Limb Deficits Research Articles

Effectiveness of a Virtual Reality rehabilitation in stroke patients with sensory-motor and proprioception upper limb deficit: A study protocol.

Stroke is the second leading cause of death in Europe. In the case of stroke survival (almost 70%), only 25% of patients recover completely, while the remaining 75% will undergo a rehabilitation phase that varying from months to years. The primary outcomes of a stroke involve motor impairment in the upper limbs, resulting in a partial or complete inability to move the limb on the right or left side, depending on the affected hemisphere. Furthermore, the motor deficit distorts the proprioception of the body and the embodiment ability of the injured limb. This could be rehabilitated through the paradigm of body illusion that modulates the motor rehabilitation. The present protocol aims to investigate the effectiveness of a Virtual Reality system for sensorimotor and proprioception upper limb deficit compared to a traditional upper limb rehabilitation program. This study has a randomized and controlled design with control and experimental groups, and 4 measurement times: pre-intervention, immediately after the intervention, and two follow-ups (at 6 and 12 months). The inclusion criteria are: (a) Being 18 to 85 years old, both males and females; (b) Suffering from ischemic or haemorrhagic stroke; (c) The stroke event must have occurred from two to eighteen months before recruitment; (d) Patients must have moderate to severe upper limb motor deficit, and the alteration of sensorimotor and proprioception abilities of the injury upper limb; (e) Patients must understand and sign the written consent for enrolment. The rehabilitation last four weeks with three sessions per week at Bellaria Hospital of Bologna (Italy). The VR protocol uses two types of technology: immersive and non-immersive, and the control group follow the traditional rehabilitation program.

Constraint Induced Movement Therapy Confers only a Transient Behavioral Benefit but Enduring Functional Circuit-Level Changes after Experimental TBI.

Although the behavioral outcome of Constraint-Induced Movement Therapy (CIMT) is well known, and that a combination of CIMT and arm use training potentiates the effect, there has been limited study of the brain circuits involved that respond to therapy. An understanding of CIMT from a brain network level would be useful for guiding the duration of effective therapy, the type of training regime to potentiate the outcome, as well as brain regional targets that might be amenable for direct neuromodulation. Here we investigated the effect of CIMT therapy alone unconfounded by additional rehabilitation training in order to determine the impact of intervention at the circuit level. Adult rats were injured by controlled cortical impact injury and studied before and then after 2wks of CIMT or noCIMT at 1-3wks post-injury using a combination of forelimb behavioral tasks and task-based and resting state functional magnetic resonance imaging at 3 and 7wks post-injury and compared to sham rats. There was no difference in behavior or functional imaging between CIMT and noCIMT after injury before intervention so that data are unlikely to be confounded by differences in injury severity. CIMT produced only a transient reduction in limb deficits compared to noCIMT immediately after the intervention, but no difference thereafter. However, CIMT resulted in a persistent reduction in contralesional limb-evoked activation and a corresponding ipsilesional cortical plasticity compared to noCIMT that endured 4wks after intervention. This was associated with a significant amelioration of intra and inter-hemispheric connectivity present in the noCIMT group at 7wks post-injury.

Task-specific differences in lower limb biomechanics during dynamic movements in individuals with chronic ankle instability compared with controls

BackgroundChronic ankle instability (CAI) has been associated with lower limb deficits that can lead to altered biomechanics during dynamic tasks. There have been contradictory findings in terms of ankle and hip joint biomechanics to date, influenced by the variety of movement tasks and varying definitions of the CAI condition. Research QuestionHow do biomechanical variables of the lower extremity differ during walking, running, and jump-landing in individuals with CAI compared with those without CAI? MethodsThirty-two individuals (17 CAI and 15 controls) participated in this retrospective case-control study. Sagittal and frontal plane ankle and hip joint angles and moments, and mediolateral foot balance (MLFB) were calculated during the tasks. Statistical parametric mapping (SPM) was used for the whole trajectory analysis to detect group differences. Discrete variables, including initial contact (IC) and peak angles and moments, were additionally compared. ResultsNo differences were found between groups during walking. During running, the CAI group exhibited a lower plantar flexor moment (p < 0.001) and more laterally deviated MLFB (p = 0.014) during mid-stance when compared to controls. Additionally, participants with CAI had a significantly greater peak plantar flexion angle in early stance (p = 0.022) and a reduced peak plantar flexor moment (p = 0.002). In the jump-landing, the CAI group demonstrated an increased hip extensor moment (p = 0.008), and a greater peak hip adduction angle (p = 0.039) shortly after ground contact compared to the control group. SignificanceDifferences in ankle and hip biomechanics were observed between groups during running and jump landing, but not during walking. These differences may be indicative of impairments in the sensorimotor system or of learnt strategies adopted to try to minimise instability and injury risk and can help to inform future intervention design.

