Two types of ipsilateral reorganization in congenital hemiparesis: a TMS and fMRI study

EEG-based sensorimotor neurofeedback for motor neurorehabilitation in children and adults: A scoping review

OBJECTIVE

Therapeutic interventions for children and young people with dystonia and dystonic/dyskinetic cerebral palsy are limited. EEG-based neurofeedback is emerging as a neurorehabilitation tool. This scoping review maps research investigating EEG-based sensorimotor neurofeedback in adults and children with neurological motor impairments, including augmentative strategies.

METHODS

MEDLINE, CINAHL and Web of Science databases were searched up to 2023 for relevant studies. Study selection and data extraction were conducted independently by at least two reviewers.

RESULTS

Of 4380 identified studies, 133 were included, only three enrolling children. The most common diagnosis was adult-onset stroke (77%). Paradigms mostly involved upper limb motor imagery or motor attempt. Common neurofeedback modes included visual, haptic and/or electrical stimulation. EEG parameters varied widely and were often incompletely described. Two studies applied augmentative strategies. Outcome measures varied widely and included classification accuracy of the Brain-Computer Interface, degree of enhancement of mu rhythm modulation or other neurophysiological parameters, and clinical/motor outcome scores. Few studies investigated whether functional outcomes related specifically to the EEG-based neurofeedback.

CONCLUSIONS

There is limited evidence exploring EEG-based sensorimotor neurofeedback in individuals with movement disorders, especially in children. Further clarity of neurophysiological parameters is required to develop optimal paradigms for evaluating sensorimotor neurofeedback.

SIGNIFICANCE

The expanding field of sensorimotor neurofeedback offers exciting potential as a non-invasive therapy. However, this needs to be balanced by robust study design and detailed methodological reporting to ensure reproducibility and validation that clinical improvements relate to induced neurophysiological changes.

The excitability of ipsilateral motor evoked potentials is not task-specific and spatially distinct from the contralateral motor hotspot

OBJECTIVE

The role of ipsilateral descending motor pathways in voluntary movement of humans is still a matter of debate, with partly contradictory results. The aim of our study therefore was to examine the excitability of ipsilateral motor evoked potentials (iMEPs) regarding site and the specificity for unilateral and bilateral elbow flexion extension tasks.

METHODS

MR-navigated transcranial magnetic stimulation mapping of the dominant hemisphere was performed in twenty healthy participants during tonic unilateral (iBB), bilateral homologous (bBB) or bilateral antagonistic elbow flexion-extension (iBB-cAE), the map center of gravity (CoG) and iMEP area from BB were obtained.

RESULTS

The map CoG of the ipsilateral BB was located more anterior-laterally than the hotspot of the contralateral BB within the primary motor cortex, with a significant difference in CoG in iBB and iBB-cAE, but not bBB compared to the hotspot for the contralateral BB (each p < 0.05). However, different tasks had no effect on the size of the iMEPs.

CONCLUSION

Our data demonstrated that excitability of ipsilateral and contralateral MEP differ spatially in a task-specific manner suggesting the involvement of different motor networks within the motor cortex.

Safety and efficacy of non-invasive brain stimulation for the upper extremities in children with cerebral palsy: A systematic review

AIM

To evaluate available evidence examining safety and efficacy of non-invasive brain stimulation (NIBS) on upper extremity outcomes in children with cerebral palsy (CP).

METHOD

We electronically searched 12 sources up to May 2023 using JBI and Cochrane guidelines. Two reviewers selected articles with predetermined eligibility criteria, conducted data extraction, and assessed risk of bias using the Cochrane Risk of Bias criteria.

RESULTS

Nineteen studies were included: eight using repetitive transcranial magnetic stimulation (rTMS) and 11 using transcranial direct current stimulation (tDCS). Moderate certainty evidence supports the safety of rTMS and tDCS for children with CP. Very low to moderate certainty evidence suggests that rTMS and tDCS result in little to no difference in upper extremity outcomes.

INTERPRETATION

Evidence indicates that NIBS is a safe and feasible intervention to target upper extremity outcomes in children with CP, although it also indicates little to no significant impact on upper extremity outcomes. These findings are discussed in relation to the heterogeneous participants' characteristics and stimulation parameters. Larger studies of high methodological quality are required to inform future research and protocols for NIBS.

A Training Program Using Modified Joystick-Operated Ride-on Toys to Complement Conventional Upper Extremity Rehabilitation in Children with Cerebral Palsy: Results from a Pilot Study

The pilot study assessed the utility of a training program using modified, commercially available dual-joystick-operated ride-on toys to promote unimanual and bimanual upper extremity (UE) function in children with cerebral palsy (CP). The ride-on-toy training was integrated within a 3-week, intensive, task-oriented training camp for children with CP. Eleven children with hemiplegia between 4 and 10 years received the ride-on-toy training program 20-30 min/day, 5 days/week for 3 weeks. Unimanual motor function was assessed using the Quality of Upper Extremity Skills Test (QUEST) before and after the camp. During ride-on-toy training sessions, children wore activity monitors on both wrists to assess the duration and intensity of bimanual UE activity. Video data from early and late sessions were coded for bimanual UE use, independent navigation, and movement bouts. Children improved their total and subscale QUEST scores from pretest to post-test while increasing moderate activity in their affected UE from early to late sessions, demonstrating more equal use of both UEs across sessions. There were no significant changes in the rates of movement bouts from early to late sessions. We can conclude that joystick-operated ride-on toys function as child-friendly, intrinsically rewarding tools that can complement conventional therapy and promote bimanual motor functions in children with CP.

Lesion mapping and functional characterization of hemiplegic children with different patterns of hand manipulation

Brain damage in children with unilateral cerebral palsy (UCP) affects motor function, with varying severity, making it difficult the performance of daily actions. Recently, qualitative and semi-quantitative methods have been developed for lesion classification, but studies on mild to moderate hand impairment are lacking. The present study aimed to characterize lesion topography and preserved brain areas in UCP children with specific patterns of hand manipulation. A homogeneous sample of 16 UCP children, aged 9 to 14 years, was enrolled in the study. Motor assessment included the characterization of the specific pattern of hand manipulation, by means of unimanual and bimanual measures (Kinematic Hand Classification, KHC; Manual Ability Classification System, MACS; House Functional Classification System, HFCS; Melbourne Unilateral Upper Limb Assessment, MUUL; Assisting Hand Assessment, AHA). The MRI morphological study included multiple methods: (a) qualitative lesion classification, (b) semi-quantitative classification (sq-MRI), (c) voxel-based morphometry comparing UCP and typically developed children (VBM-DARTEL), and (d) quantitative brain tissue segmentation (q-BTS). In addition, functional MRI was used to assess spared functional activations and cluster lateralization in the ipsilesional and contralesional hemispheres of UCP children during the execution of simple movements and grasping actions with the more affected hand. Lesions most frequently involved the periventricular white matter, corpus callosum, posterior limb of the internal capsule, thalamus, basal ganglia and brainstem. VMB-DARTEL analysis allowed to detect mainly white matter lesions. Both sq-MRI classification and q-BTS identified lesions of thalamus, brainstem, and basal ganglia. In particular, UCP patients with synergic hand pattern showed larger involvement of subcortical structures, as compared to those with semi-functional hand. Furthermore, sparing of gray matter in basal ganglia and thalamus was positively correlated with MUUL and AHA scores. Concerning white matter, q-BTS revealed a larger damage of fronto-striatal connections in patients with synergic hand, as compared to those with semi-functional hand. The volume of these connections was correlated to unimanual function (MUUL score). The fMRI results showed that all patients, but one, including those with cortical lesions, had activation in ipsilesional areas, regardless of lesion timing. Children with synergic hand showed more lateralized activation in the ipsilesional hemisphere both during grasping and simple movements, while children with semi-functional hand exhibited more bilateral activation during grasping. The study demonstrates that lesion localization, rather than lesion type based on the timing of their occurrence, is more associated with the functional level of hand manipulation. Overall, the preservation of subcortical structures and white matter can predict a better functional outcome. Future studies integrating different techniques (structural and functional imaging, TMS) could provide further evidence on the relation between brain reorganization and specific pattern of manipulation in UCP children.

Determinants of Functional Outcome after Pediatric Hemispherotomy

OBJECTIVE

We aimed to evaluate determinants of functional outcome after pediatric hemispherotomy in a large and recent multicenter cohort.

