Assessing muscle tone is an essential component of the diagnosis, prognosis, and treatment planning of developmental disabilities (DD) in children and is of great help in developing clinical diagnosis patterns. The purpose of this study was to investigate intra-rater and inter-rater reliability using the myotonometer, which is an assessment tool to measure muscle tone in children with DD. This study included 26 children diagnosed with DD. Two physical therapists measured the children’s muscle tone using a myotonometer. For all the muscles measured, reliability was determined using the intra-class correlation coefficient (ICC), the standard measurement error (SEM), and the minimal detectable change (MDC). The intra-rater reliability for all muscles was excellent (ICC = 0.75~0.78), except for the biceps brachii (ICC = 0.68). The inter-rater reliability was also excellent for all muscles (ICC = 0.75~0.95), and the SEM and MDC showed small measurement errors. Therefore, the intra-rater and inter-rater reliability of measurements by the myotonometer was found to be good or excellent. This suggests that the myotonometer is a tool that can objectively assess muscle tone, and it can be utilized in clinical practice to quickly and conveniently measure muscle tone in children with DD.

Background: Good trunk control is essential for higher developmental stages as the trunk is activated first when movement occurs, providing stability for the head and extremities. Purpose: To determine if neurodevelopmental treatment-based trunk control exercise (NDT-TCE) is effective in improving gross motor function and trunk control in children with developmental disabilities (DD). Materials and Methods: Twenty children with developmental disabilities were randomly assigned to the NDT-TCE (12 children) and control (8 children) groups. Results: After the intervention; the NDT-TCE group showed improvement in GMFM (Gross Motor Function Measure; except for the GMFM-E dimension) and SATCo scores. The control group showed improvement in GMFM-A; B; C; and total scores; as well as static and active control of SATCo. The NDT-TCE group had a significant improvement in the GMFM B dimension and total score compared to the control group. The NDT-TCE group showed a significant improvement in static and active control of SATCo compared to the control group, but there was no significant difference in reactive control. Conclusions: The NDT-TCE intervention specifically improved GMFM-B and trunk control scores. Therefore, NDT-TCE can be applied as a trunk-focused intervention for children with DD who have difficulty controlling their trunk.