A randomized controlled trial on the effects induced by robot-assisted and usual-care rehabilitation on upper limb muscle synergies in post-stroke subjects.

Muscle synergies are hypothesized to reflect connections among motoneurons in the spinal cord activated by central commands and sensory feedback. Robotic rehabilitation of upper limb in post-stroke subjects has shown promising results in terms of improvement of arm function and motor control achieved by reassembling muscle synergies into a set more similar to that of healthy people. However, in stroke survivors the potentially neurophysiological changes induced by robot-mediated learning versus usual care have not yet been investigated. We quantified upper limb motor deficits and the changes induced by rehabilitation in 32 post-stroke subjects through the movement analysis of two virtual untrained tasks of object placing and pronation. The sample analyzed in this study is part of a larger bi-center study and included all subjects who underwent kinematic analysis and were randomized into robot and usual care groups. Post-stroke subjects who followed robotic rehabilitation showed larger improvements in axial-to-proximal muscle synergies with respect to those who underwent usual care. This was associated to a significant improvement of the proximal kinematics. Both treatments had negative effects in muscle synergies controlling the distal district. This study supports the definition of new rehabilitative treatments for improving the neurophysiological recovery after stroke.

WITHDRAWN: Assessment of the inter-laboratory repeatability of gait analysis measurements in patients with multiple sclerosis.

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Differential actigraphy for monitoring asymmetry in upper limb motor activities.

Most applications of accelerometry-based actigraphy require a single sensor, properly located onto the body, to estimate, for example, the level of activity or the energy expenditure. Some approaches adopt a multi-sensor setup to improve those analyses or to classify different types of activity. The specific case of two symmetrically placed actigraphs allowing, by some kind of differential analysis, for the assessment of asymmetric motor behaviors, has been considered in relatively few studies. This article presents a novel method for differential actigraphy, which requires the synchronized measurements of two triaxial accelerometers (programmable eZ430-Chronos, Texas Instruments, USA) placed symmetrically on both wrists. The method involved the definition of a robust epoch-related activity index and its implementation on-board the adopted programmable platform. Finally, the activity recordings from both sensors allowed us to define a novel asymmetry index AR24 h ranging from -100% (only the left arm moves) to +100% (only the right arm moves) with null value marking a perfect symmetrical behavior. The accuracy of the AR24 h index was 1.3%. Round-the-clock monitoring on 31 healthy participants (20-79 years old, 10 left handed) provided for the AR24 h reference data (range -5% to 21%) and a fairly good correlation to the clinical handedness index (r = 0.66, p < 0.001). A subset of 20 participants repeated the monitoring one week apart evidencing an excellent test-retest reliability (r = 0.70, p < 0.001). Such figures support future applications of the methodology for the study of pathologies involving motor asymmetries, such as in patients with motor hemisyndromes and, in general, for those subjects for whom a quantification of the asymmetry in daily motor performances is required to complement laboratory tests.

Does gait analysis change clinical decision-making in poststroke patients? Results from a pragmatic prospective observational study.

BACKGROUND: Gait analysis (GA) was demonstrated to change presurgical planning and improve gait outcomes in children with Cerebral Palsy. GA is often used also to assess walking capability of poststroke subjects, although its influence in the clinical management of these patients has not yet been established. OBJECTIVE: To assess the impact of GA on clinical decision-making in adult chronic poststroke patients. DESIGN: Pragmatic prospective observational study. SETTING: Rehabilitation hospital, both outpatients and inpatients. POPULATION: Forty-nine patients (age: 53.3±14.5 years) who had had a cerebrovascular accident 35.2±26.4 months before and were referred to the gait analysis service. METHODS: Recommendations of therapeutic treatments before and after the analysis of GA data were compared, together with the confidence level of recommendations on a 10-point scale. Frequency of changes of post-GA vs pre-GA recommendations were computed for each recommendation type: surgery, botulinum toxin (BT), orthotic management and physiotherapy. RESULTS: Based on the analysis of GA data, 71% of poststroke subjects had their treatment planning changed in some components. Indeed, 73% of patients with indications for surgery had their surgical planning changed; 81%, 37% and 32% had, respectively, their BT, orthotic and physiotherapy planning changed. Confidence level of recommendations increased significantly after GA, in both the whole group of patients (from 6.7±1.4 to 8.7±0.6, P<0.01) and the subgroup whose recommendations had not changed (7.0±1.5 vs. 8.8±0.4, P<0.01). CONCLUSION: GA significantly influences the therapeutic planning and reinforces decision-making for chronic poststroke patients. Further work should be done to better translate GA results into indications for specific physiotherapy. CLINICAL REHABILITATION IMPACT: The use of GA as a tool to better define the rehabilitation planning in post-stroke patients should be fostered, particularly when surgery or botulinum toxin are considered and/or the prescription of orthoses is hypothesised.

