyzed using two-way ANOVA to evaluate the interaction of CNP and muscle fatigue on standing balance and muscle control upon self-initiated perturbations.

METHODS

All participants were instructed to perform shoulder flexion movements in the standing position before and after a neck flexor muscle fatigue exercise under either the eyes-open or eyes-closed condition.

RESULTS

The CNP group exhibited significantly larger body sway, greater neck muscle activation (SCM and SSC), and longer onset time of neck flexor muscle (SCM) compared with the control group. The CNP group also demonstrated a trend of greater postural sway and shorter muscle onset under the eyes-closed condition than those under the eyes-open condition. After muscle fatigue, the CNP group further exhibited (1) greater body sway during the eyes-open condition but decreased body sway during the eyes-closed condition, (2) higher activation of the neck flexor (SCM) and lower activation of the trunk extensor (erector spinae), and (3) early onset of the neck muscles (SCM and SSC).

CONCLUSIONS

CNP causes poor postural control and altered neck muscle control patterns. The addition of neck flexor muscle fatigue further decreases balance stability and provokes a protective neck muscle control strategy during the shoulder flexion movement. Those findings facilitate the understanding of the strategies adopted by patients and suggest that neck endurance training programs may be beneficial to improve whole postural control in patients with CNP.

Perturbation-Based Balance Training in Postoperative Individuals With Degenerative Cervical Myelopathy

Degenerative cervical myelopathy (DCM) is a common aging condition caused by spinal cord compression. Individuals with DCM often presented with residual balance and functional impairments postoperatively. Perturbation-based balance training (PBT) has been shown to have positive effects on populations with neurological disorders but has yet to be investigated in DCM. The objective of this study was therefore to evaluate the effects of PBT on balance and functional performance in postoperative individuals with DCM. Fifteen postoperative individuals with DCM (DCM group) and 14 healthy adults (healthy control group) were recruited. The DCM group received a 4-weeks PBT using a perturbation treadmill. The outcome measures included mean velocity of center of pressure (COP) during quiet standing; center of mass (COM) variance and reaction time to balance perturbation during standing with forward and backward perturbation; gait speed during level ground walking; Timed Up and Go Test (TUG) and disability questionnaire scores including Visual Analog Scale, Neck Disability Index, and Lower Extremity Function of Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire. The assessments were conducted pre- and post-training postoperatively for the DCM group but only once for the healthy control group. Significant improvements were observed in the mean velocity of COP, COM variance, reaction time, gait speed, and TUG in the DCM group. Disability questionnaire scores were not significantly different after training in DCM group. For between-group comparisons, significant differences that were observed pre-training were not observed post-training. The 4-weeks PBT is a potential rehabilitation strategy for addressing balance and functional impairment in postoperative individuals with DCM. In addition, the post-training performance in the DCM group exhibited trends comparable to those of age-matched healthy controls. Furthermore, the training regimens offer a practical reference for future studies on populations with balance disorders. Future studies complemented with neurophysiological assessments could reveal more information of the underlying mechanisms of PBT.