Alexandra Borstad

Neural correlates supporting sensory discrimination after left hemisphere stroke.

BACKGROUNDnNearly half of stroke patients have impaired sensory discrimination, however, the neural structures that support post-stroke sensory function have not been described.nnnOBJECTIVESn1) To evaluate the role of the primary somatosensory (S1) cortex in post-stroke sensory discrimination and 2) To determine the relationship between post-stroke sensory discrimination and structural integrity of the sensory component of the superior thalamic radiation (sSTR).nnnMETHODSn10 healthy adults and 10 individuals with left hemisphere stroke participated. Stroke participants completed sensory discrimination testing. An fMRI was conducted during right, impaired hand sensory discrimination. Fractional anisotropy and volume of the sSTR were quantified using diffusion tensor tractography.nnnRESULTSnSensory discrimination was impaired in 60% of participants with left stroke. Peak activation in the left (S1) did not correlate with sensory discrimination ability, rather a more distributed pattern of activation was evident in post-stroke subjects with a positive correlation between peak activation in the parietal cortex and discrimination ability (r=.70, p=.023). The only brain region in which stroke participants had significantly different cortical activation than control participants was the precuneus. Region of interest analysis of the precuneus across stroke participants revealed a positive correlation between peak activation and sensory discrimination ability (r=.77, p=.008). The L/R ratio of sSTR fractional anisotropy also correlated with right hand sensory discrimination (r=.69, p=.027).nnnCONCLUSIONSnPrecuneus cortex, distributed parietal lobe activity, and microstructure of the sSTR support sensory discrimination after left hemisphere stroke.

Sensorimotor Training and Neural Reorganization After Stroke: A Case Series

BACKGROUND AND PURPOSEnImpaired hand function decreases quality of life after stroke. The purpose of this study was to pilot a novel 2-week upper extremity sensorimotor training program. This case series describes the training program and highlights outcome measures used for documenting behavioral change and neural reorganization.nnnCASE DESCRIPTIONnBehavioral/performance changes were identified via sensorimotor evaluation. Activity-induced neural reorganization was examined using sensory functional magnetic resonance imaging, diffusion tensor tractography, and brain volume measurement. Participant 1 was a 75-year-old right-handed man 1 year post-right hemisphere stroke, with severe sensory impairment across domains in his left hand; he reported limited left-hand/arm use. Participant 2 was a 63-year-old right-handed woman who had experienced a left hemisphere stroke 9 months earlier, resulting in mild sensory impairment across domains in her right hand, as well as mild motor deficit.nnnINTERVENTIONnParticipants were trained 4 hours per day, 5 days per week for 2 weeks. Training tasks required sensory discrimination of temperature, weights, textures, shapes, and objects in the context of active exploration with the involved hand. Random multimodal feedback was used.nnnOUTCOMESnBoth participants had improved scores on the Wolf Motor Function Test after training. Participant 1 had no measurable change in sensory function, while participant 2 improved in touch perception, proprioception, and haptic performance. Sensory functional magnetic resonance imaging suggested neural reorganization in both participants; participant 1 had a small increase in brain volume, while superior thalamic radiation white matter connectivity was unchanged in either participant.nnnDISCUSSIONnParticipating in sensorimotor training focused on sensory discrimination during manual manipulation was feasible for both participants. Future research to determine efficacy and identify optimal measures of sensory function and neural reorganization is recommended.nnnVIDEO ABSTRACT AVAILABLEn(see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A38) for more insights from the authors.

Assessing and Treating Higher Level Somatosensory Impairments Post Stroke

Abstract Poststroke somatosensory impairment is prevalent, yet commonly used clinical measures lack the sensitivity needed to quantify impairment and detect change due to intervention. This selective review, prepared and presented as a part of the I-Treat Conference (June 22, 2013, Columbus, Ohio), discusses the prevalence of somatosensory impairment after stroke, highlights measures of higher level somatosensory processing, and briefly reviews sensorimotor rehabilitation. The goal of this article is to encourage dialogue regarding the development and use of measures of higher level somatosensory function that will enable personalization of sensorimotor rehabilitation.