Postural stabilization and balance assessment in Charcot-Marie-Tooth 1A subjects.

The aim of the present study was to assess postural stabilization skill in adult subjects affected by Charcot-Marie-Tooth disease (CMT) type 1A. For this purpose ground reaction force (GRF) was measured by means of a piezoelectric force platform during the sit-to-stand (STS) movement, until a steady state erect posture was achieved. Specific indexes to quantify Centre of Mass acceleration, both during postural stabilization and during quiet standing, were computed using a mathematical model. Forty-seven CMT1A subjects were recruited for the study, and the control group was formed by forty-one age- and sex-matched healthy subjects. The results show that CMT1A subjects are less stable than controls during the quiet stance. Greater difficulty (high values of Yinf, the final instability rate) to maintain erect posture appears to be mainly associated with plantar-flexor muscle weakness, rather than to damage of the proprioceptive system. The worst performances shown by CMT1A subjects in the stabilization phase (high values of I, the global index of postural stabilization performance) seem to be associated with reduced muscle strength and the loss of large sensory nerve fibres. Distal muscle weakness appears to affect both postural stabilization and quiet erect posture. The presented protocol and the analysis of postural stabilization parameters provide useful information on CMT1A balance disorders.

Correlation among lesion level, muscle strength and hand function in cervical spinal cord injury.

BACKGROUND: Few epidemiological data are available regarding distribution of cervical spinal cord injury with respect to level of lesion and the relationship between the neurological level of lesion and residual hand function. Such data are important to evaluate the relevance of innovative therapeutic approaches, and to plan prospective clinical trials. AIM: To examine the frequency distribution of neurological level of lesion and to investigate the correlation among level, active muscles in the arm and the relation to hand function. DESIGN: Cross-sectional study. SETTING: Two spinal units in the Lombardy region of Italy. POPULATION: Patients with cervical spinal cord lesion. METHODS: Consecutive records, taken from an 8-year interval of admission to either spinal unit, of patients with a cervical spinal cord lesion were examined, and individuals with a C5 to C7 neurological level of lesion were called in for clinical examination. The arm muscles were evaluated according to the International Classification for Surgery of the Hand in Tetraplegia (ICSHT), and hand function was tested with the Action Research Arm Test (ARAT). A correlation analysis was made of the ICSHT, ARAT and neurological level of lesion. RESULTS: In 253 clinical records we found the most frequent lesions to be C5 (21%), C6 (31%) and C7 (21%); 76 of these patients were enrolled for a clinical evaluation. Both ICSHT (Spearmans' rho=0.6; P<0.001) and ARAT (rho=0.2; P<0.05) were poorly correlated with the neurological level of lesion. ARAT was also poorly correlated with the ICSHT group (rho=0.5; P<0.001). CONCLUSION: Our study suggests that 73% of tetraplegic subjects have a neurological level of lesion between C5 and C7, and that it is not possible to accurately predict residual hand function from the level of lesion obtained from the clinical records, or from an ICSHT evaluation. CLINICAL REHABILITATION IMPACT: The results of our work show that a large number of patients with cervical spinal cord lesion have impaired hand function. Residual hand function must be assessed with specific functional tests; it cannot be derived simply from a lesion's neurological level.

Myoelectrically driven functional electrical stimulation may increase motor recovery of upper limb in poststroke subjects: a randomized controlled pilot study.

