Assessment of presentation patterns, clinical severity, and sensorial mechanism of tip-toe behavior in severe ASD subjects with intellectual disability: A cohort observational study.

We assessed presentation patterns and characteristics of tip-toe behavior (TTB), more commonly known as toe walking, in a cohort of severe autism spectrum disorder (ASD) subjects with intellectual disability in two studies. The first study included 69 consecutive ASD subjects (57 males, mean age = 14 years-3.7 SD) under observation at our institute. A therapist assessed the presence of TTB during standing, walking, and running through direct observation and an interview with the subjects main caregiver. The prevalence of TTB was 32%. We found three clinical presentation patterns of TTB: (1) present when standing, walking and running (45.5%), (2) present when walking and running (18.4%), or (3) present only when running (36.4%). TTB subjects were more frequently nonverbal than those without TTB (72.7% vs. 44.6%-P = 0.03). On the other hand, no significant difference in ASD severity according to the ADOS scale was found between TTB and non-TTB subjects. In the second study, carried out in a subgroup of 14 ASD subjects (7 TTB and 7 non-TTB), we evidenced that a soft floor surface (foam mats) made a substantial difference in reducing the TTB phenomenon. TTB is frequently present in ASD individuals and may occur in three mutually exclusive modalities, which ultimately defines what is commonly known as toe walking. The presence of TTB seems correlated to the severity of language delay. Foot contact on soft surfaces reduces TTB both during static and/or dynamic tasks. Further evaluation is needed to clarify the potential pathophysiological implications of this phenomenon. Autism Res 2017, 10: 1547-1557.