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Facilitation of leg muscle activity by active arm movements during locomotor tasks could be beneficial during gait rehabilitation after spinal cord injury. The present study explored the effects of arm movements on leg muscle activity during submaximal recumbent stepping. Healthy subjects exercised on a recumbent stepping machine both with and without arm movements. Activity of five leg muscles was recorded and compared for stepping with and without arm movements. To determine which arm movements are optimal for leg muscle facilitation, subjects were instructed to step with 1) mechanically coupled vs. decoupled arm and leg movements, 2) synchronous vs. asynchronous arm movements, and 3) at 50 vs. 70 RPM. Leg muscle activity was increased by active arm movements in all muscles, except the vastus lateralis muscle. Activity of other extensors (soleus, medial gastrocnemius, and biceps femoris) was primarily increased during the extension phase, whereas activity of flexors (tibialis anterior) was also increased during the flexion phase. Facilitation was more or less consistent for both frequencies and for synchronous and asynchronous movements. For coupled arm movements, facilitation tended to be diminished or absent. The observed facilitation in the present study is probably of neuromuscular rather than biomechanical origin, since the arms are probably hardly involved in postural control or weightbearing during recumbent stepping. Further studies in patients should explore the possibility to integrate neuromuscular facilitation in rehabilitation programs. [ABSTRACT FROM AUTHOR]

Background. The description of the natural course of recovery from a spinal cord injury (SCI) with spontaneous improvement of neurological, neurophysiological, and functional measures is an important prerequisite in appraising effects of upcoming interventional therapies. Objective. To describe the spontaneous evolution of motor-evoked potentials of the anterior tibial muscle (TA-MEP) and their relation to outcomes of lower extremity motor scores (LEMS) and walking function in patients recovering from an acute SCI. Methods. TA-MEPs were assessed in 255 SCI subjects within 5 time intervals throughout the first year after SCI with combined neurological and functional measures. Tibial nerve conduction studies were performed to screen for peripheral nerve damage. Results. TA-MEP allowed stratification of SCI according to lesion severity and outcome. As MEP amplitudes increased over 12 months after SCI, this was paralleled by a significant improvement of LEMS and walking function. TA-MEP latencies remained usually stable. Conclusion. Clinical outcome and walking function after SCI can be predicted independent of clinical measures by assessment of TA-MEP reflecting corticospinal tract integrity. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the neural basis of adaptation, memory and skill transfer during human stepping over obstacles. Whilst walking on a treadmill, subjects had to perform uni- and bilateral obstacle steps. Acoustic feedback information about foot clearance was provided. Non-noxious electrical stimuli were applied to the right tibial nerve during the mid-stance phase of the right leg, i.e. 'prior' to the right or 'during' the left leg swing over the obstacle. The electromyogram (EMG) responses evoked by these stimuli in arm and leg muscles are known to reflect the neural coordination during normal and obstacle steps. The leading and trailing legs rapidly adapted foot clearance during obstacle steps with small further changes when the same obstacle condition was repeated. This adaptation was associated with a corresponding decrease in arm and leg muscle reflex EMG responses. Arm (but not leg) muscle EMG responses were greater when the stimulus was applied 'during' obstacle crossing by the left leg leading compared with stimulation 'prior' to right leg swing over the obstacle. A corresponding difference existed in arm muscle background EMG. The results indicate that, firstly, the somatosensory information gained by the performance and adaptation of uni- and bilateral obstacle stepping becomes transferred to the trailing leg in a context-specific manner. Secondly, EMG activity in arm and leg muscles parallels biomechanical adaptation of foot clearance. Thirdly, a consistently high EMG activity in the arm muscles during swing over the obstacle is required for equilibrium control. Thus, such a precision locomotor task is achieved by a context-specific, coordinated activation of arm and leg muscles for performance and equilibrium control that includes adaptation, memory and skill transfer. [ABSTRACT FROM AUTHOR]