The objective of this randomized controlled pilot study was to assess the feasibility and effectiveness of myoelectrically controlled functional electrical stimulation (MeCFES) for rehabilitation of the upper limb in poststroke subjects. Eleven poststroke hemiparetic subjects with residual proximal control of the arm, but impaired volitional opening of the paretic hand, were enrolled and randomized into a treated and a control group. Subjects received 3 to 5 treatment sessions per week until totaling 25 sessions. In the experimental group, myoelectric activity from wrist and finger extensors was used to control stimulation of the same muscles. Patients treated with MeCFES (n = 5) had a significant (p = 0.04) and clinically important improvement in Action Research Arm Test score (median change 9 points), confirmed by an Individually Prioritized Problem Assessment self-evaluation score. This improvement was maintained at follow-up. The control group did not show a significant improvement (p = 0.13). The reduced sample size of participants, together with confounding factors such as spontaneous recovery, calls for larger studies to draw definite conclusions. However, the large and persistent treatment effect seen in our results indicate that MeCFES could play an important role as a clinical tool for stroke rehabilitation.

Gait pattern classification in children with Charcot-Marie-Tooth disease type 1A.

Gait pattern classification may assist in clinical decision making and cluster analysis (CA) has been often adopted to this aim. The goal of this study was to identify, through CA, typical walking patterns in a group of 21 young subjects with CMT1A, a hereditary progressive neuropathy, and to study possible correlation with the disease's clinical status. The protocol included kinematic/kinetic analysis of natural walking and more demanding locomotor tasks, i.e. toe- and heel-walking. Hierarchical cluster analysis was carried out on parameters related to primary signs (foot-drop and push-off deficit) and, separately, to compensatory mechanisms at proximal (pelvis, hip and knee) or distal (ankle) level. CA on primary signs during natural walking identified three clusters: (1) pseudo-normal patients (PN), not significantly different from controls; (2) patients showing only foot-drop (FD); (3) patients with foot-drop and push-off deficit (FD&POD). Patients belonging to the PN subgroup showed distal abnormalities during heel-walking. The FD&POD subgroup was associated to a significantly worse clinical score (CMTES, p<0.05). The main compensatory strategies, which occurred independently from primary clusterization, included augmented hip/knee flexion in swing (steppage) and early ankle plantarflexion at mid stance (vaulting). We concluded that, although a number of young CMT1A patients do not show typical primary deviations during natural walking, they do show significant abnormalities in more demanding locomotor tasks that should be therefore considered. It is also hypothesized that progression of this degenerative condition may be associated to the migration of patients to more severe clusters, with possible appearance of compensatory strategies.

Reliability of instrumented movement analysis as outcome measure in Charcot-Marie-Tooth disease: results from a multitask locomotor protocol.

Some neurodegenerative diseases at early stage may not drastically affect basic gait ability, whereas more demanding locomotor tasks are more prone to disease-induced abnormalities. In this study, we evaluated the interday test-retest reliability, 4-6 weeks apart, of instrumented movement analysis on a group of 20 subjects with Charcot-Marie-Tooth (CMT) disease considering a set of kinematic and kinetic curves and related parameters obtained during natural walking (NW) and faster walking, heel and toe-walking, step ascending and descending. Results showed that the reliability was good for NW, with the exception of trunk curves, pelvic tilt and EMG profiles (moderate reliability), and trunk ROM in sagittal/transverse plane (poor reliability). Comparing our results with literature, CMT patients did not present a greater variability during NW than healthy subjects or patients with diseases of CNS. Additional locomotor tasks showed a slight reduction of reliability, although the moderate-to-good level shown in NW was almost never reduced to poor. Most of SEM values (absolute measurement errors) were smaller than 5°, a clinically acceptable threshold. In particular THS, an ankle joint related parameter computed across heel and toe-walking tasks, showed an optimal reliability (ICC=0.95, SEM=2.7°) and correlation with CMT clinical scores. Toe and heel-walking and step ascending tasks maximised the number of parameters with a moderate-to-good correlation with patients' clinical status. We concluded that, in addition to natural walking, more challenging locomotor tasks are good candidates to provide reliable and sensitive outcome measures for CMT patients.

