Efficacy of a new video observational training method (intensive visual simulation) for motor recovery in the upper limb in subacute stroke: a feasibility and proof-of-concept study.

OBJECTIVE: To demonstrate the feasibility and efficacy  of a new video-observation training method (intensive visual simulation) to improve upper limb function. DESIGN: Small sample, randomized, evaluator-blind, monocentric study. PATIENTS: Seventeen early subacute ischaemic stroke patients with complete hemiplegia were  randomly assigned to the therapeutic group (n = 8) or control group (CG, n = 9). METHODS: Thirty sessions of intensive visual simulation combined with corrected visual feedback (therapeutic group) or uncorrected visual feedback (control group) were performed over 6 weeks on top of a standard rehabilitation programme. MAIN OUTCOME MEASURE: 400-point hand assessment test (400p-HA). SECONDARY OUTCOME MEASURES: Box and Blocks (B&B), Purdue Pegboard test, Minnesota. RESULTS: The 400p-HA test improved significantly from T0 to 6 months for both groups, with a significant difference between groups at 3 months (MW-UT p = 0.046) and 4 months (MW-UT p = 0.046) in favour of the therapeutic group. One-phase exponential modelling of 400p-HA showed a greater plateau for the therapeutic group (F test p = 0.0021). There was also faster recovery of the ability to perform the B&B tests for the therapeutic group (log-rank test p = 0.03). CONCLUSION: This study demonstrated the feasibility and potential efficacy of an intensive visual simulation training programme to improve upper limb  function in subacute stroke patients. A larger study is needed to confirm these results.

Treatment of Acquired Deforming Hypertonia with Botulinum Toxin in Older Population: A Retrospective Study.

Acquired deforming hypertonia (ADH) affects the daily care of numerous nursing home residents. The aim of this study was to analyze the practice, aims, and effectiveness of botulinum toxin injections (BTxis) in the treatment of older patients with contractures, an indication for which BTxis are still underused. Data were extracted retrospectively from medical records regarding population, contractures, and injections. A prospective analysis was conducted to evaluate treatment goals set by goal attainment scaling (GAS) at T0 and at T1, to evaluate the therapeutic effects. We also recorded the occurrence of side effects, using a telephone questionnaire. This study included 41 patients older than 70 years who had received one or more BTxis for the first time between January 2018 and December 2021. Most of the older people we included lived in an institution (66%), manifested severe dependence, and presented significant morbi-mortality (37% of the patients died in the year after the last injection). The main objectives of these injections were purely comfort, without any functional goals. The GAS scores suggested effectiveness for comfort GAS scores. No complications were recorded. This study highlights the BTxis potential to address the needs of a larger number of older patients with ADH.

Neural basis of lower-limb visual feedback therapy: an EEG study in healthy subjects.

BACKGROUND: Video-feedback observational therapy (VOT) is an intensive rehabilitation technique based on movement repetition and visualization that has shown benefits for motor rehabilitation of the upper and lower limbs. Despite an increase in recent literature on the neurophysiological effects of VOT in the upper limb, there is little knowledge about the cortical effects of visual feedback therapies when applied to the lower limbs. The aim of our study was to better understand the neurophysiological effects of VOT. Thus, we identified and compared the EEG biomarkers of healthy subjects undergoing lower limb VOT during three tasks: passive observation, observation and motor imagery, observation and motor execution. METHODS: We recruited 38 healthy volunteers and monitored their EEG activity while they performed a right ankle dorsiflexion task in the VOT. Three graded motor tasks associated with action observation were tested: action observation alone (O), motor imagery with action observation (OI), and motor execution synchronized with action observation (OM). The alpha and beta event-related desynchronization (ERD) and event-related synchronization (or beta rebound, ERS) rhythms were used as biomarkers of cortical activation and compared between conditions with a permutation test. Changes in connectivity during the task were computed with phase locking value (PLV). RESULTS: During the task, in the alpha band, the ERD was comparable between O and OI activities across the precentral, central and parietal electrodes. OM involved the same regions but had greater ERD over the central electrodes. In the beta band, there was a gradation of ERD intensity in O, OI and OM over central electrodes. After the task, the ERS changes were weak during the O task but were strong during the OI and OM (Cz) tasks, with no differences between OI and OM. CONCLUSION: Alpha band ERD results demonstrated the recruitment of mirror neurons during lower limb VOT due to visual feedback. Beta band ERD reflects strong recruitment of the sensorimotor cortex evoked by motor imagery and action execution. These results also emphasize the need for an active motor task, either motor imagery or motor execution task during VOT, to elicit a post-task ERS, which is absent during passive observation. Trial Registration NCT05743647.