Abstract: In patients suffering an incomplete spinal cord injury (SCI) an improvement in walking function can be achieved by providing a functional training with an appropriate afferent input. In contrast, in immobilized incomplete and complete subjects a negative neuroplasticity leads to a neuronal dysfunction. After an SCI, neuronal centers below the level of lesion exhibit plasticity that either can be exploited by specific training paradigms or undergo a degradation of function due to the loss of appropriate input. Load- and hip-joint-related afferent inputs seem to be of crucial importance for the generation of a locomotor pattern and, consequently, the effectiveness of the locomotor training. In severely affected SCI subjects rehabilitation robots allow for a longer and more intensive training and can provide feedback information. Conversely, in severely affected chronic SCI individuals without functional training the locomotor activity in the leg muscles exhausts rapidly during assisted locomotion. This is accompanied by a shift from early to dominant late spinal reflex components. The exhaustion of locomotor activity is also observed in non-ambulatory patients with an incomplete SCI. It is assumed that in chronic SCI the patient''s immobility results in a reduced input from supraspinal and peripheral sources and leads to a dominance of inhibitory drive within spinal neuronal circuitries underlying locomotor pattern and spinal reflex generation. A training with an enhancement of an appropriate proprioceptive input early after an SCI might serve as an intervention to prevent neuronal dysfunction. [Copyright &y& Elsevier]

Background. Alterations in the function of spinal neuronal circuits underlying locomotion after a spinal cord injury (SCI) are associated with changes in the behavior of spinal reflexes (SRs) in both rats and humans. In healthy subjects, the SR consists of a dominant early reflex component, whereas in chronic, severely affected SCI subjects, a later component dominates. Objective. The aim of this study was to investigate the relationship between SR behavior and walking ability in para-/tetraplegic subjects. Method. The SR was evoked by nonnoxious tibial nerve stimulation. Walking ability was assessed by functional tests and questionnaires. Results. There was a correlation between walking ability and SR behavior in chronic SCI: Severely affected SCI subjects unable to walk showed dominant late SR components, whereas in ambulatory SCI subjects an early SR component dominated. A functional training with an improvement of locomotor ability was accompanied by both a shift from a dominant to a smaller late and the appearance of an early SR component. Conclusions. Our findings indicate that SR can serve as a marker for the locomotor ability of SCI subjects. Neuronal plasticity exploited by a functional training is reflected in both an improvement of locomotor ability and a change in balance of SR components toward the early SR component. [ABSTRACT FROM PUBLISHER]

During recent years, evidence has come up that bipedal locomotion is based on a quadrupedal limb coordination. A task-dependent neuronal coupling of upper and lower limbs allows one to involve the arms during gait but to uncouple this connection during voluntarily guided arm/hand movements. Hence, despite the evolution of a strong cortico-spinal control of hand/arm movements in humans, a quadrupedal limb coordination persists during locomotion. This has consequences for the limb coordination in movement disorders such as in Parkinson's disease (PD) and after stroke. In patients suffering PD, the quadrupedal coordination of gait is basically preserved. The activation of upper limb muscles during locomotion is strong, similar as in age-matched healthy subjects although arm swing is reduced. This suggests a contribution of biomechanical constraints to immobility. In post-stroke subjects a close interactions between unaffected and affected sides with an impaired processing of afferent input takes place. An afferent volley applied to a leg nerve of the unaffected leg leads to a normal reflex activation of proximal arm muscles of both sides. In contrast, when the nerve of the affected leg was stimulated, neither on the affected nor in the unaffected arm muscles EMG responses appear. Muscle activation on the affected arm becomes normalized by influences of the unaffected side during locomotion. These observations have consequences for the rehabilitation of patients suffering movement disorders. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the sensorimotor interactions between unaffected and affected sides of post-stroke subjects during locomotion. In healthy subjects, stimulation of the tibial nerve during the mid-stance phase is followed by electromyography responses not only in the ipsilateral tibialis anterior, but also in the proximal arm muscles of both sides, with larger amplitudes prior to swing over an obstacle compared with normal swing. In post-stroke subjects, the electromyography responses were stronger on both sides when the tibial nerve of the unaffected leg was stimulated compared with stimulation of the affected leg. This difference was more pronounced when stimuli were applied prior to swing over an obstacle than prior to normal swing. This indicates an impaired processing of afferent input from the affected leg resulting in attenuated and little task-modulated reflex responses in the arm muscles on both sides. In contrast, an afferent volley from the unaffected leg resulted in larger electromyography responses, even in the muscles of the affected arm. Arm muscle activations were stronger during swing over an obstacle than during normal swing, with no difference in electromyography amplitudes between the unaffected and affected sides. It is concluded that the deficits of the affected arm are compensated for by influences from the unaffected side. These observations indicate strong mutual influences between unaffected and affected sides during locomotion of post-stroke subjects, which might be used to optimize rehabilitation approaches. [ABSTRACT FROM AUTHOR]

