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Biomedical subjects

G Zilvold

Publications and source records attributed to G Zilvold.

At least 19 recordsLinked to original sources
PubMed2004

Electrical stimulation of the upper limb in stroke: stimulation of the extensors of the hand vs. alternate stimulation of flexors and extensors.

OBJECTIVE: To investigate whether there is a difference in functional improvement in the affected arm of chronic stroke patients when comparing two methods of electrical stimulation. DESIGN: Explanatory trial in which 30 chronic stroke patients with impaired arm function were randomly allocated to either alternating electrical stimulation of the extensor and flexor muscles of the hand (group A) or electrical stimulation of the extensors only (group B). Primary outcome measure was the Action Research Arm test to assess arm function. Grip strength, Motricity Index, Ashworth Scale, and range of motion of the wrist were secondary outcome measures. RESULTS: Improvement on the Action Research Arm test was 1.0 point in group A and 3.3 points in group B; the difference in functional gain was 2.3 points (95% confidence interval, -1.06 to 5.60). The success rate (i.e., percentage of patients with a clinically relevant improvement of >5.7 points on the Action Research Arm test) was 27% in group B (four patients) and 8% in group A (one patient). The differences in functional gain and success rate were not statistically significant, neither were the differences between the two groups on the secondary outcome measures. CONCLUSION: The difference between the two stimulation strategies was not statistically significant.

Adult↗
PubMed2002

Application of a dual channel peroneal nerve stimulator in a patient with a "central" drop foot.

Dropped foot is a common mobility problem amongst patients after a cerebro vascular accident. The condition arises from paresis of the muscles that control the foot movement during the swing phase of gait. If the abnormal movement is not compensated for, it results in a significant decrease in the mobility and hence quality of life. Compensation for the drop foot can be achieved through the application of functional electrical stimulation. To date, in the clinical environment, the stimulation has been applied through electrodes placed on the skin over the common peroneal nerve, and using a single channel implant device. It is well known that with these techniques it is difficult to establish a balanced response of the foot. An implantable dual channel system for stimulation of the deep and superficial peroneal nerve has now been developed for patients with a drop foot following a stroke. By stimulation of the two branches of the common peroneal nerve separately it is possible to achieve a precisely balanced dorsal flexion and eversion of the foot. Stimulation occurs via small bipolar electrodes which are placed subepineural. After successful tests on animals we have now started the two channel peroneal nerve stimulator implantation in patients. The preliminary results of the first implants are presented.

Cerebrovascular Disorders↗
PubMed2002

Daily hassles and stress vulnerability in patients with a whiplash-associated disorder.

The objectives of this study were to examine the self-reported, daily problems of patients with a whiplash-associated disorder (WAD) and a healthy control group, with the hypothesis that WAD patients would report more person-dependent hassles and perceive them as more serious than the healthy control group, due to the prior experience of a whiplash injury. In addition, it was expected that the person-independent seriousness rating would be elevated, reflecting the increased vulnerability of WAD patients to common stressors. Finally, a strong relationship was expected between frequency or seriousness of daily problems on the one hand and level of distress on the other. Forty-seven WAD patients seeking treatment and 47 matched healthy control participants completed the everyday problem checklist (EPCL). The level of distress was measured by the symptom checklist (SCL-90). As expected, most EPCL-scores in the WAD group were higher than the scores of the healthy participants. Regression analysis further revealed that 61% of the variance in general distress in the WAD group could be explained by EPCL scores and educational background. Chronic WAD patients report a high stress load, which is related specifically to personal functioning after the whiplash injury. In addition, WAD patients (especially those with a low educational level) appear to be more vulnerable and react with more distress than healthy people to all kinds of stressors. Stress responses probably play an important role in the maintenance or deterioration of whiplash-associated complaints.

Adult↗
PubMed2001

Functional electrical stimulation by means of the 'Ness Handmaster Orthosis' in chronic stroke patients: an exploratory study.

