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Biomedical subjects

Victor W Mark

Publications and source records attributed to Victor W Mark.

11 recordsLinked to original sources
PubMed2006

Bias in magnitude estimation following left hemisphere injury.

There is a growing interest both in identifying the neural mechanisms of magnitude estimation and in identifying forms of bias that can explain aspects of behavioral syndromes like unilateral neglect. Magnitude estimation is associated with activation of temporo-parietal cortex in both cerebral hemispheres of normal subjects; however, it is unclear if and how left hemisphere lesions bias magnitude estimation because the infrequency of neglect and the presence of aphasia in these subjects confound examination. In contrast, we examined magnitude estimation using 12 different types of sensory stimuli that spanned five sensory domains in two patients with very different clinical presentations following unilateral left hemisphere stroke. One patient had neglect sub-acutely without aphasia. The other had aphasia chronically after a temporo-parietal lesion but not neglect. The neglect patient was re-examined 48 h after being treated with modafinil (Provigil) for decreased arousal. Both patients demonstrated bias in magnitude estimation relative to normal subjects (n=83). Alertness improved in the neglect patient after taking modafinil. His neglect also resolved and his magnitude estimates more closely resembled those of normal subjects. This is the first evidence, to our knowledge, that left hemisphere injury can bias magnitude estimation in a manner similar but not identical to that associated with right hemisphere injury.

Adult↗
PubMed2006

The influence of neuropsychological characteristics on the use of CI therapy with persons with traumatic brain injury.

The great prevalence of traumatic brain injury (TBI) and its high economic costs make reducing TBI-related disability a national health care priority. In our research laboratory, CI therapy has been found to significantly improve upper extremity function for persons with chronic TBI. The results have suggested that persons with TBI are less likely to adhere to critical components of the CI therapy protocol than participants with stroke in other studies. Treatment outcomes have also been more variable. Our findings suggest that some cognitive skills appear related to treatment outcome. In addition, cognitive and behavioral deficits, commonly seen with participants with TBI, challenge the delivery of the standard CI therapy protocol with some persons. We discuss the implications of these neuropsychological factors for CI therapy used for chronic TBI and propose further research to more thoroughly investigate these issues.

Adult↗
PubMed2006

Cognitive assessment for CI therapy in the outpatient clinic.

OBJECTIVE: To evaluate in a preliminary fashion whether several standard cognitive assessments predict treatment outcomes on real-world functional activities following Constraint-Induced Movement therapy (CI therapy) for either the upper extremity (UE) or the lower extremity (LE) for chronic stroke hemiparesis in the outpatient therapy clinic. METHODS: 15 UE and 14 LE patients in the clinic underwent a short battery of cognitive assessments that evaluated sustained attention, episodic memory, executive control abilities, and general cognitive function. Spearman correlation analysis was used to evaluate whether each cognitive test predicted treatment outcome on the limb-specific Motor Activity Log (MAL). RESULTS: Two assessments (delayed verbal memory and Trail Making Test form B) significantly correlated with LE MAL change that followed therapy. CONCLUSIONS: We tentatively conclude from this exploratory and preliminary study that cognitive performance may predict treatment changes in response to CI therapy for the LE. Moderate to large correlations that we observed between other cognitive assessments and CI therapy outcomes recommend replicating this study with a larger and more cognitively diverse sample of stroke patients to learn if these findings are generalizable.

Adult↗
PubMed2006

A treatment for a chronic stroke patient with a plegic hand combining CI therapy with conventional rehabilitation procedures: case report.

Constraint-Induced Movement therapy (CI therapy) is a recognized rehabilitation approach for persons having stroke with mild to moderately severe motor upper extremity deficits. To date, no rehabilitation treatment protocol has been proven effective that addresses both motor performance and spontaneous upper extremity use in the life situation for chronic stroke participants having severe upper extremity impairment with no active finger extension or thumb abduction. This case report describes treatment of a chronic stroke participant with a plegic hand using a CI therapy protocol that combines CI therapy with selected occupational and physical therapy techniques. Treatment consisted of six sessions of adaptive equipment and upper extremity orthotics training followed by a three-week, six-hour daily intervention of CI therapy plus neurodevelopmental treatment. Outcome measures included the Motor Activity Log for very low functioning patients (Grade 5 MAL), upper extremity portion of the Fugl-Meyer Motor Assessment, Graded Wolf Motor Function Test - for very low functioning patients (gWMFT- Grade 5), and Modified Ashworth Scale. The participant showed improvement on each outcome measure with the largest improvement on the Grade 5 MAL. In follow-up, the participant had good retention of his gains in motor performance and use of his more affected arm for real world activities after 3 months; after a one-week brush-up at 3 months, and at one year post-treatment.

