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Background: Perinatal stroke (PS) causes most hemiparetic cerebral palsy (CP) and results in lifelong disability. Children with severe hemiparesis have limited rehabilitation options. Brain computer interface- activated functional electrical stimulation (BCI-FES) of target muscles may enhance upper extremity function in hemiparetic adults. We conducted a pilot clinical trial to assess the safety and feasibility of BCI-FES in children with hemiparetic CP. Methods: Thirteen participants (mean age = 12.2 years, 31% female) were recruited from a population-based cohort. Inclusion criteria were: (1) MRIconfirmed PS, (2) disabling hemiparetic CP, (3) age 6–18 years, (4) informed consent/assent. Those with neurological comorbidities or unstable epilepsy were excluded. Participants attended two BCI sessions: training and rehabilitation. They wore an EEG-BCI headset and two forearm extensor stimulation electrodes. Participants’ imagination of wrist extension was classified on EEG, after which muscle stimulation and visual feedback were provided when the correct visualization was detected. Results: No serious adverse events or dropouts occurred. The most common complaints were mild headache, headset discomfort and muscle fatigue. Children ranked the experience as comparable to a long car ride and none reported as unpleasant. Sessions lasted a mean of 87 min with 33 min of stimulation delivered. Mean classification accuracies were (M = 78.78%, SD = 9.97) for training and (M = 73.48, SD = 12.41) for rehabilitation. Mean Cohen’s Kappa across rehabilitation trials was M = 0.43, SD = 0.29, range = 0.019–1.00, suggesting BCI competency. Conclusion: Brain computer interface-FES was well -tolerated and feasible in children with hemiparesis. This paves the way for clinical trials to optimize approaches and test efficacy. [ABSTRACT FROM AUTHOR]

Brain stimulation combined with intensive therapy may improve hand function in children with perinatal stroke‐induced unilateral cerebral palsy (UCP). However, response to therapy varies and underlying neuroplasticity mechanisms remain unclear. Here, we aimed to characterize robotic motor mapping outcomes in children with UCP. Twenty‐nine children with perinatal stroke and UCP (median age 11 ± 2 years) were compared to 24 typically developing controls (TDC). Robotic, neuronavigated transcranial magnetic stimulation was employed to define bilateral motor maps including area, volume, and peak motor evoked potential (MEP). Map outcomes were compared to the primary clinical outcome of the Jebsen–Taylor Test of Hand Function (JTT). Maps were reliably obtained in the contralesional motor cortex (24/29) but challenging in the lesioned hemisphere (5/29). Within the contralesional M1 of participants with UCP, area and peak MEP amplitude of the unaffected map were larger than the affected map. When comparing bilateral maps within the contralesional M1 in children with UCP to that of TDC, only peak MEP amplitudes were different, being smaller for the affected hand as compared to TDC. We observed correlations between the unaffected map when stimulating the contralesional M1 and function of the unaffected hand. Robotic motor mapping can characterize motor cortex neurophysiology in children with perinatal stroke. Map area and peak MEP amplitude may represent discrete biomarkers of developmental plasticity in the contralesional M1. Correlations between map metrics and hand function suggest clinical relevance and utility in studies of interventional plasticity. [ABSTRACT FROM AUTHOR]

Perinatal stroke causes hemiparetic cerebral palsy (HCP) and lifelong disability. Constraint-induced movement therapy (CIMT) and neurostimulation may enhance motor function, but the individual factors associated with responsiveness are undetermined. We explored the clinical and neurophysiological factors associated with responsiveness to CIMT and/or brain stimulation within a clinical trial. PLASTIC CHAMPS was a randomized, blinded, sham-controlled trial (n = 45) of CIMT and neurostimulation paired with intensive, goal-directed therapy. Primary outcome was the Assisting Hand Assessment (AHA). Classification trees created through recursive partitioning suggested clinical and neurophysiological profiles associated with improvement at 6-months. Both clinical (stroke side (left) and age >14 years) and neurophysiological (intracortical inhibition/facilitation and motor threshold) were associated with responsiveness across treatment groups with positive predictive values (PPV) approaching 80%. This preliminary analysis suggested sets of variables that may be associated with response to intensive therapies in HCP. Further modeling in larger trials is required. [ABSTRACT FROM AUTHOR]