OBJECTIVE: To gain experience with 'Ness Handmaster Orthosis' treatment in chronic stroke patients, to identify suitable patients, and to study the effects of treatment. DESIGN: Exploratory, uncontrolled trial with measurement of motor functions and muscle tone of the upper extremity prior to, during, upon completion, and six weeks after a treatment period. SETTING: A rehabilitation centre in the Netherlands. SUBJECTS: Eighteen chronic stroke patients (more than six months post stroke), who exhibited upper extremity dysfunction due to spastic paresis. INTERVENTION: A 10-week therapy programme of functional electrical stimulation by means of the 'Ness Handmaster Orthosis'. RESULTS: The results of 15 patients were available for analysis. The differences in motor score and muscle tone before and at the end of treatment were statistically significant (p = 0.008 and 0.021, respectively). The follow-up measurements showed that the effects on motor functions and muscle tone decreased after therapy completion. Stratification of the patients in two subgroups indicated that patients with initial high motor scores benefited most during the intervention period. CONCLUSION: The present study suggests that Handmaster treatment possesses therapeutic opportunities in chronic stroke patients with spastic paresis of the upper extremity.

Activities of Daily Living↗
PubMed2001

Differences in treatment outcome between subgroups of patients with chronic low back pain using lumbar dynamometry and psychological aspects.

OBJECTIVE: To investigate whether subgroups of patients with chronic low back pain show differences in treatment outcome, measured with the Roland Disability Questionnaire. (RDQ). SETTING: The study was carried out in a rehabilitation centre. SUBJECTS: Eighty-four patients with chronic low back pain participated in this study. INTERVENTION: Patients followed a multidisciplinary treatment programme that primarily targets physical aspects. DESIGN AND MAIN OUTCOME MEASURE: Based on pretreatment lumbar dynamometry results and Symptom Checklist (SCL-90) scores, patients were divided into subgroups. The dynamometry subgroups were: performances lower than healthy subjects (expected performance), performances comparable with those of healthy subjects (normal performance) and inconsistent performances (submaximal performance). The SCL-90 subgroups were: a total score of 'average' or lower compared with a population of chronic pain patients (low psychological score) and a total score of 'above average' or higher compared with this population (high psychological score). Patients answered the RDQ in the week before (RDQ1; n = 84) and after treatment (RDQ2; n = 78) to investigate whether the subgroups show differences in outcome expressed as the percentage change between RDQ2 and RDQ1, (%RDQ2-1). A %RDQ2-1 > or = 20% was classified as an improvement. RESULTS: Improvement on disability level > or = 20% is shown in 64% and 55% of the patients with 'normal' and 'expected' lumbar dynamometry performances and low psychological scores compared with only 33% and 25% of those with high psychological scores. Patients with submaximal performances show hardly any changes in disability level and there are no differences betweenthose with low psychological scores (14%) and those reporting high scores (0%). CONCLUSION: The fact that patient subgroups with differences in treatment outcome can be defined using lumbar dynamometry and psychological questionnaires suggests that these instruments might facilitate treatment indication in clinical practice.

Adult↗
PubMed2000

Cervical muscle dysfunction in the chronic whiplash associated disorder grade II (WAD-II).

STUDY DESIGN: In a cross-sectional study, surface electromyography measurements of the upper trapezius muscles were obtained during different functional tasks in patients with a chronic whiplash associated disorder Grade II and healthy control subjects. OBJECTIVES: To investigate whether muscle dysfunction of the upper trapezius muscles, as assessed by surface electromyography, can be used to distinguish patients with whiplash associated disorder Grade II from healthy control subjects. SUMMARY OF BACKGROUND INFORMATION: In the whiplash associated disorder, there is need to improve the diagnostic tools. Whiplash associated disorder Grade II is characterized by the presence of "musculoskeletal signs." Surface electromyography to assess these musculoskeletal signs objectively may be a useful tool. METHODS: Normalized smoothed rectified electromyography levels of the upper trapezius muscles of patients with whiplash associated disorder Grade II (n = 18) and healthy control subjects (n = 19) were compared during three static postures, during a unilateral dynamic manual exercise, and during relaxation after the manual exercise. Coefficients of variation were computed to identify the measurement condition that discriminated best between the two groups. RESULTS: The most pronounced differences between patients with whiplash associated disorder Grade II and healthy control subjects were found particularly in situations in which the biomechanical load was low. Patients showed higher coactivation levels during physical exercise and a decreased ability to relax muscles after physical exercise. CONCLUSIONS: Patients with whiplash associated disorder Grade II can be distinguished from healthy control subjects according to the presence of cervical muscle dysfunction, as assessed by surface electromyography of the upper trapezius muscles. Particularly the decreased ability to relax the trapezius muscles seems to be a promising feature to identify patients with whiplash associated disorder Grade II. Assessment of the muscle (dys)function by surface electromyography offers a refinement of the whiplash associated disorder classification and provides an indication to a suitable therapeutic approach.