Frontoparietal white matter integrity predicts haptic performance in chronic stroke

Frontoparietal white matter supports information transfer between brain areas involved in complex haptic tasks such as somatosensory discrimination. The purpose of this study was to gain an understanding of the relationship between microstructural integrity of frontoparietal network white matter and haptic performance in persons with chronic stroke and to compare frontoparietal network integrity in participants with stroke and age matched control participants. Nineteen individuals with stroke and 16 controls participated. Haptic performance was quantified using the Hand Active Sensation Test (HASTe), an 18-item match-to-sample test of weight and texture discrimination. Three tesla MRI was used to obtain diffusion-weighted and high-resolution anatomical images of the whole brain. Probabilistic tractography was used to define 10 frontoparietal tracts total; Four intrahemispheric tracts measured bilaterally 1) thalamus to primary somatosensory cortex (T–S1), 2) thalamus to primary motor cortex (T–M1), 3) primary to secondary somatosensory cortex (S1 to SII) and 4) primary somatosensory cortex to middle frontal gyrus (S1 to MFG) and, 2 interhemispheric tracts; S1–S1 and precuneus interhemispheric. A control tract outside the network, the cuneus interhemispheric tract, was also examined. The diffusion metrics fractional anisotropy (FA), mean diffusivity (MD), axial (AD) and radial diffusivity (RD) were quantified for each tract. Diminished FA and elevated MD values are associated with poorer white matter integrity in chronic stroke. Nine of 10 tracts quantified in the frontoparietal network had diminished structural integrity poststroke compared to the controls. The precuneus interhemispheric tract was not significantly different between groups. Principle component analysis across all frontoparietal white matter tract MD values indicated a single factor explained 47% and 57% of the variance in tract mean diffusivity in stroke and control groups respectively. Age strongly correlated with the shared variance across tracts in the control, but not in the poststroke participants. A moderate to good relationship was found between ipsilesional T–M1 MD and affected hand HASTe score (r = − 0.62, p = 0.006) and less affected hand HASTe score (r = − 0.53, p = 0.022). Regression analysis revealed approximately 90% of the variance in affected hand HASTe score was predicted by the white matter integrity in the frontoparietal network (as indexed by MD) in poststroke participants while 87% of the variance in HASTe score was predicted in control participants. This study demonstrates the importance of frontoparietal white matter in mediating haptic performance and specifically identifies that T–M1 and precuneus interhemispheric tracts may be appropriate targets for piloting rehabilitation interventions, such as noninvasive brain stimulation, when the goal is to improve poststroke haptic performance.

The Brief Kinesthesia test is feasible and sensitive: a study in stroke

BACKGROUND: Clinicians lack a quantitative measure of kinesthetic sense, an important contributor to sensorimotor control of the hand and arm. OBJECTIVES: The objective here was to determine the feasibility of administering the Brief Kinesthesia Test (BKT) and begin to validate it by 1) reporting BKT scores from persons with chronic stroke and a healthy comparison group and 2) examining the relationship between the BKT scores and other valid sensory and motor measures. METHOD: Adults with stroke and mild to moderate hemiparesis (N=12) and an age-, gender-, and handedness-matched healthy comparison group (N=12) completed the BKT by reproducing three targeted reaching movements per hand with vision occluded. OTHER MEASURES: the Hand Active Sensation Test (HASTe), Touch-Test(tm) monofilament aesthesiometer, 6-item Wolf Motor Function Test (Wolf), the Motor Activity Log (MAL), and the Box and Blocks Test (BBT). A paired t-test compared BKT scores between groups. Pearson product-moment correlation coefficients assessed the relationship between BKT scores and other measures. RESULTS: Post-stroke participants performed more poorly on the BKT than comparison participants with their contralesional and ipsilesional upper extremity. The mean difference for the contralesional upper extremity was 3.7 cm (SE=1.1, t=3.34; p<0.008). The BKT score for the contralesional limb was strongly correlated with the MAL-how much (r=0.84, p=0.001), the MAL-how well (r=0.76, p=0.007), Wolf (r=0.69, p=0.02), and the BBT (r=0.77, p=0.006). CONCLUSIONS: The BKT was feasible to administer and sensitive to differences in reaching accuracy between persons with stroke and a comparison group. With further refinement, The BKT may become a valuable clinical measure of post-stroke kinesthetic impairment.

In-Home Delivery of Constraint-Induced Movement Therapy via Virtual Reality Gaming

PurposenPeople with chronic hemiparesis are frequently dissatisfied with the recovery of their hand and arm, yet many lack access to effective treatments. Constraint-induced movement therapy (CI therapy) effectively increases arm function and spontaneous use in persons with chronic hemiparesis. The purpose of this study was to determine the feasibility and measure safety and outcomes of an in-home model of delivering CI therapy using a custom, avatar-based virtual reality game.nnnMethodsnSeventeen individuals with chronic hemiparesis participated in this pretest/posttest quasi-experimental design study. The 10-day intervention had three components: 1) high-repetition motor practice using virtual reality gaming; 2) constraint of the stronger arm via a padded restraint mitt; and 3) a transfer package to reinforce arm use. Feasibility of the intervention was evaluated through comparison to traditional CI therapy and through participants subjective responses. The primary outcome measures were the Wolf Motor Function Test (WMFT) and the Motor Activity Log quality of movement scale (MAL-QOM).nnnResultsnOn average, participants completed 17.2 ± 8 hours and 19,436 repetitions of motor practice. No adverse events were reported. Of 7 feasibility criteria, 4 were met. WMFT rate and MAL-QOM increased, with effect size (Cohens d) of 1.5 and 1.1, respectively.nnnConclusionsnThis model of delivering CI therapy using a custom, avatar-based virtual reality game was feasible, well received, and showed preliminary evidence of being a safe intervention to use in the home for persons with chronic hemiparesis.