The goal of this study was to examine executive functioning, math performance, and visuospatial processing skills of children with perinatal stroke, which have not been well explored in this population. Participants included 18 children with perinatal stroke (aged 6-16 years old) and their primary caregiver. Each child completed standardized tests of executive function and visuospatial processing skills, Intelligence Quotient (IQ), and math achievement. Performance on executive function, IQ, math, and visuospatial processing tests was significantly lower in children with perinatal stroke when compared to normative means. Poorer inhibitory control was associated with worse math performance. Increased age at testing was associated with better performance on visuospatial ability (using standardized scores), and females performed better than males on a test of inhibitory control. Children with perinatal stroke displayed a range of neuropsychological impairments, and difficulties with executive function (inhibition) may contribute to math difficulties in this population. [ABSTRACT FROM AUTHOR]

Background: Perinatal stroke is a leading cause of hemiparetic cerebral palsy and lifelong disability. Neurodevelopmental outcomes are difficult to predict and markers of long-term poor outcome continue to be investigated. Deceleration in growth of head circumference has been associated with worse developmental outcomes in neonatal brain injury. We hypothesized that perinatal stroke would result in decreased rates of head growth during childhood that would be associated with worse developmental outcomes. Methods: Patients with magnetic resonance imaging (MRI)–confirmed neonatal arterial ischemic stroke and arterial presumed perinatal ischemic stroke were identified from a population-based research cohort (Alberta Perinatal Stroke Project). Demographics and occipital-frontal circumference data were collected from medical records. Head growth was compared to typically developing control charts using a 2-tailed t test. The Fisher exact test was used to examine associations between Pediatric Stroke Outcome Measures (PSOM) scores and occipital-frontal head circumference. Results: Three hundred fifteen occipital-frontal head circumference measurements were collected from 102 patients (48 female, 54 male), over a median of 3.2 years (standard deviation = 5.18, range = 0-18.3). After 3 months for female patients and 1 year for male patients, occipital-frontal head circumference deviated and remained below normal growth trajectories (P <.05) with a large effect size (Cohen d >0.8). Poor outcome (PSOM ≥ 1) was associated with smaller occipital-frontal head circumference (P <.05). Conclusion: Head growth deceleration is observed in children with perinatal arterial ischemic stroke and is associated with poor outcome. Head circumference may be a tool to alert clinicians to the potential of abnormal neurologic outcome. [ABSTRACT FROM AUTHOR]

• Patients with ESES show significantly higher pre-diagnosis spike-frequency than those without ESES. • Stroke patients with ESES show significantly lower pre-diagnosis delta power than those without ESES. • Using spike-frequency, clinicians may be able to identify patients at risk of developing ESES. Continuous spike and wave in slow-wave sleep (CSWS), an epileptic encephalopathy, occurs after perinatal stroke where it is associated with cognitive decline. CSWS features a distinct EEG pattern, electrical status epilepticus in sleep (ESES). Biomarkers for the prediction of ESES have not been identified but will facilitate earlier diagnosis and treatment. We hypothesized that spike-frequency and differences in power spectra would be predictive of subsequent ESES. A cross-sectional study comparing EEG spike-frequency and Power before the development of ESES in patients with perinatal stroke, patients with focal epilepsy, and appropriate controls. 43 patients met the inclusion criteria; 11 stroke-ESES, 10 stroke controls, 14 epilepsy-ESES, 8 epilepsy controls. ESES patients had higher pre-diagnosis mean spike-frequency (24.0 ± 24 versus 6.6 ± 9.1 SW/min, p = 0.002) than patients that did not develop ESES; these differences present ~ 3 years before ESES diagnosis. Pre-diagnosis, normalized delta power (1–4 Hz) was higher in the stroke-ESES group (105.7 ± 58 dB/Hz) compared to stroke controls (57.4 ± 45 dB/Hz, p = 0.036). Spike-frequency and delta power may represent EEG biomarkers of the risk of developing ESES in children with perinatal stroke. EEG biomarkers may be used by clinicians to assess which patients are more at-risk for ESES. Using spike-frequency, clinicians may be able to identify patients at risk of developing ESES. [ABSTRACT FROM AUTHOR]