Levodopa effect on electromyographic activation patterns of tibialis anterior muscle during walking in Parkinson's disease.

Previous studies have reported that patients with Parkinson's disease (PD) show, in the "off medication" state, a reduced activation of tibialis anterior (TA) in the late swing-early stance phase of the gait cycle. In PD patients the pathophysiological picture may cause differences among the stride cycles. Our aims were to evaluate how frequently TA activity is reduced in the late swing-early stance phase and if there is a relationship between the TA pattern and the clinical picture. Thirty PD patients were studied 2 h after Levodopa administration ("on-med") and 12 h after Levodopa wash-out ("off-med"). They were evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS III) and surface electromyography of TA and gastrocnemius medialis (GM). The root mean square (RMS) of the TA activity in late swing-early stance phase (RMS-A) was normalized as a percent of the RMS of the TA activity in late stance-early swing (RMS-B). RMS-A was reduced in 30% of patients in the "off-med" condition. Within these patients, the percentage of stride cycles with reduced RMS-A, ranged between 28% and 83%. After Levodopa intake, no stride cycle showed reduced RMS-A. Patients with reduced RMS-A had a lower UPDRS III total score in the "on-med" rather than in the "off-med" condition (p=0.02). Our data confirm and extend previous observations indicating that, in "off-med" the function of TA is impaired in those patients clinically more responsive to Levodopa. TA activation is reduced in a relatively high percent of gait cycles in the "off-med" state. Since the variability of TA activation disappears after Levodopa administration, this phenomenon could be the expression of an abnormal dopaminergic drive.

[Evaluation of work-related biomechanical overload: techniques for the acquisition and analysis of surface EMG signal]. / Tecniche di acquisizione ed analisi del segnale elettromiografico per lo studio del sovraccarico biomeccanico occupazionale.

OBJECTIVES: The aim of this research was to obtain information concerning muscle fatigue and muscle activation levels by measuring quantitative parameters through the surface electromyographic signal, and use such information to integrate the OCRA (Occupational Repetitive Actions) method for risk assessment of upper limb biomechanical overload Along with the main risk factors associated with the development of work-related upper limb musculoskeletal disorders (UL WMSDs) like posture, movement, frequency of action and organizational factors, this method also takes into account the muscular effort. Unlike the other risk factors that can be directly measured during inspections on farms, muscular effort is currently estimated only via a subjective assessment scale (Borg CR-10 scale). METHODS: A new apparatus and new procedures were implemented for synchronized EMG and video acquisition, which guarantee a high degree of inter- and intra-subject repeatability, and an ad hoc software for data elaboration was developed They have been specifically designed for "on the field" applications. The methodology was first tested in the laboratory on a group of 12 healthy subjects, studying a repetitive task, running in two different ways, (high/low OCRA index) and interspersed with isometric tests for an indirect measurement of dynamic fatigue. The methodology was then tested in a working environment to compare the muscular effort required during the use of different types of tools for pruning. RESULTS: Results of the laboratory protocol showed onset of fatigue for Anterior Deltoid, Middle Deltoid and Brachial Triceps muscles only for the high-risk index mode, as demonstrated by the significance of the Bonferroni tests (p < 0.05) on MDF (Median Frequency) calculated from isometric tests. They also showed significant differences in terms of higher level of muscle activation, and thus required force, in the case of high OCRA index work task compared to the one at low risk (Wilcoxon, p < 0.05) for all analysed muscle groups with regard to 10th, 50th and 90th percentile of the APDF (Amplitude Probability Distribution Function). These results clearly defined the differences of subjectively perceived effort. The results of field" application showed that the tested protocol was also easily exportable to a real working environment and that the numerical parameters extracted from the EMG signal can be a useful tool for evaluating effort levels of different muscles of the upper limb and for comparing different work tools, through effort indexes referred to single muscles. CONCLUSIONS: It can therefore be concluded that by integrating the information about the 'FORCE' factor in the OCRA method, the calculated parameters may provide objective information useful in analyzing and designing ergonomic tools and workplaces.

