Nancy Byl - Academia.edu (original) (raw)

Papers by Nancy Byl

Physical therapy, 1997

Job-related repetitive strain injuries (RSIs) are increasing, and current treatment strategies of... more Job-related repetitive strain injuries (RSIs) are increasing, and current treatment strategies often fail to return injured people to work. This study documented the neural consequences of using two different movement strategies for active, repetitive hand closing and opening. Two owl monkeys were trained for 20 weeks to repetitively close a handpiece against an 80-g force (3-400 trials per day, training at 80%-90% accuracy). One monkey used a highly articulated hand-squeezing strategy, and the other monkey used a proximal arm-pulling strategy. Changes in motor performance were analyzed, and the electrophysiological maps of the hand representation on the trained primary sensory cortex (area 3b) were compared with those of untrained control animals and the untrained sides of the trained monkeys. The monkey using the articulated hand-squeezing strategy showed motor deterioration and dedifferentiation of the normally sharply segregated areas of the hand representation in area 3b. Mild ...

The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 15, 1998

This paper concerns the characterization of performance and perceptual learning of somatosensory ... more This paper concerns the characterization of performance and perceptual learning of somatosensory interval discrimination. The purposes of this study were to define (1) the performance characteristics for interval discrimination in the somatosensory system by naive adult humans, (2) the normal capacities for improvement in somatosensory interval discrimination, and (3) the extent of generalization of interval discrimination learning. In a two-alternative forced choice procedure, subjects were presented with two pairs of vibratory pulses. One pair was separated in time by a fixed base interval; a second pair was separated by a target interval that was always longer than the base interval. Subjects indicated which pair was separated by the target interval. The length of the target interval was varied adaptively to determine discrimination thresholds. After initial determination of naive abilities, subjects were trained for 900 trials per day at base intervals of either 75 or 125 msec f...

This prospective, correlational study sought to identify a clini- cally feasible, valid measure o... more This prospective, correlational study sought to identify a clini- cally feasible, valid measure of taxane-induced peripheral neuropathy that correlated with impairments in balance, physical performance, pain, and quality of life (QOL). In all, the study included 20 breast can- cer patients who completed taxane chemotherapy and 20 healthy women who were matched by age, height, and weight. All participants completed

2012 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2012

ABSTRACT In this paper, a network-based mobile gait rehabilitation system is proposed for improve... more ABSTRACT In this paper, a network-based mobile gait rehabilitation system is proposed for improved mobility and tele-rehabilitation. In this system, an Internet-based body sensor network is employed for health monitoring and a local highspeed wireless network is developed to achieve precise control of the gait rehabilitation device, which is a compact rotary elastic actuator (cRSEA). A new wireless protocol called MBStarPlus is proposed to achieve a high sampling rate and real-time communication. To deal with packet loss in the wireless network, a modified linear quadratic Gaussian (LQG) controller is combined with a disturbance observer (DOB) to control the cRSEA over the wireless network. Successful system integration and promising experimental results validate both the system design and proposed control algorithm. The plan for clinical testing with the proposed system is discussed.

Seminars in Neurology, 2014

Upper limb recovery after a stroke is suboptimal. Only a few individuals achieve full functional ... more Upper limb recovery after a stroke is suboptimal. Only a few individuals achieve full functional use of the hemiparetic arm. Complex primary and secondary impairments may affect recovery of upper limb function in stroke survivors. In addition, multiple personal, social, behavioral, economic, and environmental factors may interact to positively or negatively influence recovery during the different stages of rehabilitation. The current management of upper limb dysfunction poststroke has become more evidence based. In this article, we review the standard of care for upper limb poststroke rehabilitation, the evidence supporting the treatment modalities that currently exist and the exciting new developments in the therapeutic pipeline.