METHODS

We retrospectively investigated the functional outcomes of 455 children who underwent hemispherotomy at 5 epilepsy centers in 2000-2016. We identified determinants of unaided walking, voluntary grasping with the hemiplegic hand, and speaking through Bayesian multivariable regression modeling using missing data imputation.

RESULTS

Seventy-five percent of children were seizure-free, and 44% stopped antiseizure medication at a 5.1-year mean follow-up (range = 1-17.1). Seventy-seven percent of children could walk unaided, 8% could grasp voluntarily, and 68% could speak at the last follow-up. Children were unlikely to walk when they had contralateral magnetic resonance imaging (MRI) abnormalities (40/73, p = 0.04), recurrent seizures following hemispherotomy (62/109, p = 0.04), and moderately (50/61, p = 0.03) or severely impaired (127/199, p = 0.001) postsurgical intellectual functioning, but were likely to walk when they were older at outcome determination (p = 0.01). Children were unlikely to grasp voluntarily with the hand contralateral to surgery when they had Rasmussen encephalitis (0/61, p = 0.001) or Sturge-Weber syndrome (0/32, p = 0.007). Children were unlikely to speak when they had contralateral MRI abnormalities (30/69, p = 0.002) and longer epilepsy duration (p = 0.01), but likely to speak when they had Sturge-Weber syndrome (29/35, p = 0.01), were older at surgery (p = 0.04), and were older at outcome determination (p < 0.001).

INTERPRETATION

Etiology and bilaterality of structural brain abnormalities were key determinants of functional outcome after hemispherotomy. Longer epilepsy duration affected language outcomes. Not surprisingly, walking and talking ability increased with older age at outcome evaluation. ANN NEUROL 2024;95:377-387.

Cortical activity associated with focal muscle vibration applied directly to the affected forearm flexor muscle in post-stroke patients: an fNIRS study

Objective

The purpose of this study was to utilize functional near-infrared spectroscopy (fNIRS) to identify changes in cortical activity caused by focal muscle vibration (FMV), which was directly administered to the affected forearm flexor muscles of hemiplegic stroke patients. Additionally, the study aimed to investigate the correlation between these changes and the clinical characteristics of the patients, thereby expanding the understanding of potential neurophysiological mechanisms linked to these effects.

Methods

Twenty-two stroke patients with right hemiplegia who were admitted to our ward for rehabilitation were selected for this study. The fNIRS data were collected from subjects using a block-design paradigm. Subsequently, the collected data were analyzed using the NirSpark software to determine the mean Oxyhemoglobin (Hbo) concentrations for each cortical region of interest (ROI) in the task and rest states for every subject. The stimulation task was FMV (frequency 60 Hz, amplitude 6 mm) directly applied to belly of the flexor carpi radialis muscle (FCR) on the affected side. Hbo was measured in six regions of interest (ROIs) in the cerebral cortex, which included the bilateral prefrontal cortex (PFC), sensorimotor cortex (SMC), and occipital cortex (OC). The clinical characteristics of the patients were assessed concurrently, including Lovett's 6-level muscle strength assessment, clinical muscle tone assessment, the upper extremity function items of the Fugl-Meyer Assessment (FMA-UE), Bruunstrom staging scale (BRS), and Modified Barthel index (MBI). Statistical analyses were conducted to determine the activation in the ROIs and to comprehend its correlation with the clinical characteristics of the patients.

Results

Statistical analysis revealed that, except for right OC, there were statistically significant differences between the mean Hbo in the task state and rest state for bilateral SMC, PFC, and left OC. A positive correlation was observed between the muscle strength of the affected wrist flexor group and the change values of Hbo (Hbo-CV), as well as the beta values in the left SMC, PFC, and OC. However, no statistical correlation was found between muscle strength and Hbo-CV or beta values in the right SMC, PFC, and OC. The BRS of the affected upper limb exhibited a positive correlation with the Hbo-CV or beta values in the left SMC and PFC. In contrast, no statistical correlation was observed in the right SMC, PFC, and bilateral OC. No significant correlation was found between the muscle tone of the affected wrist flexor group, FMA-UE, MBI, and Hbo-CV or beta values of cortical ROIs.

Conclusion

FMV-evoked sensory stimulation applied directly to the FCR belly on the paralyzed side activated additional brain cortices, including bilateral PFC and ipsilesional OC, along with bilateral SMC in stroke patients. However, the clinical characteristics of the patients were only correlated with the intensity of ipsilesional SMC and PFC activation. The results of this study provide neurophysiological theoretical support for the expanded clinical application of FMV.

Stroke in the Developing Brain: Neurophysiologic Implications of Stroke Timing, Location, and Comorbid Factors

BACKGROUND

Pediatric stroke, which is unique in that it represents a static insult to a developing brain, often leads to long-term neurological disability. Neuroplasticity in infants and children influences neurophysiologic recovery patterns after stroke; therefore outcomes depend on several factors including the timing and location of stroke and the presence of comorbid conditions.

METHODS

In this review, we discuss the unique implications of stroke occurring in the fetal, perinatal, and childhood/adolescent time periods. First, we highlight the impact of the developmental stage of the brain at the time of insult on the motor, sensory, cognitive, speech, and behavioral domains. Next, we consider the influence of location of stroke on the presence and severity of motor and nonmotor outcomes. Finally, we discuss the impact of associated conditions on long-term outcomes and risk for stroke recurrence.

RESULTS

Hemiparesis is common after stroke at any age, although the severity of impairment differs by age group. Risk of epilepsy is elevated in all age groups compared with those without stroke. Outcomes in other domains vary by age, although several studies suggest worse cognitive outcomes when stroke occurs in early childhood compared with fetal and later childhood epochs. Conditions such as congenital heart disease, sickle cell disease, and moyamoya increase the risk of stroke and leave patients differentially vulnerable to neurodevelopmental delay, stroke recurrence, silent infarcts, and cognitive impairment.

CONCLUSIONS

A comprehensive understanding of the interplay of various factors is essential in guiding the clinical care of patients with pediatric stroke.

Neural Correlates of Impaired Grasp Function in Children with Unilateral Spastic Cerebral Palsy

Unilateral spastic cerebral palsy (USCP) is caused by damage to the developing brain and affects motor function, mainly lateralized to one side of the body. Children with USCP have difficulties grasping objects, which can affect their ability to perform daily activities. Although cerebral palsy is typically classified according to motor function, sensory abnormalities are often present as well and may contribute to motor impairments, including grasping. In this review, we show that the integrity and connectivity pattern of the corticospinal tract (CST) is related to execution and anticipatory control of grasping. However, as this may not explain all the variance of impairments in grasping function, we also describe the potential roles of sensory and sensorimotor integration deficits that contribute to grasp impairments. We highlight studies measuring fingertip forces during object manipulation tasks, as this approach allows for the dissection of the close association of sensory and motor function and can detect the discriminant use of sensory information during a complex, functional task (i.e., grasping). In addition, we discuss the importance of examining the interactions of the sensory and motor systems together, rather than in isolation. Finally, we suggest future directions for research to understand the underlying mechanisms of grasp impairments.

Responses to Sensory Events in Daily Life in Children with Cerebral Palsy from a Parent Reported Perspective and in a Swedish Context

The motor disorders of cerebral palsy (CP) are often accompanied by sensory disturbances, but knowledge of their relationship to motor functioning is sparse. This study explored responses to sensory events in relation to spastic subtype and motor functioning in children with CP. Parents of 60 children with CP (unilateral: 18, bilateral: 42) with GMFCS levels I:29, II:13, III:15 and IV:3 of mean age 12.3 years (3.7 SD) participated. The parents (n = 55) rated their children´s responses with the norm-referenced questionnaire Child Sensory Profile-2© (CSP-2©), Swedish version, incorporating nine sections and four sensory processing patterns/quadrants, and replied (n = 57) to two additional questions. On the CSP-2©, thirty (55%) of the children were reported to have responses "much more than others" (>2 SD) in one or more of the sections and/or quadrants and 22 (40%) in the section of Body Position, overrepresented by the children with bilateral CP. The additional questions revealed that a greater proportion of children at GMFCS levels III-IV compared to level I frequently were requested to sit/stand up straight (14/17 versus 6/26, p < 0.001) and were sound sensitive at a younger age (14/17 versus 10/26, p = 0.005). The findings of this study highlight the sensory aspects of motor functioning in children with spastic CP.

