Investigating sensory perception at the lumbopelvic region in a healthy, pain-free cohort: CSP2023: 498. Volume 123, Supplement 1, E260

Purpose: Chronic low back pain affects approximately 1 in 6 people (16.9%) in England. It is associated with body perception alterations, with people reporting experiencing their back to be expanded or shrunken. The two-point estimation (TPE) task is one frequently used method for the assessment of body perception disturbance, where the distance between two points is estimated. All previous research on the TPE has used two points orientated horizontally. However, the perceived distance between two touches is anisotropic in many body regions, with touches orientated across the body width perceived larger than along body length. However, two studies investigating the lower thoracic spine have shown a reversed anisotropy. Given the high prevalence of low back pain and presence of body perception disturbances, there is a need to understand if such an anisotropy exists at the lumbopelvic region. Results will act as a foundation for future research into the body perception of those experiencing chronic pain at the lumbopelvic region, providing evidence of the somatosensory organisation at the area.

Objective: To determine if TDA is present at the lumbopelvic region, and if this differs to a known anisotropy at the hand.

Methods: A repeated measures experiment using the TPE task was conducted with eight participants. Participants received two rounds of testing at the hand, lumbar and pelvic girdle. Testing consisted of six horizontal and six vertical applications per stimuli distance, totalling 36 stimuli applications per round, per body area. Estimations were given to the nearest millimetre, or 0cm if only one point was distinguished. Analysis was conducted using a two-way analysis of variance (ANOVA), a 3x2 factorial ANOVA and a post-hoc Tukey test, to test the overall hypothesis that TDA in the lumbopelvic region would be opposite of that in the hand.

Results: Analyses highlighted the perceived stimuli size was significantly smaller when applied horizontally compared to vertically for the lumbar region (-75.9% vs -52.7%; p <0.001) and pelvic girdle (-83.5% vs -53.6%; p <0.001) when compared to the hand. Therefore, results revealed an anisotropy is present at the lumbopelvic region; opposite to that of the hand.

Conclusion(s): Results showed a healthy population overestimated horizontal distances compared to vertical distances at the hand, whereas the lumbopelvic region identified horizontal distances were underestimated compared to vertical; highlighting a reversal of anisotropy. This is the first study to demonstrate the presence of a TDA at the lumbopelvic region.

Impact: This study was the first to investigate TDA at the lumbopelvic region, demonstrating a reversal of the phenomenon seen at many other body regions. It contributes to the understanding of body perception and will in future aid the understanding of body perception disturbances in lumbopelvic pain disorders. Future research should investigate these anisotropies in a population experiencing lumbopelvic pain.