Behavior Therapy↗
PubMed2005

AutoCITE: automated delivery of CI therapy with reduced effort by therapists.

BACKGROUND AND PURPOSE: To evaluate the effectiveness of a device that automates Constraint-Induced Movement therapy (CI therapy), termed AutoCITE, when only partially supervised by therapists. METHODS: Twenty-seven participants with chronic stroke trained with AutoCITE for 3 hours per day for 10 consecutive weekdays. Participants were assigned to 1 of 3 groups in a fixed irregular order (ie, in alternating blocks): supervision from a therapist for 100%, 50%, or 25% of training time. RESULTS: The effect sizes of the treatment gains for the 3 groups on the Motor Activity Log (MAL) were very large and for the Wolf Motor Function Test they were large (all P<0.001) but were not significantly different from one another. Gains were comparable to those previously reported for participants who received an equal amount of standard one-on-one CI therapy without the device. At 1-month and long-term follow-up, gains from pretreatment on the MAL were also significant (P<0.001). CONCLUSIONS: These results demonstrate that AutoCITE training with greatly reduced supervision from a therapist is as effective as standard one-on-one CI therapy.

Activities of Daily Living↗
PubMed2005

Ballism after stroke responds to standard physical therapeutic interventions.

OBJECTIVE: To report the effects of noninvasive standard physical therapy (PT) interventions on an involuntary movement disorder after stroke. DESIGN: Single case with clinical follow-up over 2 years. SETTING: Inpatient stroke and rehabilitation services and outpatient clinic. PARTICIPANT: A man with acute bilateral ballism after unilateral subthalamic infarction. INTERVENTIONS: Rhythmic coordinated bilateral limb movements and firm tactile stimulation to the hand. MAIN OUTCOME MEASURES: We had not anticipated that dyskinesia itself would specifically improve during treatment. Consequently, we used qualitative clinical observations, including review of videotaped performance, and self-reported limb control. Hypotheses concerning treatment effects were developed after data collection. RESULTS: Involuntary movements recurrently improved within treatment sessions. CONCLUSIONS: PT may improve dyskinesia after stroke. The benefit may be adjunctive or alternative to current invasive treatments of movement disorders after brain injury and merits confirmation. The improvements are consistent with current research indicating that (1) intact cortical, subcortical, cerebellar, and spinal areas interact to generate bilateral rhythmic limb movements that can overcome dyskinesia and (2) tactile stimulation can improve motor deficits associated with basal ganglia disorders. Finally, because functional activities assessments improved our evaluation of ballism, these should be routinely used along with conventional neurologic examination to assess involuntary movement disorders.

Activities of Daily Living↗
PubMed2005

Biases in attentional orientation and magnitude estimation explain crossover: neglect is a disorder of both.

Crossover refers to a pattern of performance on the line bisection test in which short lines are bisected on the side opposite the true center of long lines. Although most patients with spatial neglect demonstrate crossover, contemporary theories of neglect cannot explain it. In contrast, we show that blending the psychophysical construct of magnitude estimation with neglect theory not only explains crossover, but also addresses a quantitative feature of neglect that is independent of spatial deficits. We report a prospective validation study of the orientation/estimation hypothesis of crossover. Forty subjects (17 patients with and without neglect following unilateral brain injury and 23 normal controls) completed four experiments that examined crossover using line bisection, line bisection with cueing, and reproducing line lengths from both memory and a standard. Replicating earlier findings, all except one subject group exhibited crossover on the standard line bisection test, all groups showed a spontaneous preference to orient attention to one end of the lines, and all groups overestimated the length of short lines and underestimated long lines. Biases in attentional orientation and magnitude estimation are exaggerated in patients with neglect. The truly novel finding of this study occurred when, after removing the line from the bisection task, the direction of crossover was completely reversed in all subject groups depending on where attention was oriented. These findings are consistent with our hypothesis of crossover: (1) crossover is a normal component of performance on line bisection; (2) crossover results from the interplay of biases in attentional orientation and magnitude estimation; and (3) attentional orientation predicts the direction of crossover, whereas a disorder of magnitude estimation, not previously emphasized in neglect, accounts for the quantitative changes in length estimation that make crossover more obvious in neglect subjects. Paradoxically, we observed that the traditional line bisection test is suboptimal for exploring crossover because lines elicit spontaneous orientation responses from subjects that confound experimental manipulations of attention. We conclude that attentional orientation and magnitude estimation are necessary and sufficient to explain crossover and that bias in magnitude estimation is a core component of neglect.