Adult↗
PubMed2000

Use of the NESS handmaster to restore handfunction in tetraplegia: clinical experiences in ten patients.

OBJECTIVE: To explore possible functional effects of the Handmaster in tetraplegia and to determine suitable patients for the system. PATIENTS: Patients with a cervical spinal cord injury between C4 and C6, motor group 0 - 3. Important selection criteria were a stable clinical situation and the absence of other medical problems and complications. DESIGN: Ten patients were consecutively selected from the in- and outpatient department of a large rehabilitation hospital in The Netherlands. Each patient was fitted with a Handmaster by a qualified therapist and underwent muscle strength and functional training for at least 2 months. METHODS: Functional evaluation comprised the performance of a defined set of tasks and at least one additional task as selected by patients themselves. Tasks were performed both with and without the Handmaster. Finally, patients were asked for their opinion on Handmaster use as well as their willingness to future use. RESULTS: In six patients a stimulated grasp and release with either one or both grasp modes (key- and palmar pinch) of the Handmaster was possible. Four patients could perform the set of tasks using the Handmaster, while they were not able to do so without the Handmaster. Eventually, one patient continued using the Handmaster during ADL at home. CONCLUSION: The Handmaster has a functional benefit in a limited group of patients with a C5 SCI motor group 0 and 1. Suitable patients should have sufficient shoulder and biceps function combined with absent or weak wrist extensors. Though functional use was the main reason for using the Handmaster, this case series showed that therapeutic use can also be considered.

Activities of Daily Living↗
PubMed1999

Distribution of psychological aspects in subgroups of chronic low back pain patients divided on the score of physical performance.

This study investigates whether different subgroups of chronic low back pain patients (CLBPs) differ in psychological aspects assessed with the Symptom Checklist (SCL-90) and the Multidimensional Pain Questionnaire (MPI-DLV). Four subgroups of CLBPs are discerned using the results of lumbar dynamometry: 1. Patients with performances lower than healthy subjects (expected performance; n = 45). 2. Patients with performances comparable to healthy subjects (normal performance; n = 18). 3. Patients with inconsistent test behaviour (submaximal performance; n = 6). 4. Patients with performances that could be either maximal or submaximal (gray-zone performance; n = 10). Significant differences in psychological aspects were found between patients with submaximal and patients with expected performances but not between patients with normal and patients with expected performances. All patients with submaximal performance report a high degree of psychological distress, in contrast to 30% of those with normal performance and 20% of those with expected performance. Because of the differences found in psychological aspects between the CLBP subgroups, it is thought that a physical screening together with a psychological screening provides better insight in the two aspects of the deconditioning syndrome and thus can give better treatment indications than a physical screening alone.

Adult↗
PubMed1999

Comparative trials on hybrid walking systems for people with paraplegia: an analysis of study methodology.

A new orthosis (SEPRIX) which combines user friendliness with low energy cost of walking has been developed and will be subject to a clinical comparison with conventional hip-knee-ankle-foot orthoses. In designing such comparative trials it was considered it may be worthwhile to use previous clinical studies as practical examples. A literature search was conducted in order to select all comparative trials which have studied two walking systems (hip-knee-ankle-foot orthoses) for patients with a complete thoracic lesion. Study population, intervention, study design, outcome measurement and statistical analyses were examined. Statistical power was calculated where possible. Of 12 selected studies, 7 were simple A-B comparisons, 2 A-B comparisons with a replication, 2 cross-over trials and 1 nonrandomised parallel group design, the last of which was considered internally invalid due to severe confounding by indication. All A-B comparisons were considered internally invalid as well, since they have not taken into account that a comparison of two orthoses requires a control for aspecific effects (like test effects) which may cause a difference. Statistical power could only be examined in 4 studies and the highest statistical power achieved in one study was 47%. It is concluded that statistical power was too low to be able to detect differences. Even analysis through interval estimation showed that the estimation of the difference was too imprecise to be useful. Since the majority of the surveyed papers have reported small studies (of only 4-6 patients), it is assumed that lack of statistical power is a more general problem. Three possibilities are discussed in order to enhance statistical power in comparative trials, i.e. multicentre studies, statistical pooling of results and improving the efficiency of study design by means of interrupted time series designs.

