Biomedical subjects

Joseph Hidler

Publications and source records attributed to Joseph Hidler.

4 recordsLinked to original sources

PubMed2006

Quantification of functional weakness and abnormal synergy patterns in the lower limb of individuals with chronic stroke.

BACKGROUND: The presence of abnormal muscle activation patterns is a well documented factor limiting the motor rehabilitation of patients following stroke. These abnormal muscle activation patterns, or synergies, have previously been quantified in the upper limbs. Presented here are the lower limb joint torque patterns measured in a standing position of sixteen chronic hemiparetic stroke subjects and sixteen age matched controls used to examine differences in strength and coordination between the two groups. METHODS: With the trunk stabilized, stroke subjects stood on their unaffected leg while their affected foot was attached to a 6-degree of freedom load cell (JR3, Woodland CA) which recorded forces and torques. The subjects were asked to generate a maximum torque about a given joint (hip abduction/adduction; hip, knee, and ankle flexion/extension) and provided feedback of the torque they generated for that primary joint axis. In parallel, EMG data from eight muscle groups were recorded, and secondary torques generated about the adjacent joints were calculated. Differences in mean primary torque, secondary torque, and EMG data were compared using a single factor ANOVA. RESULTS: The stroke group was significantly weaker in six of the eight directions tested. Analysis of the secondary torques showed that the control and stroke subjects used similar strategies to generate maximum torques during seven of the eight joint movements tested. The only time a different strategy was used was during maximal hip abduction exertions where stroke subjects tended to flex instead of extend their hip, which was consistent with the classically defined "flexion synergy." The EMG data of the stroke group was different than the control group in that there was a strong presence of co-contraction of antagonistic muscle groups, especially during ankle flexion and ankle and knee extension. CONCLUSION: The results of this study indicate that in a standing position stroke subjects are significantly weaker in their affected leg when compared to age-matched controls, yet showed little evidence of the classic lower-limb abnormal synergy patterns previously reported. The findings here suggest that the primary contributor to isometric lower limb motor deficits in chronic stroke subjects is weakness.

Journal Article↗

PubMed2006

MR compatible force sensing system for real-time monitoring of wrist moments during fMRI testing.

Functional magnetic resonance imaging (fMRI) of brain function is used in neurorehabilitation to gain insight into the mechanisms of neural recovery following neurological injuries such as stroke. The behavioral paradigms involving the use of force motor tasks utilized in the scanner often lack the ability to control details of motor performance. They are often limited by subjectiveness, lack of repeatability, and complexity that may exclude evaluation of patients with poor function. In this paper we describe a novel MR compatible wrist device that is capable of measuring isometric forces generated at the hand and joint moments along wrist flexion-extension and wrist ulnar-radial deviation axes. Joint moments measured by the system can be visually displayed to the individual and used during target matching block or event related paradigms. Through a small set of pilot testing both inside and outside the MR environment, we have found that the force tracking tasks and performance in the scanner are reproducible, and that high quality force and moment recordings can be made during fMRI studies without compromising the fMRI images. Furthermore, the device recordings are extremely sensitive making it possible for individuals with poor hand and wrist function to be tested.

Adult↗

PubMed2006

Activity-based therapies.

Therapeutic activity is a mainstay of clinical neurorehabilitation, but is typically unstructured and directed at compensation rather than restoration of central nervous system function. Newer activity-based therapies (ABTs) are in early stages of development and testing. The ABTs attempt to restore function via standardized therapeutic activity based on principles of experimental psychology, exercise physiology, and neuroscience. Three of the best developed ABTs are constraint-induced therapy, robotic therapy directed at the hemiplegic arm, and treadmill training techniques aimed at improving gait in persons with stroke and spinal cord injury. These treatments appear effective in improving arm function and gait, but they have not yet been clearly demonstrated to be more effective than equal amounts of traditional techniques. Resistance training is clearly demonstrated to improve strength in persons with stroke and brain injury, and most studies show that it does not increase hypertonia. Clinical trials of ABTs face several methodological challenges. These challenges include defining dosage, standardizing treatment parameters across subjects and within treatment sessions, and determining what constitutes clinically significant treatment effects. The long-term goal is to develop prescriptive ABT, where specific activities are proven to treat specific motor system disorders. Activity-based therapies are not a cure, but are likely to play an important role in future treatment cocktails for stroke and spinal cord injury.

Animals↗

PubMed2005

Advances in the understanding and treatment of stroke impairment using robotic devices.

The presence of robotic devices in rehabilitation centers is now becoming commonplace across the world, challenging heath care professionals to rethink treatment strategies for motor impairment in hemiparetic stroke patients. In this article, we will discuss some of the motivations for using these devices, review clinical outcomes following robotic-assisted training in both the upper and lower extremities, and detail how these devices can provide quantitative evaluations of function. We will also address the clinical issues that need to be considered when using robotic devices to treat stroke patients, and finally a vision of where this field is heading will be discussed.

Decision Making↗