Percutaneous needle tenotomies: indications, procedures, efficacy and safety. A systematic review.

BACKGROUND: Percutaneous needle tenotomies constitute a promising approach that enables direct access to tendons through minimally invasive interventions. They can be performed rapidly without need for large incisions or general anaesthesia. However, the reported procedures are heterogeneous and currently conducted without guidelines. OBJECTIVES: We aimed to determine the indications for percutaneous needle tenotomies described in the current literature. Our secondary aim was to identify the different procedures reported, as well as their efficacy and their safety. METHODS: A systematic review following PRISMA guidelines was conducted to identify original articles that mentioned percutaneous needle tenotomy in humans and reported its application, description, effectiveness or adverse events. Non-percutaneous tendinous surgical procedures and ineligible designs were excluded. The Downs and Black checklist was used to assess the risk of bias. RESULTS: A total of 540 studies were identified from the MEDLINE, Embase, Cochrane Library, and PEDro databases. Fourteen clinical studies met the inclusion criteria and were found to have an acceptable quality (674 individuals, 1664 tenotomies). Our results indicated a wide variety of indications for percutaneous needle tenotomies in children and in adults. We highlighted 24 tendons as eligible targets in the upper and lower limbs. Tenotomies were performed with either 16- or 18-Ga needles, lasted from 1 to 30 min, and were performed using various procedures. Their efficacy was mainly assessed through clinical outcomes highlighting tendon discontinuity on palpation after the procedure. Passive range-of-motion gains after tenotomy were reported for both upper and lower limbs with an estimated 5 % complication rate. CONCLUSION: This is the first review to systematically synthesize all the available evidence on the indications, procedures, efficacy and safety of percutaneous tenotomies exclusively performed with needles. Current evidence suggests that procedures are safe and effective for treating various deformities. PROSPERO REGISTRATION: CRD42022350571.

Factors Associated with Fatigue in COVID-19 ICU Survivors.

PURPOSE: Approximately 30% of people infected with COVID-19 require hospitalization, and 20% of them are admitted to an intensive care unit (ICU). Most of these patients experience symptoms of fatigue weeks post-ICU, so understanding the factors associated with fatigue in this population is crucial. METHODS: Fifty-nine patients (38-78 yr) hospitalized in ICU for COVID-19 infection for 32 (6-80) d, including 23 (3-57) d of mechanical ventilation, visited the laboratory on two separate occasions. The first visit occurred 52 ± 15 d after discharge and was dedicated to questionnaires, blood sampling, and cardiopulmonary exercise testing, whereas measurements of the knee extensors neuromuscular function and performance fatigability were performed in the second visit 7 ± 2 d later. RESULTS: Using the FACIT-F questionnaire, 56% of patients were classified as fatigued. Fatigued patients had worse lung function score than non-fatigued (i.e., 2.9 ± 0.8 L vs 3.6 ± 0.8 L; 2.4 ± 0.7 L vs 3.0 ± 0.7 L for forced vital capacity and forced expiratory volume in 1 s, respectively), and forced vital capacity was identified as a predictor of being fatigued. Maximal voluntary activation was lower in fatigued patients than non-fatigued patients (82% ± 14% vs 91% ± 3%) and was the only neuromuscular variable that discriminated between fatigued and non-fatigued patients. Patient-reported outcomes also showed differences between fatigued and non-fatigued patients for sleep, physical activity, depression, and quality of life ( P < 0.05). CONCLUSIONS: COVID-19 survivors showed altered respiratory function 4 to 8 wk after discharge, which was further deteriorated in fatigued patients. Fatigue was also associated with lower voluntary activation and patient-reported impairments (i.e., sleep satisfaction, quality of life, or depressive state). The present study reinforces the importance of exercise intervention and rehabilitation to counteract cardiorespiratory and neuromuscular impairments of COVID-19 patients admitted in ICU, especially individuals experiencing fatigue.

