Biomedical subjects

H I Krebs

Publications and source records attributed to H I Krebs.

11 recordsLinked to original sources

PubMed2002

Assessing the motor status score: a scale for the evaluation of upper limb motor outcomes in patients after stroke.

The Motor Status Scale (MSS) measures shoulder, elbow (maximum score = 40), wrist, hand, and finger movements (maximum score = 42), and expands the measurement of upper extremity impairment and disability provided by the Fugl-Meyer (FM) score. This work examines the interrater reliability and criterion validity of the MSS performed in patients admitted to a rehabilitation hospital 21 +/- 4 days after stroke. Using the MSS and the FM, 7 occupational therapists masked to each other's judgments, evaluated 12 consecutive patients with stroke. Two therapists evaluated 6 additional patients on consecutive days. Intraclass correlation coefficients were significant for each group of raters for the shoulder/elbow and for the wrist/band (P < 0.0001); test-retest measures were also significant for the shoulder/elbow (Pearson correlation coefficient r = 0.99, P < 0.004) and for the wrist/hand (Pearson correlation coefficient r = 0.99, P < 0.003). The internal item consistency for the overall MSS was significant (Cronbach alpha = 0.98, P < 0.0001). Finally the correlation between the MSS and the FM (R2 = 0.964) was significant (P < 0.0001). The MSS affords a reliable and valid assessment of upper limb impairment and disability following stroke.

Disability Evaluation↗

PubMed2001

Procedural motor learning in Parkinson's disease.

We have been investigating motor control and learning in parkinsonian subjects. In the current study, we sought to explore the existence of deficits in procedural motor learning, which is a form of implicit motor learning where skill improves over repetitive blocks of trials. We sought to determine, in particular, whether any such deficit is accentuated during specific types or phases of learning. We would expect that those specific learning tasks would require the greatest participation of the basal ganglia. Numerous studies have found that Parkinson's disease (PD) patients may show deficits in learning. Combined with information about basal ganglia neuronal connections and activity, this led some investigators to suggest that one of the key functions of the basal ganglia is to facilitate learning. To investigate these learning deficits, we used a robotic device to generate conservative force fields that disturbed the subjects' arm movements, thereby generating a "virtual mechanical environment" that subjects learned to manipulate. Movements were successively grouped into blocks comprising five different conditions: motor performance, early learning, late learning, negative transfer, and aftereffect motor performance. Our results with eight right-handed PD subjects and nine age-matched controls showed a relative decrease in the rate of learning for the PD patients in all blocks, but greater differences emerged between groups during novelty phases of learning. In particular, the difference in performance during the negative transfer condition reached statistical significance, suggesting that the basal ganglia might be a key center for "switching" motor patterns. Our results support the hypothesis that deficiencies in procedural motor learning are characteristic of PD. They add to existing evidence which has suggested a key role for the basal ganglia when new sensorimotor mappings are required by novel task environments. Better understanding of these deficits should facilitate the rehabilitation of PD patients.

Aged↗

PubMed2001

Is robot-aided sensorimotor training in stroke rehabilitation a realistic option?

Stroke is the leading cause of disability, despite continued advances in prevention and treatment techniques based on novel delivery of new fibrinolytic drugs. Improved medical treatment of the complications caused by acute stroke has contributed to decreased mortality, but 90% of the survivors have significant neurological deficits. Reducing the degree of permanent disability remains the goal of poststroke neuro-rehabilitation programs, and new approaches to impairment reduction through managing sensorimotor experience may contribute further to altering disability. Recent reports from a number of laboratories using enhanced sensorimotor training protocols, particularly those with robotic devices, have indicated modest success in reducing impairment and increasing motor power in the exercised limb of patients with stroke when compared with control individuals. Whether arming the therapist with new tools, especially robotic devices, to treat impairment is a realistic approach to modern interdisciplinary rehabilitation raises questions regarding the added value of impairment reduction, and under what conditions should scientific and clinical development of robotic studies continue.

Disability Evaluation↗

PubMed2000

A novel approach to stroke rehabilitation: robot-aided sensorimotor stimulation.