Functional resources to increase gait speed in people with stroke: strategies adopted compared to healthy controls.

Thirty-nine adult individuals with stroke in the stable phase were asked to walk at their preferred speed and then as fast as possible. A set of gait indexes were computed, including spatial temporal parameters, ankle and hip mechanical work, and timing of ankle push-off onset, for comparison with normal velocity-dependent profiles. Algorithms were used to classify the resulting gait patterns when the patients walked at their preferred speed and fast and to identify the patients' strategies to maximise speed. Patients' strategies were characterised by a variation in the parameters, which were reduced, equal or increased, in relation to normal patterns. At both speeds, stroke individuals tended to walk at higher cadence and with shorter stride length. At the preferred speed the investigated parameters for all patients were mostly within the normal profile (71.8-94.9%). The exception was the finding of positive work at the ankle where 64% of the stroke individuals showed reduced work production. At fast speed (increments to 36%BH/s) fewer patients presented values within the normal profile for all the parameters (17.9-74.4%), with the exception of negative work at the ankle and hip. The parameter variations showed a more consistently abnormal picture. The results indicate that, in order to increase gait speed, patients with hemiparesis have different functional resources on which to draw, and these vary from individual to individual. Thus, gait analysis at different gait speed should be adopted to develop individualised programs that will improve quality of life for the patients.

Influence of basal ganglia on upper limb locomotor synergies. Evidence from deep brain stimulation and L-DOPA treatment in Parkinson's disease.

Clinical evidence of impaired arm swing while walking in patients with Parkinson's disease suggests that basal ganglia and related systems play an important part in the control of upper limb locomotor automatism. To gain more information on this supraspinal influence, we measured arm and thigh kinematics during walking in 10 Parkinson's disease patients, under four conditions: (i) baseline (no treatment), (ii) therapeutic stimulation of the subthalamic nucleus (STN), (iii)L-DOPA medication and (iv) combined STN stimulation and L-DOPA. Ten age-matched controls provided reference data. Under baseline conditions the range of patients' arm motion was severely restricted, with no correlation with the excursion of the thigh. In addition, the arm swing was abnormally coupled in time with oscillation of the ipsilateral thigh. STN stimulation significantly increased the gait speed and improved the spatio-temporal parameters of arm and thigh motion. The kinematic changes as a function of gait speed changes, however, were significantly smaller for the upper than the lower limb, in contrast to healthy controls. Arm motion was also less responsive after L-DOPA. Simultaneous deep brain stimulation and L-DOPA had additive effects on thigh motion, but not on arm motion and arm-thigh coupling. The evidence that locomotor automatisms of the upper and lower limbs display uncorrelated impairment upon dysfunction of the basal ganglia, as well as different susceptibility to electrophysiological and pharmacological interventions, points to the presence of heterogeneously distributed, possibly partially independent, supraspinal control channels, whereby STN and dopaminergic systems have relatively weaker influence on the executive structures involved in the arm swing and preferential action on those for lower limb movements. These findings might be considered in the light of phylogenetic changes in supraspinal control of limb motion related to primate bipedalism.

Effect of L-dopa and subthalamic nucleus stimulation on arm and leg swing during gait in Parkinson's Disease.

The effects of subthalamic nucleus (STN) stimulation and L-dopa administration on the arm and leg swing movements associated with overground walking were studied in a group of patients with idiopathic Parkinson's disease (PD). Ten patients undergoing deep brain stimulation and twenty controls were tested using 3D kinematic motion analysis. Parkinsonian patients under basal conditions walked more slowly and with reduced arm and leg swing compared to controls. Moreover, they displayed significant impairments of the normal interlimb coordination. Both STN stimulation and L-dopa increased the walking speed and the amplitude of arm and leg swing movements. Additional improvements of the coordination between upper and lower limb were documented by reductions of the phase-shift between arm and ipsilateral leg motion, with displacement toward the control range (perfect counterphase). STN stimulation alone and L-dopa alone produced similar effects on the variables analyzed. The combination of the two treatments, instead, yielded additive effects on the gait speed and a slight increase of the upper and lower limb range of motion, in the absence of further improvements in the inter-segmental coordination. Moreover, whereas the increased arm swing could be accounted by the sole adoption of a higher gait speed, both the increment of the leg movement amplitude and the decreased interlimb phase shift appeared to imply an additional effect, possibly related to the treatment. These results may suggest that differential supraspinal controls operate on the neural networks subserving upper and lower limb motion during human walking.