The challenge of controlling an auditory BCI in the case of severe motor disability.

BACKGROUND: The locked-in syndrome (LIS), due to a lesion in the pons, impedes communication. This situation can also be met after some severe brain injury or in advanced Amyotrophic Lateral Sclerosis (ALS). In the most severe condition, the persons cannot communicate at all because of a complete oculomotor paralysis (Complete LIS or CLIS). This even prevents the detection of consciousness. Some studies suggest that auditory brain-computer interface (BCI) could restore a communication through a « yes-no¼ code. METHODS: We developed an auditory EEG-based interface which makes use of voluntary modulations of attention, to restore a yes-no communication code in non-responding persons. This binary BCI uses repeated speech sounds (alternating "yes" on the right ear and "no" on the left ear) corresponding to either frequent (short) or rare (long) stimuli. Users are instructed to pay attention to the relevant stimuli only. We tested this BCI with 18 healthy subjects, and 7 people with severe motor disability (3 "classical" persons with locked-in syndrome and 4 persons with ALS). RESULTS: We report online BCI performance and offline event-related potential analysis. On average in healthy subjects, online BCI accuracy reached 86% based on 50 questions. Only one out of 18 subjects could not perform above chance level. Ten subjects had an accuracy above 90%. However, most patients could not produce online performance above chance level, except for two people with ALS who obtained 100% accuracy. We report individual event-related potentials and their modulation by attention. In addition to the classical P3b, we observed a signature of sustained attention on responses to frequent sounds, but in healthy subjects and patients with good BCI control only. CONCLUSIONS: Auditory BCI can be very well controlled by healthy subjects, but it is not a guarantee that it can be readily used by the target population of persons in LIS or CLIS. A conclusion that is supported by a few previous findings in BCI and should now trigger research to assess the reasons of such a gap in order to propose new and efficient solutions. CLINICAL TRIAL REGISTRATIONS: No. NCT02567201 (2015) and NCT03233282 (2013).

Structural and pathophysiological muscle changes up to one year after post-stroke hemiplegia: a systematic review.

INTRODUCTION: Muscle changes after stroke cannot be explained solely on the basis of corticospinal bundle damage. Muscle-specific changes contribute to limited functional recovery but have been poorly characterized. EVIDENCE ACQUISITION: We conducted a systematic review of muscular changes occurring at the histological, neuromuscular and functional levels during the first year after the onset of post-stroke hemiplegia. A literature search was performed on PubMed, Embase and CINHAL databases up to November 2022 using a keyword combination comprising cerebral stroke, hemiplegic, atrophy, muscle structure, paresis, skeletal muscle fiber type, motor unit, oxidative stress, strength, motor control. EVIDENCE SYNTHESIS: Twenty-seven trial reports were included in the review, out of 12,798 articles screened. Structural modifications described on the paretic side include atrophy, transformation of type II fibers into type I fibers, decrease in fiber diameter and apparent myofilament disorganization from the first week post-stroke up to the fourth month. Reported biochemical changes comprise the abnormal presence of lipid droplets and glycogen granules in the subsarcolemmal region during the first month post-stroke. At the neurophysiological level, studies indicate an early decrease in the number and activity of motor units, correlated with the degree of motor impairment. All these modifications were present to a lesser degree on the non-paretic side. Although only sparse data concerning the subacute stage are available, these changes seem to appear during the first two weeks post-stroke and continue up to the third or fourth month. CONCLUSIONS: Considering these early pathophysiological changes on both the paretic and non-paretic sides, it seems crucial to promptly stimulate central and also peripheral muscular activation after stroke through specific rehabilitation programs focused on the maintenance of muscle capacities associated with neurological recovery or plasticity.

Time course response after single injection of botulinum toxin to treat spasticity after stroke: Systematic review with pharmacodynamic model-based meta-analysis.

