Trunk Motor Research Articles

Effects of Robotic Postural Stand Training with Epidural Stimulation on Sitting Postural Control in Individuals with Spinal Cord Injury: A Pilot Study.

(1) Background. High-level spinal cord injury (SCI) disrupts trunk control, leading to an impaired performance of upright postural tasks in sitting and standing. We previously showed that a novel robotic postural stand training with spinal cord epidural stimulation targeted at facilitating standing (Stand-scES) largely improved standing trunk control in individuals with high-level motor complete SCI. Here, we aimed at assessing the effects of robotic postural stand training with Stand-scES on sitting postural control in the same population. (2) Methods. Individuals with cervical (n = 5) or high-thoracic (n = 1) motor complete SCI underwent approximately 80 sessions (1 h/day; 5 days/week) of robotic postural stand training with Stand-scES, which was performed with free hands (i.e., without using handlebars) and included periods of standing with steady trunk control, self-initiated trunk and arm movements, and trunk perturbations. Sitting postural control was assessed on a standard therapy mat, with and without scES targeted at facilitating sitting (Sit-scES), before and after robotic postural stand training. Independent sit time and trunk center of mass (CM) displacement were assessed during a 5 min time window to evaluate steady sitting control. Self-initiated antero-posterior and medial-lateral trunk movements were also attempted from a sitting position, with the goal of covering the largest distance in the respective cardinal directions. Finally, the four Neuromuscular Recovery Scale items focused on sitting trunk control (Sit, Sit-up, Trunk extension in sitting, Reverse sit-up) were assessed. (3) Results. In summary, neither statistically significant differences nor large Effect Size were promoted by robotic postural stand training for the sitting outcomes considered for analysis. (4) Conclusions. The findings of the present study, together with previous observations, may suggest that robotic postural stand training with Stand-scES promoted trunk motor learning that was posture- and/or task-specific and, by itself, was not sufficient to significantly impact sitting postural control.

Categorizing knee hyperextension patterns in hemiparetic gait and examining associated impairments in patients with chronic stroke

BackgroundPost-stroke hemiparetic gait exhibits considerable variations in motion patterns and abnormal muscle activities, notably knee hyperextension during the stance phase. Existing studies have primarily concentrated on its joint angle or moment. However, the underlying causes remain unclear. Thus, the causes of knee hyperextension were explored from a new perspective based on temporal-durational factors. Research QuestionDoes the temporal-durational difference of knee hyperextension presence result from specific decreased motor functions? MethodsBarefoot gait at a comfortable speed was captured using a three-dimensional camera system. Scores of knee hyperextension used a metric with the temporal-durational factor of knee hyperextension presence in each of four stance phases (1st double support, DS1; early single-leg stance, ESS; late single-leg stance, LSS; 2nd double support, DS2). These scores were used in cluster analysis. The classification and regression tree analysis characterizing each knee hyperextension cluster used the clinical measures of the lower limb and trunk motor function, muscle strength, and spasticity as explanatory variables. ResultsThirty patients with hemiparetic chronic stroke who exhibited knee hyperextension during gait were included. Four knee hyperextension clusters were shown: Momentary (almost no hyperextension), Continuous (DS1–DS2), ESS–LSS, and ESS–DS2. Knee flexor strength was lower in the groups with long hyperextension durations (Continuous and ESS–DS2) compared with short durations (ESS–LSS and Momentary). ESS–DS2 exhibited higher trunk motor function than Continuous, whereas more severe spasticity was observed in ESS–LSS than in Momentary. SignificanceThis study successfully classified four hemiparetic gait patterns with knee hyperextension based on the temporal-durational factor, providing valuable perspectives for understanding and addressing specific functional physical impairments. These findings offer guidance for focusing on related physical functions when striving for gait improvement with knee hyperextension and are expected to serve as a reference for treatment decision-making.

