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Study protocol: Responsiveness of postural control of children with and without a
developmental coordination disorder after Transcranial Direct Current Stimulation
MARIA C. D. S. DE MOURA
1
| FUAD A. HAZIME
2
| ABRAHÃO F. BAPTISTA
3
| JORGE A. OLIVEIRA
4
| RENATA H.
HASUE
1
1
Universidade de São Paulo, Faculdade de Medicina, Departamento de Fisioterapia, Fonoaudiologia e Terapia Ocupacional. São Paulo, SP, Brazil
2
Universidade Federal do Delta do Parnaíba, Programa de Pós-Graduação em Ciências Biomédicas. Parnaíba, Piauí, Brazil
3
Universidade Federal do ABC, Centro de Matemática, Computação e Cognição. São Bernardo do Campo, SP, Brazil
4
Universidade de São Paulo, Escola de Educação Física e Esporte, Departamento de Pedagogia do Movimento do Corpo Humano. São Paulo, SP, Brazil
Correspondence to:!Maria Clara Drummond Soares de Moura
Department of Physical Therapy, Communication Sciences and Disorders, and Occupational Therapy - Faculdade de Medicina da Universidade de São Paulo – USP,
São Paulo, SP – Brasil - Rua Cipotânea, 51, Cidade Universitária, CEP: 05360-160.
email: mclaramoura@usp.br
https://doi.org/10.20338/bjmb.v18i1.400
ABBREVIATIONS
AF Assent form
AP Antero-posterior displacement
COP Center of pressure
DCD Developmental coordination disorder
DCDQ Developmental Coordination Disorder
Questionnaire (Brazilian version)
DSM-5 Diagnostic and Statistical Manual of Mental
Disorders - 5th edition
FP Force plataform
FpZ Central forehead region
ICF Informed consent form
MABC-2 Movement Battery Assessment for Children
(Second Edition)
ML Medio-lateral displacement
M1 Primary motor cortex
SOT Sensory organization test
TD Typical development
tDCS Transcranial direct current stimulation
PUBLICATION DATA
Received 21 09 2023
Accepted 19 03 2024
Published 27 04 2024
BACKGROUND: Developmental coordination disorder (DCD) is a neurodevelopmental
disorder that affects around 5% of school-age children worldwide. DCD negatively impacts
motor repertoire, quality of life, and overall health. One of the main motor impairments
affecting activity and participation is poor postural balance. Although the neural basis of DCD
is not yet clear, morphological and functional alterations have been found in children with DCD
in crucial areas for postural control, such as the cerebellum and the primary motor cortex.
Transcranial direct current stimulation (tDCS) is a noninvasive technique for inducing synaptic
modulation, promoting neuromodulation that can help in understanding physiopathology and
determining therapeutic strategies for people with DCD.
AIM: The proposed randomized clinical trial will verify the immediate effects of tDCS in the
primary motor cortex and the cerebellum on postural balance in children with and without
DCD.
METHOD: Fifteen children with DCD and 15 typically developing children will be randomized
to receive a single session of anodal cerebellar tDCS, cathodal cerebellar tDCS, anodal
primary motor cortex tDCS, or sham tDCS in a crossover design. Postural balance will be
assessed by posturography with and without visual and somatosensory system manipulation
immediately before and after each tDCS session.
RESULTS AND INTERPRETATION: This paper presents a detailed description protocol of a
double-blind, placebo-controlled, crossover clinical trial. The results can bolster understanding
of the postural control of children with DCD compared to children with typical development as
well as knowledge about the possible effects of tDCS on the postural balance of such
children.
KEYWORDS: Motor skills disorder | Neurodevelopmental disorders | Postural balance |
Transcranial direct current stimulation | Child development
INTRODUCTION
Developmental coordination disorder (DCD) is a neurodevelopmental disorder characterized by difficulties in acquiring and
performing motor tasks
1
. DCD can occur in all cultures, ethnicities, and socioeconomic levels, with the most accepted prevalence
estimated between 5% and 6% of school-age children worldwide
2,3
. The early motor development of children with DCD may be delayed,
and movement execution may appear more clumsy, slow, varied, or less accurate than their peers
2,4
. Alterations in the acquisition and
performance of age-related motor skills restrain the activity and participation of these children
5
. The impact on quality of life is even more
significant, with psychological and social aspects also compromised
6,7
.
