Constraint-induced movement therapy (CIMT) is one of the best studied treatments for hemiplegic cerebral palsy (CP), which is one of the most common types of CP and is estimated to affect 1 per every 1000 children.1,2  Therefore, optimizing the delivery of and access to CIMT has the potential for a broad-reaching and significant impact in pediatric care.

CIMT is composed of 2 key components: (1) restraint of the unaffected upper limb, and (2) an intensive structured therapy program. The pathophysiologic rationale behind CIMT is that developmental disregard of the weaker arm can further limit its function. Multiple small studies in children using functional MRI have suggested that CIMT can lead to enlargement of the injured sensorimotor cortex, which is associated with improvement in motor skills in the affected limb in children with hemiplegic CP.3 

CIMT focuses primarily on improving upper-extremity use in children with hemiplegic CP, a goal with clear functional importance. Impaired use of an upper limb can restrict a child’s participation in independent activities of daily living and bimanual school tasks. The efficacy of CIMT is clearest when compared with a less intensive therapy regimen as measured by improvements in hand and finger dexterity, speed of hand and arm movements, and the ability to make isolated and independent movements of different parts of the upper limb.4  However, when compared with similar therapy dosages (ie, similar total number of therapy hours), the benefits of CIMT are less apparent.4  In a 2019 Cochrane review on CIMT for children with hemiplegic CP, it was suggested that CIMT may be more beneficial in bimanual performance and unimanual capacity than other lower-intensity upper-extremity therapies. CIMT did not appear to impact strength or muscle tone. The certainty of the evidence was graded low to very low, in part because of small sample sizes and heterogeneity in the CIMT parameters used.5 

Studies demonstrating CIMT efficacy have widely varied in the following CIMT parameters: duration and frequency of structured therapy (ie, dosage), type of restraint used (cast, mitt, sling), type of therapy program (motor learning, repetition), duration of wearing the restraint, location of therapy provided (in-home versus institution), and therapy provider (parent, therapist).6  The optimal combination of these different CIMT parameters remains unknown.4 

In this issue of Pediatrics, Ramey et al7  help address the questions of optimal CIMT dosage and CIMT restraint type. They compared the effects of 2 doses of CIMT and 2 types of restraints in children with hemiplegic CP as part of the Children with Hemiparesis Arm-and-hand Movement Project (CHAMP) study. Their control group was children with hemiplegic CP receiving only community-based therapy services (average of 4–5 hours of combined therapies per week). High-dose CIMT was defined as 3 hours per day for 5 days a week, and moderate-dose CIMT as 2.5 hours per day for 3 days a week, both over 4 weeks. The cast restraint was full-arm and worn continuously as compared with the splint restraint, which was worn only during the treatment sessions. They enrolled 118 children from 2 to 8 years of age with hemiplegic CP across 3 sites. Children had baseline, end of treatment, and 6-months posttreatment assessments that consisted of 3 practitioner-assessed outcomes and 2 caregiver-reported outcomes.8  Across all primary outcomes (both practitioner and caregiver-reported), the high-dose CIMT group had the largest improvements at both assessment time points after treatment. This includes improvements in functionally relevant outcomes like practitioner-assessed ability to use the affected arm as a “helper” in bimanual tasks and caregiver-reported frequency of use of the affected arm. Overall, the type of restraint used did not significantly change outcomes.

This study provides clear guidance on optimal dosing for CIMT in children with hemiplegic CP, suggesting that higher dosing is better. Furthermore, the lack of effect of restraint type was a potentially valuable finding with regards to the practical applicability of CIMT. Families and children with hemiplegic CP may be better able to tolerate intermittent splint wearing as opposed to a continuously worn cast. To this end, the inclusion of caregiver-reported outcomes in this study was critical to assess the real-world impact of CIMT and should be considered a standard feature for all studies like this one. Future work may formally assess caregiver and child preferences regarding restraint type and barriers to use of different restraints.

Other strengths of this study include relatively broad inclusion criteria that improve its generalizability. First, the authors included participants (40%) who had previous CIMT.6  Second, the authors include all etiologies of hemiplegic CP (including those with perinatal stroke and asymmetric periventricular leukomalacia), which supports the use of CIMT across all children with hemiplegic CP. Regarding further broadening of this study’s inclusion criteria, Children with Hemiparesis Arm-and-hand Movement Project recruited children 2 to 8 years old. It is yet unknown whether institution of CIMT in infancy when the brain is more developmentally plastic would yield better outcomes. This is currently being evaluated in a phase 3 clinical trial of infant survivors of perinatal stroke, I-ACQUIRE, by the same authors of the current study.9 

Given that the benefits of CIMT in this study were tied to dosage and not restraint type, researchers in future studies should consider comparing high-dose CIMT to an equivalent dosage of therapy without restraint. In this study, the control group (which averaged less than a third of the therapy dosage of the high-dose CIMT group) still demonstrated objective improvements at end of treatment and 6-months posttreatment on blinded outcome measures. That is, it remains unclear whether the primary benefits of CIMT are tied to therapy dosage and perhaps less so to restraint of the unaffected limb. Risks of CIMT are minimal but can include inability to tolerate the intensity of the therapy itself and the child refusing the restraint.5  In this study, no treatment-related adverse events occurred and they had remarkable compliance, given that only one child stopped treatment because of a family emergency.7 

Although the study population was heterogenous in terms of hemiplegic CP etiology and previously received therapies, it is important to note that racial diversity could have been improved in this study and many other studies on CP. In this study, 78% of participants were White, which may have been a reflection of the clinic populations at the participating study sites. However, it is particularly valuable to include different races in studies focused on CP because CP is 1.8 times more common among Black children as compared with White children1  and may be more commonly associated with motor functional impairment in Black children compared with White children.10  Additionally, study populations inclusive of people from different socioeconomic backgrounds and whose families do not primarily speak English would be useful to ensure that interventions are studied in a way that optimizes their delivery to people of all backgrounds.