Experimental Brain Research, 2014

Among other diminished motor capabilities, survivors of a stroke often exhibit pathological joint... more Among other diminished motor capabilities, survivors of a stroke often exhibit pathological joint synergies. With respect to the upper limbs, these deficits diminish coordination in reaching, pointing, and daily task performance. Past research on pathological synergies suggests that the synergistic relationship between joints is different for flexion than in extension. One explanation for different flexion and extension synergies is that there exists a time difference between the joint being volitionally moved and the joint that moves in synergy. The goal of this research was to measure these synergistic time differences. The experiment included 11 hemiparetic subjects who performed rhythmic elbow motions at five different frequencies. A motion capture system was used to record the resulting shoulder synergies. Synergistic shoulder rotations were found to exhibit frequency-dependent phase lags (delays) and leads (advances) in the paretic arm. Furthermore, the synergistic leads and lags varied with frequency and were subject specific. We found that timing differences between joints in pathological movements are comparable to differences that were observed by other researchers for normal, able-bodied movement synergies. Moreover, the fact that pathological synergies were evident in rhythmic motion suggests that they are spinal in origin. A significant amount research exists relating to able-bodied spinal synergies. Thus, the supposition that pathological synergies are an expression of normal synergies would tie disabled movement into a larger body of work related to able-bodied synergies. The rehabilitation implications of this possible connection are discussed.

Games for Health Journal, 2012

2013 IEEE 13th International Conference on Rehabilitation Robotics (ICORR), 2013

Stroke is the leading cause of long-term neurological disability and the principle reason for see... more Stroke is the leading cause of long-term neurological disability and the principle reason for seeking rehabilitative services in the US. Learning based rehabilitation training enables independent mobility in the majority of patients post stroke, however, restoration of fine manipulation, motor function and task specific functions of the hemiplegic arm and hand is noted in fewer than 15% of the stroke patients. Brain plasticity is the innate mechanism enabling the recovery of motor skills through neurological reorganization of the brain as a response to limbs' manipulation. The objective of this research was to evaluate the therapeutic efficacy for the upper limbs with a dual arm exoskeleton system (EXO-UL7) using three different modalities: bilateral mirror image with symmetric movements of both arms, unilateral movement of the affected arm and standard care. Five hemiparetic subjects were randomly assigned to each therapy modality. An upper limb exoskeleton was used to provide bilateral and unilateral treatments. Standard care was provided by a licensed physical therapist. Subjects were evaluated before and after the interventions using 13 different clinical measures. Following these treatments all of the subjects demonstrated significant improved of their fine motor control and gross control across all the treatment modalities. Subjects exhibited significant improvements in range of motion of the shoulder, and improved muscle strength for bilateral training and standard care, but not for unilateral training. In conclusion, a synergetic approach in which robotic treatments (unilateral and bilateral depending on the level of the motor control) are supplemented by the standard of care may maximize the outcome of the motor control recover following stroke.

Journal of neurologic physical therapy : JNPT, 2008

To determine whether trunk position sense is impaired in people with poststroke hemiparesis. Good... more To determine whether trunk position sense is impaired in people with poststroke hemiparesis. Good trunk stability is essential for balance and extremity use during daily functional activities and higher level tasks. Dynamic stability of the trunk requires adequate flexibility, muscle strength, neural control, and proprioception. While deficits of trunk muscle strength have been identified in people post-stroke, it is not clear whether they have adequate postural control and proprioception to ensure a stable foundation of balance to enable skilled extremity use. Trunk position sense is an essential element of trunk postural control. Even a small impairment in trunk position sense may contribute to trunk instability. However, a specific impairment of trunk position sense has not been reported in people post-stroke. Twenty subjects with chronic stroke and 21 nonneurologically impaired subjects participated in the study. Trunk repositioning error during sitting forward flexion movements...

Somatosensory & Motor Research, 2002

Neuroscience Letters, 1997

Neurorehabilitation & Neural Repair, 2003

Based on the principles of neuroplasticity, the purpose of this crossover study was to determine ... more Based on the principles of neuroplasticity, the purpose of this crossover study was to determine if improvement in upper extremity (UE) function and independence could be achieved in patients 6 months to 7 years poststroke following an outpatient rehabilitation program (supervised 1.5 hours per week for 8 weeks reinforced with home gloving unaffected side and attended, graded, repetitive sensory and motor training activities). Twenty-one subjects (right or left hemiparesis; able to walk 100 feet with or without a cane; partially opened and closed the hand; partially elevated the shoulder and elbow against gravity) were randomly assigned to Group A (sensory training 4 weeks, motor training 4 weeks) or Group B (motor training 4 weeks, sensory training 4 weeks). Greater than 20% (P < 0.01) improvement was measured in functional independence and UE function (fine motor, sensory discrimination, and musculoskeletal performance). Gains were hemispheric and training specific and maintained over 3 months. This study provides evidence documenting significant improvement in function in the late poststroke recovery period following 12 hours of supervised learning based sensory motor training.