Perinatal stroke is the most common form of stroke in childhood and is followed by a variety of outcomes, with many children experiencing specific functional and neuropsychological deficits. The association of these outcomes with the psychosocial impact caregivers face is not well documented. The goal of our pilot study was to examine caregivers' perception of executive behavior and functional abilities among children with perinatal stroke, and how these outcomes impact the caregivers. We administered three questionnaires to primary caregivers of children with perinatal stroke to obtain caregiver-reported measures of (1) executive behavior of their child (Behavior Rating Inventory of Executive Function, Second Edition), (2) the functional abilities of their child (Pediatric Evaluation of Disability Inventory Computer Adaptive Test), and (3) the psychosocial impact experienced by the caregiver themselves (Parental Outcome Measure). Participants included 20 children (mean age = 9.3 years, range = 6–16 years) with perinatal stroke and their primary caregivers. Functional abilities in the children were rated as clinically impaired in the domains of daily activities and mobility. Half of the children exhibited clinically impaired ratings on at least one executive behavior domain, but the mean scores for these domains did not reach clinically impaired levels. Greater ratings of problems in daily activities for the child was associated with greater caregiver guilt (r = −0.55, p = 0.02). Caregivers of children with perinatal stroke who experience limitations in performing daily activities should be more closely monitored for adverse impact and be provided the necessary support and education to alleviate the associated guilt. [ABSTRACT FROM AUTHOR]

Aim: We aimed to characterize the phenotype and outcome of children with bilateral, large vessel perinatal arterial ischemic stroke.Methods: Patients with bilateral, large vessel perinatal arterial ischemic stroke were identified from a large, population-based cohort (Alberta Perinatal Stroke Project). Subjects were included if stroke involving a major cerebral artery territory was documented in both cerebral hemispheres on magnetic resonance imaging. Standardized variables were extracted from charts including clinical presentations, associated potential risk factors, and outcomes. Outcome measures included the Pediatric Stroke Outcome Measure, Gross Motor Function Classification System, and epilepsy frequency score. Electroencephalographies were reviewed for sleep, epileptiform activity, and background.Results: Of 174 children with perinatal arterial ischemic stroke, eight (5%) had bilateral large artery infarcts. Patients were followed for a mean of 9.7 years (range 1.8 to 14.6 years). One child died. All children had a total Pediatric Stroke Outcome Measure of ≥2 (median 8, range 2 to 10) and Gross Motor Function Classification System ≥ II. Seven of eight (88%) children had a history of epilepsy.Conclusions: Children with bilateral, large vessel perinatal stroke are at high risk of severe cognitive and motor sequelae. Epilepsy may also be more common than unilateral strokes. Cautious discussions with families regarding prognosis are recommended. [ABSTRACT FROM AUTHOR]