Differences in the organization of the primary motor cortex in people with and without low back pain and associations with motor control and sensory tests

Differences in organization of the primary motor cortex and altered trunk motor control (sensing, processing and motor output) have been reported in people with low back pain (LBP). Little is known to what extent these differences are related. We investigated differences in 1) organization of the primary motor cortex and 2) motor and sensory tests between people with and without LBP, and 3) investigated associations between the organization of the primary motor cortex and motor and sensory tests. We conducted a case-control study in people with (N=25) and without (N=25) LBP. The organization of the primary motor cortex (Center of Gravity (CoG) and Area of the cortical representation of trunk muscles) was assessed using neuronavigated transcranial magnetic stimulation, based on individual MRIs. Sensory tests (quantitative sensory testing, graphaesthesia, two-point discrimination threshold) and a motor test (spiral-tracking test) were assessed. Participants with LBP had a more lateral and lower location of the CoG and a higher temporal summation of pain. For all participants combined, better vibration test scores were associated with a more anterior, lateral, and lower CoG and a better two-point discrimination threshold was associated with a lower CoG. A small subset of variables showed significance. Although this aligns with the concept of altered organization of the primary motor cortex in LBP, there is no strong evidence of the association between altered organization of the primary motor cortex and motor and sensory test performance in LBP. Focusing on subgroup analyses regarding pain duration can be a topic for future research.

Trends and insights review. Nerve procedures in the management of upper limb spasticity.

This article reviews the recent advances or nerve-oriented surgical procedures in the treatment of the spastic upper limb. The idea to intervene on the nerve is not recent, but new trends have developed in nerve surgery over the past few years, stimulating experiments and research. Specific surgical procedures involving the nerves have been described at different levels from proximal to distal: at the cervical spinal cord and the dorsal root entry zone (rhizotomy), at the level of the roots (contralateral C7 transfer) or in the peripheral nerve, within the motor trunk (selective neurectomy) or as its branches penetrate the muscles (hyperselective neurectomy). All of these neurosurgical procedures are only effective on spasticity but do not address the other deformities, such as contractures and motor deficit. Additional procedures may have to be planned in conjunction with nerve procedures to optimize outcomes.

Increased velocity feedback gains in the presence of sensory noise can explain paradoxical changes in trunk motor control related to back pain

Literature reports paradoxical findings regarding effects of low-back pain (LBP) on trunk motor control. Compared to healthy individuals, patients with LBP, especially those with high pain-related anxiety, showed stronger trunk extensor reflexes and more resistance against perturbations. On the other hand, LBP patients and especially those with high pain-related anxiety showed decreased precision in unperturbed trunk movement and posture. These paradoxical effects might be explained by arousal potentially increasing average and variance of muscle spindle firing rates. Increased average firing rates could increase resistance against perturbations, but increased variance could decrease precision. We performed a simulation study to test this hypothesis.We modeled the trunk as a 2D inverted pendulum, stabilized by two antagonistic Hill-type muscles, based on their open-loop muscle activation dependent intrinsic stiffness and damping and through 25 ms-delayed, noisy contractile element length and velocity feedback. Reference feedback gains and sensory noise levels were tuned based on previously reported experimental data. We assessed the effect of increasing feedback gains on precision of trunk orientation at different perturbation magnitudes and assessed sensitivity of the effects to open-loop muscle stimulation and noise levels.At low perturbation magnitudes, increasing reflex gains consistently caused an increase in the variance of trunk orientation. At larger perturbation magnitudes, increasing reflex gains consistently caused a decrease in the variance of trunk orientation.Our results support the notion that LBP and related anxiety may increase reflex gains, resulting in an increase in the average and variance of spindle afference, which in turn increase resistance against perturbations and decrease movement precision.

Premotor cortex is hypoactive during sustained vowel production in individuals with Parkinson's disease and hypophonia.