Equipment Design↗
PubMed1998

Electromyography in the biomechanical analysis of human movement and its clinical application.

This article introduces the area of scientific study of human movement. It is primarily intended for readers who wish to form a judgement on the usefulness of scientific movement analysis techniques in the treatment process of patients with abnormal movement patterns. With a focus on the analysis of human locomotion, the paper outlines the historical development of a biomechanical approach towards the understanding of human movement patterns. This approach alone proves to be inadequate in supplying reliable information on neuromuscular control of movement. It follows that electromyographic techniques are essential for this purpose. Scientific literature reveals relevant practical usability of such information. This is the rationale for a review of the historical, physiological, technical and methodological background of electromyographic analysis of movement. The field of management and rehabilitation of motor disability is identified as one important application area. On the basis of relevant literature, the present paper asserts that scientific analysis of human movement patterns can materially affect patient treatment. It provides evidence that patient management and rehabilitation processes in central neurological disorders can be improved through electromyographic techniques. In particular, this evidence supports the use of electromyography for surgical planning in children with cerebral palsy. The paper concludes with a view on future directions in research, development and applications of scientific analysis of human movement. Copyright 1998 Elsevier Science B.V.

Journal Article↗
PubMed1998

Speed dependence of crutch force and oxygen uptake: implications for design of comparative trials on orthoses for people with paraplegia.

OBJECTIVE: To determine speed dependence of crutch force and oxygen uptake, and to discuss the implications of differences in self-selected walking speed between orthoses in a comparative trial. DESIGN: Cross-sectional comparison. SETTING: Treadmill experiments and gait laboratory experiments were performed at five and three different imposed walking speeds, respectively. PATIENTS: Five paraplegic subjects with lesions between T9 and T12 were included. All subjects had experience with ambulation using the advanced reciprocating gait orthosis (ARGO) as well as walking on a treadmill. MAIN OUTCOME MEASURES: Crutch force time integral (CFTI), crutch peak force on stance and swing side (CPFstance and CPFswing), oxygen uptake (VO2), oxygen cost (EO2). RESULTS: VO2, EO2, and CFTI were strongly dependent on walking speed. CPFstance and CPFswing were less dependent. However, depending on the clinically relevant difference that should be detected in a comparative trial, the peak forces can still be confounded by walking speed. CONCLUSION: CFTI, CPFswing, VO2, and EO2 should be adjusted for walking speed if differences in walking speed between orthoses are found, but this correction is relevant only if there is no effect modification. Such modification (different slopes between orthoses) cannot be excluded for the studied outcome measures. In addition, because determination of effect modification is difficult in small studies, standardization of walking speed, by means of a three-point design, is recommended.

Adult↗
PubMed1997

The influence of the reciprocal cable linkage in the advanced reciprocating gait orthosis on paraplegic gait performance.

A wide variety of mechanical orthoses is available to provide ambulation to paraplegic patients. Evaluation of energy cost during walking in each of these devices has been acknowledged as an important topic in this field of research. In order to investigate the benefits of a ballistic swing on gait performance in the Advanced Reciprocating Gait Orthosis (ARGO) a study was conducted in which the ARGO was compared with an orthosis with freely swinging legs. This Non Reciprocally linked Orthosis (NRO) was obtained by removing the reciprocal linkage in the subjects' own ARGOs. Subsequently, flexion/extension limits were mounted to permit adjustment of stride length. Six male paraplegic subjects with lesions ranging from T4 to T12 were included in the study. A single case experimental design (B-A-B-A) was conducted in order to improve internal validity. Biomechanical and physiological parameters were assessed and the subjects' preference for either ARGO or NRO was determined. It was found that large inter-individual differences produced insufficient evidence in this study to draw general conclusions about difference in energy expenditure between both orthoses. However, individual analysis of the results showed a reduction of oxygen cost (range: 4%-14%) in the NRO in T9 and T12 lesions, while oxygen cost in subjects with T4 lesions increased markedly (22% and 40%). It is concluded that patients with low level lesions could benefit in terms of oxygen lost from removing the reciprocal cable linkage in the ARGO. However, only one subject preferred the NRO for walking, whereas none of the subject chose the NRO for use in daily living activities. Removal of the reciprocal cable linkage in the ARGO may not be desirable for these patients.