Perinatal stroke causes lifelong disability, particularly hemiparetic cerebral palsy. Arterial ischemic strokes (AIS) are large, cortical, and subcortical injuries acquired near birth due to acute occlusion of the middle cerebral artery. Periventricular venous infarctions (PVI) are smaller, subcortical strokes acquired prior to 34 weeks gestation involving injury to the periventricular white matter. Both stroke types can damage motor pathways, thus, we investigated resulting alterations in functional motor networks and probed function. We measured blood oxygen level dependent (BOLD) fluctuations at rest in 38 participants [10 arterial patients (age = 14.7 ± 4.1 years), 10 venous patients (age = 13.5 ± 3.7 years), and 18 typically developing controls (TDCs) (age = 15.3 ± 5.1 years)] and explored strength and laterality of functional connectivity in the motor network. Inclusion criteria included MRI‐confirmed, unilateral perinatal stroke, symptomatic hemiparetic cerebral palsy, and 6–19 years old at time of imaging. Seed‐based functional connectivity analyses measured temporal correlations in BOLD response over the whole brain using primary motor cortices as seeds. Laterality indices based on mean z‐scores in lesioned and nonlesioned hemispheres explored laterality. In AIS patients, significant differences in both strength and laterality of motor network connections were observed compared with TDCs. In PVI patients, motor networks largely resembled those of healthy controls, albeit slightly weaker and asymmetric, despite subcortical damage and hemiparesis. Functional connectivity strengths were not related to motor outcome scores for either stroke group. This study serves as a foundation to better understand how resting‐state fMRI can assess motor functional connectivity and potentially be applied to explore mechanisms of interventional therapies after perinatal stroke. [ABSTRACT FROM AUTHOR]

Abstract: Perinatal stroke is the leading cause of hemiparetic cerebral palsy (CP), resulting in life‐long disability. In this study, we examined the relationship between robotic upper extremity motor impairment and corticospinal tract (CST) diffusion properties. Thirty‐three children with unilateral perinatal ischemic stroke (17 arterial, 16 venous) and hemiparesis were recruited from a population‐based research cohort. Bilateral CSTs were defined using diffusion tensor imaging (DTI) and four diffusion metrics were quantified: fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivities. Participants completed a visually guided reaching task using the KINARM robot to define 10 movement parameters including movement time and maximum speed. Twenty‐six typically developing children underwent the same evaluations. Partial correlations assessed the relationship between robotic reaching and CST diffusion parameters. All diffusion properties of the lesioned CST differed from controls in the arterial group, whereas only FA was reduced in the venous group. Non‐lesioned CST diffusion measures were similar between stroke groups and controls. Both stroke groups demonstrated impaired reaching performance. Multiple reaching parameters of the affected limb correlated with lesioned CST diffusion properties. Lower FA and higher MD were associated with greater movement time. Few correlations were observed between non‐lesioned CST diffusion and unaffected limb function though FA was associated with reaction time (R = −0.39, p < .01). Diffusion properties of the lesioned CST are altered after perinatal stroke, the degree of which correlates with specific elements of visually guided reaching performance, suggesting specific relevance of CST structural connectivity to clinical motor function in hemiparetic children. [ABSTRACT FROM AUTHOR]