BACKGROUND: The time-course response after a single injection of botulinum toxin (BoNT) for post-stroke spasticity is debated. We addressed this issue by conducting a systematic review and a pharmacodynamic model-based meta-analysis. METHODS: We searched Medline, PeDro and Google Scholar databases up to March 2020, selecting randomized controlled trials of post-stroke and traumatic brain injury patients with arm or leg muscle hypertonia, comparing BoNT to placebo, or different BoNT preparations. The main outcome was change in Modified Ashworth Scale (MAS) score. A non-linear mixed effect model was used to estimate maximal toxin and placebo effects (Emax and EPlacebo), the effect disappearance half-life (T1/2off) of BoNT and the doses achieving 50 and 80% of Emax (D50 and D80). The equivalence ratios between different BoNT preparations were calculated from D50 values. Adverse events were recorded. RESULTS: Altogether, 2,236 unique records were screened by 2 independent reviewers: 35 eligible trials including 3011 patients (95% post-stroke) were identified. For all BoNT preparations, the BoNT Emax of -1.11 (95% credible interval -1.31; -0.29) was reached at 5 weeks; the maximal placebo effect was -0.30 (-0.37; -0.22). Both D50 and D80 differed significantly by muscle volume. At D50, the equivalence ratio was significantly higher for abobotulinumtoxinA (3.35) than onabotulinumtoxinA and lower for letibotulinumtoxinA (0.41). T1/2off was longer for abobotulinumtoxinA than for onabotulinumtoxinA and the other preparations (13.1 weeks [95% credible interval 7.7; 19.3] vs 8.6 weeks [7.1; 10.1]). Adverse events were minor, with a weak, but significant, dose-response relation for muscle weakness. CONCLUSIONS: This first pharmacodynamic model-based meta-analysis of individuals with stroke revealed that for all BoNT-A preparations, BoNT-A injections to treat spasticity have maximal effect at 5 weeks. The T1/2off was longer for abobotulinumtoxinA than other preparations. Differences between certain BoNT unit scales were also confirmed.

Effects of prismatic adaptation on balance and postural disorders in patients with chronic right stroke: protocol for a multicentre double-blind randomised sham-controlled trial.

INTRODUCTION: Patients with right stroke lesion have postural and balance disorders, including weight-bearing asymmetry, more pronounced than patients with left stroke lesion. Spatial cognition disorders post-stroke, such as misperceptions of subjective straight-ahead and subjective longitudinal body axis, are suspected to be involved in these postural and balance disorders. Prismatic adaptation has showed beneficial effects to reduce visuomotor disorders but also an expansion of effects on cognitive functions, including spatial cognition. Preliminary studies with a low level of evidence have suggested positive effects of prismatic adaptation on weight-bearing asymmetry and balance after stroke. The objective is to investigate the effects of this intervention on balance but also on postural disorders, subjective straight-ahead, longitudinal body axis and autonomy in patients with chronic right stroke lesion. METHODS AND ANALYSIS: In this multicentre randomised double-blind sham-controlled trial, we will include 28 patients aged from 18 to 80 years, with a first right supratentorial stroke lesion at chronic stage (≥12 months) and having a bearing ≥60% of body weight on the right lower limb. Participants will be randomly assigned to the experimental group (performing pointing tasks while wearing glasses shifting optical axis of 10 degrees towards the right side) or to the control group (performing the same procedure while wearing neutral glasses without optical deviation). All participants will receive a 20 min daily session for 2 weeks in addition to conventional rehabilitation. The primary outcome will be the balance measured using the Berg Balance Scale. Secondary outcomes will include weight-bearing asymmetry and parameters of body sway during static posturographic assessments, as well as lateropulsion (measured using the Scale for Contraversive Pushing), subjective straight-ahead, longitudinal body axis and autonomy (measured using the Barthel Index). ETHICS AND DISSEMINATION: The study has been approved by the ethical review board in France. Findings will be submitted to peer-reviewed journals relative to rehabilitation or stroke. TRIAL REGISTRATION NUMBER: NCT03154138.

The Effects of Anodal Transcranial Direct Current Stimulation on the Walking Performance of Chronic Hemiplegic Patients.