Constraint-induced movement therapy through telerehabilitation for upper extremity function in stroke

BackgroundStroke is considered to be a leading cause of impairment. After experiencing strokes, patients are frequently left with impaired motor function, making it difficult to carry out daily tasks. The most extensively researched method for treating stroke patients in recent decades is CIMT (constraint-induced movement therapy), which was developed to treat upper limb deficits following stroke. CIMT entails limiting the use of the unaffected limb, altering behavior to increase the use of the affected limb, and finally, mass-training of the affected limb. ObjectiveThe current study aimed to determine the effectiveness of CIMT through TR for upper extremity function in stroke patients. Materials and methodsThirty post-stroke participants were selected on the basis of inclusion and exclusion criteria, and allocated into group A and group B. Group A was treated with CIMT in the physiotherapy department and group B was treated with CIMT through TR. Outcome measures were the Fugl-Meyer Assessment scale for upper extremities (FMA-UE), the Wolf Motor Function Test (WMFT), and the Motor Activity Log (MAL). ResultsBoth groups showed significant improvements in FMA-UE, WMFT and MAL-A0U, MAL-Q0M scores. However, there were no significant differences between groups A and B in FMA-UE, WMFT, MAL-AOU, and MAL-QOM scores in the inter-group analysis. ConclusionCIMT via TR was equally effective than CIMT in physiotherapy department for upper extremity function in stroke. Further studies should be conducted to identify the long-term effectiveness of this approach.

Abstract TMP34: Lower Limb Motor Performance is Proportional to Corticospinal Tract Integrity in Chronic Stroke

Introduction: Gait is a complex behavior characterized by an array of measures, each contributing to our understanding of gait performance. To improve gait recovery after stroke, we need to connect complex clinical function and brain structure. Here, our purpose is to evaluate the relationship between lower limb performance and structural integrity of corticospinal tract (CST) in ambulatory chronic stroke survivors. Methods: Diffusion weighted images (DWIs) and lower limb performance measures were acquired from 36 chronic (&gt;6 months) stroke survivors with lower limb deficits. Clinical measures included Fugl-Meyer(FM), Gait Assessment and Intervention Tool (GAIT), timed-up-and-go (TUG) and fastest gait speed (GS). Lesions were manually outlined on the MRIs, and left hemisphere lesions were flipped. DWIs were preprocessed using standard denoising techniques before calculating fractional anisotropy (FA), mean diffusivity (MD) and radial diffusivity (RD). Tract-based spatial statistics (TBSS) was used to normalize all data to MNI space and project it onto a skeleton of white matter tracts. CSTs were isolated. Voxel-wise analysis was performed with permutation testing (5000 permutations). A regression model was created for each clinical variable using lesion masks as a regressor. Results: Participants were 64±8.9 y/o, 83% male and 53% left hemisphere lesion. FM was 24.1±4.1. Mild correlations were present for FM with GAIT (Pearson, r = -0.33, p = 0.045) and GS (r = 0.34, p = 0.038), and GS with GAIT (r = -0.35, p = 0.036). TUG was highly correlated with GS (r = -0.93, p = 0.000). In exploratory analysis, findings for ipsilesional CST were as follows: 1) better FM was associated with higher FA, MD and RD, p = 0.001, 0.002 and 0.006 respectively; 2) better GS with higher FA, p = 0.034,3) better TUG scores with lower RD, p = 0.041 and 4) a trend of GAIT with RD, p=0.054. Location of statistically significant voxels varied for different clinical measures. No associations were found for contralesional CST. Conclusion: Structural correlates of lower limb performance can be detected using diffusion weighted tractography. FM, an impairment measure of paretic limb, has a stronger association with CST integrity than the measures of global gait function (TUG and GS).

