A functional hierarchy of semicircular canal and otolith contributions to early motor development

The vestibular system is critical for early motor development, yet the respective roles of its two subsystems, the semicircular canals and otolith organs, remain poorly defined. Here we analyse 411 children with comprehensive vestibular assessment to determine whether a functional hierarchy underlies their contributions to the acquisition of four postural and motor milestones during the first two years of life. Using Type III ANOVA to account for the frequent co-occurrence of canal and otolith dysfunction, we show that canal areflexia is associated with a 7.0-month delay in independent walking, three times larger than the otolith effect. Canal function is the only component reaching significance after Bonferroni correction across four milestones. Canal function alone predicts walking delay (>18 months) with an area under the curve of 0.83. Canal areflexia carries a positive predictive value of 80.2% for walking delay, while normal canal function effectively rules out a walking delay of vestibular origin (negative predictive value 93.5%). These findings establish a functional hierarchy of vestibular contributions to motor development and identify canal function as a powerful developmental biomarker.