Although this study provides excellent practical guidance about the value of high-dose CIMT in improving upper limb function in children with hemiplegic CP, the practical challenges to implementing this intervention (3 hours per day, 5 days per week, for 4 weeks) should be extensively explored. Barriers likely include therapist availability, cost of treatment, and availability of family support resources. The ability of a caregiver to take an extended leave from work and the availability of reliable transportation can directly impact the practical feasibility of a high-dose CIMT program. Ongoing CIMT research should include cost-benefit analyses of therapy dosages and types. Although home programs have been trialed and are ongoing, it still involves a caregiver providing the intensive therapy, a collaborative partnership between a trained therapist and the caregiver, and adequate caregiver support. This inherently involves multiple layers of medical and social resources that are not yet available in many regions around the world, including to many families in the United States.4  Therefore, future research should not just focus on the optimal parameters for CIMT but also on the optimal implementation of CIMT for all children with hemiplegic CP. Assurance that the study population includes diverse racial, ethnic, socioeconomic, and geographical representation is critical to achieve this goal.

Opinions expressed in these commentaries are those of the authors and not necessarily those of the American Academy of Pediatrics or its Committees.

FUNDING: Dr Aravamuthan receives research funding from the National Institute of Neurologic Disorders (1K08NS117850-01A1) and Stroke and reports consulting fees from Neurocrine Biosciences. Dr Smith reports no external funding. Funded by the National Institutes of Health (NIH).

COMPANION PAPER: A companion to this article can be found online at www.pediatrics.org/cgi/doi/10.1542/peds.2020-033878.

CIMT

constraint-induced movement therapy

CP

cerebral palsy

1
Van Naarden Braun
K
,
Doernberg
N
,
Schieve
L
,
Christensen
D
,
Goodman
A
,
Yeargin-Allsopp
M
.
Birth prevalence of cerebral palsy: a population-based Study
.
Pediatrics
.
2016
;
137
(
1
):
e20152872
2
Himmelmann
K
,
Hagberg
G
,
Uvebrant
P
.
The changing panorama of cerebral palsy in Sweden. X. Prevalence and origin in the birth-year period 1999–2002
.
Acta Paediatr
.
2010
;
99
(
9
):
1337
1343
3
Inguaggiato
E
,
Sgandurra
G
,
Perazza
S
,
Guzzetta
A
,
Cioni
G
.
Brain reorganization following intervention in children with congenital hemiplegia: a systematic review
.
Neural Plast
.
2013
;
2013
:
356275
4
Sakzewski
L
,
Ziviani
J
,
Boyd
RN
.
Efficacy of upper limb therapies for unilateral cerebral palsy: a meta-analysis
.
Pediatrics
.
2014
;
133
(
1
):
e175
e204
5
Hoare
BJ
,
Wallen
MA
,
Thorley
MN
,
Jackman
ML
,
Carey
LM
,
Imms
C
.
Constraint-induced movement therapy in children with unilateral cerebral palsy
.
Cochrane Database Syst Rev
.
2019
;
4
(
4
):
CD004149
6
Eliasson
AC
,
Krumlinde-Sundholm
L
,
Gordon
AM
, et al;
European network for Health Technology Assessment (EUnetHTA)
.
Guidelines for future research in constraint-induced movement therapy for children with unilateral cerebral palsy: an expert consensus
.
Dev Med Child Neurol
.
2014
;
56
(
2
):
125
137
7
Ramey
S
,
DeLuca
S
,
Stevenson
R
,
Conaway
M
,
Darragh
A
,
Lo
W
.
Constraint-induced movement therapy for cerebral palsy: a randomized trial
.
Pediatrics
.
2021
;
148
(
5
):
e2020033878
8
Ramey
SL
,
DeLuca
S
,
Stevenson
RD
,
Case-Smith
J
,
Darragh
A
,
Conaway
M
.
Children with Hemiparesis Arm and Movement Project (CHAMP): protocol for a multisite comparative efficacy trial of paediatric constraint-induced movement therapy (CIMT) testing effects of dosage and type of constraint for children with hemiparetic cerebral palsy
.
BMJ Open
.
2019
;
9
(
1
):
e023285
9
ClinicalTrials.gov
.
A Multi-site RCT of Intensive Infant Rehabilitation (I-ACQUIRE)
.
NCT03910075. 2021. Available at: https://www.clinicaltrials.gov/ct2/show/NCT03910075. Accessed August 13, 2021
10
Maenner
MJ
,
Benedict
RE
,
Arneson
CL
, et al
.
Children with cerebral palsy: racial disparities in functional limitations
.
Epidemiology
.
2012
;
23
(
1
):
35
43

Competing Interests

POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no conflicts of interest to disclose.

FINACIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.