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Cortical and Biomechanical Dynamics of Ankle Robotics Training in Stroke

2014-08-27 03:15:48 | BioPortfolio

Summary

Reduced mobility and increased fall risk are significant long-term health problems facing those who have persistent weakness or paralysis in their legs resulting from stroke. Recent innovations in post-stroke therapy have applied motor learning principles to improve motor skills through regular practice of activities using the weaker limb. Because the ankle is so critical in providing forces for normal walking and balance function, impairments at the affected ankle pose a major limitation to achieving optimal rehabilitation outcomes. To address this we have developed a novel ankle robot (Anklebot) to enhance physical therapy for improving walking and balance functions after stroke. It is a computer controlled exercise machine that can be worn during walking or in a seated position for practice with video games. The Anklebot controllers allow for assisting users when they cannot complete a movement, or resisting movement, or simply recording movements and forces.

Passive movement therapy has shown promise in exciting brain to muscle connections for recovery of walking function; however it does not appear to yield optimal results, suggesting that active involvement in task-oriented therapy is essential. Not only is voluntary movement important to initiate this excitation, the brain mechanisms of reward and motivation play an important role. These mechanisms have been widely studied in both humans and animals. Core brain networks involved in reward and motivation are designed to increase a person's involvement with their surroundings, to focus attention and to prompt one to approach reward and avoid punishers. These increases in involvement and the elevated emotions that are part of it have been shown to enhance performance, memory and learning.

The primary purpose of this pilot study is to investigate responses of brain and muscle activity in stroke patients who use the Anklebot during a 3-week / 3-session/week motor learning based training. These responses will be compared to a 3-week delayed entry period in which the participants will perform an at-home walking program equal in time spent to the time they will spend on the Anklebot during the 3-week / 3x/week training. In Addition, after the 3-week delayed entry walking program the subjects will be divided into low and high reward-feedback groups. The low reward-feedback group will receive the Anklebot training with only immediate feedback (they will know if they succeeded on the current trial but they will never know their cumulative score and they will receive minimal social interaction with research team members. While the high-reward feedback group will know their cumulative scores, will receive controlled but abundant social interaction with the research team and will be eligible for prizes of restaurant and movie coupons during individual training sessions and at completion of the study. This will be done to assess the ability of higher reward conditions to increase recovery beyond that of the Anklebot training alone.

To accomplish this subjects with chronic stroke will be divided into the high and low-reward/feedback groups and will then play a series of videogames using the Anklebot, as we noninvasively record brain activity using electroencephalography (EEG) and muscle activity using electromyography (EMG). We will also monitor heart rate using electrocardiograms (ECG). In addition to analyzing brain and muscle information before, during, and after the Anklebot training, we will also assess walking and balance functions immediately before and after the first and last robotic training session and ask the subjects to fill out some standardized questionnaires.

Description

After informed consent is obtained, this pilot study will require at least eleven visits for all subjects. The first visit will entail screening and eligibility tests that last about 3 hours and will occur at the VAMC (Veteran's Administration Medical Center) in the Geriatric Assessment Clinic (GAC). The second and third visits will last approximately 3 hours at the VAMC Human Motor Performance Laboratory and will involve collection of noninvasive EEG, surface EMG and ECG, and practice of ankle movements by using the ankle robot to play video games. In addition measures of gait and balance function will be assessed pre- and post- the Anklebot training. For the next 3-weeks the subjects will take part in an at-home, monitored (log) walking program. The next seven visits (the training program) entail further practice of ankle movements by using the ankle robot to play video games, collection of motor control data but not the collection of any electrophysiological data.. Visit eleven (final) is the same as visits 2 & 3.

Visit 1: Screening evaluations include review of medical records, medical and neurologic examinations to determine eligibility. Clinical evaluations will also include the Mini Mental State Exam (MMSE) and the Center for Epidemiologic Study (CES-D). Clinical suspicion or evidence on these screening instruments of dementia, depression, or other cognitive deficits that could interfere with the study will preclude further study evaluation and prompt referral to psychiatry or other appropriate health professional for further evaluation. The Automated Neuropsychological Assessment Metrics (ANAM) is also administered as a comprehensive neuropsychological tool for measuring multiple facets of neuropsychological processes that pertain to cognitive function and motor learning. In addition participants will be asked to walk 10 meters 3 times across a gait measuring mat at their preferred speed while in a safety harness and accompanied (not assisted) by an expeienced research assistant. This will help determine their deficit severity for grouping during data analysis. Finally, a standard neurological examination is conducted by medically credentialed staff.

Visit 2 & 3 & 11: After study enrollment and medical screening, subjects will be tested with the Anklebot while EEG, EMG, and heart rate (ECG) are recorded.

