Differences in head orientation between girls with and girls without idiopathic scoliosis in conditions with sensory conflicts

Eijgelaar, P.N. (2011) Differences in head orientation between girls with and girls without idiopathic scoliosis in conditions with sensory conflicts. thesis, Human Movement Sciences.

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Abstract

The possibility is examined of whether integration of the three perceptual systems -visual, vestibular and somatosensory- for estimation of verticality and head position, plays a part in the development of idiopathic scoliosis (IS). The hypothesis is that patients with IS form 1 their representations of head and body position related to gravity differently than individuals without scoliosis do. 25 girls with IS and 16 girls without scoliosis (NS) between the age of 10 to 16 were measured in four experimental conditions. Subjects stand on a rolltilting platform, which tilts 14 degrees to the left and 14 degrees to right, while their head angles are recorded. Visual information is either manipulated by using a box with vertical and horizontal framework to surround the subject (condition 1 and 2), or present and correct (condition 3), or absent (condition 4). Results are discussed in the light of the Bayesian decision theory, which states that for correct motor behaviour, one makes an estimation of states of the world and of the body based on the 'prior' probability (an assumption of state based on prior experiences) combined with perceptual information. When the sensory inputs are not in conflict with each other, the prior and the vestibular and somatosensory systems are most important in estimation of verticality. When the subject is tilted at small angles, the prior is most important, and as the tilt angles increase and the vestibular and proprioceptive cues are stronger, but are still in agreement with each other, reweighing occurs and the contributions of these sensory systems become greater. When sensory inputs are in conflict with each other, differences between the NS and the IS are greater, especially for different age categories. In this situation vision appears to become the most important input, especially for the girls with IS. An exception to this are the 13-14-yearolds with IS, who show a smaller role played by the visual system. The differences in reliance on the sensory systems between the groups with and without scoliosis suggests that the central nervous systems of girls with scoliosis have a different way of determining how reliable a sensory system is and which system is most reliable. This supports our hypothesis. The differences between the groups for different age categories, suggest that the process of development of the sensory integration for estimation of verticality also appears to be different for girls with scoliosis than for girls without scoliosis.

Item Type:	Thesis (Thesis)
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:40
Last Modified:	25 Jun 2020 10:40
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/204

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