Hypophonia is a common feature of Parkinson's disease (PD); however, the contribution of motor cortical activity to reduced phonatory scaling in PD is still not clear. In this study, we employed a sustained vowel production task during functional magnetic resonance imaging to compare brain activity between individuals with PD and hypophonia and an older healthy control (OHC) group. When comparing vowel production versus rest, the PD group showed fewer regions with significant BOLD activity compared to OHCs. Within the motor cortices, both OHC and PD groups showed bilateral activation of the laryngeal/phonatory area (LPA) of the primary motor cortex as well as activation of the supplementary motor area. The OHC group also recruited additional activity in the bilateral trunk motor area and right dorsal premotor cortex (PMd). A voxel-wise comparison of PD and HC groups showed that activity in right PMd was significantly lower in the PD group compared to OHC (p < 0.001, uncorrected). Right PMd activity was positively correlated with maximum phonation time in the PD group and negatively correlated with perceptual severity ratings of loudness and pitch. Our findings suggest that hypoactivation of PMd may be associated with abnormal phonatory control in PD.

Spinal Cord Epidural Stimulation Improves Lower Spine Sitting Posture Following Severe Cervical Spinal Cord Injury.

Cervical spinal cord injury (SCI) leads to impaired trunk motor control, negatively impacting the performance of activities of daily living in the affected individuals. Improved trunk control with better sitting posture has been previously observed due to neuromuscular electrical stimulation and transcutaneous spinal stimulation, while improved postural stability has been observed with spinal cord epidural stimulation (scES). Hence, we studied how trunk-specific scES impacts sitting independence and posture. Fourteen individuals with chronic, severe cervical SCI with an implanted neurostimulator performed a 5-min tall-sit task without and with trunk-specific scES. Spine posture was assessed by placing markers on five spine levels and evaluating vertical spine inclination angles. Duration of trunk manual assistance was used to assess independence along with the number of independence changes and average independence score across those changes. With scES, the sacrum-L1 inclination and number of independence changes tended to decrease by 1.64 ± 3.16° (p = 0.07; Cohen's d = 0.53) and 9.86 ± 16.8 (p = 0.047; Cohen's d = 0.59), respectively. Additionally, for the participants who had poor sitting independence without scES, level of independence tended to increase by 12.91% [0%, 31.52%] (p = 0.38; Cohen's d = 0.96) when scES was present. Hence, trunk-specific scES promoted improvements in lower spine posture and lower levels of trunk assistance.

Why do children with unilateral cerebral palsy struggle with the single leg stance test? A kinematic and centre of pressure analysis

BackgroundChildren with unilateral cerebral palsy often report difficulty with balance in everyday life. The single leg stance test is a challenging task, requiring rapid sensory input and precise motor adjustment. The purpose of this study was to examine how children with cerebral palsy perform this test, compared to typically developing children. MethodsThree-dimensional kinematics of the trunk and lower limbs of 10 children with cerebral palsy and 15 children with typical development were captured as they performed a single leg stance test on their non-dominant leg on a force platform. Stance time, joint kinematics and centre of pressure sway were measured and examined. FindingsThere was evidence of shorter single leg stance performance and increased mediolateral centre of pressure sway in children with cerebral palsy. Coronal plane movement at the subtalar joint and foot was reduced (−6.0° (−10.9, −1.2°)), while proximally there was greater trunk movement in the coronal (13.5° (2.4°, 24.5°)) and transverse planes (9.9° (0.7, 19°)) and pelvis movement in the transverse plane (6.1° (1.7, 10.5°). An association existed between stance time and mediolateral centre of pressure sway (p < 0.01), with an average reduction in stance time of 0.15 s for every 1 mm/s increase in mediolateral sway. InterpretationChildren with cerebral palsy showed poor mediolateral control of centre of pressure sway, leading to shorter stance time. They have a less effective coronal foot-tilt strategy and excessive trunk and pelvis movement. Interventions aimed at improving single leg stance performance should consider addressing both ankle / foot and trunk motor control.

A comparison of elbow and wrist kinematics and kinetics during swing-through versus reciprocal gait with crutches in persons with incomplete spinal cord injury.