Neurology, 1996

In this study we tested a neuroplasticity/learning origins hypothesis for repetitive strain injur... more In this study we tested a neuroplasticity/learning origins hypothesis for repetitive strain injuries (RSIs), including occupationally induced focal dystonia. Repetitive movements produced in a specific form and in an appropriate behavioral context cause a degradation of the sensory feedback information controlling fine motor movements, resulting in the "learned" genesis of RSIs. Two adult New World owl monkeys were trained at a behavioral task that required them to maintain an attended grasp on a hand grip that repetitively and rapidly (20 msec) opened and closed over short distances. The monkeys completed 300 behavioral trials per day (1,100 to 3,000 movement events) with an accuracy of 80 to 90%. A movement control disorder was recorded in both monkeys. Training was continued until the performance accuracy dropped to below 50%. We subsequently conducted an electrophysiologic mapping study of the representations of the hand within the primary somatosensory (SI) cortical zone. The hand representation in the true primary somatosensory cortical field, SI area 3b, was found to be markedly degraded in these monkeys, as characterized by (1) a dedifferentiation of cortical representations of the skin of the hand manifested by receptive fields that were 10 to 20 times larger than normal, (2) the emergence of many receptive fields that covered the entire glabrous surface of individual digits or that extended across the surfaces of two or more digits, (3) a breakdown of the normally sharply segregated area 3b representations of volar glabrous and dorsal hairy skin of the hand, and (4) a breakdown of the local shifted-overlap receptive field topography of area 3b, with many digital receptive fields overlapping the fields of neurons sampled in cortical penetrations up to more than four times farther apart than normal. Thus, rapid, repetitive, highly stereotypic movements applied in a learning context can actively degrade cortical representations of sensory information guiding fine motor hand movements. This cortical plasticity/learning-based dedifferentiation of sensory feedback information from the hand contributes to the genesis of occupationally derived repetitive strain injuries, including focal dystonia of the hand. Successful treatment of patients with RSI will plausibly require learning-based restoration of differentiated representations of sensory feedback information from the hand.

Journal of Orthopaedic & Sports Physical Therapy, 1997

Sporadic research reports of decreased proprioception and balance problems have been reported in ... more Sporadic research reports of decreased proprioception and balance problems have been reported in subjects with idiopathic scoliosis, yet these sensory motor deficits have not been addressed in conservative clinical management programs. The purpose of this study was to compare both balance reactions and vibratory sensitivity (as an estimate of proprioception) in patients with idiopathic scoliosis (N = 24) and age-matched controls (N = 24). Balance was measured by the ability to pass a series of simple static and complex sensory-challenged balance tasks. Vibratory thresholds were measured with the Bio-Thesiometer at the cervical spine, wrist, and foot. Compared with age-matched controls, regardless of curve severity or spinal fusion, the subjects with idiopathic scoliosis had similar simple static balance responses when the somatosensory system was stable (with or without vision or head turning), but they were significantly more likely to fail the complex, sensory-challenged balance tasks when the somatosensory system was challenged by an unstable position of the feet, particularly when the eyes were closed. The vibratory thresholds were similar in subjects with scoliosis and their age-matched controls, but individuals with moderate to severe scoliosis (> 25 degrees) had significantly higher vibratory thresholds than those with mild curves. These findings suggest there may be problems with postural righting in patients with idiopathic scoliosis, particularly when the balance task challenges the vestibular pathways. Although vibration sensitivity did not distinguish normal healthy individuals from individuals with idiopathic scoliosis, those with more severe scoliotic curves appear to have a high threshold to vibration. These balance and vibratory differences could either be interpreted as etiologic risk factors or as consequences of spinal asymmetry. In either case, given that curves can continue to progress even into the adult years, improving the ability to right the body with gravity could help maintain the balance of the spine despite structural asymmetry.