The static balance of children with DCD is significantly impaired when visual, somesthetic, and vestibular afferents are
manipulated, even if all these sensory modalities are available
8,9
during bipodal side-by-side support
10
. Impaired balance is more evident
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in situations of greater sensorimotor demand when there is conflict or reduction in any sensory information
8,11
.
Although sensorimotor integration has been investigated to understand altered postural control in children with DCD, discussion
about the neural basis of this motor-control deficit is incipient. It is hypothesized that a poor ability to learn and perform motor skills is
associated with a delay or dysfunction at the neuro-maturational level
12
. Some studies have pointed to the cerebellum as the core of
DCD deficits
5,13
, mainly due to the classic signs of uncoordinated and clumsy behavior and altered postural balance
14
. Cortical brain
areas also seem to be involved in the etiology of DCD deficits. Children with DCD have impaired anticipatory postural adjustments,
interfering in the production of coordinated movements secondary to poor neuromuscular timing
15
, which results in slowing down task
execution
16
. The primary motor cortex (M1) plays a crucial role in impaired anticipatory postural adjustments and voluntary motor control
in DCD. In this context, neuromodulatory strategies targeting cerebellar and cortical motor areas may be useful for improving motor
control deficits in children with DCD.
Transcranial direct current stimulation (tDCS) is a low-cost, easy-to-manipulate, noninvasive brain stimulation technique that
induces regional changes in cortical excitability dependent on current electric intensity, time of application, and electrode montages. In
general, stimulation by direct current through an anode increases cortical excitability, while cathodal stimulation decreases it
17,18
,
promoting a neural modulation
19
. The safe use of tDCS in children is well established, with the absence of significant adverse effects and
good tolerance reported in both clinical trials
20
and computational models
21
.
The tDCS technique has been proven to be a very effective tool in motor rehabilitation situations
22
, with positive effects on the
postural balance of children with spastic
23,24
and ataxic cerebral palsy
25
. In children with DCD, preliminary studies using the M1
26
and
cerebellar anodal tDCS
27
did not improve the learning or execution of fine motor tasks. Nevertheless, the hypothesis of the positive
effects of the neuromodulation of the M1 and the cerebellum on postural balance had yet to be tested. Physiological responses to
noninvasive neuromodulation in healthy children also had yet to be described. Analyzing the effect of different tDCS montages on static
posture oscillation patterns will provide a better comprehension of the neural basis of the deficits of children with DCD, possibly revealing
a new technique for the motor rehabilitation of these children.
The primary objective of this study will be to investigate the impact of brain facilitation/inhibition on postural balance in children
with DCD and children with typical development (TD). Our secondary objective will be to investigate whether there are significant
differences between primary motor cortex facilitation, cerebellar facilitation, and cerebellar inhibition in the postural balance of children
with DCD or healthy controls. We hypothesized that tDCS would improve postural balance in children with DCD and those with TD.
Comparing all the montages, anodal CE-tDCS may be the most effective way to reduce the sway rates of children with DCD, like that
observed in ataxic children
25
, based on studies that attributed DCD-children to cerebellar dysfunction.
METHODS
Study protocol
A randomized, double-blind, placebo-controlled crossover study will be conducted to evaluate the impact of brain electrical
stimulation on postural balance and TD in children with DCD. This study was approved by the research ethics committee of the Faculty of
Medicine of the University of São Paulo (CAAE: 39398214.4.0000.0065) and registered at clinicaltrials.gov (NCT03892083), entitled “The
effect of tDCS on the postural control of children with DCD”.
Participants will be randomized to receive a single session of four different tDCS protocols: (1) cerebellar anodal stimulation
(anodal tDCS-CE), (2) cerebellar cathodal stimulation (cathodal tDCS-CE), (3) M1 anodal stimulation (tDCS-M1), and (4) sham tDCS.