OBJECTIVE: To evaluate the effect of a single session of tDCS over the primary motor cortex of the lower limb (M1-LL) vs. placebo on the walking performance in chronic hemiplegic patients. PATIENTS AND METHODS: Randomized, cross-over, double-blinded study. Eighteen patients with initially complete hemiplegia and poststroke delay >6 months were included. Each patient received a single session of anodal stimulation (2 mA, 20 min) over M1-LL (a-tDCS condition) and a pseudostimulation session (SHAM condition). The order of the two sessions was randomly assigned, with an 11-day interval between the two sessions. The anodal electrode was centered on the hotspot identified with Transcranial magnetic stimulation. The cathode was placed above the contralesional orbitofrontal cortex. Walking performance was evaluated with the Wade test and the 6-minute walk test (6MWT), gait parameters with GAITRite, and balance with posturography. These tests were performed during and 1 hour after the stimulation. Baseline assessments were performed the day before and 10 days after each session. RESULTS: The comparison between the 6MWT under a-tDCS vs. SHAM conditions demonstrated a nonsignificant positive effect of the stimulation by 15% during stimulation (p = 0.360) and a significant positive effect of 25% 1 hour after stimulation (p = 0.038). No significant differences were observed for the other evaluations. DISCUSSION: These results showed a significant positive effect of a single session of anodal tDCS of the M1-LL in chronic hemiplegic patients. This proof-of-concept study supports the conduct of clinical studies evaluating the effectiveness of a walking training program associated with iterative tDCS stimulation. CONFLICT OF INTEREST: The authors reported no conflict of interest.

Numerical Model Reduction for the Prediction of Interface Pressure Applied by Compression Bandages on the Lower Leg.

OBJECTIVE: To develop a new method for the prediction of interface pressure applied by medical compression bandages. METHODS: A finite element simulation of bandage application was designed, based on patient-specific leg geometries. For personalized interface pressure prediction, a model reduction approach was proposed, which included the parametrization of the leg geometry. Pressure values computed with this reduced model were then confronted to experimental pressure values. RESULTS: The most influencing parameters were found to be the bandage tension, the skin-to-bandage friction coefficient and the leg morphology. Thanks to the model reduction approach, it was possible to compute interface pressure as a linear combination of these parameters. The pressures computed with this reduced model were in agreement with experimental pressure values measured on 66 patients' legs. CONCLUSION: This methodology helps to predict patient-specific interface pressure applied by compression bandages within a few minutes whereas it would take a few days for the numerical simulation. The results of this method show less bias than Laplace's Law, which is for now the only other method for interface pressure computation.

Superimposition of elastic and nonelastic compression bandages.

OBJECTIVE: The objective of this study was to investigate the pressure applied by superimposed bandages and to compare it with the pressure applied by single-component bandages. METHODS: Six different bandages, composed of one elastic bandage, one nonelastic bandage, or both, were applied in a spiral pattern on both legs of 25 patients at risk of venous thrombosis as a consequence of central or peripheral motor deficiency. Pressure was measured at four measurement points on the leg (B1 and C on the medial and lateral sides of the leg) and in three positions: supine, sitting, and standing. RESULTS: The two single bandages applied similar pressure in the supine position. Their superimposition showed different pressure levels (P < .05) but similar static stiffness index, depending on the order in which the bandage components were applied on the leg. The highest interface pressure was measured at point B1 on the medial side of the leg. This point also showed the highest pressure increase from supine to standing position. The pressure applied by the superimposition of two bandages was computed as a linear combination of the pressure applied by each single component (with a constant term set to 0). However, this linear combination did not properly fit the experimental pressure measurements. CONCLUSIONS: The order of bandage application showed a significant impact on interface pressure. However, the poor correlation between the pressure applied by each bandage component and the pressure resulting from their superimposition underlined the poor understanding of interface pressure generated by the superimposition of compression bandages and should lead to further investigations.

Numerical Approach for the Assessment of Pressure Generated by Elastic Compression Bandage.