Descriptive study with cross-sectional data collection. To analyse and compare the 3D kinematics and kinetics of thorax, elbow and wrist, and the spatio-temporal parameters during swing-through gait (SG) and reciprocal gait (RG). Hospital Nacional de Parapléjicos in Toledo, Spain. An instrumented biomechanical analysis of the upper body of 15 adults with an incomplete lumbar or thoracic spinal cord injury was performed using a marker motion capture system and load cell crutches. Five walks of each gait pattern were analysed. The elbow was in flexion, valgus and pronation and the wrist was in extension and ulnar deviation in both SG and RG. Their kinematic patterns were quite similar, except in elbow valgus and wrist extension in which statistically significant differences were observed. In the thorax prevailed flexion movement in SG and rotation movement in RG. The reaction forces in the elbow and the wrist were notably higher in SG than in RG, but the joint moments were similar in both gait patterns. SG showed greater demands and RG showed higher requirements on trunk motor control. In addition, SG could increase the probability of back and neck pain. Therefore RG should be recommended, whenever possible, in incomplete spinal cord injured people. Rehabilitative management should consider adapting properly the crutch height and the inclination cane, loading the minimum weight on the crutches, using cushioning devices, reducing the duration of support phase, and limiting the overall use time of the crutches.

Comparative effects of kinect-based versus therapist-based constraint-induced movement therapy on motor control and daily motor function in children with unilateral cerebral palsy: a randomized control trial

BackgroundConstraint-induced movement therapy (CIMT) is a prominent neurorehabilitation approach for improving affected upper extremity motor function in children with unilateral cerebral palsy (UCP). However, the restraint of the less-affected upper extremity and intensive training protocol during CIMT may decrease children’s motivation and increase the therapist’s workload and family’s burden. A kinect-based CIMT program, aiming to mitigate the concerns of CIMT, has been developed. The preliminary results demonstrated that this program was child-friendly and feasible for improving upper extremity motor function. However, whether the kinect-based CIMT can achieve better or at least comparable effects to that of traditional CIMT (i.e., therapist-based CIMT) should be further investigated. Therefore, this study aimed to compare the effects of kinect-based CIMT with that of therapist-based CIMT on upper extremity and trunk motor control and on daily motor function in children with UCP.MethodsTwenty-nine children with UCP were recruited and randomly allocated to kinect-based CIMT (n = 14) or therapist-based CIMT (n = 15). The intervention dosage was 2.25 h a day, 2 days a week for 8 weeks. Outcome measures, namely upper extremity and trunk motor control and daily motor function, were evaluated before and after 36-h interventions. Upper extremity and trunk motor control were assessed with unimanual reach-to-grasp kinematics, and daily motor function was evaluated with the Revised Pediatric Motor Activity Log. Between-group comparisons of effectiveness on all outcome measures were analyzed by analysis of covariance (α = 0.05).ResultsThe two groups demonstrated similar improvements in upper extremity motor control and daily motor function. In addition, the kinect-based CIMT group demonstrated greater improvements in trunk motor control than the therapist-based CIMT group did (F(1,28) > 4.862, p < 0.036).ConclusionKinect-based CIMT has effects comparable to that of therapist-based CIMT on UE motor control and daily motor function. Moreover, kinect-based CIMT helps decrease trunk compensation during reaching in children with UCP. Therefore, kinect-based CIMT can be used as an alternative approach to therapist-based CIMT.Trial registration: ClinicalTrials.gov Identifier: NCT02808195. Registered on 2016/06/21, https://clinicaltrials.gov/ct2/show/NCT02808195.

Variability of trunk muscle synergies underlying the multidirectional movements and stability trunk motor tasks in healthy individuals

Muscle synergy analysis is useful for investigating trunk coordination patterns based on the assumption that the central nervous system reduces the dimensionality of muscle activation to simplify movement. This study aimed to quantify the variability in trunk muscle synergy during various trunk motor tasks in healthy participants to provide reference data for evaluating trunk control strategies in patients and athletes. Sixteen healthy individuals performed 11 trunk movement and stability tasks with electromyography (EMG) recording of their spinal and abdominal muscles (6 bilaterally). Non-negative matrix factorization applied to the concatenated EMG of all tasks identified the five trunk muscle synergies (W) with their corresponding temporal patterns (C). The medians of within-cluster similarity defined by scalar products in W and rmax coefficient using the cross-correlation function in C were 0.73–0.86 and 0.64–0.75, respectively, while the inter-session similarities were 0.81–0.96 and 0.74–0.84, respectively. However, the lowest and highest values of both similarity indices were broad, reflecting the musculoskeletal system’s redundancy within and between participants. Furthermore, the significant differences in the degree of variability between the trunk synergies may represent the different neural features of synergy organization and strategies to overcome the various mechanical demands of a motor task.

