Biomarkers of Rehabilitation Therapy Vary According To Stroke Severity

Biomarkers that capture treatment effects could improve the precision of clinical decision making for restorative therapies. We examined the performance of candidate structural, functional,and angiogenesis-related MRI biomarkers before and after a 3-week course of standardized robotic therapy in 18 patients with chronic stroke and hypothesized that results vary significantly according to stroke severity. Patients were 4.1 ± 1 months poststroke, with baseline arm Fugl-Meyer scores of 20–60. When all patients were examined together, no imaging measure changed over time in a manner that correlated with treatment-induced motor gains. However, when also considering the interaction with baseline motor status, treatment-induced motor gains were significantly related to change in three functional connectivity measures: ipsilesional motor cortex connectivity with (1) contralesional motor cortex (p = 0 003), (2) contralesional dorsal premotor cortex (p = 0 005), and (3) ipsilesional dorsal premotor cortex (p = 0 004). In more impaired patients, larger treatment gains were associated with greater increases in functional connectivity, whereas in less impaired patients larger treatment gains were associated with greater decreases in functional connectivity. Functional connectivity measures performed best as biomarkers of treatment effects after stroke. The relationship between changes in functional connectivity and treatment gains varied according to baseline stroke severity. Biomarkers of restorative therapy effects are not one-size-fits-all after stroke

Role of Corpus Callosum Integrity in Arm Function Differs Based on Motor Severity After Stroke

While the corpus callosum (CC) is important to normal sensorimotor function, its role in motor function after stroke is less well understood. This study examined the relationship between structural integrity of the motor and sensory sections of the CC, as reflected by fractional anisotropy (FA), and motor function in individuals with a range of motor impairment level due to stroke. Fifty-five individuals with chronic stroke (Fugl-Meyer motor score range 14 to 61) and 18 healthy controls underwent diffusion tensor imaging and a set of motor behavior tests. Mean FA from the motor and sensory regions of the CC and from corticospinal tract (CST) were extracted and relationships with behavioral measures evaluated. Across all participants, FA in both CC regions was significantly decreased after stroke (p \u3c 0.001) and showed a significant, positive correlation with level of motor function. However, these relationships varied based on degree of motor impairment: in individuals with relatively less motor impairment (Fugl-Meyer motor score \u3e 39), motor status correlated with FA in the CC but not the CST, while in individuals with relatively greater motor impairment (Fugl-Meyer motor score ≤ 39), motor status correlated with FA in the CST but not the CC. The role interhemispheric motor connections play in motor function after stroke may differ based on level of motor impairment. These findings emphasize the heterogeneity of stroke, and suggest that biomarkers and treatment approaches targeting separate subgroups may be warranted

Validity of Robot-based Assessments of Upper Extremity Function

Objective To examine the validity of 5 robot-based assessments of arm motor function post-stroke. Design Cross sectional. Setting Outpatient clinical research center. Participants Volunteer sample of 40 participants, age \u3e18 years, 3-6 months post-stroke, with arm motor deficits that had plateaued. Intervention None. Main Outcome Measures Clinical standards included the Fugl-Meyer Arm Motor Scale (FMA), and 5 secondary motor outcomes: hand/wrist subsection of the FMA; Action Research Arm Test (ART); Box & Blocks test (B/B); hand subscale of Stroke Impact Scale-2 (SIS); and the Barthel Index (BI). Robot-based assessments included: wrist targeting; finger targeting; finger movement speed; reaction time; and a robotic version of the (B/B) test. Anatomical measures included percentage injury to the corticospinal tract (CST) and primary motor cortex (M1, hand region) obtained from MRI . Results Subjects had moderate-severe impairment (arm FMA scores = 35.6±14.4, range 13.5-60). Performance on the robot-based tests, including speed (r=0.82, p\u3c0.0001), wrist targeting (r=0.72, p\u3c0.0001), and finger targeting (r=0.67, p\u3c0.0001) correlated significantly with the FMA scores. Wrist targeting (r=0.57 - 0.82) and finger targeting (r=0.49 - 0.68) correlated significantly with all 5 secondary motor outcomes and with percent CST injury. The robotic version of the B/B correlated significantly with the clinical B/B test but was less prone to floor effect. Robot-based assessments were comparable to FMA score in relation to percent CST injury and superior in relation to M1 hand injury. Conclusions The current findings support using a battery of robot-based methods for assessing the upper extremity motor function in subjects with chronic stroke