This study investigated the interactions of supraspinal with spinal neuronal circuits during obstacle steps by recordings of electroencephalography (EEG), reflex activity and limb muscle electromyography (EMG). Subjects walking with reduced vision on a treadmill were acoustically informed about an approaching obstacle and received feedback about task performance. Only following a task-relevant acoustic signal, spinal reflex responses, evoked by tibial nerve stimulation during mid-stance, were enhanced in proximal arm and leg flexor muscles prior to obstacle compared to normal swing, reflecting the neuronal preparation of the task. During swing over the obstacle, limb muscle EMG activity was greater than in normal swing. Both the preparation and the performance (i.e. ascending movement slope of the obstacle-crossing leg) were associated with an enhanced EEG signal mainly in the prefrontal cortex of the right hemisphere. Adaptational changes in performance, reflex activity and muscle activation during repetitive obstacle stepping were not reflected in the EEG activity, probably due to an insufficient resolution of the EEG. The observations suggest that drive from supraspinal centers initiates and maintains spinal neuronal activity underlying obstacle task preparation and performance. [ABSTRACT FROM AUTHOR]

This short review summarizes developments and achievements made during the last few years in spinal neurology and includes all relevant papers published in the Journal of Neurology during this time. A focus of the review concerns the debate about the significance of translational medicine in spinal cord injury with the introduction of new drugs directed to achieve some spinal cord repairs. [ABSTRACT FROM AUTHOR]

This Review discusses the spinal neuronal changes that occur after a complete spinal cord injury (SCI) in humans. Early after an SCI, neither locomotor nor spinal reflex activity can be evoked. Once spinal shock has resolved, locomotor activity and an early spinal reflex component reappear in response to appropriate peripheral afferent input. In the subsequent 4-8 months, clinical signs of spasticity appear, largely as a result of non-neuronal (for example, muscular) changes, whereas locomotor and spinal reflex activity undergo little change. At 9-12 months, the electromyographic amplitude in the leg muscles during assisted locomotion declines, accompanied by a decrease in the amplitude of the early spinal reflex component and an increase in the amplitude of a late spinal reflex component. This exhaustion of locomotor activity also occurs in nonambulatory patients with incomplete SCI. Neuronal dysfunction is fully established 1 year after the injury without further alterations in subsequent years. In chronic SCI, the absence of input from supraspinal sources has been suggested to lead to degradation of neuronal function below the level of the lesion or, alternatively, a predominance of inhibitory signaling to the locomotor pattern generator. Appropriate training and/or provision of afferent input to spinal neurons might help to prevent neuronal dysfunction in chronic SCI. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to explore factors that influence the occurrence of the Babinski sign (BS) in complete spinal cord injury patients. At Balgrist University Hospital, Zurich, Switzerland, thirty-five subjects suffering from a complete traumatic spinal cord injury (ASIA A) were examined for the occurrence of the BS, tendon reflex excitability and spastic muscle tone (Modified Ashworth Scale). Five subjects were acute/subacute (1–6 months after spinal cord injury (SCI)), 30 were chronic (SCI > 1 year). In one subject, the measures were examined before and after injection of intrathecal Baclofen. Subjects with a negative BS were investigated electrophysiologically for possible peripheral nerve damage. In 17 subjects (49%), the BS was present, while it was absent in 18 subjects (51%). The occurrence of the BS did not depend on the level of lesion. Most patients with a positive BS also presented a high spastic muscle tone, while those with a negative BS showed low level or absent spastic muscle tone. In 11 SCI subjects, absence of the BS was associated with peripheral nerve damage. In one patient, the BS along with spastic signs disappeared after intrathecal injection of Baclofen. In complete SCI subjects, the occurrence of the BS is connected with spastic muscle tone. The absence of the BS is frequently due to associated peripheral nerve damage. [ABSTRACT FROM AUTHOR]