Corticomuscular Coherence in Children with Unilateral Cerebral Palsy: A Feasibility and Preliminary Protocol Study

Objective This study assessed the feasibility of corticomuscular coherence measurement during a goal-directed task in children with unilateral cerebral palsy while establishing optimal experimental parameters. Methods Participants (Manual Ability Classification System levels I-III) completed a submaximal isometric goal-directed grip task during simultaneous electroencephalography and electromyography (EMG) acquisition. Results All participants (n = 11, 6 females, mean age 11.3 ±2.4 years) completed corticomuscular coherence procedures. Of the 40 trials obtained per extremity, an average of 29 (n = 9) and 27 (n = 10) trials were retained from the more- and less-affected extremities, respectively. Obtaining measurement stability required an average of 28 trials per extremity. Conclusion Findings from this work support the feasibility of corticomuscular coherence measurement in children with unilateral cerebral palsy. Acquiring 28 to 40 corticomuscular coherence trials per extremity is ideal. The experimental parameters established in this work will inform future corticomuscular coherence application in pediatric unilateral cerebral palsy.

Mirror movements and brain pathology in children with unilateral cerebral palsy

AIM

We systematically examined the relationship between mirror movements and brain lesion type, corticospinal tract (CST) organization, and hand function to determine the relevance between mirror movements, brain lesion, the CST pattern, and hand function in children with unilateral cerebral palsy (CP).

METHOD

Forty-eight children (mean age 9y 9mo [SD 3y 3mo], range 6-18y; 30 males, 18 females) with unilateral CP participated. Mirror movements, brain lesion type, CST pattern identified by transcranial magnetic stimulation, and clinical outcomes were evaluated. Children performed four unilateral tasks: hand opening/closing, finger opposition, individuation, and finger 'walking'. Mirror movements induced in the contralateral hand were scored using standardized criteria (scores 0-4 using the Woods and Teuber scale).

RESULTS

We found that children with periventricular lesion may have stronger mirror movement scores induced in either hand than those with middle cerebral artery lesion (more affected hand: p=0.02; less affected hand: p<0.01). The highest mirror movement score a child exhibits across the tested tasks (i.e. scores of 3-4 using the Woods and Teuber scoring criteria) may potentially be an indicator of an ipsilateral CST connectivity pattern (p=0.03). Significant correlations were observed between higher mirror movement scores when performing hand opening/closing as well as finger walking and better unimanual dexterity (Spearman's rank correlation coefficient r_s =0.44, p=0.002; r_s =0.46, p=0.002 respectively).

INTERPRETATION

Brain lesions may be predictive of the strength of mirror movements in either hand in children with unilateral CP. Our findings warrant further studies to extensively investigate the relationship between mirror movements and the underlying brain pathology.

WHAT THIS PAPER ADDS

Brain lesion type may be predictive of mirror movement scores induced in either hand in children with unilateral cerebral palsy. The highest mirror movement score a child exhibits across the tested tasks may indicate corticospinal tract connectivity pattern in children with unilateral cerebral palsy.

Assessment of Motor Evoked Potentials in Multiple Sclerosis

Transcranial magnetic stimulation (TMS) is a noninvasive technique mainly used for the assessment of corticospinal tract integrity and excitability of the primary motor cortices. Motor evoked potentials (MEPs) play a pivotal role in TMS studies. TMS clinical guidelines, concerning the use and interpretation of MEPs in diagnosing and monitoring corticospinal tract integrity in people with multiple sclerosis (pwMS), were established almost ten years ago and refer mainly to the use of TMS implementation; this comprises the magnetic stimulator connected to a standard EMG unit, with the positioning of the coil performed by using the external landmarks on the head. The aim of the present work was to conduct a narrative literature review on the MEP assessment and outcome measures in clinical and research settings, assessed by TMS Methodological characteristics of different TMS system implementations (TMS without navigation, line-navigated TMS and e-field-navigated TMS); these were discussed in the context of mapping the corticospinal tract integrity in MS. An MEP assessment of two case reports, by using an e-field-navigated TMS, was presented; the results of the correspondence between the e-field-navigated TMS with MRI, and the EDSS classifications were presented. Practical and technical guiding principles for the improvement of TMS studies in MEP assessment for MS are discussed, suggesting the use of e-field TMS assessment in the sense that it can improve the accuracy of corticospinal tract integrity testing by providing a more objective correspondence of the neurophysiological (e-field-navigated TMS) and clinical (Expanded Disability Status Scale-EDSS) classifications.

Restoring After Central Nervous System Injuries: Neural Mechanisms and Translational Applications of Motor Recovery

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are leading causes of long-term disability. It is estimated that more than half of the survivors of severe unilateral injury are unable to use the denervated limb. Previous studies have focused on neuroprotective interventions in the affected hemisphere to limit brain lesions and neurorepair measures to promote recovery. However, the ability to increase plasticity in the injured brain is restricted and difficult to improve. Therefore, over several decades, researchers have been prompted to enhance the compensation by the unaffected hemisphere. Animal experiments have revealed that regrowth of ipsilateral descending fibers from the unaffected hemisphere to denervated motor neurons plays a significant role in the restoration of motor function. In addition, several clinical treatments have been designed to restore ipsilateral motor control, including brain stimulation, nerve transfer surgery, and brain–computer interface systems. Here, we comprehensively review the neural mechanisms as well as translational applications of ipsilateral motor control upon rehabilitation after CNS injuries.

The impact of brain lesion characteristics and the corticospinal tract wiring on mirror movements in unilateral cerebral palsy

Mirror movements (MM) influence bimanual performance in children with unilateral cerebral palsy (uCP). Whilst MM are related to brain lesion characteristics and the corticospinal tract (CST) wiring pattern, the combined impact of these neurological factors remains unknown. Forty-nine children with uCP (mean age 10y6mo) performed a repetitive squeezing task to quantify similarity (MM-similarity) and strength (MM-intensity) of the MM activity. We used MRI data to evaluate lesion type (periventricular white matter, N = 30; cortico-subcortical, N = 19), extent of ipsilesional damage, presence of bilateral lesions, and damage to basal ganglia, thalamus and corpus callosum. The CST wiring was assessed with Transcranial Magnetic Stimulation (17 CSTcontralateral, 16 CSTipsilateral, 16 CSTbilateral). Data was analyzed with regression analyses. In the more-affected hand, MM-similarity and intensity were higher with CSTbilateral/ipsilateral. In the less-affected hand, MM-similarity was higher in children with (1) CSTcontra with CSC lesions, (2) CSTbilat/ipsi with PVL lesions and (3) CSTbilat/ipsi with unilateralized lesions. MM-intensity was higher with larger damage to the corpus callosum and unilateral lesions. A complex combination of neurological factors influences MM characteristics, and the mechanisms differ between hands.

Functional MRI in Radiology—A Personal Review

We, here, provide a personal review article on the development of a functional MRI in the radiology departments of two German university medicine units. Although the international community for human brain mapping has met since 1995, the researchers fascinated by human brain function are still young and innovative. However, the impact of functional magnetic resonance imaging (fMRI) on prognosis and treatment decisions is restricted, even though standardized methods have been developed. The tradeoff between the groundbreaking studies on brain function and the attempt to provide reliable biomarkers for clinical decisions is large. By describing some historical developments in the field of fMRI, from a personal view, the rise of this method in clinical neuroscience during the last 25 years might be understandable. We aim to provide some background for (a) the historical developments of fMRI, (b) the establishment of two research units for fMRI in the departments of radiology in Germany, and (c) a description of some contributions within the selected fields of systems neuroscience, clinical neurology, and behavioral psychology.

Exploring Clinical and Neurophysiological Factors Associated with Response to Constraint Therapy and Brain Stimulation in Children with Hemiparetic Cerebral Palsy

BACKGROUND

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.

OBJECTIVE

We explored the clinical and neurophysiological factors associated with responsiveness to CIMT and/or brain stimulation within a clinical trial.

METHODS

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.

RESULTS

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%.

CONCLUSION

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.

Corticomuscular coherence is reduced in relation to dorsiflexion fatigability to the same extent in adults with cerebral palsy as in neurologically intact adults

PURPOSE

Fatigue is frequent in adults with cerebral palsy (CP) and it is unclear whether this is due to altered corticospinal drive. We aimed to compare changes in corticospinal drive following sustained muscle contractions in adults with CP and neurologically intact (NI) adults.

