Quantifying Sensory Function Associated With Idiopathic Toe Walking in Children

PURPOSE: The purpose of this research is to quantify sensory differences in children with idiopathic toe walking (ITW). Toe walking is characterized by the absence of heel contact during gait. Children who consistently toe walk without a medical cause after age 3 are considered idiopathic toe walkers. Long-term consequences of persistent toe walking include shortened Achilles tendon and ankle equinus, which can lead to abnormal gait patterns and posture and balance problems in adulthood.

Clinicians have suggested links between ITW and sensory processing dysfunction, but to date limited research has examined this relationship. Areas of sensory processing that potentially relate to ITW include sensory seeking behaviors, tactile defensiveness, poor proprioceptive awareness, vestibular dysfunction, and difficulties with sensory modulation.

METHOD: This poster presents preliminary results of a two-group descriptive study. Children aged 4–12 yr who toe walk are recruited from the Virginia Commonwealth University Health Systems and local clinics. Age-matched typically walking participants are recruited from the local community. Potential participants are excluded if they are unable to follow basic instructions, have had muscle lengthening surgery, or have a neuromuscular or orthopedic diagnosis for the toe walking.

Children are assessed using a set of activities to differentiate profiles of sensory dysfunction related to toe walking. Balance-related proprioceptive, vestibular, and visual processing is assessed with the Sensory Organization Test (SOT) and perturbation tests using the NeuroCom SMART Balance Master (Natus Medical, Pleasanton, CA). Using the NeuroCom data analyzer software, equilibrium scores are calculated for each SOT condition, and response latency and sway energy are calculated for perturbation tests.

Proprioceptive processing is assessed by testing ankle position sense (without vision) and force perception (matching forces without visual feedback). We compute mean errors for joint position matching and force matching in MATLAB (MathWorks, Natick, MA). Sensory modulation response to stimuli is examined by measuring skin conductance in response to repeat stimuli: textures presented to the feet (tactile) and tilt in place while seated (vestibular). Peak response to each stimulus is tracked and computed from baseline skin conductance level using custom MATLAB script.

RESULTS: Preliminary results show that children with ITW have difficulty using vestibular and vision information to correct for inaccurate somatosensory information for balance, as evident in increased falls and low equilibrium scores in the sway-referenced surface conditions in the SOT. They also have increased latency and larger response magnitude to balance perturbation. Children with ITW showed increasing skin conductance response when the vestibular stimuli were delivered repeatedly, indicating potential sensory modulation difficulty with vestibular stimuli. Children with ITW have not shown significant deficits in proprioception discrimination tasks.

CONCLUSION: Currently, no comprehensive evidence-based framework exists for the underlying causes of ITW. Our preliminary results show that children with ITW have differences in sensory processing, particularly in the area of vestibular processing. Further testing in more children with ITW will allow us to examine subtypes of sensory differences in ITW.

IMPACT STATEMENT: This research will significantly advance our understanding of ITW by providing a standardized framework for detecting and analyzing the underlying sensory differences in children who toe walk. Our research strives to better understand the causes of ITW so that more effective treatment strategies can be developed to guide earlier intervention to prevent long-term consequences of persistent toe walking.

References

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Wick, J. Y., & Zanni, G. R. (2010). Tiptoeing around gait disorders: Multiple presentations, many causes. Consultant Pharmacist, 25, 724–737. https://doi.org/10.4140/TCP.n.2010.724

Williams, C. M., Tinley, P., & Curtin, M. (2010). Idiopathic toe walking and sensory processing dysfunction. Journal of Foot and Ankle Research, 3, 16. https://doi.org/10.1186/1757-1146-3-16

Williams, C. M., Tinley, P., Curtin, M., Wakefield, S., & Nielsen, S. (2014). Is idiopathic toe walking really idiopathic? The motor skills and sensory processing abilities associated with idiopathic toe walking gait. Journal of Child Neurology, 29, 71–78. https://doi.org/10.1177/0883073812470001