Jumping Asymmetries and Risk of Injuries in Preprofessional Ballet

Background: Preprofessional ballet dancers are exposed to the risk of injuries, primarily in the lower extremities, with most injuries occurring during jumping and landing activities. Interlimb asymmetry during jumping and landing activities has been associated with the injury risk in adolescent athletes, but this has not been examined in dancers. Purpose: To investigate associations between interlimb asymmetry during a double-leg countermovement jump (DL-CMJ) and single-leg jump (SLJ) and the injury risk in adolescent preprofessional ballet dancers. Study Design: Cohort study; Level of evidence, 2. Methods: Adolescent preprofessional ballet dancers (N = 255) performed 3 DL-CMJs and 3 SLJs on force plates during annual screening. Absolute and directional (separate values for left and right limb dominance) asymmetries in a set of kinetic variables during a DL-CMJ and in jump height during an SLJ were calculated. Each variable was characterized as having “high” or “normal” asymmetry according to the percentage of asymmetry (greater than or less than or equal to, respectively, the mean ± 0.5 SD) based on the present sample. Risk ratios (RRs) and 95% CIs were calculated based on the injury incidence in the subsequent academic year. Results: Of the 242 dancers that satisfied the inclusion criteria, 128 injuries were observed in the subsequent academic year. In the whole sample, 3 absolute, 7 left limb–dominant, and 1 right limb–dominant kinetic asymmetry in the eccentric, concentric, and landing phases of the DL-CMJ as well as left limb–dominant jump height asymmetry in the SLJ were associated with a significant (P < .001) increase in the injury risk (RR, 1.28-1.69 [95% CI, 1.02-2.37]). Separating by sex, asymmetries in the eccentric and landing phase of the DL-CMJ were not significant in boys, while in girls, RRs for asymmetries in the eccentric and landing phase of the DL-CMJ increased, and SLJ jump height asymmetry was not significant. Conclusion: Higher asymmetries in certain kinetic variables during the DL-CMJ and in jump height during the SLJ were associated with an elevated risk of injuries in elite preprofessional ballet dancers with some sex-specific differences. Associations were mainly identified for high left limb–dominant asymmetry in the takeoff phase, suggesting that the injury risk may be specific to a relative right limb deficit.

IMPROVING REHABILITATION OUTCOMES FOR PEOPLE AGING WITH LONG-TERM HAND IMPAIRMENTS

Abstract Despite the importance of hand and upper extremity function in ADL performance and successful aging-in-place, contextual and engaging in-home rehabilitation interventions that promote use, feedback of progress, and long-term monitoring of changes in functional ability among individuals with chronic upper limb deficits are lacking. This presentation will present the findings from three TechSAge pilot projects focused on the use of technology to support in-home rehabilitation for individuals aging with long-term upper extremity disabilities. DigiHand, is a smartphone-based application combined with sensor-embedded objects used in daily activities (e.g., coffee cup) that enables users to self-manage their own rehabilitation, obtain feedback on progress to refine movements, and allow remote monitoring by therapists. Similarly, KeyStroke is an in-home piano training mobile app that provides engaging music exercises to promote long-term rehabilitation and therapists’ monitoring of progress of stroke survivors. Finally, 3DP for AT is generating design requirements to support the development of an open-source software tool that would allow assistive technology service providers, who are novice users of 3D printers, to create and fabricate highly customized 3D-printed assistive devices that are more durable, aesthetic, and will better meet the unique needs of people aging with long-term hand impairments.

Vagus Nerve Stimulation in Ischemic Stroke.

Vagus nerve stimulation (VNS) has emerged as a potential therapeutic approach for neurological and psychiatric disorders. In recent years, there has been increasing interest in VNS for treating ischemic stroke. This review discusses the evidence supporting VNS as a treatment option for ischemic stroke and elucidates its underlying mechanisms. Preclinical studies investigating VNS in stroke models have shown reduced infarct volumes and improved neurological deficits. Additionally, VNS has been found to reduce reperfusion injury. VNS may promote neuroprotection by reducing inflammation, enhancing cerebral blood flow, and modulating the release of neurotransmitters. Additionally, VNS may stimulate neuroplasticity, thereby facilitating post-stroke recovery. The Food and Drug Administration has approved invasive VNS (iVNS) combined with rehabilitation for ischemic stroke patients with moderate to severe upper limb deficits. However, iVNS is not feasible in acute stroke due to its time-sensitive nature. Non-invasive VNS (nVNS) may be an alternative approach for treating ischemic stroke. While the evidence from preclinical studies and clinical trials of nVNS is promising, the mechanisms through which VNS exerts its beneficial effects on ischemic stroke are still being elucidated. Therefore, further research is needed to better understand the efficacy and underlying mechanisms of nVNS in ischemic stroke. Moreover, large-scale randomizedclinical trials are necessary to determine the optimal nVNS protocols, assess its long-term effects on stroke recovery and outcomes, and identify the potential benefits of combining nVNS with other rehabilitation strategies.