Journal of Hand Therapy, 2000

Focal hand dystonia is a disabling, involuntary disorder of movement that can disrupt a successfu... more Focal hand dystonia is a disabling, involuntary disorder of movement that can disrupt a successful musician's career. This problem is difficult to treat, to some extent because we do not fully understand its origin. Somatosensory degradation has been proposed as one etiology. The purpose of this case study was to compare the differences in the somatosensory hand representation of two female flutists, one with focal dystonia of the left hand (digits 4 and 5) and one a healthy subject (the control). Noninvasive magnetic source imaging was performed on both subjects. The somatosensory evoked potentials of controlled taps to the fingers were measured with a 37-channel biomagnetometer and reported in terms of the neuronal organization, latency, amplitude, density, location, and spread of the digits on each axis (x, y, and z). The somatosensory representation of the involved hand of the flutist with dystonia differed from that of the healthy flutist. The magnetic fields evoked from the primary somatosensory cortex had a disorganized pattern of firing, with a short latency and excessive amplitude in the involved digits of the affected hand, as well as inconsistency (decreased density). In addition, the patterns of firing were different in terms of the location of the digits on the x, y, and z axes and sequential organization of the digits. This study confirms that somatosensory evoked magnetic fields can be used to describe the representation of the hand on the somatosensory cortex in area 3b. Degradation in the hand representation of the flutist with focal hand dystonia was evident, compared with the hand representation of the healthy flutist. It is not clear whether the sensory degradation was the cause or the consequence of the dystonia. The questions are whether re-differentiation of the representation could be achieved with aggressive sensory retraining and whether improvement in structure would be correlated with improvement in function.

Journal of Hand Therapy, 2013

Survivors post stroke commonly have upper limb impairments. Patients can drive neural reorganizat... more Survivors post stroke commonly have upper limb impairments. Patients can drive neural reorganization, brain recovery and return of function with task specific repetitive training (TSRT). Fifteen community independent stroke survivors (25-75 years, >6 months post stroke, Upper Limb Fugl Meyer [ULFM] scores 16-39) participated in this randomized feasibility study to compare outcomes of upper limb TSRT guided by a robotic orthosis (bilateral or unilateral) or a physical therapist. After 6 weeks of training (18 h), across all subjects, there were significant improvements in depression, flexibility, strength, tone, pain and voluntary movement (ULFM) (p < 0.05; effect sizes 0.49-3.53). Each training group significantly improved ULFM scores and range of motion without significant group differences. Virtual or actual TSRT performed with a robotic orthosis or a physical therapist significantly reduced arm impairments around the shoulder and elbow without significant gains in fine motor hand control, activities of daily living or independence.

Physical therapy, 1997

Job-related repetitive strain injuries (RSIs) are increasing, and current treatment strategies of... more Job-related repetitive strain injuries (RSIs) are increasing, and current treatment strategies often fail to return injured people to work. This study documented the neural consequences of using two different movement strategies for active, repetitive hand closing and opening. Two owl monkeys were trained for 20 weeks to repetitively close a handpiece against an 80-g force (3-400 trials per day, training at 80%-90% accuracy). One monkey used a highly articulated hand-squeezing strategy, and the other monkey used a proximal arm-pulling strategy. Changes in motor performance were analyzed, and the electrophysiological maps of the hand representation on the trained primary sensory cortex (area 3b) were compared with those of untrained control animals and the untrained sides of the trained monkeys. The monkey using the articulated hand-squeezing strategy showed motor deterioration and dedifferentiation of the normally sharply segregated areas of the hand representation in area 3b. Mild ...

The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 15, 1998

This paper concerns the characterization of performance and perceptual learning of somatosensory ... more This paper concerns the characterization of performance and perceptual learning of somatosensory interval discrimination. The purposes of this study were to define (1) the performance characteristics for interval discrimination in the somatosensory system by naive adult humans, (2) the normal capacities for improvement in somatosensory interval discrimination, and (3) the extent of generalization of interval discrimination learning. In a two-alternative forced choice procedure, subjects were presented with two pairs of vibratory pulses. One pair was separated in time by a fixed base interval; a second pair was separated by a target interval that was always longer than the base interval. Subjects indicated which pair was separated by the target interval. The length of the target interval was varied adaptively to determine discrimination thresholds. After initial determination of naive abilities, subjects were trained for 900 trials per day at base intervals of either 75 or 125 msec f...