Motor Control Changes in Trunk Muscles after Using Anatomical Posture Control Orthosis in the Elderly Hyperkyphotic Subjects

Introduction: Hyperkyphosis is known to interfere with the normal function of the trunk musculature in the elderly. Although the effectiveness of orthoses in improving posture and balance in hyperkyphotic elderly people has received much attention, the effect of an orthosis on motor control of muscles remains unknown. This study aimed to evaluate changes in motor control strategies of trunk muscles during walking in elderly hyperkyphotic subjects after using an anatomical posture control (APC) orthosis.&#x0D; Materials and Methods: A total of 19 elderlies (11 women and 8 men) with thoracic hyperkyphosis of more than 45 degrees were enrolled in the study. Surface electromyography (EMG) signals were recorded from 6 trunk muscles bilaterally with and without orthosis. The voluntary response index (VRI) was calculated from quantitative analysis of surface electromyography (sEMG) data during level walking in those with and without orthosis. The outcome variables of VRI included the similarity index (SI) and electromyographic magnitude (MAG) of muscle groups. The effects of APC orthosis on trunk motor control were tested using a Wilcoxon non-parametric test. Cohen’s d effect sizes were also calculated.&#x0D; Results: A significant improvement was observed (P&lt;0.05) in MAG and response vector (RV) of five muscles from the right and left sides and the VRI increased significantly after using this posture control orthosis (P&lt;0.05; effect size [ES]: 0.27).&#x0D; Conclusion: Improving trunk motor control after using orthosis, with relatively medium effect sizes, was observed in the elderly with hyperkyphosis during walking.&#x0D;

Central Pattern Generators for Breathing and Gait and Possible Medical Application of Oriental BodyWork: Access to Extrapyramidal and Body Trunk Movement System Through Breathing Methods

The neurophysiological background of oriental bodywork based on breathing methods is poorly understood. Recently, experimental techniques using genetically engineered animals have been applied to identify and analyze the functions of motor columns such as medial motor column (MMC), known as evolutionarily old locomotion central pattern generators (CPGs) in lamprey. In oriental bodywork between two individuals, locomotion-related body reactions are often observed. In Nishino Breathing Methods (NBM), the extrapyramidal system is likely to be accessed through the practice of Sokushin-kokyu (whole body awareness with breathing), Karin (body axis rotation and reactivation with breathing), and Taiki (body trunk mutual signaling with breathing; the coordination of two individual body trunks). In addition, kinesiological discussions of ancient oriental traditions, such as the practice of mysterious hand-back contact and the active expiration that relates to music and body trunk reaction, are presented. Based on the hypothesis that oriental bodywork is accessing the extrapyramidal body trunk motor system (basal ganglia to spiral locomotion CPGs), this paper discusses the inter-individual body reactions coexisting through different evolutionary levels in multilayered motor systems, and their possible medical applications.

Clinical Motor Coordination Tests in Adult Neurology: A Scoping Review.