OBJECTIVE: In patients with stroke, the authors tested whether additional sensorimotor training of the paralyzed or paretic upper limb delivered by a robotic device enhanced motor outcome. METHODS: Fifty-six patients with stroke and hemiparesis or hemiplegia received standard poststroke multidisciplinary rehabilitation, and were randomly assigned either to receive robotic training (at least 25 hours) or exposure to the robotic device without training. Outcomes were assessed by the same masked raters, before treatment began and at the end of treatment, with the upper extremity component of the Fugl-Meyer Motor Assessment, the Motor Status score, the Motor Power score, and Functional Independence Measurement. RESULT: The robot treatment and control group had comparable clinical characteristics, lesion size, and pretreatment impairment scores. By the end of treatment, the robot-trained group demonstrated improvement in motor outcome for the trained shoulder and elbow (Motor Power score, p < 0.001; Motor Status score, p < 0. 01) that did not generalize to untrained wrist and hand. The robot-treated group also demonstrated significantly improved functional outcome (Functional Independence Measurement-Motor, p < 0. 01). CONCLUSION: Robot-delivered quantitative and reproducible sensorimotor training enhanced the motor performance of the exercised shoulder and elbow. The robot-treated group also demonstrated improved functional outcome. When added to standard multidisciplinary rehabilitation, robotics provides novel therapeutic strategies that focus on impairment reduction and improved motor performance.

Adult↗

PubMed1999

Robot training enhanced motor outcome in patients with stroke maintained over 3 years.

In an attempt to improve motor recovery of the upper limb after stroke, we added a robot (MIT-Manus) experience that provided additional goal-directed sensorimotor activity to standard rehabilitation treatments. The first trial produced a significant decrease in motor impairment in the upper limb for the treated group. In re-evaluating 12 of those 20 patients, nearly 3 years later, robot-trained patients showed further significant decreases in impairment measures of the affected limb. The groups were comparable at the start of the study.

Aged↗

PubMed1999

Quantization of continuous arm movements in humans with brain injury.

Segmentation of apparently continuous movement has been reported for over a century by human movement researchers, but the existence of primitive submovements has never been proved. In 20 patients recovering from a single cerebral vascular accident (stroke), we identified the apparent submovements that composed a continuous arm motion in an unloaded task. Kinematic analysis demonstrated a submovement speed profile that was invariant across patients with different brain lesions and provided experimental verification of the detailed shape of primitive submovements. The submovement shape was unaffected by its peak speed, and to test further the invariance of shape with speed, we analyzed movement behavior in a patient with myoclonus. This patient occasionally made involuntary shock-like arm movements, which occurred near the maximum capacity of the neuromuscular system, exhibited speed profiles that were comparable to those identified in stroke patients, and were also independent of speed.

Arm↗

PubMed1999

Overview of clinical trials with MIT-MANUS: a robot-aided neuro-rehabilitation facility.

We are applying robotics and information technology to assist, enhance, and quantify neuro-rehabilitation. Our goal is a new class of interactive, user-affectionate clinical devices designed not only for evaluating patients, but also-for delivering meaningful therapy via engaging "video games". Notably, the novel robot MIT-MANUS has been designed and programmed for clinical neurological applications, and has undergone extensive clinical trials for more than four years at Burke Rehabilitation Hospital - White Plains, NY. This paper will review results of the first clinical trial of 20 patients, which showed that: - Stroke patients treated daily with additional robot-aided therapy during acute rehabilitation had improved outcome in motor activity at hospital discharge, when compared to a control group that received only standard acute rehabilitation treatment. - This improved outcome was sustained after three years. - The neuro-recovery process continued far beyond the commonly accepted 3 months post-stroke interval.

Double-Blind Method↗

PubMed1998

Robot-aided neurorehabilitation.

Our goal is to apply robotics and automation technology to assist, enhance, quantify, and document neurorehabilitation. This paper reviews a clinical trial involving 20 stroke patients with a prototype robot-aided rehabilitation facility developed at the Massachusetts Institute of Technology, Cambridge, (MIT) and tested at Burke Rehabilitation Hospital, White Plains, NY. It also presents our approach to analyze kinematic data collected in the robot-aided assessment procedure. In particular, we present evidence 1) that robot-aided therapy does not have adverse effects, 2) that patients tolerate the procedure, and 3) that peripheral manipulation of the impaired limb may influence brain recovery. These results are based on standard clinical assessment procedures. We also present one approach using kinematic data in a robot-aided assessment procedure.