Randomization of the sequence of tDCS sessions for all children will be performed by an independent researcher via a randomized
generating program (www.randomization.com), using sequential numbers from 1 to 21 (21 children with DCD and 21 children with TD)
and including them in sealed opaque envelopes. The “blinding” of the evaluator and the children will be maintained until the end of the
research and data processing.
Study Population, Recruitment, and Inclusion
Participants will be recruited from municipal schools and speech therapy and physiotherapy clinics at public universities in São
Paulo, Brazil. Children who meet the following criteria will be eligible: (1) children of both sexes, aged between 7 years and 10 years 11
months, (2) children with indicative of DCD according to the Diagnostic and Statistical Manual of Mental Disorders - 5th edition (DSM -5),
with percentile ≤ 5 both in total score as well as in balance domain of the MABC-2
28,29
(DCD group), (3) by the score indicated for each
age by the Developmental Coordination Disorder Questionnaire DCDQ-Brazil
30
or by reports of parents or teachers matching DSM-5
criterion B and (4) children without DCD, matched in age and gender, showing a percentile of ≥ 50 in the MABC-2 Motor Assessment
Battery Balance total score and domain, without being indicative of DCD by the DCDQ-Brazil (TD group) or report of parents/teachers
with no motor/coordination complaints.
Children will be excluded from the survey under the following conditions: (1) signs of excessive discomfort during or after any
procedures or sessions involved in the research, (2) previous tDCS treatment, (3) visual or hearing impairments, heart disease,
rheumatologic or orthopedic dysfunctions, neurological or psychiatric problems (except ADHD and language/speech disorders as the
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most comorbid disorders with DCD), and (4) tDCS contraindications such as skin problems, the presence of metal plates on the head, or
a history of epilepsy.
The sample size was estimated by the analysis of power
31
from our pilot study data involving four children with DCD. Mean
differences between the effects of anodal and sham anodal cerebellar tDCS on the center of pressure (COP) oscillation area variable
were incorporated into the G*power 3 software, with α < 0.05 and a test power of 80%. The children performed the task of remaining in
bipodal support, with eyes closed and feet over foam, when data of pre-tDCS was MD = 0.74 ± 5.31 and post-tDCS was MD = -3.85 ±
6.24. The effect size of 0.78 was calculated using the error probability of type 1 (α) and type 2 (β) (0.05, and 0.02, respectively).
However, assuming a more conservative estimate of the effect size, we will consider 0.39 or 15% of the variance explained by the tDCS
effect. According to the data from the sample calculation, a minimum of 21 children with DCD is required.
Informed Consent Procedure
To participate in this study, a child has to consent in an assent form (AF) and be accepted by parents and/or guardians for
participation by signing an informed consent form (ICF).
Study Intervention
Both children’s groups (DCD and TD) will receive a single session of four brain electrical stimulation protocols, with a minimum
interval of seven days
32
and a maximum of 15 days between each intervention, to avoid the cumulative effect of tDCS and minimize the
learning effect without interfering with a child’s overall physiological development. In each session, the following sequence of procedures
will take place: an initial posturography evaluation performed by two researchers; a tDCS session applied in a closed and quiet place by
the lead researcher (M.C.D.S.M.), and finally, the child will return for a balance reevaluation (Figure 1).
Figure 1. Flowchart of the study. DCDQ: Developmental coordination disorder questionnaire; MABC - 2: Movement battery assessment for children - Second Edition. AF:
Assent Form, ICF: Informed Consent Form; DCD: Developmental coordination disorder; TD: Typical development; tDCS: Transcranial direct current stimulation. *tDCS
intervention will be applied in a random order of the following protocols: tDCS-M1: anodal tDCS over the primary motor cortex; tDCS-CEa: anodal cerebellar tDCS; tDCS-
CEc: cathodal cerebellar tDCS; sham tDCS.
Postural Balance Assessment
The postural balance will be assessed on a force platform immediately before and after the tDCS (anodal tDCS-CE, cathodal
tDCS-CE, tDCS-M1, or sham tDCS). The evaluation of static balance involved four conditions of progressive difficulty, triggered by the