Effect of a Sensorimotor Exercise Regime for Upper Limb Deficits in the In-Hospital Phase After a Supratentorial Stroke (SMULS)—Protocol for a Randomized Controlled Trial

Background Somatosensory impairments in the upper limb are a common occurrence in &gt;50% of post-stroke individuals. The effects of a combined sensorimotor therapy program on improving functional outcomes have not been studied extensively especially in the acute and subacute phase post-stroke. Methods Through a randomized controlled trial of PROBE design, participants, selected on a pre-set selection criteria will either receive the a structured regime of sensorimotor therapy in addition to routine care or only routine care for over 14 days or until discharge. Outcomes will be analyzed on the “Action Research Arm test” and “Erasmus modified Nottingham Sensory Assessment” scale at discharge and then at the third and sixth months. Results and Conclusion The proposed study will allow development and implementation of sensory rehabilitation components to the existing stroke rehabilitation protocols. Initiating intervention within the acute and subacute phase post-stroke in suitable patients will allow early intervention for sensorimotor impairments subsequently leading to improved upper limb outcomes.

Task-specific training versus usual care to improve upper limb function after stroke: the "Task-AT Home" randomised controlled trial protocol.

Sixty percent of people have non-functional arms 6 months after stroke. More effective treatments are needed. Cochrane Reviews show low-quality evidence that task-specific training improves upper limb function. Our feasibility trial showed 56 h of task-specific training over 6 weeks resulted in an increase of a median 6 points on the Action Research Arm test (ARAT), demonstrating the need for more definitive evidence from a larger randomised controlled trial. Task-AT Home is a two-arm, assessor-blinded, multicentre randomised, controlled study, conducted in the home setting. The objective is to determine whether task-specific training is a more effective treatment than usual care, for improving upper limb function, amount of upper limb use, and health related quality of life at 6 weeks and 6 months after intervention commencement. Our primary hypothesis is that upper limb function will achieve a ≥ 5 point improvement on the ARAT in the task-specific training group compared to the usual care group, after 6 weeks of intervention. Participants living at home, with remaining upper limb deficit, are recruited at 3 months after stroke from sites in NSW and Victoria, Australia. Following baseline assessment, participants are randomised to 6 weeks of either task-specific or usual care intervention, stratified for upper limb function based on the ARAT score. The task-specific group receive 14 h of therapist-led task-specific training plus 42 h of guided self-practice. The primary outcome measure is the ARAT at 6 weeks. Secondary measures include the Motor Activity Log (MAL) at 6 weeks and the ARAT, MAL and EQ5D-5 L at 6 months. Assessments occur at baseline, after 6 weeks of intervention, and at 6 months after intervention commencement. Analysis will be intention to treat using a generalised linear mixed model to report estimated mean differences in scores between the two groups at each timepoint with 95% confidence interval and value of p. If the task-specific home-based training programme is more effective than usual care in improving arm function, implementation of the programme into clinical practice would potentially lead to improvements in upper limb function and quality of life for people with stroke. ANZCTR.org.au/ACTRN12617001631392p.aspx.

Lesion Network Mapping for Neurological Deficit in Acute Ischemic Stroke.