Adult↗
PubMed2004

Constraint-induced movement therapy for chronic stroke hemiparesis and other disabilities.

Constraint-Induced Movement Therapy (CI therapy) refers to a family of treatments for motor disability that combines constraint of movement, massed practice, and shaping of behavior to improve the amount of use of the targeted limb. CI therapy has controlled evidence for efficacy that supports its benefit for patients with chronic disability following central nervous system injury, regardless of their age or the interval since illness onset. Furthermore, the benefits transfer to real-world measures of limb use. Significant functional improvement may occur even after the patient has been treated with conventional physical therapy. In this paper we review the evidence for the efficacy of CI therapy, particularly for chronic stroke hemiparesis, but also for diverse other chronic disabling illnesses, including non-motor disorders such as phantom limb pain and aphasia. The adaptation of the therapy to the stroke clinic is described, along with a review of the neurophysiologic mechanisms that are postulated to underlie the treatment benefit (overcoming learned nonuse, plastic brain reorganization). Critical to the success of CI therapy is its modification according to disease factors, economic considerations, limitations of the practice setting, and the cognitive and physical status of the patient. We conclude by recommending future areas for research on CI therapy.

Chronic Disease↗
PubMed2003

Acute versus chronic functional aspects of unilateral spatial neglect.

This article reviews the impact of unilateral spatial neglect on daily living ("functional") activities. Its disturbances on basic functional activities, such as feeding, grooming, and locomotion, are easily identifiable. Patients with neglect frequently lack insight into their disorder and do not initiate compensatory behaviors, which probably impedes recovery. Simple standard tests of neglect during visual exploration correlate with impaired recovery of functional skills acutely following brain injury. However, unilateral neglect resolves in most individuals, yet many patients remain chronically impaired during daily living activities. This suggests that some other disorder associated with neglect may contribute to the failure to regain functional independence. A candidate disorder is general (non-spatial) inattention. However, cognitive studies in stroke are biased toward assessing neglect and are usually insensitive to other disorders that may accompany stroke, such as general inattention and executive dysfunction. Therefore, the contribution of unilateral neglect toward functional status relative to diverse other cognitive disorders after stroke is unclear. Treatments for unilateral neglect have been largely unsuccessful or impractical, or they were not evaluated in controlled studies. Intensive practice of scanning appears to benefit, but this observation needs to be replicated in a controlled manner. A recently developed treatment that involves wearing prisms to shift the view ipsilaterally has been associated with transfer of training effects to untreated spatial activities and prolonged improvement of neglect. However, despite some promising lines of investigation in neglect rehabilitation, further research is required to understand where neglect stands in relation to other cognitive disturbances that follow stroke with respect to functional significance and recovery, to decide what disorders should be targeted for rehabilitation.

Activities of Daily Living↗
PubMedDate not supplied

A telerehabilitation approach to delivery of constraint-induced movement therapy.

We have developed a device called AutoCITE (Automated Constraint-Induced Therapy Extension) that automates the intensive training component of constraint-induced (CI) movement therapy, also known as CI therapy. This study evaluated the effectiveness of AutoCITE training in a telerehabilitation setting when supervised remotely and with only intermittent interaction with a therapist. Seven participants with chronic stroke trained with AutoCITE for 3 h/d for 10 consecutive weekdays. The therapist supervised the training from a different room in the clinic using remote control of the AutoCITE computer and teleconferencing equipment when needed. Treatment gains on the Motor Activity Log were quite large (p < 0.001, d' = 3), while gains on the Wolf Motor Function Test and the Jebsen-Taylor Hand Function Test were large (p < 0.05, d' > 0.9). Gains were comparable in size with those previously reported for participants who received equal intensities of directly supervised AutoCITE training or standard one-on-one CI therapy without the device.

Activities of Daily Living↗