A large percentage of spinal cord-injured subjects suffer from neuropathic pain below the level of the lesion (bNP). The neural mechanisms underlying this condition are not clear. The aim of this study was to elucidate the general effects of spinal deafferentiation and of bNP on electroencephalographic (EEG) activity. In addition, the relationship between the presence of bNP and impaired function of the spinothalamic tract was studied. Measurements were performed in complete and incomplete spinal cord-injured subjects with and without bNP as well as in a healthy control group. Spinothalamic tract function, assessed by contact heat evoked potentials, did not differ between subjects with and without bNP; nevertheless, it was impaired in 94% of subjects suffering from bNP. In the EEG recordings, the degree of deafferentiation was reflected in a slowing of EEG peak frequency in the 6–12-Hz band. Taking into account this unspecific effect, spinal cord-injured subjects with bNP showed significantly slower EEG activity than subjects without bNP. A discrimination analysis in the subjects with spinothalamic tract dysfunction correctly classified 84% of subjects as belonging to either the group with bNP or the group without bNP, according to their EEG peak frequency. These findings could be helpful for both the development of an objective diagnosis of bNP and for testing the effectiveness of new therapeutic agents. [ABSTRACT FROM AUTHOR]

During evolution, the increased influence of a direct cortical–motoneuronal system in parallel with a more specialized hand function might have replaced phylogenetically older systems that organized locomotor movements. However, recent research indicates that interlimb coordination during human locomotion is organized in a way similar to that in the cat. During locomotion, corticospinal excitation of upper-limb motoneurons is mediated indirectly, via propriospinal neurons in the cervical spinal cord. This allows a task-dependent neuronal linkage of cervical and thoracolumbar propriospinal circuits controlling leg and arm movements during human locomotor activities. During obstacle avoidance steps, an anticipatory quadrupedal limb coordination is up-regulated, with an involvement of proximal arm muscles during the acquisition and performance of this precision locomotor task. [ABSTRACT FROM AUTHOR]

Patients with Parkinson’s disease (PD) have difficulties in performing complex bimanual movements. Here we have examined acquisition and performance of a bilateral obstacle stepping task to see whether these difficulties are also present during bipedal movements. Subjects had to minimize foot clearance when repeatedly stepping on a treadmill over randomly approaching obstacles on either side. The subjects had full vision and received acoustic feedback information about task performance. Foot clearance improved in healthy and PD subjects during the acquisition of the task. However, PD subjects showed a slower improvement and achieved a poorer performance level. Thus, in contrast to unilateral obstacle stepping, where no deficits in performance after task repetition were found in PD subjects, bilateral obstacle stepping was poorer in these subjects compared to healthy subjects. The present results extend findings from upper to lower limb movements, namely that PD subjects have difficulties in the performance of bilateral motor tasks. [ABSTRACT FROM AUTHOR]

Objective. This study assessed the validity and responsiveness of the Spinal Cord Independence Measure (SCIM II) items indoor mobility, mobility for moderate distances, and outdoor mobility. Methods. The data of 886 spinal cord injury subjects were derived from the European Multicenter Study for Human Spinal Cord Injury (EM-SCI) and analyzed at 2 weeks and 1, 3, 6, and 12 months after injury. The SCIM II items were compared using the preferred walking speed and the Walking Index for Spinal Cord Injury (WISCI II). The responsiveness to assess differences over time was determined. The analyses were performed for subjects with varying impairment scales according to the American Spinal Injury Association (ASIA). Results. An initially moderate correlation between walking capacity and the SCIM II mobility items improved to excellent at 6 and 12 months after injury. The correlations were higher for indoor mobility compared with outdoor mobility. These correlations increased in ASIA C, but decreased over time in ASIA D subjects. The SCIM II mobility items showed initially positive responsiveness in ASIA A and B subjects. In ASIA C and D subjects, SCIM II responsiveness was significant within the first 6 months. Conclusions. The SCIM II items assess mobility (wheelchair and walking) during daily life. They show good validity and responsiveness, including postdischarge. They can be considered appropriate for evaluating the efficacy of new interventions on ambulatory function. Depending on the severity of the initial lesion and time of assessment, clinically applied walking tests can accurately predict walking performance during daily life. [ABSTRACT FROM AUTHOR]

