Prevalence of motor impairment in autism spectrum disorders

Autism spectrum disorders (ASD) are manifest as impairments in social interaction, language and speech development, and the appearance of repetitive behaviors with restricted interests. Motor impairments in individuals with ASD have been categorized as "associated symptoms". The objective of this study was to describe the prevalence of motor deficits in ASD. Specifically, using retrospective clinical record review, we report the prevalence of hypotonia, motor apraxia, reduced ankle mobility, history of gross motor delay, and toe-walking, as well as the improvement of these symptoms with age, in a cohort of 154 children with ASD. The possible association of motor deficits with epilepsy or developmental regression was also assessed. To address whether the motor deficits in children with ASD were properly identified and treated, we evaluated whether the children with the motor deficits were more likely to receive physical and/or occupational therapies as compared to the children with ASD who did not show motor deficits. Hypotonia was the most common motor symptom in our ASD cohort (51%) and this appeared to improve over time, as suggested by the significant reduction in prevalence in older children (p=0.002). Likewise, motor apraxia (34%) showed a tendency to be more prevalent among younger children as compared with older children (p=0.06). Historical intermittent toe-walking was found in 19% of children while reduced ankle mobility was a rare occurrence. Gross motor delay was reported in 9% of children, all of whom gained motor independence by the time of examination. Except for gross motor delay, ASD children with fine motor deficits were not more likely to receive interventional services, as compared with ASD children without the motor deficits. The results suggest that fine motor control and programming deficits are common co-occurrence of children with ASD in this cohort. The reduced prevalence of these motor deficits in older children suggests improvement over time, whether through natural progression, results of interventional therapy, or the combination of the two. However, ASD children with the motor deficits were not more likely to receive service than those without the motor deficits.