To create a comprehensive map of strategic lesion network localizations for neurological deficits, and identify prognostic neuroimaging biomarkers to facilitate the early detection of patients with a high risk of poor functional outcomes in acute ischemic stroke (AIS). In a large-scale multicenter study of 7,807 patients with AIS, we performed voxel-based lesion-symptom mapping, functional disconnection mapping (FDC), and structural disconnection mapping (SDC) to identify distinct lesion and network localizations for National Institutes of Health Stroke Scale (NIHSS) score. Impact scores were calculated based on the odds ratios or t-values of voxels from voxel-based lesion-symptom mapping, FDC, and SDC results. Ordinal regression models were used to investigate the predictive value of the impact scores on functional outcome (defined as the modified Rankin score at 3 months). We constructed lesion, FDC, and SDC maps for each item of the NIHSS score, which provided insights into the neuroanatomical substrate and network localization of neurological function deficits after AIS. The lesion impact score of limb ataxia, the SDC impact score of limb deficit, and FDC impact score of sensation and dysarthria were significantly associated with modified Rankin Scale at 3 months. Adding the SDC impact score, FDC impact score, and lesion impact score to the NIHSS total score improved the performance in predicting functional outcomes, as compared with using the NIHSS score alone. We constructed comprehensive maps of strategic lesion network localizations for neurological deficits that were predictive of functional outcomes in AIS. These results may provide specifically localized targets for future neuromodulation therapies. ANN NEUROL 2023.

A computer-vision based hand rehabilitation assessment suite

Post-stroke patients very commonly present upper limb deficits, while their rehabilitation comprises regular monitoring and kinematic assessments to evaluate motor recovery. The Box and Block Test (BBT), as well as the Sollerman Hand function Test (SHT), are two of the most used and recommended tools to objectively measure upper limb dexterity, in addition to evaluating the rehabilitation of fine motor skills in patients. However, the tests themselves require the use of very specific equipment, along with the physical attendance of a therapist, making the whole procedure time consuming and clinic dependent. This paper proposes a computer vision hand rehabilitation assessment suite, which stands as a virtual alternative to the real-world scenarios. Our application integrates all the original tests’ guidelines and procedures into an interactive computer vision experience that utilizes bleeding edge technologies such as MediaPipe Hands for hand and finger tracking. This innovative tool requires neither any additional computer peripherals (smart gloves, VR headsets) nor any kind of extra physical equipment (wooden box, blocks), but works instead with just a mid-range PC and a camera. Our system can be deployed in residential spaces via modern 5G/6G or FTTx networks, and the test results can be sent remotely to any physician or rehabilitation expert. Finally, we shortly discuss some technical issues of our approach, as well as present some future directions regarding our tool’s score normalization and feature expansion.

Rate control deficits during pinch grip and ankle dorsiflexion in early-stage Parkinson's disease.

Much of our understanding of the deficits in force control in Parkinson's disease (PD) relies on findings in the upper extremity. Currently, there is a paucity of data pertaining to the effect of PD on lower limb force control. The purpose of this study was to concurrently evaluate upper- and lower-limb force control in early-stage PD and a group of age- and gender-matched healthy controls. Twenty individuals with PD and twenty-one healthy older adults participated in this study. Participants performed two visually guided, submaximal (15% of maximum voluntary contractions) isometric force tasks: a pinch grip task and an ankle dorsiflexion task. PD were tested on their more affected side and after overnight withdrawal from antiparkinsonian medication. The tested side in controls was randomized. Differences in force control capacity were assessed by manipulating speed-based and variability-based task parameters. Compared with controls, PD demonstrated slower rates of force development and force relaxation during the foot task, and a slower rate of relaxation during the hand task. Force variability was similar across groups but greater in the foot than in the hand in both PD and controls. Lower limb rate control deficits were greater in PD with more severe symptoms based on the Hoehn and Yahr stage. Together, these results provide quantitative evidence of an impaired capacity in PD to produce submaximal and rapid force across multiple effectors. Moreover, results suggest that force control deficits in the lower limb may become more severe with disease progression.

Toward Improving Actuation Transparency and Safety of a Hip Exoskeleton With a Novel Nonlinear Series Elastic Actuator