First, subjects will be fitted with a stretch-lycra cap that houses 64 recessed EEG sensors formed from tin. The participant's skin will be lightly abraded or rubbed with the end of a Q-tip at each sensor site to remove oil and dead epidermal tissue to establish good conductance of the EEG signal. The skin will not be broken. Using a blunt applicator attached to a syringe, an FDA-approved non-toxic conducting gel will then be applied through an opening in each of the 64 recording sensors to establish continuous contact of the gel between the skin at the recording sites and the corresponding sensors. Recording sensors will also be positioned on the skin above and below the left eye to monitor eye movements as well as on both ear lobes to serve as "non-brain" reference sites. A ground electrode site will be applied in the frontal region. The eye-channel and reference sites will be lightly abraded with a pad, rubbed with alcohol, and prepared with the conducting gel to enable continuous connection between the scalp and the sensor surface. Also, surface EMG electrodes will be applied to tibialis anterior, gastrocnemius, and, if needed, the peroneal muscles of the paretic leg. Leads for ECG recording will be applied bilaterally to locations immediately inferior to the clavicles.

Once the set-up is complete, subjects will be asked to walk 10 m over an instrumented gait mat to record gait parameters during 3 preferred and 3 fastest walking trials. Subjects will be asked to repeat these walking tasks while performing a concurrent cognitive task consisting of solving and verbally reporting answers to simple arithmetic problems. They will wear a gait belt and be attended closely by research staff as they walk and receive seated rests as required to prevent fatigue. A second test will measure balance control by recording 30 second trials of postural sway during quiet standing on a force plate. Three balance conditions include eyes open, eyes closed, and eyes open while performing a concurrent cognitive task consisting of solving and verbally reporting answers to simple arithmetic problems. Seated rests will be provided as needed.

After baseline functional testing participants will be seated in a chair and the ankle robot will be attached to their paretic leg by means of an orthopedic knee brace and an orthopedic shoe. Pads and cushioning will be applied as needed for proper fitting, and the knee brace will be mounted to the chair for stability. The leg will rest on a cushioned support with the knee at 45 degrees and the foot free to move.

Once the set-up is completed, subjects will be asked to "play" a series of videogames by plantar- or dorsi-flexing the paretic ankle to move a corresponding cursor on a computer screen in order to hit slowly moving targets. The first game is about two-minutes duration and is played without robotic assistance to assess subjects' baseline motor control and ability. Subsequently, 6 games of about 4-minutes duration will provide differing levels of robotic support to guide or encourage the subjects to complete the prescribed ankle movements. The nature and amount of robotic support will be varied across the session to promote short-term motor learning and control of the paretic ankle. Upon completion of the performance-based training series, a repeat of the two-minute unassisted game completes the session.` Finally, subjects will be asked to repeat the postural sway and walking tests as before.

Visits 4-10: participants will be seated in a chair and the ankle robot will be attached to their paretic leg by means of an orthopedic knee brace and an orthopedic shoe. Pads and cushioning will be applied as needed for proper fitting, and the knee brace will be mounted to the chair for stability. The leg will rest on a cushioned support with the knee at 45 degrees and the foot free to move.

Once the set-up is completed, subjects will be asked to "play" a series of videogames by plantar- or dorsi-flexing the paretic ankle to move a corresponding cursor on a computer screen in order to hit slowly moving targets. The first game is about two-minutes duration and is played without robotic assistance to assess subjects' baseline motor control and ability. Subsequently, 6 games of about 4-minutes duration will provide differing levels of robotic support to guide or encourage the subjects to complete the prescribed ankle movements. The nature and amount of robotic support will be varied across the session to promote short-term motor learning and control of the paretic ankle. Upon completion of the performance-based training series, a repeat of the two-minute unassisted game completes the session. During these training sessions no electrophysiological data will be acquired, only motor control data acquired by the Anklebot itself.

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Factorial Assignment, Masking: Open Label, Primary Purpose: Treatment

Conditions

Cerebral Stroke

Intervention

Anklebot (Ankle Robot)

Location

VA Maryland Health Care System, Baltimore
Baltimore
Maryland
United States
21201

Status

Not yet recruiting

Source

Department of Veterans Affairs

Results (where available)

View Results

Links

Published on BioPortfolio: 2014-08-27T03:15:48-0400

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Medical and Biotech [MESH] Definitions

Harm or hurt to the ankle or ankle joint usually inflicted by an external source.

A familial, cerebral arteriopathy mapped to chromosome 19q12, and characterized by the presence of granular deposits in small CEREBRAL ARTERIES producing ischemic STROKE; PSEUDOBULBAR PALSY; and multiple subcortical infarcts (CEREBRAL INFARCTION). CADASIL is an acronym for Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy. CADASIL differs from BINSWANGER DISEASE by the presence of MIGRAINE WITH AURA and usually by the lack of history of arterial HYPERTENSION. (From Bradley et al, Neurology in Clinical Practice, 2000, p1146)

Restoration of functions to the maximum degree possible in a person or persons suffering from a stroke.

Replacement of the ANKLE JOINT.

Fractures of any of the bones of the ANKLE.

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