Background and Purpose. Robotic devices for walking rehabilitation allow new possibilities for providing performance-related information to patients during gait training. Based on motor learning principles, augmented feedback during robotic- assisted gait training might improve the rehabilitation process used to regain walking function. This report presents a method to provide visual feedback implemented in a driven gait orthosis (DGO). The purpose of the study was to compare the immediate effect on motor output in subjects during robotic-assisted gait training when they used computerized visual feedback and when they followed verbal instructions of a physical therapist. Subjects. Twelve people with neurological gait disorders due to incomplete spinal cord injury participated. Methods. Subjects were instructed to walk within the DGO in 2 different conditions. They were asked to increase their motor output by following the instructions of a therapist and by observing visual feedback. In addition, the subjects' opinions about using visual feedback were investigated by a questionnaire. Results. Computerized visual feedback and verbal instructions by the therapist were observed to result in a similar change in motor output in subjects when walking within the DGO. Subjects reported that they were more motivated and concentrated on their movements when using computerized visual feedback compared with when no form of feedback was provided. Discussion and Conclusion. Computerized visual feedback is a'valuable adjunct to robotic-assisted gait training. It represents a relevant tool to increase patients' motor output, involvement, and motivation during gait training, similar to verbal instructions by a therapist. [ABSTRACT FROM AUTHOR]

Background. This study investigated whether loading the legs during the swing phase of walking enhances flexor muscle activity in ambulatory patients with incomplete spinal cord injury (SCI).Methods. Nine patients had surface electromyography (EMG) and joint kinematics recorded from the lower extremities during treadmill walking. Swing phase loading of the legs was achieved by weights (1-3 kg) attached to each lower extremity or by a velocity-dependent resistance applied by the Lokomat robotic gait orthosis. Results. When patients walked with the weights, there was a consistent increase in the activity of the knee flexors and sometimes of hip or ankle flexor activity during swing. Similarly, when the robot applied the velocity-dependent resistance during walking, swing phase flexor EMG activity tended to be greater. Enhanced knee flexion was observed in all patients after the weights or the robot-generated resistance was removed. Conclusions. Flexor muscle activity during swing can be enhanced through additional proprioceptive input in patients with incomplete SCI with brief aftereffects. Further testing of this strategy is necessary to determine if it can improve the gait of ambulatory patients. [ABSTRACT FROM AUTHOR]

Summary: In clinical practice, signs of exaggerated tendon tap reflexes associated with muscle hypertonia are generally thought to be responsible for spastic movement disorders. Most antispastic treatments are, therefore, directed at the reduction of reflex activity. In recent years, however, researchers have noticed a discrepancy between spasticity as measured in the clinic and functional spastic movement disorders, which is primarily due to the different roles of reflexes in passive and active states, respectively. We now know that central motor lesions are associated with loss of supraspinal drive and defective use of afferent input with impaired behaviour of short-latency and long-latency reflexes. These changes lead to paresis and maladaptation of the movement pattern. Secondary changes in mechanical muscle fibre, collagen tissue, and tendon properties (eg, loss of sarcomeres, subclinical contractures) result in spastic muscle tone, which in part compensates for paresis and allows functional movements on a simpler level of organisation. Antispastic drugs can accentuate paresis and therefore should be applied with caution in mobile patients. [Copyright &y& Elsevier]

Motor evoked potential (MEP) amplitudes have the disadvantage of a high variability when repeatedly assessed. This affects the reliability of MEP amplitude measurements taken during the course of motor incomplete spinal cord injury (iSCI). The study investigated the reliability of anterior tibial (TA) MEP measures controlled for dorsal flexion torque and motor task. TA MEPs were recorded at 10, 20, 40 and 60% of maximal voluntary contraction (MVC) during a static and dynamic (isometric increase of dorsal flexion torque) motor task. To determine reliability, 20 healthy and five chronic iSCI subjects were tested twice (≥7 days) by the same investigator. Intraclass correlation coefficients (ICCs) were calculated. MEP amplitudes and latencies were compared between 20 healthy and 29 iSCI subjects. The reliability of MEP amplitude was in general good (ICC ≥ 0.52) and was highest during the static task at 40% MVC (ICC = 0.77). The increased facilitation by the dynamic motor task showed the best reliability at 20% MVC (ICC = 0.48). The reliability was good to excellent for MEP latency (0.46 ≤ ICC ≤ 0.81), MVC (ICC ≥ 0.90) and for the TMS threshold required to evoke a MEP response (ICC ≥ 0.77). The torque generated by the MEP response ()0.02 ≤ ICC ≤ 0.55) and the duration of the silent period (0.07 ≤ ICC ≤ 0.50) were not reliable. Both MEP amplitudes and latencies differed significantly between healthy and iSCI subjects. Controlling for torque generation and motor task establishes a reliability of TA MEP amplitudes that is sufficient for longitudinal assessments in motor incomplete SCI. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Responses to afferent input during locomotion are organized at the spinal level but modulated by supraspinal centers. The study aim was to examine whether supraspinal influences affect the behavior of complex electromyographic (EMG) responses to single limb perturbations during walking. Methods: Subjects with motor-complete (MCSCI), motor-incomplete spinal cord injury (MISCI), and non-disabled (ND) subjects participated. Hip or knee joint trajectory was briefly arrested by a robotic device at early or late swing phase. EMG responses from muscles of both legs were analyzed. Results: Perturbation-induced EMG responses of spinal cord injured and ND individuals were similar in basic structure, with the exception that tibialis anterior onset times were delayed for SCI subjects. Across all groups, perturbations in late swing (i.e., near the swing-to-stance transition) were associated with shorter muscle onset times and higher EMG amplitudes. Knee perturbations were associated with shorter muscle response onset times, while hip perturbations elicited higher response amplitudes. EMG responses were also evoked in muscles contralateral to the perturbation. Conclusions: These data indicate that neuronal circuits within the spinal cord deprived of normal supraspinal input respond to swing phase perturbations in a manner that is similar to that of the intact spinal cord. Significance: The adult human spinal cord is capable of generating complex, phase-appropriate responses much as has been observed in studies of human infants and in spinal animals. [Copyright &y& Elsevier]