METHODS

Fourteen adults with CP [age 37.6 (10.1), seven females, GMFCS levels I-II] and ten NI adults [age 35.4 (10.3), 6 females] performed 1-min static dorsiflexion at 30% of maximal voluntary contraction (MVC) before and after a submaximal contraction at 60% MVC. Electroencephalography (EEG) and electromyography (EMG) from the anterior tibial muscle were analyzed to quantify the coupling, expressed by corticomuscular coherence (CMC).

RESULTS

Adults with CP had lower MVCs but similar time to exhaustion during the relative load of the fatigability trial. Both groups exhibited fatigability-related changes in EMG median frequency and EMG amplitude. The CP group showed lower beta band (16-35 Hz) CMC before fatigability, but both groups decreased beta band CMC following fatigability. There was a linear correlation between decrease of beta band CMC and fatigability-related increase in EMG.

CONCLUSION

Fatigability following static contraction until failure was related to decreased beta band CMC in both NI adults and adults with CP. Our findings indicate that compensatory mechanisms to fatigability are present in both groups, and that fatigability affects the corticospinal drive in the same way. We suggest that the perceived physical fatigue in CP is related to the high relative load of activities of daily living rather than any particular physiological mechanism.

Spinal cord microstructural changes are connected with the aberrant sensorimotor cortical oscillatory activity in adults with cerebral palsy

Previous animal models have illustrated that reduced cortical activity in the developing brain has cascading activity-dependent effects on the microstructural organization of the spinal cord. A limited number of studies have attempted to translate these findings to humans with cerebral palsy (CP). Essentially, the aberrations in sensorimotor cortical activity in those with CP could have an adverse effect on the spinal cord microstructure. To investigate this knowledge gap, we utilized magnetoencephalographic (MEG) brain imaging to quantify motor-related oscillatory activity in fourteen adults with CP and sixteen neurotypical (NT) controls. A subset of these participants also underwent cervical-thoracic spinal cord MRI. Our results showed that the strength of the peri-movement beta desynchronization and the post-movement beta rebound were each weaker in the adults with CP relative to the controls, and these weakened responses were associated with poorer task performance. Additionally, our results showed that the strength of the peri-movement beta response was associated with the total cross-sectional area of the spinal cord and the white matter cross-sectional area. Altogether these results suggest that the altered sensorimotor cortical activity seen in CP may result in activity-dependent plastic changes within the spinal cord microstructure, which could ultimately contribute to the sensorimotor deficits seen in this population.

A Novel Approach to Increase Attention during Mirror Therapy among Stroke Patients: A Video-Based Behavioral Analysis

Stroke is a major cause of disability and an evident rehabilitation strategy is crucial. Mirror therapy (MT) is one of the popular rehabilitation methods that is known to be effective as the patients benefit from the mirror illusion. However, the patient’s attention to the mirror illusion during treatment is unclear. Therefore, the present study assesses the duration and frequency of the mirror gaze, distraction, and preparation of sixteen stroke patients during two MT methods using a behavioral coding software. During the 30 min treatment, the total mirror gaze duration during conventional bilateral MT (BMT) was 564.04 s, while it was 1482.45 s in unilateral MT using a screen (UMT). The total distracted time was 945.61 s in BMT, while it was only 162.03 s in UMT. The total preparatory duration was 290.35 s in BMT and 155.53 s in UMT. The total number of distracted bouts were 136.45 in BMT, while it was 73.38 in UMT. The total number of preparatory bouts were 18.42 in BMT and 9.56 in UMT. The average times of gaze duration per bout were 5.52 s in BMT and 21.81 s in UMT. The average times of distraction per bout were 9.22 s in BMT and 3.00 s in UMT. The total number of mirror gaze bouts and average time of preparation per bout did not present a statistical significance in the comparisons of the two methods. This study assesses two methods of MT using observational coding software to evaluate the duration and frequency of the mirror gaze during treatment. The results suggest that UMT may be an alternative option to provide MT for stroke patients to increase their attention towards the mirror.

From Hemispheric Asymmetry through Sensorimotor Experiences to Cognitive Outcomes in Children with Cerebral Palsy

Recent neuroimaging studies allowed us to explore abnormal brain structures and interhemispheric connectivity in children with cerebral palsy (CP). Behavioral researchers have long reported that children with CP exhibit suboptimal performance in different cognitive domains (e.g., receptive and expressive language skills, reading, mental imagery, spatial processing, subitizing, math, and executive functions). However, there has been very limited cross-domain research involving these two areas of scientific inquiry. To stimulate such research, this perspective paper proposes some possible neurological mechanisms involved in the cognitive delays and impairments in children with CP. Additionally, the paper examines the ways motor and sensorimotor experience during the development of these neural substrates could enable more optimal development for children with CP. Understanding these developmental mechanisms could guide more effective interventions to promote the development of both sensorimotor and cognitive skills in children with CP.

Functional outcomes in children related to self-care, mobility, and social function after stroke in early childhood: a cohort study

ABSTRACT Background: Stroke has been increasingly recognized as an important morbidity and mortality factor in neonates and children. Children have different and more diverse risk factors than adults, commonly related to an underlying disease. Stroke may compromise functional capacity in children. Few studies have focused on functional outcomes related to activities and participation. Objectives: To investigate post-stroke functionality of children related to self-care, mobility, and social function. Methods: We assessed the functional outcome of 14 children younger than 7.5 years who suffered a stroke in early childhood through the use of the Pediatric Evaluation of Disability Inventory (PEDI). Results: The average age of the sample at assessment was 3.6 ± 1.4 years (2 - 6 years). The average scores in the PEDI functional domains of self-care, mobility, and social function were, respectively, 37.6 ± 15.4, 36.2 ± 15.4, and 48.7 ± 11.1. Children showed age-appropriate functional outcomes in the PEDI functional domains: 71.4% of them in self-care and mobility and 92.9% in social function. Children with bilateral injuries (p = 0.05) and longer hospital stays (r = -0.79, p = 0.001) showed the worst scores in PEDI's social function domains. Conclusions: Overall, our sample of preschool children showed age-appropriate functional outcomes on self-care, mobility, and social function domains after stroke. However, children with bilateral injuries and longer hospital stays showed the worst scores in social function domains. We recommend focusing on functional rehabilitation to promote activities and participation and to monitor the development of children's social skills after stroke.

Plasticity in the developing brain: neurophysiological basis for lesion-induced motor reorganization

The plasticity of the developing brain can be observed following injury to the motor cortex and/or corticospinal tracts, the most commonly injured brain area in the pre- or peri-natal period. Factors such as the timing of injury, lesion size and lesion location may affect a single hemisphere’s ability to acquire bilateral motor representation. Bilateral motor representation of single hemisphere origin is most likely to occur if brain injury occurs before the age of 2 years; however, the link between injury aetiology, reorganization type and functional outcome is largely understudied. We performed a retrospective review to examine reorganized cortical motor maps identified through transcranial magnetic stimulation in a cohort of 52 patients. Subsequent clinical, anthropometric and demographic information was recorded for each patient. Each patient’s primary hand motor cortex centre of gravity, along with the Euclidian distance between reorganized and normally located motor cortices, was also calculated. The patients were classified into broad groups including reorganization type (inter- and intrahemispheric motor reorganization), age at the time of injury (before 2 years and after 2 years) and injury aetiology (developmental disorders and acquired injuries). All measures were analysed to find commonalities between motor reorganization type and injury aetiology, function and centre of gravity distance. There was a significant effect of injury aetiology on type of motor reorganization (P < 0.01), with 60.7% of patients with acquired injuries and 15.8% of patients with developmental disorders demonstrating interhemispheric motor reorganization. Within the interhemispheric motor reorganization group, ipsilaterally and contralaterally projecting hand motor cortex centres of gravity overlapped, indicating shared cortical motor representation. Furthermore, the data suggest significantly higher prevalence of bilateral motor representation from a single hemisphere in cases of acquired injuries compared to those of developmental origin. Functional outcome was found to be negatively affected by acquired injuries and interhemispheric motor reorganization relative to their respective counterparts with developmental lesions and intrahemispheric motor reorganization. These results provide novel information regarding motor reorganization in the developing brain via an unprecedented cohort sample size and transcranial magnetic stimulation. Transcranial magnetic stimulation is uniquely suited for use in understanding the principles of motor reorganization, thereby aiding in the development of more efficacious therapeutic techniques to improve functional recovery following motor cortex injury.