This prospective, correlational study sought to identify a clini- cally feasible, valid measure o... more This prospective, correlational study sought to identify a clini- cally feasible, valid measure of taxane-induced peripheral neuropathy that correlated with impairments in balance, physical performance, pain, and quality of life (QOL). In all, the study included 20 breast can- cer patients who completed taxane chemotherapy and 20 healthy women who were matched by age, height, and weight. All participants completed

2012 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2012

ABSTRACT In this paper, a network-based mobile gait rehabilitation system is proposed for improve... more ABSTRACT In this paper, a network-based mobile gait rehabilitation system is proposed for improved mobility and tele-rehabilitation. In this system, an Internet-based body sensor network is employed for health monitoring and a local highspeed wireless network is developed to achieve precise control of the gait rehabilitation device, which is a compact rotary elastic actuator (cRSEA). A new wireless protocol called MBStarPlus is proposed to achieve a high sampling rate and real-time communication. To deal with packet loss in the wireless network, a modified linear quadratic Gaussian (LQG) controller is combined with a disturbance observer (DOB) to control the cRSEA over the wireless network. Successful system integration and promising experimental results validate both the system design and proposed control algorithm. The plan for clinical testing with the proposed system is discussed.

Seminars in Neurology, 2014

Upper limb recovery after a stroke is suboptimal. Only a few individuals achieve full functional ... more Upper limb recovery after a stroke is suboptimal. Only a few individuals achieve full functional use of the hemiparetic arm. Complex primary and secondary impairments may affect recovery of upper limb function in stroke survivors. In addition, multiple personal, social, behavioral, economic, and environmental factors may interact to positively or negatively influence recovery during the different stages of rehabilitation. The current management of upper limb dysfunction poststroke has become more evidence based. In this article, we review the standard of care for upper limb poststroke rehabilitation, the evidence supporting the treatment modalities that currently exist and the exciting new developments in the therapeutic pipeline.

Experimental Brain Research, 2014

Among other diminished motor capabilities, survivors of a stroke often exhibit pathological joint... more Among other diminished motor capabilities, survivors of a stroke often exhibit pathological joint synergies. With respect to the upper limbs, these deficits diminish coordination in reaching, pointing, and daily task performance. Past research on pathological synergies suggests that the synergistic relationship between joints is different for flexion than in extension. One explanation for different flexion and extension synergies is that there exists a time difference between the joint being volitionally moved and the joint that moves in synergy. The goal of this research was to measure these synergistic time differences. The experiment included 11 hemiparetic subjects who performed rhythmic elbow motions at five different frequencies. A motion capture system was used to record the resulting shoulder synergies. Synergistic shoulder rotations were found to exhibit frequency-dependent phase lags (delays) and leads (advances) in the paretic arm. Furthermore, the synergistic leads and lags varied with frequency and were subject specific. We found that timing differences between joints in pathological movements are comparable to differences that were observed by other researchers for normal, able-bodied movement synergies. Moreover, the fact that pathological synergies were evident in rhythmic motion suggests that they are spinal in origin. A significant amount research exists relating to able-bodied spinal synergies. Thus, the supposition that pathological synergies are an expression of normal synergies would tie disabled movement into a larger body of work related to able-bodied synergies. The rehabilitation implications of this possible connection are discussed.

Games for Health Journal, 2012

2013 IEEE 13th International Conference on Rehabilitation Robotics (ICORR), 2013

Stroke is the leading cause of long-term neurological disability and the principle reason for see... more Stroke is the leading cause of long-term neurological disability and the principle reason for seeking rehabilitative services in the US. Learning based rehabilitation training enables independent mobility in the majority of patients post stroke, however, restoration of fine manipulation, motor function and task specific functions of the hemiplegic arm and hand is noted in fewer than 15% of the stroke patients. Brain plasticity is the innate mechanism enabling the recovery of motor skills through neurological reorganization of the brain as a response to limbs' manipulation. The objective of this research was to evaluate the therapeutic efficacy for the upper limbs with a dual arm exoskeleton system (EXO-UL7) using three different modalities: bilateral mirror image with symmetric movements of both arms, unilateral movement of the affected arm and standard care. Five hemiparetic subjects were randomly assigned to each therapy modality. An upper limb exoskeleton was used to provide bilateral and unilateral treatments. Standard care was provided by a licensed physical therapist. Subjects were evaluated before and after the interventions using 13 different clinical measures. Following these treatments all of the subjects demonstrated significant improved of their fine motor control and gross control across all the treatment modalities. Subjects exhibited significant improvements in range of motion of the shoulder, and improved muscle strength for bilateral training and standard care, but not for unilateral training. In conclusion, a synergetic approach in which robotic treatments (unilateral and bilateral depending on the level of the motor control) are supplemented by the standard of care may maximize the outcome of the motor control recover following stroke.