Abstract: Wirz M, van Hedel HJ, Rupp R, Curt A, Dietz V. Muscle force and gait performance: relationships after spinal cord injury. Objectives: To relate locomotor function improvement, within the first 6 months after spinal cord injury (SCI), to an increase in Lower Extremity Motor Score (LEMS) and to assess the extent to which the level of lesion influenced the outcome of ambulatory capacity. Design: Longitudinal and cross-sectional analyses. Setting: Seven SCI rehabilitation centers. Participants: Patients (N=178) were analyzed longitudinally (group A, motor complete; group B, motor incomplete; nonwalking or group C, motor incomplete and able to stand). The cross-sectional analysis included 86 patients (paraplegic, n=46; tetraplegic, n=40; group 1 with limited and group 2 with unrestricted walking function 6mo after SCI). Interventions: Not applicable. Main Outcome Measures: Walking Index for Spinal Cord Injury (WISCI), gait speed, and LEMS. Results: For group A, 24.8% of the patients improved in LEMS (median range, 0–10) and 7.7% in walking function (WISCI median range, 0–8; mean gait speed range, 0 to .14±.10m/s). For group B, LEMS improved in 93.5% of the patients (median range, 14–28) and walking function in 84.8% of the patients (WISCI median range, 0–10; mean gait speed range, 0 to .41±.45m/s) (P<.001). For group C, LEMS and walking function improved in 100% of the patients (LEMS median range, 29–41; WISCI median range, 8–16; mean gait speed range, .36±.29m/s to .88±.44m/s) (P=.001). In groups B and C, the improvement of walking function was greater than in LEMS. The cross-sectional analysis showed that group 1 patients with tetraplegia had more muscle strength (median LEMS, 31.5), and equal walking function (WISCI, 8; walking speed, 0.4±0.3m/s) compared with patients with paraplegia (LEMS, 23; P<.01; WISCI, 12; P=0.6; speed, 0.4±0.3m/s; P=.68). In group 2, patients with tetraplegia had slightly more strength (LEMS, 48) and equal walking function (WISCI, 20; walking speed, 1.4±0.4m/s) compared with patients with paraplegia (LEMS, 45; P<.05; WISCI, 20; P=1.0; speed, 1.4±0.3m/s; P=.89). Conclusions: An improvement in locomotor function does not always reflect an increase in LEMS, and LEMS improvement is not necessarily associated with improved locomotor function. LEMS and ambulatory capacity are differently associated in patients with tetra- and paraplegia. Functional tests seem to complement clinical assessment. [Copyright &y& Elsevier]