A transcranial magnetic stimulation study for the characterization of corticospinal pathway plasticity in children with neurological disorders

We aimed to investigate cortical and radicular TMS-evoked motor evoked potentials (MEPs) in children with neurological disorders (n = 57, mean age: 5.45 years) and agematched healthy controls (n = 46). Four TMS parameters were analyzed: MEP amplitudes, the latencies of MEP, the latency jump (cortical MEP latency at rest - cortical active-MEP latency at with slightly contracted targeted muscle), and central motor conduction time. Children with neurological disorders were categorized according to the two major types of neuronal plasticity; excessive plasticity: 29 children with cerebral palsy and impaired plasticity: 28 children with neurodegenerative diseases, stroke, and central nervous system infections. The active-MEP abnormalities (absent and prolonged latencies) were correlated with the location of cortical involvement on MRI patterns. We obtained a significantly increased rate of abnormal cortical active-MEPs in children with impaired plasticity (21/28, 75%) compared with excessive plasticity (18/29, 62%). The rate of absent MEP response is three times more in children with impaired plasticity (43%) than in children with excessive plasticity (14%). A more reduced latency jump was measured in children with impaired plasticity compared to children with excessive plasticity. TMS-evoked active-MEPs and latency jumping are valuable parameters for characterizing neuronal plasticity in children with neurological disorders.

Neural mechanisms mediating cross education: With additional considerations for the ageing brain

CALVERT, G.H.M., and CARSON, R.G. Neural mechanisms mediating cross education: With additional considerations for the ageing brain. NEUROSCI BIOBEHAV REV 21(1) XXX-XXX, 2021. - Cross education (CE) is the process whereby a regimen of unilateral limb training engenders bilateral improvements in motor function. The contralateral gains thus derived may impart therapeutic benefits for patients with unilateral deficits arising from orthopaedic injury or stroke. Despite this prospective therapeutic utility, there is little consensus concerning its mechanistic basis. The precise means through which the neuroanatomical structures and cellular processes that mediate CE may be influenced by age-related neurodegeneration are also almost entirely unknown. Notwithstanding the increased incidence of unilateral impairment in later life, age-related variations in the expression of CE have been examined only infrequently. In this narrative review, we consider several mechanisms which may mediate the expression of CE with specific reference to the ageing CNS. We focus on the adaptive potential of cellular processes that are subserved by a specific set of neuroanatomical pathways including: the corticospinal tract, corticoreticulospinal projections, transcallosal fibres, and thalamocortical radiations. This analysis may inform the development of interventions that exploit the therapeutic utility of CE training in older persons.

Motor Organization in Schizencephaly: Outcomes of Transcranial Magnetic Stimulation and Diffusion Tensor Imaging of Motor Tract Projections Correlate with the Different Domains of Hand Function

Objective

Schizencephaly is a rare congenital malformation that causes motor impairment. To determine the treatment strategy, each domain of the motor functions should be appropriately evaluated. We correlated a color map of diffusion tensor imaging (DTI) and transcranial magnetic stimulation (TMS) with the hand function test (HFT) to identify the type of hand function that each test (DTI and TMS) reflects. Further, we attempted to demonstrate the motor neuron organization in schizencephaly.

Method

This retrospective study was conducted on 12 patients with schizencephaly. TMS was conducted in the first dorsal interosseous (FDI), biceps (BB), and deltoid muscles of the upper extremity, and contralateral MEP (cMEP) and ipsilateral MEP (iMEP) were recorded. The HFT included the grip strength, box and block (B&B), and 9-hole peg test. The schizencephalic cleft was confirmed using magnetic resonance imaging, and the corticospinal tract (CST) was identified using the color map of DTI. The symmetry indices for the peduncle and CST at pons level were calculated as the ratios of the cross-sectional area of the less-affected side and that of the more-affected side.

Result

In the more-affected hemisphere TMS, no iMEP was obtained. In the less-affected hemisphere TMS, the iMEP response was detected in 9 patients and cMEP in all patients, which was similar to the pattern observed in unilateral lesion. Paretic hand grip strength was strongly correlated with the presence of iMEP (p = 0.044). The symmetry index of the color map of DTI was significantly correlated with the B&B (p = 0.008, R ² = 0.416), whereas the symmetry index of the peduncle was not correlated with all HFTs.

Conclusion

In patients with schizencephaly, the iMEP response rate is correlated with the hand function related to strength, while the symmetricity of the CST by the color map of DTI is correlated with the hand function associated with dexterity. Additionally, we suggest the possible motor organization pattern of schizencephaly following interhemispheric competition.

Between Limb Muscle Co-activation Patterns in the Paretic Arm During Non-paretic Arm Tasks in Hemiparetic Cerebral Palsy

Tasks of daily life require the independent use of the arms and hands. Individuals with hemiparetic cerebral palsy (HCP) often experience difficulty with fine motor tasks demonstrating mirrored movements between the arms. In this study, bilateral muscle activations were quantified during single arm isometric maximum efforts and submaximal reaching tasks. The magnitude and direction of mirrored activation was examined in 14 individuals with HCP and 9 age-matched controls. Participants generated maximum voluntary torques (MVTs) in five different directions and completed ballistic reaches while producing up to 80% of shoulder abduction MVT. Electromyography (EMG) signals were recorded from six upper extremity muscles bilaterally. Participants with HCP demonstrated more mirrored activation when volitionally contracting the non-paretic (NP) arm than the paretic arm (F = 83.543, p < 0.001) in isometric efforts. Increased EMG activation during reach acceleration resulted in a larger increase in rest arm co-activation when reaching with the NP arm compared to the paretic arm in the HCP group (t = 8.425, p < 0.001). Mirrored activation is more pronounced when driving the NP arm and scales with effort level. This directionality of mirroring is indicative of the use of ipsilaterally terminating projections of the corticospinal tract (CST) originating in the non-lesioned hemisphere. Peripheral measures of muscle activation provide insight into the descending pathways available for control of the upper extremity after early unilateral brain injury.

Sensorimotor Integration in Childhood Dystonia and Dystonic Cerebral Palsy-A Developmental Perspective

Dystonia is a disorder of sensorimotor integration, involving dysfunction within the basal ganglia, cortex, cerebellum, or their inter-connections as part of the sensorimotor network. Some forms of dystonia are also characterized by maladaptive or exaggerated plasticity. Development of the neuronal processes underlying sensorimotor integration is incompletely understood but involves activity-dependent modeling and refining of sensorimotor circuits through processes that are already taking place in utero and which continue through infancy, childhood, and into adolescence. Several genetic dystonias have clinical onset in early childhood, but there is evidence that sensorimotor circuit development may already be disrupted prenatally in these conditions. Dystonic cerebral palsy (DCP) is a form of acquired dystonia with perinatal onset during a period of rapid neurodevelopment and activity-dependent refinement of sensorimotor networks. However, physiological studies of children with dystonia are sparse. This discussion paper addresses the role of neuroplasticity in the development of sensorimotor integration with particular focus on the relevance of these mechanisms for understanding childhood dystonia, DCP, and implications for therapy selection, including neuromodulation and timing of intervention.

Perinatal stroke: mapping and modulating developmental plasticity

Most cases of hemiparetic cerebral palsy are caused by perinatal stroke, resulting in lifelong disability for millions of people. However, our understanding of how the motor system develops following such early unilateral brain injury is increasing. Tools such as neuroimaging and brain stimulation are generating informed maps of the unique motor networks that emerge following perinatal stroke. As a focal injury of defined timing in an otherwise healthy brain, perinatal stroke represents an ideal human model of developmental plasticity. Here, we provide an introduction to perinatal stroke epidemiology and outcomes, before reviewing models of developmental plasticity after perinatal stroke. We then examine existing therapeutic approaches, including constraint, bimanual and other occupational therapies, and their potential synergy with non-invasive neurostimulation. We end by discussing the promise of exciting new therapies, including novel neurostimulation, brain-computer interfaces and robotics, all focused on improving outcomes after perinatal stroke.

Clinical Utility of Transcranial Magnetic Stimulation (TMS) in the Presurgical Evaluation of Motor, Speech, and Language Functions in Young Children With Refractory Epilepsy or Brain Tumor: Preliminary Evidence

Accurate presurgical mapping of motor, speech, and language cortices, while crucial for neurosurgical planning and minimizing post-operative functional deficits, is challenging in young children with neurological disease. In such children, both invasive (cortical stimulation mapping) and non-invasive functional mapping imaging methods (MEG, fMRI) have limited success, often leading to delayed surgery or adverse post-surgical outcomes. We therefore examined the clinical utility of transcranial magnetic stimulation (TMS) in young children who require functional mapping. In a retrospective chart review of TMS studies performed on children with refractory epilepsy or a brain tumor, at our institution, we identified 47 mapping sessions in 36 children 3 years of age or younger, in whom upper and lower extremity motor mapping was attempted; and 13 children 5–6 years old in whom language mapping, using a naming paradigm, was attempted. The primary hand motor cortex was identified in at least one hemisphere in 33 of 36 patients, and in both hemispheres in 27 children. In 17 children, primary leg motor cortex was also successfully identified. The language cortices in temporal regions were successfully mapped in 11 of 13 patients, and in six of them language cortices in frontal regions were also mapped, with most children (n = 5) showing right hemisphere dominance for expressive language. Ten children had a seizure that was consistent with their clinical semiology during or immediately following TMS, none of which required intervention or impeded completion of mapping. Using TMS, both normal motor, speech, and language developmental patterns and apparent disease induced reorganization were demonstrated in this young cohort. The successful localization of motor, speech, and language cortices in young children improved the understanding of the risk-benefit ratio prior to surgery and facilitated surgical planning aimed at preserving motor, speech, and language functions. Post-operatively, motor function was preserved or improved in nine out of 11 children who underwent surgery, as was language function in all seven children who had surgery for lesions near eloquent cortices. We provide feasibility data that TMS is a safe, reliable, and effective tool to map eloquent cortices in young children.

Improvements in Upper Extremity Function Following Intensive Training Are Independent of Corticospinal Tract Organization in Children With Unilateral Spastic Cerebral Palsy: A Clinical Randomized Trial

Background/Objectives: Intensive training of the more affected upper extremity (UE) has been shown to be effective for children with unilateral spastic cerebral palsy (USCP). Two types of UE training have been particularly successful: Constraint-Induced Movement Therapy (CIMT) and Bimanual training. Reorganization of the corticospinal tract (CST) early during development often occurs in USCP. Prior studies have suggested that children with an ipsilateral CST controlling the affected UE may improve less following CIMT than children with a contralateral CST. We tested the hypothesis that improvements in UE function after intensive training depend on CST laterality.

Study Participants and Setting: Eighty-two children with USCP, age 5 years 10 months to 17 years, University laboratory setting.

Materials/Methods: Single-pulse transcranial magnetic stimulation (TMS) was used to determine each child's CST connectivity pattern. Children were stratified by age, sex, baseline hand function and CST connectivity pattern, and randomized to receive either CIMT or Bimanual training, each of which were provided in a day-camp setting (90 h). Hand function was tested before, immediately and 6 months after the intervention with the Jebsen-Taylor Test of Hand Function, the Assisting Hand Assessment, the Box and Block Test, and ABILHAND-Kids. The Canadian Occupational Performance Measure was used to track goal achievement and the Pediatric Evaluation of Disability Inventory was used to assess functioning in daily living activities at home.

Results: In contrast to our hypothesis, participants had statistically similar improvements for both CIMT and Bimanual training for all measures independent of their CST connectivity pattern (contralateral, ipsilateral, or bilateral) (p < 0.05 in all cases).

Conclusions/Significance: The efficacy of CIMT and Bimanual training is independent of CST connectivity pattern. Children with an ipsilateral CST, previously thought to be maladaptive, have the capacity to improve as well as children with a contralateral or bilateral CST following intensive CIMT or Bimanual training.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT02918890.

Validity and reliability of an electromyography-based upper limb assessment quantifying selective voluntary motor control in children with upper motor neuron lesions

Current clinical assessments evaluating selective voluntary motor control are measured on an ordinal scale. We combined the Selective Control of the Upper Extremity Scale (SCUES) with surface electromyography to develop a more objective and interval-scaled assessment of selective voluntary motor control. The resulting Similarity Index (SI) quantifies the similarity of muscle activation patterns. We aimed to evaluate the validity and reliability of this new assessment named SISCUES (Similarity Index of the SCUES) in children with upper motor neuron lesions. Thirty-three patients (12.2 years [8.8;14.9]) affected by upper motor neuron lesions with mild to moderate impairments and 31 typically developing children (11.6 years [8.5;13.9]) participated. We calculated reference muscle activation patterns for the SISCUES using data of 33 neurologically healthy adults (median [1st; 3rd quantile]: 32.5 [27.9; 38.3]). We calculated Spearman correlations (ρ) between the SISCUES and the SCUES and the Manual Ability Classification System (MACS) to establish concurrent validity. Discriminative validity was tested by comparing scores of patients and healthy peers with a robust ANCOVA. Intraclass correlation coefficients2,1 and minimal detectable changes indicated relative and absolute reliability. The SISCUES correlates strongly with SCUES (ρ = 0.76, p < 0.001) and moderately with the MACS (ρ = -0.58, p < 0.001). The average SISCUES can discriminate between patients and peers. The intraclass correlation coefficient2,1 was 0.90 and the minimal detectable change was 0.07 (8% of patients' median score). Concurrent validity, discriminative validity, and reliability of the SISCUES were established. Further studies are needed to evaluate whether it is responsive enough to detect changes from therapeutic interventions.

Functional connectivity and upper limb function in patients after pediatric arterial ischemic stroke with contralateral corticospinal tract wiring

To develop individualized motor rehabilitation, knowledge of the relationship between neuroplastic reorganization and motor recovery after pediatric arterial ischemic stroke (AIS) is crucial. Thus, we investigated functional connectivity in patients after AIS with good motor outcome and in patients with hemiparesis compared with typically developing peers. We included 18 patients (n = 9 with hemiparesis, n = 9 with good motor outcome) with pediatric AIS in the chronic phase (≥ 2 years after diagnosis, diagnosed > 16 years) and 18 peers matched by age and gender. Participants underwent a standardized motor assessment, single-pulse transcranial magnetic stimulation to determine the type of corticospinal tract wiring, and resting-state functional magnetic resonance imaging to examine motor network connectivity. Corticospinal tract wiring was contralateral in all participants. Patients with hemiparesis had lower interhemispheric connectivity strength compared with patients with good clinical outcome and peers. Patients with good clinical outcome had higher intrahemispheric connectivity strength compared with peers. Further, higher intrahemispheric connectivity was related to better motor outcome in patients. Our findings suggest that better motor outcome after pediatric AIS is related to higher motor network connectivity strength. Thus, resting-state functional connectivity might be predictive for motor recovery after pediatric AIS.

Functional Lateralization of the Mirror Neuron System in Monkey and Humans

To date, both in monkeys and humans, very few studies have addressed the issue of the lateralization of the cortical parietal and premotor areas involved in the organization of voluntary movements and in-action understanding. In this review, we will first analyze studies in the monkey, describing the functional properties of neurons of the parieto-frontal circuits, involved in the organization of reaching-grasping actions, in terms of unilateral or bilateral control. We will concentrate, in particular, on the properties of the mirror neuron system (MNS). Then, we will consider the evidence about the mirror neuron mechanism in humans, describing studies in which action perception, as well as action execution, produces unilateral or bilateral brain activation. Finally, we will report some investigations demonstrating plastic changes of the MNS following specific unilateral brain damage, discussing how this plasticity can be related to the rehabilitation outcome

Upper Extremity Muscle Strength in Children With Unilateral Spastic Cerebral Palsy: A Bilateral Problem?

OBJECTIVE

The objective was to investigate whether muscle strength in the nonaffected and affected upper extremities (UEs) in children (7-12 years) with unilateral spastic cerebral palsy (USCP) differs from that in children with typical development (TD).

METHODS

A cross-sectional study design was used. Isometric arm strength (wrist flexion, wrist extension with flexed and extended fingers, elbow flexion/extension) was assessed in 72 children (mean age = 9.3 [SD = 1.9] years) with USCP, and isometric grip/pinch strength was assessed in 86 children (mean age = 9.3 [SD = 1.8] years) with USCP. Arm/grip/pinch strength was assessed in 120 children (mean age = 9.5 [SD = 1.7] years) with TD. Arm strength was measured with a hand-held dynamometer, and grip/pinch strength was measured with a calibrated, modified (digitized) grip dynamometer and a pinch meter. The nonaffected UE of children with USCP was compared with the preferred UE of children with TD because both sides represent the preferred UE. The affected UE was compared with the nonpreferred UE of children with TD, as both sides represent the nonpreferred UE.

RESULTS

In all measurements except for grip strength of the preferred UE, children with USCP were weaker than children with TD.

CONCLUSIONS

In children with USCP, muscle strength weakness exists in both UEs.

IMPACT

When unimanual or bimanual ability limitations are present in children with unilateral cerebral palsy, investigation of the muscle strength of the nonaffected UE should be part of the assessment.

Multimodal assessment of motor pathways and intracortical connections in functional hemispherectomy

PURPOSE

For selected children with medically intractable epilepsy, hemispherectomy can be an excellent treatment option and its efficacy in achieving seizure freedom or reduction in seizure frequency has been shown in several studies, but patients' selection could not be straightforward and often it is taken on subjective basis. We described a multimodal approach to assess patient eligible for hemispherectomy and possibly predicting post-surgical outcomes.

METHODS

We describe pre- and post-surgical clinical features along with neuroradiological results by magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), MR-tractography (MRT), and neurophysiological study by single and paired pulses transcranial magnetic stimulation (TMS) in a child with cerebral palsy with epileptic encephalopathy, eligible for epilepsy surgery.

RESULTS

Presurgical TMS evaluation showed a lateralization of motor function on the left motor cortex for both arms, and results were confirmed by MRI studies. Interestingly, after surgery, both epilepsy and motor performances improved and TMS showed enhancement of intracortical inhibition and facilitation activity.

CONCLUSION

Functional hemispherectomy is an effective treatment for drug-resistant epilepsy, and multimodal presurgical assessment may be a useful approach to guide surgeons in selecting patients. Moreover, pre- and post-surgical evaluation of these patients may enhance our understanding of brain plasticity phenomena.

Structural and functional connectivity of motor circuits after perinatal stroke: A machine learning study

Developmental neuroplasticity allows young brains to adapt via experiences early in life and also to compensate after injury. Why certain individuals are more adaptable remains underexplored. Perinatal stroke is an ideal human model of neuroplasticity with focal lesions acquired near birth in a healthy brain. Machine learning can identify complex patterns in multi-dimensional datasets. We used machine learning to identify structural and functional connectivity biomarkers most predictive of motor function. Forty-nine children with perinatal stroke and 27 controls were studied. Functional connectivity was quantified by fluctuations in blood oxygen-level dependent (BOLD) signal between regions. White matter tractography of corticospinal tracts quantified structural connectivity. Motor function was assessed using validated bimanual and unimanual tests. RELIEFF feature selection and random forest regression models identified predictors of each motor outcome using neuroimaging and demographic features. Unilateral motor outcomes were predicted with highest accuracy (8/54 features r = 0.58, 11/54 features, r = 0.34) but bimanual function required more features (51/54 features, r = 0.38). Connectivity of both hemispheres had important roles as did cortical and subcortical regions. Lesion size, age at scan, and type of stroke were predictive but not highly ranked. Machine learning regression models may represent a powerful tool in identifying neuroimaging biomarkers associated with clinical motor function in perinatal stroke and may inform personalized targets for neuromodulation.

Imaging Developmental and Interventional Plasticity Following Perinatal Stroke

Perinatal stroke occurs around the time of birth and leads to lifelong neurological disabilities including hemiparetic cerebral palsy. Magnetic resonance imaging (MRI) has revolutionized our understanding of developmental neuroplasticity following early injury, quantifying volumetric, structural, functional, and metabolic compensatory changes after perinatal stroke. Such techniques can also be used to investigate how the brain responds to treatment (interventional neuroplasticity). Here, we review the current state of knowledge of how established and emerging neuroimaging modalities are informing neuroplasticity models in children with perinatal stroke. Specifically, we review structural imaging characterizing lesion characteristics and volumetrics, diffusion tensor imaging investigating white matter tracts and networks, task-based functional MRI for localizing function, resting state functional imaging for characterizing functional connectomes, and spectroscopy examining neurometabolic changes. Key challenges and exciting avenues for future investigations are also considered.

An Unusual, Intermediate-Sized Lesion Affecting Motor Organization in a Patient With Schizencephaly: A Case Report

Schizencephalies are abnormal clefts of the cerebral hemispheres that result from abnormal late neuronal migration and cortical organization. In the present study, we report a different type of unusual motor organization in a patient with a schizencephalic cleft in the right hemisphere and polymicrogyria in the opposite hemisphere. Despite similar brain pathology affecting the sensorimotor cortex, motor organization differed from previously known bilateral congenital brain lesions. We conducted a transcranial magnetic stimulation (TMS) and diffusion tensor image (DTI) study to confirm the motor organization. In this case, ipsilateral corticospinal projections to the paretic hands were observed during TMS of the less affected hemisphere, along with polymicrogyria, similar to the previous study. However, a crossed corticospinal tract to the paretic hand from the more severely affected hemisphere was observed in this case-a pattern of motor organization that has yet to be reported in this patient population. Our findings indicate that motor organization after early brain injury may be affected by the interhemispheric competition of the corticospinal system and bilateral brain lesions, thereby resulting in unilateral hemiparesis.

Contralesional White Matter Alterations in Patients After Hemispherotomy

Cerebral lesions may cause degeneration and neuroplastic reorganization in both the ipsi- and the contralesional hemisphere, presumably creating an imbalance of primarily inhibitory interhemispheric influences produced via transcallosal pathways. The two hemispheres are thought to mutually hamper neuroplastic reorganization of the other hemisphere. The results of preceding degeneration and neuroplastic reorganization of white matter may be reflected by Diffusion Tensor Imaging-derived diffusivity parameters such as fractional anisotropy (FA). In this study, we applied Diffusion Tensor Imaging (DTI) to contrast the white matter status of the contralesional hemisphere of young lesioned brains with and without contralateral influences by comparing patients after hemispherotomy to those who had not undergone neurosurgery. DTI was applied to 43 healthy controls (26 females, mean age ± SD: 25.07 ± 11.33 years) and two groups of in total 51 epilepsy patients with comparable juvenile brain lesions (32 females, mean age ± SD: 25.69 ± 12.77 years) either after hemispherotomy (30 of 51 patients) or without neurosurgery (21 of 51 patients), respectively. FA values were compared between these groups using the unbiased tract-based spatial statistics approach. A voxel-wise ANCOVA controlling for age at scan yielded significant group differences in FA. A post hoc t-test between hemispherotomy patients and healthy controls revealed widespread supra-threshold voxels in the contralesional hemisphere of hemispherotomy patients indicating comparatively higher FA values (p < 0.05, FWE-corrected). The non-surgery group, in contrast, showed extensive supra-threshold voxels indicating lower FA values in the contralesional hemisphere as compared to healthy controls (p < 0.05, FWE-corrected). Whereas lower FA values are suggestive of pronounced contralesional degeneration in the non-surgery group, higher FA values in the hemispherotomy group may be interpreted as a result of preceding plastic remodeling. We conclude that, whether juvenile brain lesions are associated with contralesional degeneration or reorganization partly depends on the ipsilesional hemisphere. Contralesional reorganization as observed in hemispherotomy patients was most likely enabled by the complete neurosurgical deafferentation of the ipsilesional hemisphere and, thereby, the disinhibition of the neuroplastic potential of the contralesional hemisphere. The main argument of this study is that hemispherotomy may be seen as a major plastic stimulus and as a prerequisite for contralesional neuroplastic remodeling in patients with juvenile brain lesions.

White matter characteristics of motor, sensory and interhemispheric tracts underlying impaired upper limb function in children with unilateral cerebral palsy

This study explored the role of lesion timing (periventricular white matter versus cortical and deep grey matter lesions) and type of corticospinal tract (CST) wiring pattern (contralateral, bilateral, ipsilateral) on white matter characteristics of the CST, medial lemniscus, superior thalamic radiations and sensorimotor transcallosal fibers in children with unilateral cerebral palsy (CP), and examined the association with upper limb function. Thirty-four children (mean age 10 years 7 months ± 2 years 3 months) with unilateral CP underwent a comprehensive upper limb evaluation and diffusion weighted imaging (75 directions, b value 2800). Streamline count, fractional anisotropy and mean diffusivity were extracted from the targeted tracts and asymmetry indices were additionally calculated. Transcranial magnetic stimulation was applied to assess the CST wiring pattern. Results showed a more damaged CST in children with cortical and deep grey matter lesions (N = 10) and ipsilateral CST projections (N = 11) compared to children with periventricular white matter lesions (N = 24; p < 0.02) and contralateral CST projections (N = 9; p < 0.025), respectively. Moderate to high correlations were found between diffusion metrics of the targeted tracts and upper limb function (r = 0.45-0.72; p < 0.01). Asymmetry indices of the CST and sensory tracts could best explain bimanual performance (74%, p < 0.0001) and unimanual capacity (50%, p = 0.004). Adding lesion timing and CST wiring pattern did not further improve the model of bimanual performance, while for unimanual capacity lesion timing was additionally retained (58%, p = 0.0002). These results contribute to a better understanding of the underlying neuropathology of upper limb function in children with unilateral CP and point towards a clinical potential of tractography.

Language development and brain reorganization in a child born without the left hemisphere

We present a case of a 14-year-old girl born without the left hemisphere due to prenatal left internal carotid occlusion. We combined longitudinal language and cognitive assessments with functional and structural neuroimaging data to situate the case within age-matched, typically developing children. Despite having had a delay in getting language off the ground during the preschool years, our case performed within the normal range on a variety of standardized language tests, and exceptionally well on phonology and word reading, during the elementary and middle school years. Moreover, her spatial, number, and reasoning skills also fell in the average to above-average range based on assessments during these time periods. Functional MRI data revealed activation in right fronto-temporal areas when listening to short stories, resembling the bilateral activation patterns in age-matched typically developing children. Diffusion MRI data showed significantly larger dorsal white matter association tracts (the direct and anterior segments of the arcuate fasciculus) connecting areas active during language processing in her remaining right hemisphere, compared to either hemisphere in control children. We hypothesize that these changes in functional and structural brain organization are the result of compensatory brain plasticity, manifesting in unusually large right dorsal tracts, and exceptional performance in phonology, speech repetition, and decoding. More specifically, we posit that our case's large white matter connections might have played a compensatory role by providing fast and reliable transfer of information between cortical areas for language in the right hemisphere.

Mirror Therapy in Stroke Rehabilitation: Current Perspectives

In contrast to varied therapy approaches, mirror therapy (MT) can be used even in completely plegic stroke survivors, as it uses visual stimuli for producing a desired response in the affected limb. MT has been studied to have effects not just on motor impairments but also on sensations, visuospatial neglect, and pain after stroke. This paper attempts to systematically review and present the current perspectives on mirror therapy and its application in stroke rehabilitation, and dosage, feasibility and acceptability in stroke rehabilitation. An electronic database search across Google, PubMed, Web of Science, etc., generated 3871 results. After screening them based on the inclusion and exclusion criteria, we included 28 studies in this review. The data collected were divided on the basis of application in stroke rehabilitation, modes of intervention delivery, and types of control and outcome assessment. We found that most studies intervened for upper limb motor impairments post stroke. Studies were equally distributed between intervention in chronic and acute phases post stroke with therapy durations lasting between 1 and 8 weeks. MT showed definitive motor and sensory improvements although the extent of improvements in sensory impairments and hemineglect is limited. MT proves to be an effective and feasible approach to rehabilitate post-stroke survivors in the acute, sub-acute, and chronic phases of stroke, although its long-term effects and impact on activities of daily living need to be analysed extensively.

Hand Motor Actions of Children With Cerebral Palsy Are Associated With Abnormal Sensorimotor Cortical Oscillations

Background. The neuroimaging literature on cerebral palsy (CP) has predominantly focused on identifying the structural aberrations (eg, fiber track integrity), with very few studies examining neural activity within the key networks that serve the production of hand movements. Objective. We aimed to start to fill this knowledge gap by using magnetoencephalographic brain imaging to quantify the temporal dynamics of the sensorimotor oscillations during a hand motor action. Methods: Children with CP (n = 12; MACS [Manual Abilities Classification System] levels I-III) and typically developing (TD) children (n = 26) performed an arrow-based version of the Eriksen flanker task where a button press was performed with either the second or third digit of the right hand depending on the arrow's direction. Results: Overall, the children with CP were less accurate and had slower reaction times compared with the TD children. These behavioral differences were closely linked with aberrant sensorimotor cortical oscillations seen in the children with CP. Compared with the TD children, the children with CP had a weaker gamma (68-82 Hz) response during motor execution and a weaker post-movement beta rebound (PMBR; 14-26 Hz) response on movement termination. Moreover, we observed a significant correlation between the amplitude of the gamma and PMBR with reaction time, with weaker gamma and PMBR responses being linked with slower reaction times. Conclusions: Overall, these results suggest that aberrations in motor-related gamma and beta cortical oscillations are associated with the impaired hand motor actions seen in children with CP.

Influence of visual-coupling on bimanual coordination in unilateral spastic cerebral palsy

Controlling two objects simultaneously during a bimanual task is a cognitively demanding process; both hands need to be temporally and spatially coordinated to achieve the shared task goal. Children with unilateral spastic cerebral palsy (USCP) exhibit severe sensory and motor impairments to one side of their body that make the process of coordinating bimanual movements particularly exhausting. Prior studies have shown that performing visually-coupled task could reduce cognitive interference associated with performing 'two tasks at once' in an uncoupled bimanual task. For children with USCP, who also present with cognitive delay, performing this type of task may allow them to process and plan their movement faster. We tested this hypothesis by examining the grip force control of 7 children with USCP during unimanual and visually-coupled bimanual tasks. Results demonstrated that despite the visual coupling, the bimanual coordination of these children remained impaired. However, there may be a potential benefit of visually-coupled task in encouraging both hands to initiate in concert. The implication of the study for children with USCP is discussed.

Influence of the corticospinal tract wiring pattern on sensorimotor functional connectivity and clinical correlates of upper limb function in unilateral cerebral palsy

In children with unilateral cerebral palsy (uCP), the corticospinal tract (CST)-wiring patterns may differ (contralateral, ipsilateral or bilateral), partially determining motor deficits. However, the impact of such CST-wiring on functional connectivity remains unknown. Here, we explored resting-state sensorimotor functional connectivity in 26 uCP with periventricular white matter lesions (mean age (standard deviation): 12.87 m (±4.5), CST wiring: 9 contralateral, 9 ipsilateral, 6 bilateral) compared to 60 healthy controls (mean age (standard deviation): 14.54 (±4.8)), and between CST-wiring patterns. Functional connectivity from each M1 to three bilateral sensorimotor regions of interest (primary sensory cortex, dorsal and ventral premotor cortex) and the supplementary motor area was compared between groups (controls vs. uCP; and controls vs. each CST-wiring group). Seed-to-voxel analyses from bilateral M1 were compared between groups. Additionally, relations with upper limb motor deficits were explored. Aberrant sensorimotor functional connectivity seemed to be CST-dependent rather than specific from all the uCP population: in the dominant hemisphere, the contralateral CST group showed increased connectivity between M1 and premotor cortices, whereas the bilateral CST group showed higher connectivity between M1 and somatosensory association areas. These results suggest that functional connectivity of the sensorimotor network is CST-wiring-dependent, although the impact on upper limb function remains unclear.

Mirror Neuron System Activation in Children With Unilateral Cerebral Palsy During Observation of Actions Performed by a Pathological Model

Background. Recent evidence suggested that Action Observation Therapy (AOT), based on observation of actions followed by immediate reproduction, could be a useful rehabilitative strategy for promoting functional recovery of children affected by unilateral cerebral palsy (UCP). AOT most likely exploits properties of the parieto-premotor mirror neuron system (MNS). This is more intensely activated when participants observe actions belonging to their own motor repertoire. Objective. The aim of the present study was to investigate the issue of whether MNS of UCP children is better activated by actions performed by a paretic hand rather than a healthy one. Methods. Using functional magnetic resonance imaging, we assessed brain activation in a homogeneous group of 10 right UCP children compared with that of 10 right-handed typically developing (TD) children, during observation of grasping actions performed by a healthy or a paretic hand. Results. The results revealed a significant activation within the MNS in both UCP and TD children, more lateralized to the left hemisphere in the TD group. Most important, region of interest (ROI) analysis on parietal and premotor regions showed that, in UCP, the MNS was more strongly activated by observation of actions performed by the paretic hand, a motor model more similar to the observer’s motor repertoire. Conclusions. This study shows that children affected by spastic UCP exhibit enhanced activation of the MNS during observation of goal-directed actions performed by a pathological model with respect to a healthy one.