Compression of the lower leg by bandages is a common treatment for the advanced stages of some venous or lymphatic pathologies. The outcomes of this treatment directly result from the pressure generated onto the limb. Various bandage configurations are proposed by manufacturers: the study of these configurations requires the development of reliable methods to predict pressure distribution applied by compression bandages. Currently, clinicians and manufacturers have no dedicated tools to predict bandage pressure generation. A numerical simulation approach is presented in this work, which includes patient-specific leg geometry and bandage. This model provides the complete pressure distribution over the leg. The results were compared to experimental pressure measurements and pressure values computed with Laplace's law. Using an appropriate surrogate model, this study demonstrated that such simulation is appropriate to account for phenomena which are neglected in Laplace's law, like geometry changes due to bandage application.

Primary motor cortex changes after amputation correlate with phantom limb pain and the ability to move the phantom limb.

A substantial body of evidence documents massive reorganization of primary sensory and motor cortices following hand amputation, the extent of which is correlated with phantom limb pain. Many therapies for phantom limb pain are based upon the idea that plastic changes after amputation are maladaptive and attempt to normalize representations of cortical areas adjacent to the hand area. Recent data suggest, however, that higher levels of phantom pain are associated with stronger local activity and more structural integrity in the missing hand area rather than with reorganization of neighbouring body parts. While these models appear to be mutually exclusive they could co-exist, and one reason for the apparent discrepancy between them might be that no single study has examined the organisation of lip, elbow, and hand movements in the same participants. In this study we thoroughly examined the 3D anatomy of the central sulcus and BOLD responses during movements of the hand, elbow, and lips using MRI techniques in 11 upper-limb amputees and 17 healthy control subjects. We observed different reorganizational patterns for all three body parts as the former hand area showed few signs of reorganization, but the lip and elbow representations reorganized and shifted towards the hand area. We also found that poorer voluntary control and higher levels of pain in the phantom limb were powerful drivers of the lip and elbow topological changes. In addition to providing further support for the maladaptative plasticity model, we demonstrate for the first time that motor capacities of the phantom limb correlate with post-amputation reorganization, and that this reorganization is not limited to the face and hand representations but also includes the proximal upper-limb.

[Phantom limb pains]. / Douleurs du membre fantôme.

With the radical experience of an amputation, the adaptation of body image is often incomplete. Some people experience phantom body perceptions, often painful and difficult to treat, after the amputation of a limb.

Experimental Investigation of Pressure Applied on the Lower Leg by Elastic Compression Bandage.

Compression therapy with stockings or bandages is the most common treatment for venous or lymphatic disorders. The objective of this study was to investigate the influence of bandage mechanical properties, application technique and subject morphology on the interface pressure, which is the key of this treatment. Bandage stretch and interface pressure measurements (between the bandage and the leg) were performed on 30 healthy subjects (15 men and 15 women) at two different heights on the lower leg and in two positions (supine and standing). Two bandages were applied with two application techniques by a single operator. The statistical analysis of the results revealed: no significant difference in pressure between men and women, except for the pressure variation between supine and standing positions; a very strong correlation between pressure and bandage mechanical properties (p < 0.00001) and between pressure and bandage overlapping (p < 0.00001); a significant pressure increase from supine to standing positions (p < 0.0001). Also, it showed that pressure tended to decrease when leg circumference increased. Overall, pressure applied by elastic compression bandages varies with subject morphology, bandage mechanical properties and application technique. A better knowledge of the impact of these parameters on the applied pressure may lead to a more effective treatment.

Neuroenhancement of the aging brain: restoring skill acquisition in old subjects.

OBJECTIVE: Decline in cognitive functions, including impaired acquisition of novel skills, is a feature of older age that impacts activities of daily living, independence, and integration in modern societies. METHODS: We tested whether the acquisition of a complex motor skill can be enhanced in old subjects by the application of transcranial direct current stimulation (tDCS) to the motor cortex. RESULTS: The main finding was that old participants experienced substantial improvements when training was applied concurrent with tDCS, with effects lasting for at least 24 hours. INTERPRETATION: These results suggest noninvasive brain stimulation as a promising and safe tool to potentially assist functional independence of aged individuals in daily life.

Disentangling motor execution from motor imagery with the phantom limb.