Perinatal stroke causes most hemiparetic cerebral palsy, resulting in lifelong disability. We have demonstrated the ability of robots to quantify sensory dysfunction in hemiparetic children but the relationship between such deficits and sensory tract structural connectivity has not been explored. It was aimed to characterize the relationship between the dorsal column medial lemniscus (DCML) pathway connectivity and proprioceptive dysfunction in children with perinatal stroke. Twenty-nine participants (6-19 years old) with MRI-classified, unilateral perinatal ischemic stroke (14 arterial, 15 venous), and upper extremity deficits were recruited from a population-based cohort and compared with 21 healthy controls. Diffusion tensor imaging (DTI) defined DCML tracts and five diffusion properties were quantified: fractional anisotropy (FA), mean, radial, and axial diffusivities (MD, RD, AD), and fiber count. A robotic exoskeleton (KINARM) tested upper limb proprioception in an augmented reality environment. Correlations between robotic measures and sensory tract diffusion parameters were evaluated. Lesioned hemisphere sensory tracts demonstrated lower FA and higher MD, RD, and AD compared with the non-dominant hemisphere of controls. Dominant (contralesional) hemisphere tracts were not different from controls. Both arterial and venous stroke groups demonstrated impairments in proprioception that correlated with lesioned hemisphere DCML tract diffusion properties. Sensory tract connectivity is altered in the lesioned hemisphere of hemiparetic children with perinatal stroke. A correlation between lesioned DCML tract diffusion properties and robotic proprioceptive measures suggests clinical relevance and a possible target for therapeutic intervention. Hum Brain Mapp 38:2424-2440, 2017. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Applications of non-invasive brain stimulation including therapeutic neuromodulation are expanding at an alarming rate. Increasingly established scientific principles, including directional modulation of well-informed cortical targets, are advancing clinical trial development. However, high levels of disease burden coupled with zealous enthusiasm may be getting ahead of rational research and evidence. Experience is limited in the developing brain where additional issues must be considered. Properly designed and meticulously executed clinical trials are essential and required to advance and optimize the potential of non-invasive neuromodulation without risking the well-being of children and families. Perinatal stroke causes most hemiplegic cerebral palsy and, as a focal injury of defined timing in an otherwise healthy brain, is an ideal human model of developmental plasticity. Advanced models of how the motor systems of young brains develop following early stroke are affording novel windows of opportunity for neuromodulation clinical trials, possibly directing neuroplasticity toward better outcomes. Reviewing the principles of clinical trial design relevant to neuromodulation and using perinatal stroke as a model, this article reviews the current and future issues of advancing such trials in children. [ABSTRACT FROM AUTHOR]

Background: Perinatal stroke is a leading cause of early brain injury, cerebral palsy, and lifelong neurological morbidity. No study to date has examined the impact of raising a child with perinatal stroke on parents and families. However, a large breadth of research suggests that parents, especially mothers, may be at increased risk for psychological concerns. The primary aim of this study was to examine the impact of raising a child with perinatal stroke on mothers’ wellbeing. A secondary aim was to examine how caring for a child with perinatal stroke differentially affects mothers and fathers. Methods: In Study I, a matched case-control design was used to compare the wellbeing of mothers of children with perinatal stroke and mothers of children with typical development. In Study II, a matched case-control design was used to compare mother-father dyads. Participants completed validated measures of anxiety and depression, stress, quality of life and family functioning, marital satisfaction, and marital distress. Parents of children with perinatal stroke also completed a recently validated measure of the psychosocial impact of perinatal stroke including guilt and blame outcomes. Disease severity was categorized by parents, validated by the Pediatric Stroke Outcome Measure (PSOM), and compared across the above outcomes in Study I. Results: A total of 112 mothers participated in Study I (n = 56 per group; mean child age = 7.42 years), and 56 parents participated in Study II (n = 28 per group; mean child age = 8.25 years). In Study I, parent assessment of disease severity was correlated with PSOM scores (γ = 0.75, p < .001) and associated with parent outcomes. Mothers of children with mild conditions were indistinguishable from controls on the outcome measures. However, mothers of children with moderate/severe conditions had poorer outcomes on measures of depression, marital satisfaction, quality of life, and family functioning. In Study II, mothers and fathers had similar outcomes except mothers demonstrated a greater burden of guilt and higher levels of anxiety. Conclusions: Although most mothers of children with perinatal stroke adapt well, mothers of children with moderate/severe conditions appear to be at higher risk for psychological concerns. [ABSTRACT FROM AUTHOR]

An improved understanding of perinatal stroke epidemiology, classification, neuroimaging, and outcomes has emerged in recent years. Despite this, little is known regarding the pathophysiological mechanisms responsible for most cases. A multitude of possible associations and putative risk factors have been reported, but most lack definitive empirical evidence supporting primary causation. These include obstetrical and maternal factors, perinatal conditions, infectious diseases, prothrombotic abnormalities, cardiac disorders, medications, and many others. The bulk of evidence is weak, dominated by case reports and retrospective case series. Findings from the small number of case-control and cohort studies that exist are limited by heterogeneous populations and methodologies. The single largest barrier to ultimately understanding and potentially improving outcomes from this common and disabling condition is the lack of comprehensive, fully powered risk factor studies required to definitively describe perinatal stroke pathogenesis. This review summarizes current evidence and suggests future directions for research. [ABSTRACT FROM AUTHOR]

