Abstract
We sincerely appreciate the reader’s comment on our recent publication that highlights one of the key therapeutic options, Static Weight Bearing (SWB), to improve hand functions in children with Unilateral cerebral palsy (UCP).
Our study has considered the age range of 2-5 years (the early age) of children with UCP. This age range is crucial because children start using their hands for activities like a). picking up a toy with the right hand and then picking up the matching toy with the left hand, b). dropping the toys into a stacking cup, c). pouring out the contents from the cup, etc. At this age range, children also start to experience and develop various types of power grasp, radial digital grasp, and pincer grasp. All these activities require a quality of active ROM in the affected digit(s) (Ho, 2010) for accurate, coordinated movement of the muscles of the fingers and hands for environmental exploration and learning. (Duncan et al., 2020)
This age range (2-5 years) is crucial because fine motor deficits will affect daily functioning and school success, as successful participation requires fine motor proficiency. (Duncan et al., 2020)
We also know that brain damage removes a trophic influence on muscle, which is essential for muscle maturation, leading to regression in muscle maturation in children with CP. (F, 1961) Hence less skeletal muscle mass in children with CP as compared to typically developing (TD). These changes start contributing to passive stiffness in the muscles as early as 3 years of age. The biochemical studies of muscles in CP have shown an increased content of intramuscular collagen, with an increased amount of connective tissue around fiber bundles, i.e., a thickening of the perimysial extracellular matrix. The significant collagen deposition in the perimysium potentially causes increased resistance to passive stretch. These changes contribute to weak, thin, and stiff muscles in children with CP compared to TD. (Von Walden et al., 2017)
We also know that spasticity is the exaggeration of stretch reflexes, resulting in the velocity-dependent increase in resistance of a passively stretched muscle or muscle group. (Trompetto et al., 2014) In view of this, the therapy option must constrain the movement variations to inhibit the tone and bring a desired functional change collectively. Therefore, the SWB as a therapy option was studied in this population.
We also consciously selected the children with UCP with Manual Ability Classification System (MACS) levels IV and V to examine the effectiveness of SWB to identify if the above-reported muscle transformation is reversible or not, because children in the age range of 2-5 years are still at a malleable age where morphological transformation is a possibility.
Regarding the use of Modified Constraint-Induced Movement Therapy (m-CIMT) in children with unilateral cerebral palsy (UCP) with Manual Ability Classification System (MACS) levels IV and V, I consent with the reader’s view.
The study’s two-week intervention period without any follow-up assessment may be insufficient to produce durable neuroplastic changes in children with severe motor impairments. Paediatric neurorehabilitation literature generally supports longer duration interventions with booster sessions and structured follow-up (Yu et al., 2018). Without long-term data, it is difficult to know if improvements are sustainable or just short-term effects from task familiarity.
In view of the above point, my answer is that if two weeks of intervention can bring 37.67% changes for the grasping and 14.11% for the VMI following SWB therapy compared to the 12.78% and 4.88% following m-CIMT, respectively, so if therapy duration is prolonged then changes can be exponential even if we factor the plateau state after any intervention in children with UCP. I fully agree with the opinion that a longer duration intervention is the key to greater success in children with CP.
The follow-up was not reported in the above study. However, we are still following these children, and many of them have shown transformation to MACS level III from MACS level V, and those who were in MACS level IV have transformed to MACS level II. It means that I-II level upward progression is a reality. But none of them acquired MACS level I. This will be reported later.
Second, m-CIMT is primarily validated for children with mild to moderate impairment (MACS I–III). The authors applied this protocol to children with severe impairment (MACS IV–V) without clarifying if any adaptations were made for feasibility, engagement, or safety.
I agree that we didn’t make any adaptations.
The literature lacks consensus on m-CIMT’s suitability for this subgroup, and its unmodified use raises ethical and clinical concerns. (Hoare et al., 2019)
Studies on m-CIMT have varied protocols for the m-CIMT. We reviewed many studies before deciding on the m-CIMT and collectively decided to base for m-CIMT intervention protocol on the findings of Sakzewski et al. (2014).
Third, while the use of the Fine Motor domain of the Peabody Developmental Motor Scales-2 (FM_PDMS-2) is understandable, it does not capture spontaneous use, bimanual coordination, or real-world hand function, particularly critical in MACS IV–V populations. Tools such as the Assisting Hand Assessment (AHA) and the Quality of Upper Extremity Skills Test (QUEST) are better aligned with the ICF framework and offer greater ecological validity (Novak et al., 2013).
Future studies can re-evaluate the findings using the above-recommended outcome measures.
Furthermore, the omission of standardized scores (SS), effect sizes, and confidence intervals (CI) in reporting limits the clinical interpretability of the findings.
SS scores in PDMS-2 can be analyzed only if we do a normative study. Since we used FM-PDMS-2 as an outcome measure, raw scores were used to interpret the scores.
The effect size was analysed through the percentage change. Future study statistics presentation through CI can be considered.
Lastly, the study permitted therapist-assisted elbow extension during SWB without detailing how this assistance was standardized. Variability in manual facilitation may impact the intervention’s fidelity and reproducibility.
Since children with MACS Level IV and V were only selected for this study, hence if any children were unable to maintain a full elbow extension position, the same was incorporated manually by the investigator (supporting the elbow to the limit of their initiation till they were able to maintain the same by themselves).
Additionally, although a home program was mentioned, there was no report on adherence, frequency, or duration. This is an important omission, considering that home-based reinforcement often plays a pivotal role in paediatric therapy outcomes (Sakzewski et al., 2014)
Each position was demonstrated to the parents until they learned to perform it correctly (to be practiced at home). They were reviewed during the follow-up visit (twice in a week), but were not mentioned in the original article to assess the adherence and frequency.
In conclusion, while the study provides promising insights into the comparative potential of SWB and m-CIMT, particularly in a relatively understudied population, several design elements limit its broader clinical applicability. Future studies should explicitly tailor interventions for severely impaired populations, employ functionally relevant outcome measures, and incorporate follow-up to evaluate sustained impact. Furthermore, rigorous standardization and monitoring of both therapist-delivered and home-based components will enhance the robustness and reproducibility of the findings.
Subsequent to these findings, we have made newer and better changes to provide a stable and comfortable prone lying position to ensure equal weight bearing on both UL (through modified scooter board with wheels- lock open and lock release option), with the option of static and dynamic variability without much manual variations. These changes are bringing us more promising results.
Future studies must have more rigorous standardization and longer duration interventions to see the lasting effect.
We thank the authors for their contributions and hope these considerations inform us of future work in this important area of paediatric neurorehabilitation.
We will surely report on our findings. Thank you so much for the valuable opinion.