The association between impaired turning and normal straight walking in Parkinson's disease.

Turning whilst walking was investigated by gait analysis in a group of Parkinson's Disease (PD) patients with mild clinical impairment and no significant abnormalities in stride parameters and kinematics of steady-state, linear walking. Comparison with age-matched controls demonstrated that patients approached turns with a slower step and completed turning with a greater number of steps. Moreover, the normal cranio-caudal sequence, whereby rotation of the head toward the intended direction of travel is followed by rotation of the trunk, was replaced by nearly simultaneous rotation of head and trunk and decreased relative head excursion after the second turning step. The evidence of abnormal inter-segmental coordination during turning in mildly affected, normally walking patients suggests that task-specific pathophysiological mechanisms, not necessary related to basic locomotor deficits, underlie disturbed directional changes in PD. Furthermore, turning-related neural systems may be more vulnerable to functional impairments associated with PD, as compared with linear walking. Hierarchically higher control levels involved in the turning ability may explain the observed unexpected association.

Impact of subthalamic nucleus stimulation on the initiation of gait in Parkinson's disease.

The effects of subthalamic nucleus (STN) stimulation on the anticipatory postural actions associated with the initiation of gait were studied in ten patients with idiopathic Parkinson's disease undergoing therapeutic deep brain stimulation. Kinematic, dynamic and electromyographic analysis was performed before and while subjects were starting gait in response to an external cue. Effects of STN stimulation on the standing posture preceding the go signal included significant improvement of the vertical alignment of the trunk and shank, decrease of the hip joint moment, backward shift of the center of pressure (CoP) and reduction of abnormal tonic and/or rhythmic activity in the thigh and leg muscles. Responses to bilateral STN stimulation were more consistent than those evoked by unilateral stimulation. Moreover, comparison between postural changes induced by STN stimulation applied prior to the gait initiation cue and during simple quiet standing revealed more significant responses in the former condition. Effects on the actual gait initiation process included shortening of the imbalance phase, larger backward/lateral displacement of CoP and more physiological expression of the underlying anticipatory muscular synergy. Additional changes were shortening of the unloading phase, shortening of the first-swing phase and increase in the length of the first step. Results demonstrate substantial influence of STN stimulation on functionally basic motor control mechanisms. In particular, the evidence of more significant responses upon attention-demanding conditions and the remarkable effects on postural programmes sub-serving feed-forward regulation of the onset of complex multijoint movements, suggests a consistent action on postural sub-systems relying on cognitive data processing and internal models of body mechanics.

Experimental protocol for the kinematic analysis of the hand: definition and repeatability.

A quantitative and objective method based on the optoelectronic kinematic analysis of hand segments and on the calculation of global and partial parameters, which provide measures of the degree of long finger and thumb extension is proposed for the evaluation of the hand's voluntary range of motion and maximal opening of the fingers and thumb. To test the precision and repeatability of the method, the protocol was applied on 14 healthy subjects (28 hands). The proposed parameters are repeatable and show a precision between 5.5 degrees and 10.4 degrees (mean value: 7.3 degrees), comparable to values obtained with other methods. Advantages of the present approach include simultaneous analysis of all fingers, absence of cumbersome connecting cables and no need for individually customized devices. The method, also applied to the paretic hands of two hemiplegic stroke patients before and after electrical stimulation of the wrist and finger extensor muscles, has shown encouraging results for its clinical feasibility and utility in addition to functional tests.

Locomotor disorders in patients at early stages of Parkinson's disease: a quantitative analysis.