Gains Across WHO Dimensions of Function After Robot-Based Therapy in Stroke Subjects

Background Studies examining the effects of therapeutic interventions after stroke often focus on changes in loss of body function/structure (impairment). However, improvements in activities limitations and participation restriction are often higher patient priorities, and the relationship that these measures have with loss of body function/structure is unclear. Objective This study measured gains across WHO International Classification of Function (ICF) dimensions and examined their interrelationships. Methods Subjects were recruited 11 to 26 weeks after hemiparetic stroke. Over a 3-week period, subjects received 12 sessions of intensive robot-based therapy targeting the distal arm. Each subject was assessed at baseline and at 1 month after end of therapy. Results At baseline, subjects (n = 40) were 134.7 ± 32.4 (mean ± SD) days poststroke and had moderate-severe arm motor deficits (arm motor Fugl-Meyer score of 35.6 ± 14.4) that were stable. Subjects averaged 2579 thumb movements and 1298 wrist movements per treatment session. After robot therapy, there was significant improvement in measures of body function/structure (Fugl-Meyer score) and activity limitations (Action Research Arm Test, Barthel Index, and Stroke Impact Scale–Hand), but not participation restriction (Stroke Specific Quality of Life Scale). Furthermore, while the degree of improvement in loss of body function/structure was correlated with improvement in activity limitations, neither improvement in loss of body function/structure nor improvement in activity limitations was correlated with change in participation restriction. Conclusions After a 3-week course of robotic therapy, there was improvement in body function/structure and activity limitations but no reduction in participation restriction

Gains Across WHO Dimensions of Function After Robot-Based Therapy in Stroke Subjects

Background Studies examining the effects of therapeutic interventions after stroke often focus on changes in loss of body function/structure (impairment). However, improvements in activities limitations and participation restriction are often higher patient priorities, and the relationship that these measures have with loss of body function/structure is unclear. Objective This study measured gains across WHO International Classification of Function (ICF) dimensions and examined their interrelationships. Methods Subjects were recruited 11 to 26 weeks after hemiparetic stroke. Over a 3-week period, subjects received 12 sessions of intensive robot-based therapy targeting the distal arm. Each subject was assessed at baseline and at 1 month after end of therapy. Results At baseline, subjects (n = 40) were 134.7 ± 32.4 (mean ± SD) days poststroke and had moderate-severe arm motor deficits (arm motor Fugl-Meyer score of 35.6 ± 14.4) that were stable. Subjects averaged 2579 thumb movements and 1298 wrist movements per treatment session. After robot therapy, there was significant improvement in measures of body function/structure (Fugl-Meyer score) and activity limitations (Action Research Arm Test, Barthel Index, and Stroke Impact Scale–Hand), but not participation restriction (Stroke Specific Quality of Life Scale). Furthermore, while the degree of improvement in loss of body function/structure was correlated with improvement in activity limitations, neither improvement in loss of body function/structure nor improvement in activity limitations was correlated with change in participation restriction. Conclusions After a 3-week course of robotic therapy, there was improvement in body function/structure and activity limitations but no reduction in participation restriction

A Home-Based Telerehabilitation Program for Patients with Stroke

Background. Although rehabilitation therapy is commonly provided after stroke, many patients do not derive maximal benefit because of access, cost, and compliance. A telerehabilitation-based program may overcome these barriers. We designed, then evaluated a home-based telerehabilitation system in patients with chronic hemiparetic stroke. Methods. Patients were 3 to 24 months poststroke with stable arm motor deficits. Each received 28 days of telerehabilitation using a system delivered to their home. Each day consisted of 1 structured hour focused on individualized exercises and games, stroke education, and an hour of free play. Results. Enrollees (n = 12) had baseline Fugl-Meyer (FM) scores of 39 ± 12 (mean ± SD). Compliance was excellent: participants engaged in therapy on 329/336 (97.9%) assigned days. Arm repetitions across the 28 days averaged 24,607 ± 9934 per participant. Arm motor status showed significant gains (FM change 4.8 ± 3.8 points, P = .0015), with half of the participants exceeding the minimal clinically important difference. Although scores on tests of computer literacy declined with age (r = −0.92; P \u3c .0001), neither the motor gains nor the amount of system use varied with computer literacy. Daily stroke education via the telerehabilitation system was associated with a 39% increase in stroke prevention knowledge (P = .0007). Depression scores obtained in person correlated with scores obtained via the telerehabilitation system 16 days later (r = 0.88; P = .0001). In-person blood pressure values closely matched those obtained via this system (r = 0.99; P \u3c .0001). Conclusions. This home-based system was effective in providing telerehabilitation, education, and secondary stroke prevention to participants. Use of a computer-based interface offers many opportunities to monitor and improve the health of patients after stroke

