Quantitative assessment of tip-toe behavior in individuals with autism spectrum disorder and intellectual disability: A cross-sectional study

The term "toe walking" describes walking on the toes with a lack of heel strike upon initiation of the stance phase of gait. In individuals with autism spectrum disorder (ASD), this phenomenon, or "tip-toe behavior" (TTB), can be present in a substantial proportion of subjects even during standing. In this study, we investigated TTB in 50 persons with ASD (age range 4-26 years). We evaluated TTB through an observational/report-based assessment protocol. Subsequently, we employed a new structured video-based coding protocol based on standardized video recordings, focusing on static and dynamic conditions. Finally, the findings of the two protocols were compared. Twenty-four subjects with TTB were identified and classified according to three functional groups: TTB1, present only during running (6 subjects); TTB2, present during walking and running (11 subjects); and TTB3, present during standing, walking, and running (7 subjects). Moreover, we found that TTB3 subjects exhibited a significantly higher quantity of TTB compared with subjects in the TTB1 and TTB2 groups during both standing and walking tests. Additionally, a high quantity of TTB in the static test was found to be related to a high quantity of TTB in the dynamic test. Variables such as age, autism severity, intellectual disability, and gender were not significantly associated with the mean percent of TTB both in static and dynamic tests in multivariate analysis. This structured video-based coding approach appears feasible and useful for assessing TTB in individuals with ASD and it has the potential to provide insights into TTB trajectories and aid in designing possible interventions. Toe walking can be observed during the gait of individuals with autism spectrum disorder (ASD). As this motor behavior can also be present during standing, we used the term tip-toe behavior (TTB). TTB is an understudied sensorimotor phenomenon in ASD, and there is a lack of quantitative measures of TTB in ASD. This study proposed two standardized clinical tests to quantify TTB during walking and standing. These TTB measures could aid in understanding the natural history of TTB and in making decisions about TTB interventions.