title: A new tool to assess tactile acuity; Development &amp; its application towards understanding body perception
Creators: name: Olthof, Nickile A
Publisher: name: Griffith University
Year: 2022
Subjects: subject: chronic pain
subject: body perception
subject: tactile acuity
subject: clinical practice

description: Despite modern medicine, chronic pain remains one of the major health problems of our time. Adding to the complexity of chronic pain is an array of observable nervous system adaptations, convoluting the normally exclusive relationship between pain and the body’s physical state. Several theoretical models and neuroscientific findings suggest that reduced precision in somatosensory processing is implicated in abnormal (painful and non-painful) body-related perception. However, clinical tools designed to quantify somatosensory (im)precision are lacking. In response to this need, this thesis aimed to develop a new tool—the Imprint Tactile Acuity Device—specifically designed to improve assessment (and training) of tactile acuity, a clinical marker of somatosensory (im)precision. Moreover, it aimed to interrogate the clinimetric properties of its scores to inform further development (thesis Part A) and aimed to begin understanding its suitability for clinical practice and body perception research (thesis Part B). Chapter 1 and 2 set the scene for thesis Part A, by outlining the theoretical background that links chronic pain to vibrotactile localisation performance, and by detailing the technical aspects of the first prototype of the Device. Chapters 3-5 then describe an iterative process of testing the device, revising the prototype, and then subjecting it to further scrutiny. Across these Chapters, the thesis details the device’s response patterns, intra-rater reliability, inter-rater reliability, measurement error, internal consistency, construct validity, and floor and ceiling effects. Additionally, interpretability is promoted by interrogating the effects of age, sex, and anthropometry on test scores. Chapter 6 sets the scene for thesis Part B, by describing how somatosensory imprecision may contribute to altered body perception, with an emphasis on potential links between imprecision and a tendency toward increased perception of bodily threat. Chapters 7-8 then leverage the device to investigate these links. Specifically, Chapter 7 compares tactile localisation performance to other body-related sensory processing indicators including tactile two-point discrimination thresholds and left/right judgement (i.e., visuomotor) performance. Further, this chapter also investigates the relationships between scores (for all three indicators) and self-reported body perceptions, such as awareness and unpleasantness of body sensations. Chapter 8 then utilises the Imprint Tactile Acuity device to investigate the relationship between perceptions of inner and outer body sensations. II Discussed in Chapter 9, results from Part A suggest that the final iTAD model provides a reliable and extensive assessment of absolute and relative vibrotactile localisation performance at the neck. Further, the iTAD scores have clear face validity and our findings provide some support for their construct validity. However, validity, responsiveness, and interpretability require further examination before clinical application can be recommended. Part B of this thesis suggests that iTAD scores relate to existing sensory performance assessments that are known to be affected in chronic pain. Remarkably, scores also appear to be related to self-reported body perception domains which are not typically linked with tactile function. Specifically, lower iTAD scores appear related to increased awareness and unpleasantness of bodily sensation. This finding highlights the potential of the iTAD in progressing the science of normal and abnormal body perception. While the process of understanding and developing the iTAD in not complete, the device appears to represent a promising new tool to assess, and train, tactile acuity.