Summary: During the past few years, several approaches to spinal-cord repair have been successfully established in animal models. For their use in trials of spinal-cord injury (SCI) in human beings, specific difficulties that affect the success of clinical trials have to be recognised. First, transection of the spinal cord is commonly applied in animal models, whereas contusion, which generally leads to injury in two to three segments, represents the typical injury mechanism in human beings. Second, the quadrupedal organisation of locomotion in animals and the more complex autonomic functions in human beings, challenge translation of animal behaviour into recovery from SCI in people. Third, the extensive damage of motor neurons and roots associated with spinal-cord contusion is not addressed in current translational studies. This damage has direct implications for rehabilitation strategies and functional outcome. Fourth, there is increasing evidence for a degradation of neuronal function below the level of the lesion in chronic complete SCI. The relevance of this degradation for a regeneration-inducing treatment needs to be investigated. Fifth, the prerequisites to enable appropriate reconnection of regenerating tract fibres in a postacute stage have still to be established. [Copyright &y& Elsevier]

We evaluated the acquisition and performance of a high-precision locomotor task in patients with Parkinson's disease (PD) and healthy subjects. All subjects walked on a treadmill and had to step repetitively as low as possible over an obstacle without touching it. During blocks 1 and 2, the subjects had full vision and received additional acoustic warning and feedback signals. During block 3, vision became restricted. Changes in foot clearance and the number of obstacle hits were evaluated. Initially, PD patients performed poorer and improved foot clearance slower. After task repetition, the groups performed similarly. Restricting vision deteriorated performance in both groups. The similar performance of PD patients after task repetition might indicate that adequate training could improve adaptive locomotor behavior in PD patients. © 2005 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Objectives To improve the diagnosis of damaged spinal motor pathways in incomplete spinal cord injury (iSCI) by assessing the facilitation of lower limbs motor evoked potentials (MEP). Methods Control subjects (n=12) and iSCI patients (n=21) performed static and dynamic isometric foot dorsiflexions. MEPs induced by transcranial magnetic v stimulation and EMG background of tibialis anterior muscle (TA) were analyzed. Static and dynamic muscle activation was performed at comparable levels of maximal voluntary contraction (MVC). The influence of the motor tasks on the excitability and facilitation of MEPs was compared between controls and iSCI patients. Results In the controls an increased facilitation of TA MEP at lower levels of dynamic compared with static activation (10–20% MVC) could be shown. At matched EMG background level the MEP responses were significantly increased. In the iSCI patients at a comparable level of TA activation the MEP responses were significantly reduced and 3 different patterns of MEP responses could be distinguished: i) preserved increment of TA MEP in the dynamic motor task, ii) unchanged MEP size in the dynamic and static motor task, and iii) elicitable MEPs in the dynamic motor task, which were abolished in the static motor task. Conclusions Static and dynamic motor tasks have different effects on TA MEP facilitation. The task-dependent modulation of TA MEPs is comparable to that described for upper limb muscles. Complementary to the MEP delay this approach allows for an estimation of the severity of spinal tract damage. The task-dependent modulation of TA MEPs is an additional diagnostic tool to improve the assessment and monitoring of motor function in iSCI. [ABSTRACT FROM AUTHOR]

Task-oriented repetitive movements can improve motor performance in patients with neurological or orthopaedic lesions. The application of robotics and automation technology can serve to assist, enhance, evaluate, and document neurological and orthopedic rehabilitation. This paper deals with the application of "patient-cooperative" techniques to robot-aided gait rehabilitation of neurological disorders. We define patient-cooperative to mean that, during movement, the technical system takes into account the patient's intention and voluntary efforts rather than imposing any predefined movements or inflexible strategies. It is hypothesized that such cooperative robotic approaches can improve the therapeutic outcome compared to classical rehabilitation strategies. New cooperative strategies are presented that detect the patient's voluntary efforts. First, this enables the patient increased freedom of movement by a certain amount of robot compliance. Second, the robot behavior adapts to the existing voluntary motor abilities. And third, the robotic system displays and improves the patient contribution by visual biofeedback. Initial experimental results are presented to evaluate the basic principle and technical function of proposed approaches. Further improvements of the technical design and additional clinical testing is required to prove whether the therapeutic outcome can be enhanced by such cooperative strategies. [ABSTRACT FROM AUTHOR]

