Abstract: Background 
Effective sensorimotor postural control to maintain an upright stance is a crucial component for daily functional activity. A sound postural control system underlines a spatiotemporal integration of sensory and motor and systems. Evidence suggests that Autism Spectrum Disorder (ASD) population present postural control disruption. 
Aim 
A cross-sectional study was carried out aimed at investigating sensorimotor contributions to postural control and behavior in children and adolescents with ASD compared to typically developing (TP) peers through the Physiological Profile Assessment – long form (PPA). 
Methods 
ASD and TD age-matched TD subjects were consecutively recruited in a northern metropolitan city in Italy. Participants were assessed with the PPA by residents in physical medicine and rehabilitation clinician. PPA includes 17 tests: Visual acuity with high- and low-contrast, Edge contrast sensitivity, Depth perception, Touch sensitivity, Tactile lower limb Proprioception, Simple reaction time of hand and foot, Isometric knee extensor and flexor muscle strength, Ankle isometric dorsiflexion strength, Postural sway with eyes open and closed, first on a firm surface, then on a medium density foam rubber mattress, Maximum balance range and Coordinated stability. 
Percentiles of each PPA subset were computed from the TD peers. PPA performances of ASD participants were compared to the TD percentiles. 
Results 
Eighteen ASD individuals’ (16/2 male/female), mean age (SD) 12.4 (3.7) years, were included. Their intellectual disability ranged from mild (n=5), moderate (n=11) to severe (n=2). In the TD age-matched group, 135 subjects (100/35 male/female) were enrolled of the following ages: 6 years (n=11), 8 years (n=16), 11 years (n=21), 12 years (n=12), 13 years (n=14), 14 years (n=24), 16 years (n=18) and 18 years (n=19). ASD individuals’ scores were above the 90th percentile, i.e., poor performance, in most motor, sensory, and balance subtests. In particular: half of our sample of children and adolescents with ASD performed poorly in the tests of visual acuity, particularly when the lighting conditions were poor (low contrast). Tactile sensitivity was inferior in our ASD population, with three-quarters of participants scoring above the 90th percentile and one performing below the 10th percentile. One-quarter of ASD participants performed poorly in the test of proprioception. More than half of our participants performed above the 90th percentile in the tests of simple reaction time at the finger and the foot. Over a quarter of the children and adolescents with ASD presented muscle weakness in at least one of the three lower limb muscle groups we investigated. Performance in the majority of PPA significantly improved with older age in the TD group but not in the ASD group. 
Conclusions 
These findings suggest how poor balance performance may be due to sensorimotor deficiencies integration in ASD children and adolescents. The investigation of the mechanisms underlying impaired age-related maturation of sensorimotor systems should drive the research agenda of the scientific community. 

Notes:

(1) School of Medicine and Surgery, University of Milan-Bicocca, Milano, Italy 
(2) Autism Research Unit, Villa Santa Maria Foundation, Tavernerio, Italy
(3) Ospedale "G. Salvini" - Garbagnate MIlanese, ASST Rhodense, Garbagnate MIlanese, Italy
(4) School of Medicine and Surgery, University of Milan-Bicocca, MIlano, Italy
(5) School of Physical and Occupational Therapy, McGill University, Montreal, QC, Canada
(6) School of Medicine and Surgery, University of Milan–Bicocca, Milano, Italy
(7) Neuroscience Research Australia and School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia