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.

Children with Cerebral Palsy can imagine actions like their normally developed peers

The present study aimed at assessing whether children with Cerebral Palsy (CP) can imagine object directed actions similarly to their normally developed peers. We asked children with CP (n = 12) and paired healthy controls (n = 12) to imagine in first person perspective eight daily actions, after observing them through videoclips presented on a computer screen. During motor imagery (MI) children were interrupted at a specific timepoint (e.g., at 2.5 s) from the start. Two frames extracted from the videoclips were then presented on the screen. One of the two depicted the correct timepoint at which the imagined action was interrupted, while the other represented an earlier or later timepoint. Children had to respond by pressing the key associated to the correct frame. Children also underwent VMIQ-2 questionnaire. Both groups performed similarly in the questionnaire and in the requested task, where they showed the same error rate. Errors mainly concerned the later frame, suggesting a similar strategy to solve the task in the two groups. The results support the view that children with CP can imagine actions similarly to their normally developed peers. This encourages the use of MI as a rehabilitative tool in children with motor impairment.

Mirror neurons 30 years later: implications and applications

Mirror neurons (MNs) were first described in a seminal paper in 1992 as a class of monkey premotor cells discharging during both action execution and observation. Despite their debated origin and function, recent studies in several species, from birds to humans, revealed that beyond MNs properly so called, a variety of cell types distributed among multiple motor, sensory, and emotional brain areas form a 'mirror mechanism' more complex and flexible than originally thought, which has an evolutionarily conserved role in social interaction. Here, we trace the current limits and envisage the future trends of this discovery, showing that it inspired translational research and the development of new neurorehabilitation approaches, and constitutes a point of no return in social and affective neuroscience.

Can a pathological model improve the abilities of the paretic hand in hemiplegic children? The PAM-AOT study protocol of a randomised controlled trial

Introduction

Action Observation Treatment (AOT) is an innovative therapeutic approach consisting in the observation of actions followed by subsequent repetition. In children with unilateral cerebral palsy (UCP), it improves upper limb function in daily activities. The standard paradigm of AOT requires the observation of healthy models; however, it has been demonstrated that the mirror neuron system of children with UCP is more activated by observation of pathological models, showing a similar motor repertoire, than by the healthy model, suggesting that AOT based on pathological models is superior to the standard paradigm of AOT in the functional rehabilitation of the affected upper limb of children with UCP.

Methods and analysis

This protocol describes an active two-arm randomised controlled evaluator-blinded trial. Twenty-six children with UCP will participate in 3 weeks of intensive AOT: the experimental group will observe a pathological model, while the control group will observe a typically developed model. The primary outcome is the spontaneous use of the paretic hand, measured with the Assisting Hand Assessment. Secondary outcome measures are the Melbourne Assessment of Unilateral Upper Limb Function, the ABILHAND-Kids and the Activities Scale for Kids-performance. Assessments will be performed at baseline (T0), at the end of intensive AOT (T1), at 8–12 weeks (T2) and at 24–28 weeks (T3) after the end of intensive AOT.

Ethics and dissemination

The trial was approved by the Area Vasta Emilia Nord Ethics Committee (AVEN prot. n. 133117, 29 November 2018), and it was prospectively registered on ClinicalTrials.gov. The results will be submitted for publication to a peer-reviewed journal, discussed with parents of children participating in the trial and disseminated at suitable conferences.

Trial registration number

NCT04088994; Pre-results.

Neurophysiological Synchrony Between Children With Severe Physical Disabilities and Their Parents During Music Therapy

Although physiological synchronization has been associated with the level of empathy in emotionally meaningful relationships, little is known about the interbrain synchrony between non-speaking children with severe disabilities and their familial caregivers. In a repeated measures observational study, we ascertained the degree of interbrain synchrony during music therapy in 10 child-parent dyads, where the children were non-speaking and living with severe motor impairments. Interbrain synchrony was quantified via measurements of spectral coherence and Granger causality between child and parent electroencephalographic (EEG) signals collected during ten 15-min music therapy sessions per dyad, where parents were present as non-participating, covert observers. Using cluster-based permutation tests, we found significant child-parent interbrain synchrony, manifesting most prominently across dyads in frontal brain regions within β and low γ frequencies. Specifically, significant dyadic coherence was observed contra-laterally, between child frontal right and parental frontal left regions at β and lower γ bands in empathy-related brain areas. Furthermore, significant Granger influences were detected bidirectionally (from child to parent and vice versa) in the same frequency bands. In all dyads, significant increases in session-specific coherence and Granger influences were observed over the time course of a music therapy session. The observed interbrain synchrony suggests a cognitive-emotional coupling during music therapy between child and parent that is responsive to change. These findings encourage further study of the socio-empathic capacity and interpersonal relationships formed between caregivers and non-speaking children with severe physical impairments.

The role of mirror mechanism in the recovery, maintenance, and acquisition of motor abilities

While it is well documented that the motor system is more than a mere implementer of motor actions, the possible applications of its cognitive side are still under-exploited, often remaining as poorly organized evidence. Here, we will collect evidence showing the value of action observation treatment (AOT) in the recovery of impaired motor abilities for a vast number of clinical conditions, spanning from traumatological patients to brain injuries and neurodegenerative diseases. Alongside, we will discuss the use of AOT in the maintenance of appropriate motor behavior in subjects at risk for events with dramatic physical consequences, like fall prevention in elderly people or injury prevention in sports. Finally, we will report that AOT can help to tune existing motor competencies in fields requiring precise motor control. We will connect all these diverse dots into the neurophysiological scenario offered by decades of research on the human mirror mechanism, discussing the potentialities for individualization. Empowered by modern technologies, AOT can impact individuals' safety and quality of life across the whole lifespan.

Telerehabilitation in response to constrained physical distance: an opportunity to rethink neurorehabilitative routines

Ensuring proper dosage of treatment and repetition over time is a major challenge in neurorehabilitation. However, a requirement of physical distancing to date compromises their achievement. While mostly associated to COVID-19, physical distancing is not only required in a pandemic scenario, but also advised for several clinical conditions (e.g. immunocompromised individuals) or forced for specific social contexts (e.g. people living in remote areas worldwide). All these contexts advocate for the implementation of alternative healthcare models. The objective of this perspective is to highlight the benefits of remote administration of rehabilitative treatment, namely telerehabilitation, in counteracting physical distancing barriers in neurorehabilitation. Sustaining boosters of treatment outcome, such as compliance, sustainability, as well as motivation, telerehabilitation may adapt to multiple neurological conditions, with the further advantage of a high potential for individualization to patient's or pathology's specificities. The effectiveness of telerehabilitation can be potentiated by several technologies available to date: virtual reality can recreate realistic environments in which patients may bodily operate, wearable sensors allow to quantitatively monitor the patient's performance, and signal processing may contribute to the prediction of long-term dynamics of patient recovery. Telerehabilitation might spark its advantages far beyond the mere limitation of physical distancing effects, mitigating criticalities of daily neurorehabilitative practice, and thus paving the way to the envision of mixed models of care, where hospital-based procedures are complementarily integrated with telerehabilitative ones.

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

From movement to action: a new framework for cerebral palsy

The interpretation of cerebral palsy (CP) is closely linked to points of view that are no longer acceptable: 1) the idea that it is primarily a motor problem (posture and movement disorder); 2) the idea that it is only a central (cerebral) pathology; 3) the idea that it is a non-progressive disease (fixed encephalopathy). Actually, the problems that contribute to producing the CP clinical picture are several and complex. First of all, building of the action, starting from subject motivation, through motor imagery and subsequent project elaboration. Sequentially, executive planning, disorder often hidden under the most remarkable alteration of motor patterns and muscle tone. Finally, realization, conditioned by the idea that the locomotor apparatus is only and always the victim of an incapable central nervous system. Little known and very neglected perceptive components can contribute to compromising subject motor control. The influences that primitive changes of musculoskeletal system, often depending on site, nature, size and time of the lesion, exert on the possible choices of the central nervous system are often overlooked. Peripheral structures can in fact modify considerably the expression of palsy (understood as the form of adaptive functions) primitively. At least six different sources of error can be identified in the cerebral palsied child. For a rehabilitative intervention with greater possibilities of effectiveness, it is necessary to recognize and evaluate each of them. Especially as regards the prevention of secondary deformities, the responsibility attributed to physiotherapy must be re-evaluated.