The Hardness of Standing Support Surfaces Influences Tip-Toe Behavior of Autistic Children: Evidence from a Pilot Study

Background: As demonstrated in a previous study, 32% of autistic children observed in our Institute walk on their tiptoes (tiptoe behavior-TTB). TTB may occur in three modalities: class 1(TTB in standing, walking and running); class 2 (TTB in walking and running) and class 3 (TTB only during running). Thus far, the literature has yet to publish a standardized clinical method of assessment to "quantify" TTB during standing or walking.

Objectives: The aims of this pilot study are: 1) to propose a protocol to quantify TTB and 2) to assess whether the hardness of standing support surfaces influences motor behavior in children with ASD

Methods: Seven autistic children with TTB (6 males), age range from 7.1 to 16.4 years diagnosed according to the criteria of DSM V were admitted to this study. All subjects presented an ankle dorsiflexion range of motion wider than 90°. Video recordings were taken  during a static task (playing in front of a playing table for 3 minutes) and during a dynamic task (transporting an object from the playing table  to a therapist situated 2 meters away and back again for 15 times) over a hard floor surface. Each task was repeated on three different days. The three repeats were repeated again on a soft floor surface (foam mat). An independent therapist not involved in tests operation assessed the videos of the static task trials by calculating the time spent on full foot support versus on tiptoes. The videos of the dynamic task trials count the number of times the child was able to walk the full length with all steps on full foot support versus toe walking.

Results: On the hard floor surface, during the static tests, the subjects stayed on tiptoes for an average of 45.5/180 sec. During the dynamic tests the children toe walked an average of 23.6/30 times of the measured lengths. On the soft floor surface, during the static trials, the children used tip toe posture for an average of 24.6/180 sec. Meanwhile, during the dynamic trials they tiptoed an average of  11.2/30 times of the measured lengths. The p value of the differences were 0.11 for static tests and 0.008 for dynamic tests. The repeat observation values were consistent and reproducible. 

Conclusions:   The proposed evaluation protocol seems to be a useful tool to monitor TTB behavior. Footing on soft surfaces induces an increase in the time spent on non TTB during static and dynamic tasks. This finding suggests that TW is a reflection of a sensory integration dysfunction or of a vestibular derangement. Further evaluation is needed to clarify the potential pathophysiological implications of this phenomenon.