Data Analytics Framework for A Game-based Rehabilitation System

Stroke is a major cause of hemiparesis in United States. Constraint--Induced Movement therapy (CI therapy) is an effective treatment for upper extremity hemiparesis; however it is inaccessible to most patients. To make it more accessible, we developed a game-based rehabilitation system incorporating the major rehabilitation principles from CI therapy. We introduce a data analytics framework for our rehabilitation system in this paper that can provide objective measures of motor performance during gameplay. We design techniques of preprocessing collected data and propose a series of kinematic measurements, which are used to assess the motor performance and supplement in-clinic measures of therapeutic effect. We also present contextual filtering techniques to enable comparing movement production under different conditions, e.g., self-paced versus game-paced movement. We apply our data analytics framework on data collected from several participants. Our analysis shows that participants motor movement improves over the period of treatment, with different participants showing different patterns of improvement, e.g., speed versus range of motion. Results of kinematic measurements during gameplay are highly consistent with in-clinic performance based on the Wolf Motor Function Test. Moreover, our fine-grained trend analysis reveals potential to detect fatigue, which is related to the duration of gameplay.

Design, Fabrication, and Administration of the Hand Active Sensation Test (HASTe).

The concept of personalizing neurologic rehabilitation, based on individual impairments, has experienced a recent surge. In parallel, the number of outcome measures of upper extremity motor performance has grown. However, clinicians and researchers lack practical, quantitative measures of the hands natural role as a receptor of the environment. The Hand Active Sensation Test (HASTe), developed by Williams and colleagues in 2006, is a valid and reliable measure of haptic performance. Though not available commercially, the HASTe can be fabricated from inexpensive materials, and it has been used successfully to identify impairments in haptic touch in individuals with stroke. (Williams, 2006). This paper presents the methods of design and fabrication of the HASTe testing kit, as well as a visual screen to be used during administration, and instructions for the tests administration and scoring.

Improved quality of life following constraint-induced movement therapy is associated with gains in arm use, but not motor improvement

ABSTRACT Background. Constraint-induced movement therapy (CI therapy) is one of few treatments for upper extremity (UE) hemiparesis that has been shown to result in motor recovery and improved quality of life in chronic stroke. However, the extent to which treatment-induced improvements in motor function versus daily use of the more affected arm independently contribute to improved quality of life remains largely unexplored. Objective. The objective of this study is to identify whether motor function or daily use of a hemiparetic arm has a greater influence on quality of life after CI therapy. Methods. Two cohorts of participants with chronic stroke received either in-person CI therapy (n = 29) or video-game home-based CI therapy (n = 16). The two cohorts were combined and the motor-related outcomes (Wolf Motor Function Test, Action Research Arm Test, Motor Activity Log [MAL]) and quality of life (Stroke-Specific Quality of Life) were jointly modeled to assess the associations between outcomes. Results. The only outcome associated with improved quality of life was the MAL. Improvements in quality of life were not restricted to motor domains, but generalized to psychosocial domains as well. Conclusions. Results suggest that improved arm use during everyday activities is integral to maximizing quality of life gains during motor rehabilitation for chronic post-stroke UE hemiparesis. In contrast, gains in motor function were not associated with increases in quality of life. These findings further support the need to implement techniques into clinical practice that promote arm use during daily life if improving quality of life is a main goal of treatment. ClinicalTrials.gov Registration Numbers: NCT01725919 and NCT03005457

A Simple Non-invasive Method for Temporary Knockdown of Upper Limb Proprioception

Proprioception may be the least well measured of all contributors to the neural control of movement. New precise, reliable measures of proprioception are needed for clinical diagnosis of impairment, and to measure outcomes of proprioceptive training. The purpose of this simple, non-invasive method is to temporarily knockdown upper limb proprioception in healthy adults, to an extent that would be useful in the development and testing of upper limb proprioception measures. Knockdown models have two main advantages over studying humans with impaired proprioception: participant availability and the ability to control the extent of impairment across participants. Current published methods of temporary proprioception knockdown of the upper limb, such as ischemic nerve blocks and cryotherapy, are invasive, impractical, or uncomfortable for the participant. Here, vibration over the ulnar groove was used to reduce upper limb proprioception. High frequency vibration may reduce proprioceptive acuity by inhibiting pacinian corpuscle-induced input. The effect of vibration used in this protocol was confirmed using two quantitative measures. This method was simple to administer, comfortable for participants, and practical.