Previous research and clinical observations have indicated that children with autism spectrum disorders (ASD) often exhibit motor impairments and gait abnormalities. Among these, idiopathic toe-walking (ITW) appears to occur at a particularly high rate. However, few studies have specifically examined the incidence, prevalence, or associated features of ITW in this population. Idiopathic toe-walking is generally defined as toe-walking that persists for longer than 3 months after independent walking begins—with all other physiological and anatomical causes being excluded.
The primary purpose of this study was to examine the prevalence of ITW among children with varying ASD subtypes. Our second objective was to determine whether toe-walking is correlated with differences in specific clinical features and measures of severity among children with ASD.
Retrospective data were examined from 829 children and adolescents with ASD seen in an outpatient autism specialty clinic between 1994 and 2010. Participants ranged in age from 3 to 20 (average age of 8.0 years). Regarding diagnosis, 57.5% met diagnostic criteria for Autistic Disorder, 27.6% for PDD NOS, and 14.8% for Asperger's Syndrome. Toe-walking was determined from a parent-report history questionnaire completed at intake. Possible non-idiopathic causes of toe-walking were excluded by excluding children with abnormal MRIs or extreme prematurity. For a subset of the population, additional measures of associated clinical features were examined. Measures included Full Scale IQ (n=257), Social Communication Questionnaire (SCQ) (n=150), Vineland Adaptive Behavior Scale – 2nd Edition Communication Subscale (n=228), Child Behavior Checklist Externalizing (CBCL) Symptoms subscale (n=209), and Short Sensory Profile (SSP) (n=189).
Results indicated that prevalence of idiopathic toe-walking was high (40.5%). Autistic Disorder had the highest overall prevalence (45.1%), with a lower prevalence among those with Asperger's Syndrome (30.1%). Differences between children with and without a history of ITW were examined using ANCOVA analyses controlling for age. Children with a history of ITW had significantly higher scores on the SCQ (p < .01) and CBCL Externalizing Scale (p < .05) and significantly lower IQ (p < .01) and SSP scores (p < .01). No significant differences were found on the Vineland Communication Scale. Logistic regression analysis was used to examine subscale scores of the SSP, and results indicated that the “under responsiveness/sensation seeking” category was a statistically significant predictor of history of ITW.
The results of the current study show that a history of idiopathic toe-walking is very prevalent in children with ASD. ITW is associated with greater autism severity, and those with a history of ITW had lower cognitive functioning, greater difficulty with behavioral regulation, and more impaired sensory processing. These findings indicate that ITW may be a biomarker of poorer outcomes for children with ASD. Future studies using prospective, longitudinal designs and standardized measures of motor impairment would be helpful to more fully investigate these issues.
See more of: Epidemiology
See more of: Prevalence, Risk factors & Intervention