Abstract: Background: Perinatal stroke is a leading cause of cerebral palsy and lifelong disability, although parent and family outcomes have not yet been studied in this specific population. The Alberta Perinatal Stroke Project Parental Outcome Measure was developed as a 26-item questionnaire on the impact of perinatal stroke on parents and families. Methods: The items were derived from expert opinion and scientific literature on issues salient to parents of children with perinatal stroke, including guilt and blame, which are not well captured in existing measures of family impact. Data were collected from 82 mothers and 28 fathers who completed the Parental Outcome Measure and related questionnaires (mean age, 39.5 years; mean child age, 7.4 years). Analyses examined the Parental Outcome Measure's internal consistency, test-retest reliability, validity, and factor structure. Results: The Parental Outcome Measure demonstrated three unique theoretical constructs: Psychosocial Impact, Guilt, and Blame. The Parental Outcome Measure has excellent internal consistency (Cronbach α = 0.91) and very good test-retest reliability more than 2-5 weeks (r = 0.87). Regarding validity, the Parental Outcome Measure is sensitive to condition severity, accounts for additional variance in parent outcomes, and strongly correlates with measures of anxiety, depression, stress, quality of life, family functioning, and parent adjustment. Conclusions: The Parental Outcome Measure contributes to the literature as the first brief measure of family impact designed for parents of children with perinatal stroke. [Copyright &y& Elsevier]

Perinatal stroke affects ∼1 in 1000 births and concomitant cognitive impairments are common but poorly understood. Rates of Attention Deficit/Hyperactivity Disorder (ADHD) are increased 5–10× and executive dysfunction can be disabling. We used diffusion imaging to investigate whether stroke‐related differences in frontal white matter (WM) relate to cognitive impairments. Anterior forceps were isolated using tractography and sampled along the tract. Resulting metrics quantified frontal WM microstructure. Associations between WM metrics and parent ratings of ADHD symptoms (ADHD‐5 rating scale) and executive functioning (Behavior Rating Inventory of Executive Function (BRIEF)) were explored. Eighty‐three children were recruited (arterial ischemic stroke [AIS] n = 26; periventricular venous infarction [PVI] n = 26; controls n = 31). WM metrics were altered for stroke groups compared to controls. Along‐tract analyses showed differences in WM metrics in areas approximating the lesion as well as more remote differences at midline and in the nonlesioned hemisphere. WM metrics correlated with parental ratings of ADHD and executive function such that higher diffusivity values were associated with poorer function. These findings suggest that underlying microstructure of frontal white matter quantified via tractography may provide a relevant biomarker associated with cognition and behavior in children with perinatal stroke. [ABSTRACT FROM AUTHOR]

Background: Perinatal stroke often leads to lifelong motor impairment. Two common subtypes differ in timing, location, and mechanism of injury: periventricular venous infarcts (PVI) are fetal white matter lesions while most arterial ischemic strokes (AIS) are cortical injuries acquired near term birth. Both alter motor system development and primary motor cortex (M1) plasticity, often with retained ipsilateral corticospinal fibers from the non-lesioned motor cortex (M1').Methods: Task-based functional magnetic resonance imaging was used to define patterns of motor cortex activity during paretic and unaffected hand movement. Peak coordinates of M1, M1', and the supplementary motor area in the lesioned and intact hemispheres were compared to age-matched controls. Correlations between displacements and clinical motor function were explored.Results: Forty-nine participants included 14 PVI (12.59 ± 3.7 years), 13 AIS (14.91 ± 3.9 years), and 22 controls (13.91 ± 3.4 years). AIS displayed the greatest M1 displacement from controls in the lesioned hemisphere while PVI locations approximated controls. Peak M1' activations were displaced from the canonical hand knob in both PVI and AIS. Extent of M1 and M1' displacement were correlated (r = 0.50, P = 0.025) but were not associated with motor function. Supplementary motor area activity elicited by paretic tapping was displaced in AIS compared to controls (P = 0.003).Conclusion: Motor network components may be displaced in both hemispheres after perinatal stroke, particularly in AIS and those with ipsilateral control of the affected limb. Modest correlations with clinical function may support that more complex models of developmental plasticity are needed to inform targets for individualized neuromodulatory therapies in children with perinatal stroke. [ABSTRACT FROM AUTHOR]