Amputees can move their phantom limb at will. These 'movements without movements' have generally been considered as motor imagery rather than motor execution, but amputees can in fact perform both executed and imagined movements with their phantom and they report distinct perceptions during each task. Behavioural evidence for this dual ability comes from the fact that executed movements are associated with stump muscle contractions whereas imagined movements are not, and that phantom executed movements are slower than intact hand executed movements whereas the speed of imagined movements is identical for both hands. Since neither execution nor imagination produces any visible movement, we hypothesized that the perceptual difference between these two motor tasks relies on the activation of distinct cerebral networks. Using functional magnetic resonance imaging and changes in functional connectivity (dynamic causal modelling), we examined the activity associated with imagined and executed movements of the intact and phantom hands of 14 upper-limb amputees. Distinct but partially overlapping cerebral networks were active during both executed and imagined phantom limb movements (both performed at the same speed). A region of interest analysis revealed a 'switch' between execution and imagination; during execution there was more activity in the primary somatosensory cortex, the primary motor cortex and the anterior lobe of the cerebellum, while during imagination there was more activity in the parietal and occipital lobes, and the posterior lobe of the cerebellum. In overlapping areas, task-related differences were detected in the location of activation peaks. The dynamic causal modelling analysis further confirmed the presence of a clear neurophysiological distinction between imagination and execution, as motor imagery and motor execution had opposite effects on the supplementary motor area-primary motor cortex network. This is the first imaging evidence that the neurophysiological network activated during phantom limb movements is similar to that of executed movements of intact limbs and differs from the phantom limb imagination network. The dual ability of amputees to execute and imagine movements of their phantom limb and the fact that these two tasks activate distinct cortical networks are important factors to consider when designing rehabilitation programmes for the treatment of phantom limb pain.

The moving phantom: motor execution or motor imagery?

Amputees who have a phantom limb often report the ability to move this phantom voluntarily. In the literature, phantom limb movements are generally considered to reflect motor imagery rather than motor execution. The aim of this study was to investigate whether amputees distinguish between executing a movement of the phantom limb and imagining moving the missing limb. We examined the capacity of 19 upper-limb amputees to execute and imagine movements of both their phantom and intact limbs. Their behaviour was compared with that of 18 age-matched normal controls. A global questionnaire-based assessment of imagery ability and timed tests showed that amputees can indeed distinguish between motor execution and motor imagery with the phantom limb, and that the former is associated with activity in stump muscles while the latter is not. Amputation reduced the speed of voluntary movements with the phantom limb but did not change the speed of imagined movements, suggesting that the absence of the limb specifically affects the ability to voluntarily move the phantom but does not change the ability to imagine moving the missing limb. These results suggest that under some conditions, for example amputation, the predicted sensory consequences of a motor command are sufficient to evoke the sensation of voluntary movement. They also suggest that the distinction between imagined and executed movements should be taken into consideration when designing research protocols to investigate the analgesic effects of sensorimotor feedback.

Concurrent validation of a magnetometer-based step counter in various walking surfaces.

BACKGROUND AND AIM: Clinicians need a simple method for quantifying gait activity. The aim of this study was to develop and validate the reliability of a quantitative gait assessment based exclusively on one magnetometer located on the shank. METHODS: Twenty-five healthy volunteers were simultaneously equipped with a magnetometer (MAG system) on the right shank, and two validated step-counter systems: the StepWatch Activity Monitor (SAM) and three Force-Sensing Resistors (FSRs). Volunteers performed a standard circuit including level walking, up and down stairs and up and down a slope. The three step counting approaches were compared using the Pearson correlation coefficient and the Bland-Altman method for each of the surface-types. RESULTS: The step counts measured by the MAG and FSR were highly correlated for all the surfaces (r>.83). Congruently, the Bland-Altman analysis revealed an overall ± 5% limit of agreement. The step counts measured by the MAG and SAM were also well correlated for the level-surface condition (r=.85), with a Bland-Altman ± 5% limit of agreement but comparisons were less satisfying for the other surfaces. CONCLUSIONS: These results demonstrate that the use of a single magnetometer is an accurate tool for step counting over varied surfaces. These small sensors are easy to set up and to use and the signal processing is robust, making the MAG method highly applicable for clinical purposes, especially for the analysis of long walking periods in daily life conditions.