Thermal Grill Illusion in Chronic Lower Back Pain: A Case-Control Study

PURPOSE: This study aimed to use thermal grill illusion (TGI), an experimental model of pain processing and central mechanisms, to evaluate the perception of TGI-related sensations or pain in patients with chronic lower back pain (CLBP). PATIENTS AND METHODS: The perception of TGI (warmth/heat, cold, unpleasantness, pain, burning, stinging, and prickling) was examined in 66 patients with CLBP and compared with that in 22 healthy participants. The visual analog scale (VAS) scores for CLBP, Oswestry Disability Index (ODI), and 12-Item Short Form Survey (SF-12) scores were obtained from the included patients with CLBP. RESULTS: The CLBP group showed a less intense perception of TGI for sensations of warmth/heat, unpleasantness, and pain than the control group. The CLBP group felt burning sensations lesser than the control (2.77 vs 4.55, P=0.016). In the CLBP group, there were significant correlations between the ODI and the degree of unpleasantness (r=0.381, P=0.002) and prickling sensation (r=0.263, P=0.033). There were also significant correlations between the mental component score of the SF-12 and the degree of warmth/heat (r=−0.246, P=0.046), unpleasantness (r=−0.292, P=0.017), pain (r=−0.292, P=0.017), and burning sensations (r=−0.280, P=0.023). CONCLUSION: Our results may be useful for clinicians to evaluate the effectiveness of drugs or interventions to manage centralized LBP.