Actuation transparency and safety are important requirements in the design and control of assistive exoskeletons for individuals who suffer lower limb deficits but still maintain a certain level of voluntary motor control. In recent years, series elastic actuator (SEA) has been regarded as a promising solution for transparent actuation and safe human–robot interaction, thus SEAs are widely developed and applied in assistive exoskeletons. However, existing SEAs designed for assistive exoskeletons still lack both actuation transparency and safety because of high stiffness of the elastic element and the high mechanical impedance of the actuators. To address this problem, a novel nonlinear SEA (nSEA) is presented in this article. The optimized nonlinear series elastic element coupled with a quasi-direct drive motor creates the nSEA with low mechanical impedance, high backdrivability, and less acoustic noise. Besides, a new torque control, based on cascade PI control, is proposed for the nSEA to control the interaction torque with high accuracy and robustness. Finally, an experimental evaluation with human subjects is performed to validate the advantages of the nSEA-driven hip exoskeleton in the realization of actuation transparency and safety. The root-mean-square interaction torque in zero-impedance mode is as low as 0.051 N <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\cdot$</tex-math></inline-formula> m during walking conditions, leading to a negligible negative influence on the hip joint's range of motion, walking speed, and energy expenditure when wearing the hip exoskeleton.

Acute effects of foam rolling and dynamic stretching on angle-specific change of direction ability, flexibility and reactive strength in male basketball players.

The purpose of our study was to determine the acute effects of dynamic stretching (DS), foam rolling (FR) and foam rolling combined with dynamic stretching (Combo) protocols on angle-specific change of direction (COD) ability, drop jump (DJ) performance and flexibility. Using a counterbalance crossover study design, eleven male basketball collegiate players (20.7 ± 0.6 years) were randomly assigned to one of the four protocols - control (CON), DS, FR, Combo - for each session, for a total of four sessions. A more aggressive foam cylinder with raised nodules, which is thought to be effective in stimulating the deep layer of muscle tissue, was used to observe for changes in their performance during sit and reach (SAR), DJ and COD tasks in 45 and 180 degrees. One-way repeated measures ANOVA was used to identify differences of each variable separately between interventions. The SAR after three interventions compared to the CON was significantly improved (F (3,30) = 5.903, P = 0.003, η2 = 0.371). In the 505 test, both limbs failed to show a significant improvement in COD deficit. The non-dominant limb showed a significant improvement of 6.4% after FR when performing the Y-shaped agility (F (3,30) = 4.962, P = 0.0065 < 0.05, η2 = 0.332). In the DJ, the reactive strength index and contact time changed significantly by 17.5% and -17.5% (η2 = 0.518, η2 = 0.571), respectively, immediately after FR. The current research suggested that FR may have an enhancing effect on COD speed in a 45° cutting task and neuromuscular function, while having the potential to improve non-dominant limb deficits in both COD tasks. In contrast, the Combo warm-up protocol did not produce a cumulative effect, suggesting the need for coaches to remain cautious about excessive warm-up duration.

Imaging the lower limb network in Parkinson’s disease

BackgroundDespite the significant impact of lower limb symptoms on everyday life activities in Parkinson’s disease (PD), knowledge of the neural correlates of lower limb deficits is limited. ObjectiveWe ran an fMRI study to investigate the neural correlates of lower limb movements in individuals with and without PD. MethodsParticipants included 24 PD and 21 older adults who were scanned while performing a precisely controlled isometric force generation task by dorsiflexing their ankle. A novel MRI-compatible ankle dorsiflexion device that limits head motion during motor tasks was used. The PD were tested on their more affected side, whereas the side in controls was randomized. Importantly, PD were tested in the off-state, following overnight withdrawal from antiparkinsonian medication. ResultsThe foot task revealed extensive functional brain changes in PD compared to controls, with reduced fMRI signal during ankle dorsiflexion within the contralateral putamen and M1 foot area, and ipsilateral cerebellum. The activity of M1 foot area was negatively correlated with the severity of foot symptoms based on the Movement Disorder Society‐Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS-III). ConclusionOverall, current findings provide new evidence of brain changes underlying motor symptoms in PD. Our results suggest that pathophysiology of lower limb symptoms in PD appears to involve both the cortico-basal ganglia and cortico-cerebellar motor circuits.

The impact of pre-existing venous pathology on lower limb free flap reconstruction and the role of preoperative screening: a systematic review.