Several studies have been performed with automatic motion analysis techniques to investigated the locomotor disorders of patients with severe Parkinson's disease (PD). These are mainly related to steady-state walking. Aim of the present study was to investigate the presence and the degree of these disorders in patients at early stages of PD. For this purpose a group of patients with mild PD (H&Y < or =2) and a group of age-matched controls were assessed by means of multifactorial analysis of kinematic and kinetic variables, during the execution of the following motor tasks: steady-state walking, gait initiation and turning around an obstacle. Results showed that PD patients did not differ from controls in steady-state walking, while significant differences emerged in gait initiation and turning strategies. Main differences consisted in a limitation of the amplitude of the imbalance phase and of the first step, and, for the turning task, in a delayed initiation of the turning movement, with an altered head-trunk rotational strategy. It is concluded that patients in early stages of PD do not reveal, during steady state walking, consistent impairments of kinematic and kinetic patterns typical of severe PD patients. Nevertheless, they present significant alterations in transient conditions such as gait initiation and change of walking direction. The above results suggest that a quantitative analysis of locomotor tasks which imply the transition from one condition to another, could provide parameters useful for the characterization of early stage PD patients and, potentially, markers for a precox differential diagnosis respect other neurodegenerative diseases characterized by parkinsonisms.

Trans-femoral amputee gait: socket-pelvis constraints and compensation strategies.

The paper deals with the identification of motor strategies adopted by trans-femoral amputees to compensate for the constraints of hip motion induced by the interference of the socket with the pelvis and, particularly, with the ischial tuberosity. A group of 11 subjects with trans-femoral amputation, three of whom wore two different prostheses, giving a sample size of 14 cases, were studied by gait-analysis protocols: the present paper focuses on the pelvis-thigh kinematics at foot strike. The results showed that, at the prosthetic side, the hip is significantly less flexed and less extended, respectively, at the ipsilateral and contralateral foot strike. Moreover, the pelvis is significantly more anterior tilted at sound foot strike. The anterior step length showed a decreased sound limb anterior step in 12 out of 14 cases. The authors interpret these results as a combination of mechanical constraints and compensatory actions: the reduced prosthetic hip extension is determined by the mechanical constraint involved in the pelvis-socket interference; and the increased pelvis tilt and sound hip flexion occurring at the same time are compensating strategies, adopted by the amputees, in order to obtain a functional step length and symmetrical thigh inclinations. Those factors determine a gait pattern which is functional, only slightly slower than normal gait, and without any perceivable alterations. On the other hand, the authors show that the increased pelvis tilting necessarily overloads the lumbar tract of the spine and may be related to the frequent occurrence of low-back pain in amputee subjects, despite the positive functional gait recovery.

Procedure for the quantitative evaluation of motor disturbances in cerebellar ataxic patients.

Cerebellar ataxia is a complex motor disturbance that involves the planning and execution of movements and reduces movement accuracy and co-ordination. The quantification of ataxic signs is commonly realised through visual examination of motor tasks performed by the patient and assignment of scores to specific items composing the international co-operative ataxia rating scale (ICARS). The present work studied an experimental procedure to characterise specific aspects of motor disturbances in ataxia objectively. Four tests belonging to the ICARS were considered: walking, knee-tibia test, finger-to-nose and finger-to-finger test. Through a kinematic analysis performed during the above tests, specific indices were defined to quantify velocity, linearity, asymmetry, tremor, instability and smoothness of movement or posture. The procedure was applied to five patients with cerebellar ataxia and to ten healthy adult subjects. Results demonstrated that the patients moved significantly more slowly than the healthy subjects (0.67 against 0.97m s(-1) and 0.81 against 1.02 m s(-1), respectively, for straight walk and finger-to-nose tests) and showed poorer linearity and smoothness behaviour. Velocity, linearity, tremor, smoothness and instability indices showed moderate to good correlation with the corresponding ICARS score. Some of these indices can separately evaluate aspects that are combined in single ICARS subscores. It is concluded that the combination of clinical assessments and instrumental evaluations allows a better insight into ataxic patients' motor disturbances and is a useful tool for the definition and follow-up of rehabilitation programmes.