Background: Neonatal arterial ischemic stroke is a leading cause of cerebral palsy and lifelong disability. Diffusion-weighted imaging has revolutionized diagnosis and facilitated outcome prognostication in acute neonatal arterial ischemic stroke. Diaschisis refers to changes in brain areas functionally connected but structurally remote from primary injury. We hypothesized that acute diffusion-weighted imaging can quantify cerebral diaschisis and is associated with outcome from neonatal arterial ischemic stroke.Methods: Subjects were identified from a prospective, population-based research cohort (Alberta Perinatal Stroke Project). Inclusion criteria were unilateral middle cerebral artery neonatal arterial ischemic stroke, diffusion-weighted magnetic resonance imaging within 10 days of birth, and more than 12-months follow-up (pediatric stroke outcome measure). Diaschisis was characterized and quantified using a validated software method (ImageJ). Volumetric analysis assessed atrophy of affected structures. Diaschisis scores were corrected for infarct size and compared with outcomes (Mann-Whitney).Results: From 20 eligible neonatal arterial ischemic strokes, two were excluded for poor image quality. Of 18 remaining (61% male, median age 3.2 days), 16 (89%) demonstrated diaschisis. Thalamus (88%) was the most common location in addition to corpus callosum (50%). Age at imaging was not associated with diaschisis. Affected structures demonstrated atrophy on imaging. Long-term outcomes available in 81% (median age 7.5 years) were not associated with diaschisis scores.Conclusions: Cerebral diaschisis occurs in neonatal arterial ischemic stroke and can be quantified with diffusion-weighted imaging. Occurrence is common and should not be mistaken for additional infarction. Determining clinical significance will require larger samples with well-characterized long-term outcomes. [ABSTRACT FROM AUTHOR]

Objective Brain stimulation and constraint therapy may enhance function after perinatal stroke but mechanisms are unknown. We characterized interhemispheric interactions (IHI) in hemiparetic children and explored their relationship to motor function and neuromodulation. Methods Forty-five hemiparetic perinatal stroke subjects aged 6–19 years completed a clinical trial of repetitive-transcranial magnetic stimulation (rTMS) and constraint therapy. Paired-pulse TMS measured IHI in cases and normal controls. Suprathreshold conditioning stimuli preceded contralateral test stimuli bidirectionally: stroke to non-stroke (SNS) and non-stroke to stroke (NSS). Primary outcome was the interhemispheric ratio (IHR) between conditioned and test only MEP amplitudes X100 (<100 implied inhibition). Motor outcomes at baseline and post-intervention were compared to IHR. Results Procedures were well tolerated. IHI occurred bidirectionally in controls. Eighteen stroke participants had complete data. IHR were increased in stroke participants in both directions. SNS IHR was >100 (facilitation) in 39% of measurements and correlated with better motor function. NSS IHR correlated with poorer motor function. Intervention-induced clinical change was not associated with IHR. Conclusions Interhemispheric interactions are altered and related to clinical function, but not necessarily neuromodulation, in children with perinatal stroke. Significance Adding interhemispheric interactions to evolving models of developmental plasticity following early injury may advance neuromodulation strategies. [ABSTRACT FROM AUTHOR]