Journal of neurologic physical therapy : JNPT, 2008

To determine whether trunk position sense is impaired in people with poststroke hemiparesis. Good... more To determine whether trunk position sense is impaired in people with poststroke hemiparesis. Good trunk stability is essential for balance and extremity use during daily functional activities and higher level tasks. Dynamic stability of the trunk requires adequate flexibility, muscle strength, neural control, and proprioception. While deficits of trunk muscle strength have been identified in people post-stroke, it is not clear whether they have adequate postural control and proprioception to ensure a stable foundation of balance to enable skilled extremity use. Trunk position sense is an essential element of trunk postural control. Even a small impairment in trunk position sense may contribute to trunk instability. However, a specific impairment of trunk position sense has not been reported in people post-stroke. Twenty subjects with chronic stroke and 21 nonneurologically impaired subjects participated in the study. Trunk repositioning error during sitting forward flexion movements...

Somatosensory & Motor Research, 2002

Neuroscience Letters, 1997

Neurorehabilitation & Neural Repair, 2003

Based on the principles of neuroplasticity, the purpose of this crossover study was to determine ... more Based on the principles of neuroplasticity, the purpose of this crossover study was to determine if improvement in upper extremity (UE) function and independence could be achieved in patients 6 months to 7 years poststroke following an outpatient rehabilitation program (supervised 1.5 hours per week for 8 weeks reinforced with home gloving unaffected side and attended, graded, repetitive sensory and motor training activities). Twenty-one subjects (right or left hemiparesis; able to walk 100 feet with or without a cane; partially opened and closed the hand; partially elevated the shoulder and elbow against gravity) were randomly assigned to Group A (sensory training 4 weeks, motor training 4 weeks) or Group B (motor training 4 weeks, sensory training 4 weeks). Greater than 20% (P < 0.01) improvement was measured in functional independence and UE function (fine motor, sensory discrimination, and musculoskeletal performance). Gains were hemispheric and training specific and maintained over 3 months. This study provides evidence documenting significant improvement in function in the late poststroke recovery period following 12 hours of supervised learning based sensory motor training.

Neurology, 1996

In this study we tested a neuroplasticity/learning origins hypothesis for repetitive strain injur... more In this study we tested a neuroplasticity/learning origins hypothesis for repetitive strain injuries (RSIs), including occupationally induced focal dystonia. Repetitive movements produced in a specific form and in an appropriate behavioral context cause a degradation of the sensory feedback information controlling fine motor movements, resulting in the "learned" genesis of RSIs. Two adult New World owl monkeys were trained at a behavioral task that required them to maintain an attended grasp on a hand grip that repetitively and rapidly (20 msec) opened and closed over short distances. The monkeys completed 300 behavioral trials per day (1,100 to 3,000 movement events) with an accuracy of 80 to 90%. A movement control disorder was recorded in both monkeys. Training was continued until the performance accuracy dropped to below 50%. We subsequently conducted an electrophysiologic mapping study of the representations of the hand within the primary somatosensory (SI) cortical zone. The hand representation in the true primary somatosensory cortical field, SI area 3b, was found to be markedly degraded in these monkeys, as characterized by (1) a dedifferentiation of cortical representations of the skin of the hand manifested by receptive fields that were 10 to 20 times larger than normal, (2) the emergence of many receptive fields that covered the entire glabrous surface of individual digits or that extended across the surfaces of two or more digits, (3) a breakdown of the normally sharply segregated area 3b representations of volar glabrous and dorsal hairy skin of the hand, and (4) a breakdown of the local shifted-overlap receptive field topography of area 3b, with many digital receptive fields overlapping the fields of neurons sampled in cortical penetrations up to more than four times farther apart than normal. Thus, rapid, repetitive, highly stereotypic movements applied in a learning context can actively degrade cortical representations of sensory information guiding fine motor hand movements. This cortical plasticity/learning-based dedifferentiation of sensory feedback information from the hand contributes to the genesis of occupationally derived repetitive strain injuries, including focal dystonia of the hand. Successful treatment of patients with RSI will plausibly require learning-based restoration of differentiated representations of sensory feedback information from the hand.