Purpose: This scoping review aimed to identify which clinical tests are used to assess upper limb, lower limb, and trunk motor coordination, and their metric and measurement properties for adult neurological populations. Method: MEDLINE (1946-) and EMBASE (1996-) databases were searched using keywords such as movement quality, motor performance, motor coordination, assessment, and psychometrics. Data regarding the body part assessed, neurological condition, psychometric properties, and scored metrics of spatial and/or temporal coordination were independently extracted by two reviewers. Alternate versions of some tests such as the Finger-to-Nose Test were included. Results: Fifty-one included articles yielded 2 tests measuring spatial coordination, 7 tests measuring temporal coordination, and 10 tests measuring both. Scoring metrics and measurement properties differed between tests, with a majority of tests having good-to-excellent measurement properties. Conclusions: The metrics of motor coordination scored by current tests vary. Since tests do not assess functional task performance, the onus falls on clinicians to infer the connection between coordination impairments and functional deficits. Clinical practice would benefit from the development of a battery of tests that assesses the metrics of coordination related to functional performance.

Quantification of the development of trunk control in healthy infants using inertial measurement units.

Trunk motor control is essential for the proper functioning of the upper extremities and is an important predictor of gait capacity in children with delayed development. Early diagnosis and intervention could increase the trunk motor capabilities in later life, but current tools used to assess the level of trunk motor control are largely subjective and many lack the sensitivity to accurately monitor development and the effects of therapy. Inertial measurement units could yield an objective quantitative assessment that is inexpensive and easy-to-implement. We hypothesized that root mean square of jerk, a proxy for movement smoothness, could be used to distinguish age and thereby presumed motor development. We attached a sensor to the trunks of six young children with no known developmental deficits. Root mean square of jerk decreases with age, up to 24 months, and is correlated to a more established method, i.e., center-of-pressure velocity, as well as other standard inertial measurement unit outputs. This metric therefore shows potential as a method to differentiate trunk motor control levels.

Somatotopic Organization of Hyperdirect Pathway Projections From the Primary Motor Cortex in the Human Brain.

BackgroundThe subthalamic nucleus (STN) is an effective neurosurgical target to improve motor symptoms in Parkinson's Disease (PD) patients. MR-guided Focused Ultrasound (MRgFUS) subthalamotomy is being explored as a therapeutic alternative to Deep Brain Stimulation (DBS) of the STN. The hyperdirect pathway provides a direct connection between the cortex and the STN and is likely to play a key role in the therapeutic effects of MRgFUS intervention in PD patients.ObjectiveThis study aims to investigate the topography and somatotopy of hyperdirect pathway projections from the primary motor cortex (M1).MethodsWe used advanced multi-fiber tractography and high-resolution diffusion MRI data acquired on five subjects of the Human Connectome Project (HCP) to reconstruct hyperdirect pathway projections from M1. Two neuroanatomy experts reviewed the anatomical accuracy of the tracts. We extracted the fascicles arising from the trunk, arm, hand, face and tongue area from the reconstructed pathways. We assessed the variability among subjects based on the fractional anisotropy (FA) and mean diffusivity (MD) of the fibers. We evaluated the spatial arrangement of the different fascicles using the Dice Similarity Coefficient (DSC) of spatial overlap and the centroids of the bundles.ResultsWe successfully reconstructed hyperdirect pathway projections from M1 in all five subjects. The tracts were in agreement with the expected anatomy. We identified hyperdirect pathway fascicles projecting from the trunk, arm, hand, face and tongue area in all subjects. Tract-derived measurements showed low variability among subjects, and similar distributions of FA and MD values among the fascicles projecting from different M1 areas. We found an anterolateral somatotopic arrangement of the fascicles in the corona radiata, and an average overlap of 0.63 in the internal capsule and 0.65 in the zona incerta.ConclusionMulti-fiber tractography combined with high-resolution diffusion MRI data enables the identification of the somatotopic organization of the hyperdirect pathway. Our preliminary results suggest that the subdivisions of the hyperdirect pathway projecting from the trunk, arm, hand, face, and tongue motor area are intermixed at the level of the zona incerta and posterior limb of the internal capsule, with a predominantly overlapping topographical organization in both regions. Subject-specific knowledge of the hyperdirect pathway somatotopy could help optimize target definition in MRgFUS intervention.