Aged↗

PubMed1998

Robot-aided functional imaging: application to a motor learning study.

The purpose of this study was to examine the neural activity underlying an implicit motor learning task. In particular, our goals were to determine whether initial phases of procedural learning of a motor task involve areas of the brain distinct from those involved in later phases of learning the task, and what changes in neural activity coincide with performance improvement. We describe a novel integration of robotic technology with functional brain imaging and its use in this study of implicit motor learning. A portable robotic device was used to generate forces that disturbed the subjects' arm movements, thereby generating a "virtual mechanical environment" that the subjects learned to manipulate. Positron emission tomography (PET) was used to measure indices of neural activity underlying learning of the motor task. Eight health, right-handed male subjects participated in the study. Results support the hypothesis that different stages of implicit learning (early and late implicit learning) occur in an orderly fashion, and that distinct neural structures may be involved in these different stages. In particular, neuroimaging results indicate that the cortico-striatal loop may play a significant role during early learning, and that the cortico-cerebellar loop may play a significant role during late learning.

Adult↗

PubMed1997

The effect of robot-assisted therapy and rehabilitative training on motor recovery following stroke.

BACKGROUND: We used MIT-Manus, a robot designed to provide interactive, goal-directed motor activity for clinical neurologic applications. OBJECTIVE: To test whether this robotic manipulation of the impaired limb influenced motor recovery in patients with hemiplegia. METHODS: Sequential patients with a history of a single stroke and hemiplegia (N = 20) hospitalized on the same acute care rehabilitation floor were enrolled in a standard rehabilitation program supplemented by either robot-aided therapy or sham robot-aided therapy. These 2 groups were comparable in age, initial physical impairment, and time between onset of the stroke and enrollment in the trial. Patients, clinical team members, and the clinical evaluator were blinded to the treatment group assignments. Standardized assessment tools measured outcomes. RESULTS: Impairment and disability declined in both groups between hospital admission and discharge. The robot-treated group showed a greater degree of improvement in all 3 measures of motor recovery, and the change in motor status measured in the proximal upper limb musculature was significant (P = .002). No adverse events resulted from robot-assisted therapy. CONCLUSIONS: These results suggest that robotic manipulation of the impaired limb may favorably add to recovery following stroke and that robotics may provide new strategies for neurologic rehabilitation.

Adult↗

PubMedDate not supplied

Increasing productivity and quality of care: robot-aided neuro-rehabilitation.

This paper presents an overview of our research in robot-aided stroke neuro-rehabilitation and recovery. At the onset of this research we had to confront squarely (and solve!) a critical question: If anatomy is destiny, can we influence it? Our efforts over the last five years have been focused on answering this question and we will present a few of our clinical results from over 2,000 hours of robot-aided therapy with 76 stroke patients. To determine if exercise therapy influences plasticity and recovery of the brain following a stroke, we needed the appropriate "microscope" that would allow us to concomitantly control the amount of therapy delivered to a patient, while objectively measuring patient's performance. Back-driveable robots are the key enabling technology. Our results to date using common clinical scales suggest that robot-aided sensorimotor training does have a genuinely positive effect on reduction of impairment and the reorganization of the adult brain. Yet while clinical scales can help us to examine the impact in the neuro-recovery process, their coarse nature requires extensive and time-consuming trials, and on top of that they fail to show us details important for optimizing therapy. Alternative, robot-based scales offer the potential benefit of new finer measurements-and deeper insight into the process of recovery from neurological injury. We also plan to use present technology to establish the practicality and economic feasibility of clinician-supervised, robot-administered therapy, including classroom therapy. We feel quite optimistic that the march of progress will accelerate substantially in the near future and allow us to transfer this technology from the research realm to the everyday treatment of stroke survivors.

Efficiency↗