The empirical replicability of task-based fMRI as a function of sample size

Replicating results (i.e. obtaining consistent results using a new independent dataset) is an essential part of good science. As replicability has consequences for theories derived from empirical studies, it is of utmost importance to better understand the underlying mechanisms influencing it. A popular tool for non-invasive neuroimaging studies is functional magnetic resonance imaging (fMRI). While the effect of underpowered studies is well documented, the empirical assessment of the interplay between sample size and replicability of results for task-based fMRI studies remains limited. In this work, we extend existing work on this assessment in two ways. Firstly, we use a large database of 1400 subjects performing four types of tasks from the IMAGEN project to subsample a series of independent samples of increasing size. Secondly, replicability is evaluated using a multi-dimensional framework consisting of 3 different measures: (un)conditional test-retest reliability, coherence and stability. We demonstrate not only a positive effect of sample size, but also a trade-off between spatial resolution and replicability. When replicability is assessed voxelwise or when observing small areas of activation, a larger sample size than typically used in fMRI is required to replicate results. On the other hand, when focussing on clusters of voxels, we observe a higher replicability. In addition, we observe variability in the size of clusters of activation between experimental paradigms or contrasts of parameter estimates within these

The interaction of child abuse and rs1360780 of the FKBP5 gene is associated with amygdala resting-state functional connectivity in young adults

Extensive research has demonstrated that rs1360780, a common single nucleotide polymorphism within the FKBP5 gene, interacts with early-life stress in predicting psychopathology. Previous results suggest that carriers of the TT genotype of rs1360780 who were exposed to child abuse show differences in structure and functional activation of emotion-processing brain areas belonging to the salience network. Extending these findings on intermediate phenotypes of psychopathology, we examined if the interaction between rs1360780 and child abuse predicts resting-state functional connectivity (rsFC) between the amygdala and other areas of the salience network. We analyzed data of young European adults from the general population (N = 774; mean age = 18.76 years) who took part in the IMAGEN study. In the absence of main effects of genotype and abuse, a significant interaction effect was observed for rsFC between the right centromedial amygdala and right posterior insula (p < .025, FWE-corrected), which was driven by stronger rsFC in TT allele carriers with a history of abuse. Our results suggest that the TT genotype of rs1360780 may render individuals with a history of abuse more vulnerable to functional changes in communication between brain areas processing emotions and bodily sensations, which could underlie or increase the risk for psychopathology

Peer victimization and its impact on adolescent brain development and psychopathology

Chronic peer victimization has long-term impacts on mental health; however, the biological mediators of this adverse relationship are unknown. We sought to determine whether adolescent brain development is involved in mediating the effect of peer victimization on psychopathology. We included participants (n = 682) from the longitudinal IMAGEN study with both peer victimization and neuroimaging data. Latent profile analysis identified groups of adolescents with different experiential patterns of victimization. We then associated the victimization trajectories and brain volume changes with depression, generalized anxiety, and hyperactivity symptoms at age 19. Repeated measures ANOVA revealed time-by victimization interactions on left putamen volume (F = 4.38, p = 0.037). Changes in left putamen volume were negatively associated with generalized anxiety (t = −2.32, p = 0.020). Notably, peer victimization was indirectly associated with generalized anxiety via decreases in putamen volume (95% CI = 0.004–0.109). This was also true for the left caudate (95% CI = 0.002–0.099). These data suggest that the experience of chronic peer victimization during adolescence might induce psychopathology-relevant deviations from normative brain development. Early peer victimization interventions could prevent such pathological changes