Lower limb reconstruction is performed to replace like with like and achieve tissue durability. Free flaps are a method of reconstruction commonly used to manage cases of lower limb deficits. However, the failure rate is 8.5%, with venous thrombosis and congestion playing a significant role. Despite this, preoperative venous mapping of recipient site before free flap reconstruction is not routinely practiced, often resulting in pathologies remaining unidentified until the intraoperative stage. The aim of the review was to evaluate the existing literature on the topic of lower limb preoperative venous assessment, screening, and its effect on lower limb free flap survival. Five different databases were searched from their inception to August 2021. The search terms and included studies were independently reviewed by two investigators for their eligibility. Eleven articles were eligible for inclusion, with a combined patient population of 99, and 107 flaps were identified to have lower limb pathology at the donor or recipient vein. Venous pathology was detected preoperatively in 69 veins using ultrasound duplex scanning and computed tomography angiography; of them, 3 (4.34%) resulted in failure. In comparison, 38 veins were diagnosed with venous pathology intraoperatively; of them, 5 (13.85%) failed. The studies evaluated in this review demonstrated that preoperative screening for venous pathology showed a higher flap survival rate. It can therefore be inferred that developing a standardized preoperative process for identifying venous issues in lower limb free flap reconstruction may improve outcomes. This can be explored in future research, with a focus on assessing the validity and efficacy of such screening tools, and their role in the management of patients identified with venous pathology.

The role of corticospinal and extrapyramidal pathways in motor impairment after stroke.

Anisotropy of descending motor pathways has repeatedly been linked to the severity of motor impairment following stroke-related damage to the corticospinal tract. Despite promising findings consistently tying anisotropy of the ipsilesional corticospinal tract to motor outcome, anisotropy is not yet utilized as a biomarker for motor recovery in clinical practice as several methodological constraints hinder a conclusive understanding of degenerative processes in the ipsilesional corticospinal tract and compensatory roles of other descending motor pathways. These constraints include estimating anisotropy in voxels with multiple fibre directions, sampling biases and confounds due to ageing-related atrophy. The present study addressed these issues by combining diffusion spectrum imaging with a novel compartmentwise analysis approach differentiating voxels with one dominant fibre direction (one-directional voxels) from voxels with multiple fibre directions. Compartmentwise anisotropy for bihemispheric corticospinal and extrapyramidal tracts was compared between 25 chronic stroke patients, 22 healthy age-matched controls, and 24 healthy young controls and its associations with motor performance of the upper and lower limbs were assessed. Our results provide direct evidence for Wallerian degeneration along the entire length of the ipsilesional corticospinal tract reflected by decreased anisotropy in descending fibres compared with age-matched controls, while ageing-related atrophy was observed more ubiquitously across compartments. Anisotropy of descending ipsilesional corticospinal tract voxels showed highly robust correlations with various aspects of upper and lower limb motor impairment, highlighting the behavioural relevance of Wallerian degeneration. Moreover, anisotropy measures of two-directional voxels within bihemispheric rubrospinal and reticulospinal tracts were linked to lower limb deficits, while anisotropy of two-directional contralesional rubrospinal voxels explained gross motor performance of the affected hand. Of note, the relevant extrapyramidal structures contained fibres crossing the midline, fibres potentially mitigating output from brain stem nuclei, and fibres transferring signals between the extrapyramidal system and the cerebellum. Thus, specific parts of extrapyramidal pathways seem to compensate for impaired gross arm and leg movements incurred through stroke-related corticospinal tract lesions, while fine motor control of the paretic hand critically relies on ipsilesional corticospinal tract integrity. Importantly, our findings suggest that the extrapyramidal system may serve as a compensatory structural reserve independent of post-stroke reorganization of extrapyramidal tracts. In summary, compartment-specific anisotropy of ipsilesional corticospinal tract and extrapyramidal tracts explained distinct aspects of motor impairment, with both systems representing different pathophysiological mechanisms contributing to motor control post-stroke. Considering both systems in concert may help to develop diffusion imaging biomarkers for specific motor functions after stroke.

Brain Function and Upper Limb Deficit in Stroke With Motor Execution and Imagery: A Cross-Sectional Functional Magnetic Resonance Imaging Study