Adult↗
PubMed1997

The influence of the reciprocal hip joint link in the Advanced Reciprocating Gait Orthosis on standing performance in paraplegia.

The effect of reciprocally linking the hip hinges of a hip-knee-ankle-foot orthosis on standing performance was studied in a comparative trial of the Advanced Reciprocating Gait Orthosis (ARGO) and an ARGO in which the Bowden cable was removed (A_GO). Six male subjects with spinal cord injury (SCI) at T4 to T12 level participated in the study, which was conducted using a single case experimental design. Standing balance, the ability to handle balance disturbances (standing stability), and the performance of a functional hand task during standing were assessed in both orthosis configurations in the order A_GO-ARGO-A_GO-ARGO. No significant differences with respect to standing performance were found for the two orthosis configurations. However, the results indicate that the crutch force needed for maintaining balance during various tasks, especially for quiet standing with two crutches, may be much higher in the orthosis without Bowden cable. Therefore, it is very likely that the reciprocal hip joint link in the ARGO provides a substantial and clinically relevant reduction of upper body effort required for standing under functional conditions.

Adult↗
PubMed1996

[Linkage between ambulatory and inpatient rehabilitation in the Euregio Model].

The SASPC-oriented rehabilitation approach, combining patient's somatic situation, activities of daily living, social circumstances as well as psychological status and communication skills, has been developed in the Netherlands with special regard to impairments, disabilities and handicaps of the musculoskeletal system. In the framework of an Interreg Project, a study was carried out comparing the rehabilitation systems in place in Germany and the Netherlands. Proposals are submitted for implementation of a graded rehabilitation scheme.

Ambulatory Care↗
PubMed1992

Low-level finite state control of knee joint in paraplegic standing.

Low-level finite state (locked-unlocked) control is compared with open-loop stimulation of the knee extensor muscles in functional electrical stimulation (FES) induced paraplegic standing. The parameters were: duration of standing, relative torque loss in knee extensor muscles, knee angle stability, average stimulus output and average arm effort during standing. To investigate the impact of external mechanical conditions on controller performance, experiments were performed both under the condition of a freely moving ankle joint and of a mechanically stabilized ankle joint. Finite state control resulted in a 2.5 to 12 times increase of standing duration or in a 1.5 to 5 times decrease of relative torque loss in comparison with open-loop stimulation. Finite state control induced a limit cycle oscillation in the knee joint. Average maximum knee flexion was 6.2 degrees without ankle bracing, and half that value with ankle bracing. Average arm support was 13.9 and 7.5% of the body weight without and with ankle bracing respectively.

Adult↗
PubMed1990

Artificial-reflex stimulation for FES-induced standing with minimum quadriceps force.

A control strategy is proposed to decrease quadriceps activity during standing. Modified on/off (or artificial reflex) control is used: a non-numerical or finite-state control scheme based on feedback of knee angle and angular velocity. The control strategy is evaluated in paraplegic patients in an experimental setup using transcutaneous stimulation. The stability of the system and its sensitivity to various control parameters are determined. It is concluded that the control scheme will enable reduction of muscle force independent of additional mechanical bracing or specific posture, and may result in continuous dynamic activation of muscle.

Electric Stimulation Therapy↗
PubMed1989

Simultaneous measurement of surface EMG and movements for clinical use.

A system for simultaneous measurement of surface EMG, joint movement and temporal parameters of gait has been developed for clinical use. Some design constraints, imposed by the clinical situation, are indicated. Multiple cycles of movement are recorded and averaged patterns of muscle activation and joint movements are determined. Data processing runs concurrently with data acquisition, so that the results are available for clinical interpretation immediately after the measurement. Instrumentation, signal processing and software are described and some examples of application of the system for evaluation of therapies and functional aids are presented. It is proposed that clinically relevant quantitative information can be obtained by comparison of different recordings of the individual patient rather than comparison with patterns found with normal subjects.

Biomedical Engineering↗