Q&amp;A: Rating Brachial Plexus Injury

QUESTION: How do I assess impairment for a patient with a brachial plexus injury involving the middle and lower trunks but not the upper trunk?ANSWER: Rating impairment for a brachial plexus injury using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, is straightforward. Table 15-20, Brachial Plexus Impairment: Upper Extremity Impairments (6th ed, 434-435), lists impairments for the entire brachial plexus, as well as upper, middle, and lower trunks individually, each in different rows. If both middle and lower trunks were injured, each would be rated, and the upper limb impairments combined per instructions number 8 and 13 on page 481.The classic anatomic description of the brachial plexus describes the C5 through T1 nerve roots as contributing to the plexus, with the middle trunk composed of just the C7 nerve root, while the lower trunk is formed by the fusion of the C8 and T1 nerve roots. However, this “classic plexus” is found in only 37% to 77% of cadaver dissections.1 The two most common anatomic anomalies are “prefixed” and “postfixed” plexi. In a prefixed plexus, the C4 nerve root has a substantial contribution, while the T1 nerve root has minimal or no contribution to the plexus. In a postfixed plexus, there is minimal or no C5 contribution to the plexus and a substantial T2 nerve root contribution. Thus, standard charts of the nerve root contributing to individual peripheral nerves or trunks of the plexus may not correspond to an individual patient's anatomy.Assuming C7 supplies sensation to the middle finger and C8 and T1 to the little finger and ulnar forearm, rating sensory deficit without obvious duplication is more straightforward.Rating the motor deficit is more complex. No nerve to a single muscle leaves either the middle or lower trunk of the classic plexus. Hence, one cannot determine whether the injury does or does not involve the trunk by involvement or sparing that nerve, respectively. Normal paraspinal muscles on needle electromyography (EMG) with clear denervation in limb muscles helps localize the lesion as distal to the nerve root division into anterior and posterior primary rami. Stimulating proximal to the plexus at the level of individual nerve root during nerve conduction testing is challenging and rarely done. Magnetic resonance imaging (MRI) may not clarify the level of injury. However, in cases of open trauma with immediate surgery to repair vascular damage, the operative report may accurately describe the extent of any concomitant brachial plexus injury.Because most muscles are innervated by more than one nerve root—a fail-safe redundancy in the case of injury—residual weakness in any one muscle may be from injury to the lower trunk, middle trunk, or both. Hence, it is wise to rate the severity of the motor loss on physical examination by assuming any one muscle is innervated by nerves derived from only one trunk.For example, the triceps is classically described as innervated by the C7, C8, and partially by the T1 nerve roots. If the triceps has grade 3/5 weakness on examination, and if that is considered middle trunk weakness when rating the middle trunk, and lower trunk weakness when rating the lower trunk, the motor deficit rating will be duplicative (rating the same weakness twice).Similarly, classic innervation charts show C7 and C8 contributing to the flexor carpi ulnaris, flexor digitorum profundus, abductor digiti minimi, first dorsal interosseous, extensor digitorum communis, and extensor carpi ulnaris. Logically weakness in these muscles should be attributed to and rated as either middle or lower trunk motor deficits, but not both.Brachial plexus injuries are uncommon, and it takes considerable time and thought to thoroughly examine and correctly rate the residuals.

Task-specific fear influences abnormal trunk motor coordination in workers with chronic low back pain: a relative phase angle analysis of object-lifting

BackgroundPain-related fear influences impaired trunk movement (e.g., limited movement of range and velocity), but it is unclear how fear relates to trunk motor coordination (e.g., a more “in-phase” upper-lower trunk motion pattern). We conducted the present study to: (1) identify the motor coordination pattern of the in-phase upper-lower lumbar movements during the lifting, and (2) determine how pain-related fear is related to the trunk coordination pattern in workers with chronic low back pain (CLBP).MethodsWe examined 31 male workers with CLBP (CLBP group) and 20 healthy controls with no history of CLBP (HC group). The movement task was lifting a box, the weight of which was 10, 30%, or 50% of the subject’s body weight. We used a 3D motion capture system to calculate the mean absolute relative phase angle (MARP) angle as an index of coordination and the mean deviation phase (DP) as an index of variability. We used a numerical rating scale to assess the subjects’ task-specific fear.ResultsThe MARP angle during trunk extension movement in the 50% condition was significantly decreased in the CLBP group compared to the HCs; i.e., the upper lumbar movement was more in-phase with the lower lumbar movement. The hierarchical multiple regression analysis results demonstrated that a decreased MARP angle was associated with high task-specific fear.ConclusionsA more ‘in-phase’ upper-lower lumbar movement pattern was predicted by task-specific fear evoked when performing a work-related activity. Our findings suggest that an intervention for task-specific fear may be necessary to improve an individual’s impaired trunk motor coordination.