Journal of Orthopaedic & Sports Physical Therapy, 1997

Sporadic research reports of decreased proprioception and balance problems have been reported in ... more Sporadic research reports of decreased proprioception and balance problems have been reported in subjects with idiopathic scoliosis, yet these sensory motor deficits have not been addressed in conservative clinical management programs. The purpose of this study was to compare both balance reactions and vibratory sensitivity (as an estimate of proprioception) in patients with idiopathic scoliosis (N = 24) and age-matched controls (N = 24). Balance was measured by the ability to pass a series of simple static and complex sensory-challenged balance tasks. Vibratory thresholds were measured with the Bio-Thesiometer at the cervical spine, wrist, and foot. Compared with age-matched controls, regardless of curve severity or spinal fusion, the subjects with idiopathic scoliosis had similar simple static balance responses when the somatosensory system was stable (with or without vision or head turning), but they were significantly more likely to fail the complex, sensory-challenged balance tasks when the somatosensory system was challenged by an unstable position of the feet, particularly when the eyes were closed. The vibratory thresholds were similar in subjects with scoliosis and their age-matched controls, but individuals with moderate to severe scoliosis (> 25 degrees) had significantly higher vibratory thresholds than those with mild curves. These findings suggest there may be problems with postural righting in patients with idiopathic scoliosis, particularly when the balance task challenges the vestibular pathways. Although vibration sensitivity did not distinguish normal healthy individuals from individuals with idiopathic scoliosis, those with more severe scoliotic curves appear to have a high threshold to vibration. These balance and vibratory differences could either be interpreted as etiologic risk factors or as consequences of spinal asymmetry. In either case, given that curves can continue to progress even into the adult years, improving the ability to right the body with gravity could help maintain the balance of the spine despite structural asymmetry.

Journal of Hand Therapy, 2000

Focal hand dystonia is a disabling, involuntary disorder of movement that can disrupt a successfu... more Focal hand dystonia is a disabling, involuntary disorder of movement that can disrupt a successful musician's career. This problem is difficult to treat, to some extent because we do not fully understand its origin. Somatosensory degradation has been proposed as one etiology. The purpose of this case study was to compare the differences in the somatosensory hand representation of two female flutists, one with focal dystonia of the left hand (digits 4 and 5) and one a healthy subject (the control). Noninvasive magnetic source imaging was performed on both subjects. The somatosensory evoked potentials of controlled taps to the fingers were measured with a 37-channel biomagnetometer and reported in terms of the neuronal organization, latency, amplitude, density, location, and spread of the digits on each axis (x, y, and z). The somatosensory representation of the involved hand of the flutist with dystonia differed from that of the healthy flutist. The magnetic fields evoked from the primary somatosensory cortex had a disorganized pattern of firing, with a short latency and excessive amplitude in the involved digits of the affected hand, as well as inconsistency (decreased density). In addition, the patterns of firing were different in terms of the location of the digits on the x, y, and z axes and sequential organization of the digits. This study confirms that somatosensory evoked magnetic fields can be used to describe the representation of the hand on the somatosensory cortex in area 3b. Degradation in the hand representation of the flutist with focal hand dystonia was evident, compared with the hand representation of the healthy flutist. It is not clear whether the sensory degradation was the cause or the consequence of the dystonia. The questions are whether re-differentiation of the representation could be achieved with aggressive sensory retraining and whether improvement in structure would be correlated with improvement in function.

Journal of Hand Therapy, 2013

Survivors post stroke commonly have upper limb impairments. Patients can drive neural reorganizat... more Survivors post stroke commonly have upper limb impairments. Patients can drive neural reorganization, brain recovery and return of function with task specific repetitive training (TSRT). Fifteen community independent stroke survivors (25-75 years, >6 months post stroke, Upper Limb Fugl Meyer [ULFM] scores 16-39) participated in this randomized feasibility study to compare outcomes of upper limb TSRT guided by a robotic orthosis (bilateral or unilateral) or a physical therapist. After 6 weeks of training (18 h), across all subjects, there were significant improvements in depression, flexibility, strength, tone, pain and voluntary movement (ULFM) (p < 0.05; effect sizes 0.49-3.53). Each training group significantly improved ULFM scores and range of motion without significant group differences. Virtual or actual TSRT performed with a robotic orthosis or a physical therapist significantly reduced arm impairments around the shoulder and elbow without significant gains in fine motor hand control, activities of daily living or independence.