A reduced availability of tetrahydrobiopterin (BH4), an essential cofactor for NO-synthesis, is causally involved in the development of endothelial dysfunction associated with ischemia/reperfusion. We, therefore, investigated the effect of sepiapterin, a substrate for BH4 synthesis, on postischemic injury in myocardial infarction and myocardial stunning. In rats, myocardial stunning was induced by repetitive ischemia (5×10-min ligature of the left coronary artery, 5×20-min reperfusion) and myocardial infarction by 50-min ligature and 60-min reperfusion. Myocardial blood flow was determined by H2-clearance, regional myocardial function by pulsed Doppler and infarct size by tetrazolium staining. Myeloperoxidase (MPO) activity was measured as a marker of neutrophil extravasation. cGMP was determined in rat serum as an indicator of increased NO synthesis. In animals treated with sepiapterin, regional myocardial function was significantly improved in both myocardial stunning and infarction and infarct size was significantly reduced. MPO activity decreased with sepiapterin treatment in both models. The systemic level of cGMP was reduced both following myocardial stunning and myocardial infarction in the control group. Pretreatment with sepiapterin induced a significant increase of cGMP level at the end of the protocol in both models. Substitution of sepiapterin reduces postischemic injury both in myocardial stunning and infarction apparently by ameliorating the availability of NO, thereby attenuating the activation of neutrophils in ischemia/reperfusion. [ABSTRACT FROM AUTHOR]

The study was conducted to assess the possible impact of spine deformity in patients with idiopathic scoliosis (IS) on tibial nerve somatosensory evoked potentials (t-SSEPs) and the influence of spine correction upon postoperative SSEP recordings. In 61 consecutive patients undergoing 64 spinal instrumentations, 129 pre- and postoperative SSEPs were analyzed. The degree of spine deformity was assessed by the pre-operative Cobb angle of the major scoliotic curve. In a control group, reference values of t-SSEP latencies were established with respect to body height. In a cohort study, IS patients were compared with healthy controls with respect to t-SSEP latency, amplitude, configuration and interside difference. The results of the analysis showed that preoperative-body-height-corrected t-SSEP latencies were prolonged in 61% of patients, with a pathological interside difference in 23.4% of them. The impairment of t-SSEPs was not related to the extent of spine deformity as assessed by the Cobb angle. Even without occurrence of postoperative neurological deficits, postoperative t-SSEPs showed significantly increased latencies without changes in t-SSEP configuration. The prolongation of t-SSEP latencies was related to the surgical procedure (combined ventro-dorsal approach), but not to the extent of spine correction, level of instrumentation, or number of fused segments. The analysis of preoperative t-SSEPs was of no predictive value for intra- or postoperative neurological complications. t-SSEPs are significantly affected in IS patients, although these patients show no obvious clinical neurological deficits. The extent of t-SSEP impairment is not related to the severity of scoliosis. Even in clinically uneventful surgery, the postoperative t-SSEPs can be deteriorated depending on the surgical approach. This indicates a subclinical impact of spine surgery upon spinal cord function. [ABSTRACT FROM AUTHOR]

Examines the hypothesis that during locomotion, corticospinal excitation of upper limb motoneurons is mediate indirectly, via propriospinal neurons in the cervical spinal cord. Task-dependent neuronal linkage of cervical and thoraco-lumbar propriospinal circuits controlling leg and arm movements during human locomotor activities; Persistence of movement control.

Abstract This investigation was designed to study the spontaneous functional recovery of adult rats with incomplete spinal cord injury (SCI) at thoracic level during a time course of 2 weeks. Daily testing sessions included open field locomotor examination and electromyographic (EMG) recordings from a knee extensor (vastus lateralis, VL) and an ankle flexor muscle (tibialis anterior, TA) in the hindlimbs of treadmill walking rats. The BBB score (a locomotor score named after Basso et al. , 1995, J. Neurotrauma , 12 , 1–21) and various measures from EMG recordings were analysed (i.e. step cycle duration, rhythmicity of limb movements, flexor and extensor burst duration, EMG amplitude, root-mean-square, activity overlap between flexor and extensor muscles and hindlimb coupling). Directly after SCI, a marked drop in locomotor ability occurred in all rats with subsequent partial recovery over 14 days. The recovery was most pronounced during the first week. Significant changes were noted in the recovery of almost all analysed EMG measures. Within the 14 days of recovery, many of these measures approached control levels. Persistent abnormalities included a prolonged flexor burst and increased activity overlap between flexor and extensor muscles. Activity overlap between flexor and extensor muscles might be directly caused by altered descending input or by maladaptation of central pattern generating networks and/or sensory feedback. [ABSTRACT FROM AUTHOR]