Is Swiss-ball-based exercise superior to plinth-based exercise in improving trunk motor control and balance in subjects with sub-acute stroke? A pilot randomized control trial

IntroductionStroke is the most common cause of neurological dysfunction, associated with high mortality and morbidity. Early stroke rehabilitation is essential for optional functional recovery, particularly motor control of the trunk muscles and balance. The study investigated the effects of Swiss-ball-based and plinth-based trunk exercises for improving trunk control and functional balance in subjects with sub-acute stroke.MethodsOverall, 20 sub-acute stroke patients aged 40–60 years were recruited and divided into the experimental group (Swiss ball exercise) and the control group (plinth exercise). Upper and lower trunk exercises were performed by the patients sitting on a Swiss ball or a plinth. The 45-minute sessions were applied for 5 days a week for a total of 4 weeks. Trunk Impairment Scale, Modified Functional Reach Test, and Functional Balance Scale evaluations were performed at baseline and at the end of the 4 weeks.ResultsThe differences between the baseline characteristics of participants in both groups were not significant. After the intervention, there were significant (&lt;i&gt;p&lt;/i&gt; &gt; 0.01) changes in the Trunk Impairment Scale total, static, dynamic, and coordination scores, mental status, Modified Functional Reach Test results, and functional balance scores, with high effect sizes in the Swiss ball exercise group.ConclusionsIn patients with sub-acute stroke, trunk exercises performed on a Swiss ball were found to be more effective than those performed on a plinth to improve trunk control, forward and lateral reach, and functional balance.

Changes in task-specific fear of movement and impaired trunk motor control by pain neuroscience education and exercise: A preliminary single-case study of a worker with low back pain

We report a case (a worker with low back pain) who was provided patient education and therapeutic exercise, and we performed a detailed kinematic analysis of his work-related activity over time. The subjects were one 28-year-old male worker with low back pain. In addition, to clearly identify impaired trunk movement during work-related activity in the low back pain subject, 20 age-matched healthy males (control group) were also included as a comparison subject. He received pain neurophysiology education and exercise instruction. We analyzed the subject’s trunk movement pattern during a lifting task examined by a three-dimensional–motion capture system. In addition, task-specific fear that occurred during the task was assessed by the numerical rating scale. The assessment was performed at the baseline phase (4 data points), the intervention phase (8 data points), and the follow-up phase (8 data points), and finally at 3 and 8 months after the follow-up phase. No intervention was performed in the control group; they underwent only one kinematic evaluation at baseline. As a result, compared to the control group, the low back pain subject had slower trunk movement velocity (peak trunk flexion velocity = 50.21 deg/s, extension velocity = −47.61 deg/s), and his upper-lower trunk segments indicated an in-phase motion pattern (mean absolute relative phase = 15.59 deg) at baseline. The interventions reduced his pain intensity, fear of movement, and low back pain–related disability; in addition, his trunk velocity was increased (peak trunk flexion velocity = 82.89 deg/s, extension velocity = −77.17 deg/s). However, the in-phase motion pattern of his trunk motor control remained unchanged (mean absolute relative phase = 16.00 deg). At 8 months after the end of the follow-up, the subject’s in-phase motion pattern remained (mean absolute relative phase = 13.34 deg) and his pain intensity had increased. This report suggests that if impaired trunk motor control remains unchanged after intervention, as in the course of the low back pain subject, it may eventually be related to a recurrence of low back pain symptoms.