BackgroundMotor imagery training might be helpful in stroke rehabilitation. This study explored if a specific modulation of movement-related regions is related to motor imagery (MI) ability.MethodsTwenty-three patients with subcortical stroke and 21 age-matched controls were recruited. They were subjectively screened using the Kinesthetic and Visual Imagery Questionnaire (KVIQ). They then underwent functional magnetic resonance imaging (fMRI) while performing three repetitions of different motor tasks (motor execution and MI). Two separate runs were acquired [motor execution tasks (ME and rest) and motor imagery (MI and rest)] in a block design. For the different tasks, analyses of cerebral activation and the correlation of motor/imagery task-related activity and KVIQ scores were performed.ResultsDuring unaffected hand (UH) active grasp movement, we observed decreased activations in the contralateral precentral gyrus (PreCG), contralateral postcentral gyrus (PoCG) [p < 0.05, family wise error (FWE) corrected] and a positive correlation with the ability of FMA-UE (PreCG: r = 0.46, p = 0.028; PoCG: r = 0.44, p = 0.040). During active grasp of the affected hand (AH), decreased activation in the contralateral PoCG was observed (p < 0.05, FWE corrected). MI of the UH induced significant activations of the contralateral superior frontal gyrus, opercular region of the inferior frontal gyrus, and ipsilateral ACC and deactivation in the ipsilateral supplementary motor area (p < 0.05, AlphaSim correction). Ipsilateral anterior cingulate cortex (ACC) activity negatively correlated with MI ability (r = =–0.49, p = 0.022). Moreover, we found significant activation of the contralesional middle frontal gyrus (MFG) during MI of the AH.ConclusionOur results proved the dominant effects of MI dysfunction that exist in stroke during the processing of motor execution. In the motor execution task, the enhancement of the contralateral PreCG and PoCG contributed to reversing the motor dysfunction, while in the MI task, inhibition of the contralateral ACC can increase the impaired KVIQ ability. The bimodal balance recovery model can explain our results well. Recognizing neural mechanisms is critical to helping us formulate precise strategies when intervening with electrical or magnetic stimulation.

FV 17 Wallerian degeneration of descending fiber tracts explains motor impairment after stroke

Introduction: Structural changes post-stroke have frequently been assessed using diffusion tensor imaging (DTI). While the microstructural integrity of various parts of the corticospinal tract (CST) has been linked to motor impairment 1 , it remains unclear whether the reduction in anisotropy can be attributed to descending or crossing fibers within the CST. To address this question, we used diffusion spectrum imaging (DSI), an advanced imaging approach that overcomes the shortcomings of DTI, and delineated the influence of CST-inherent crossing and descending fibers. Patients and Methods: DSI scans of 25 chronic stroke patients (mean age=66.7, sd=11.2) and 22 age-matched controls were corrected for motion-and distortion artifacts, reconstructed, and normalized using QSIPrep 2 . Lesion and individual white matter (WM) masks were applied to the resulting generalized fractional anisotropy (gfa)-maps, focusing the analysis on secondary degeneration in WM-tracts. A deterministic mask containing the number of trackable directions per voxel 3 was applied to compartmentalize whole-brain gfa-values. Compartment-wise mean gfa was extracted from motor tracts as defined in the HCP tractography atlas 4 . Using these values, we tested for differences between patients and controls and for an association with upper and lower limb motor impairment. Results: Patients featured reduced gfa-values within the affected CST compared to age-matched controls (t(45)=-3.35, p=.002). This difference was mainly attributable to voxels containing only one fiber direction (t(45)=-3.92, p<.001), i.e., descending fibers, while voxels containing two directions, i.e., crossing fibers, showed no difference (p>0.4). Mean gfa of the affected CST significantly explained upper limb impairment (R 2 =0.30, p=.005), especially for patients suffering from persistent motor deficits (R 2 =0.43, p=.01). This association was driven by unidirectional (R 2 =0.26, p=.009) and not multidirectional voxels (p>0.3). Mean-gfa within the rubrospinal tract was related to persisting lower limb deficits. Conclusion: Anisotropy measures of the CST derived from DSI were significantly reduced and explained upper limb motor impairment in chronic stroke patients. These findings were driven by voxels containing a single fiber direction suggesting that changes in microstructural integrity of motor pathways assessed via diffusion imaging originate from Wallerian degeneration of descending fibers. In non-fully recovered stroke patients with CST damage, extrapyramidal pathways such as the rubrospinal tract may contribute to leg movements, potentially reflecting a compensatory mechanism after CST damage. Our findings underline the potential of DSI to predict motor outcome, especially when focusing the analysis on descending fibers via compartmentalization. References 1 Koch et al., 2016, Annals Clin Transl Neurol. 2 Cieslak et al., 2021, Nature Methods. 3 Volz et al., 2018, Brain Struct Funct. 4 Yeh et al., 2018, NeuroImage.