Does insertion of intramuscular electromyographic electrodes alter motor behavior during locomotion?
STUDY DESIGN Cross-sectional study. OBJECTIVE The purpose of this study is to compare pressure pain threshold (PPT) values between patients with chronic nonspecific low back pain (CLBP) and healthy individuals and correlate PPT values of the structures investigated with demographic and clinical data from patients with CLBP. SUMMARY OF BACKGROUND DATA Chronic pain may decrease pain tolerance of almost the entire spinal cord segment; however, previous studies on PPT in patients with low back pain have limited their focus to evaluating only patient complaints. METHODS Forty subjects participated in the study: 20 with a clinical diagnosis of CLBP and 20 healthy individuals. Outcome measures were PPT values of myotomes, sclerotomes, and dermatomes corresponding to segments L1 to S3; demographic, clinic, and social data; visual analogue scale, and Roland and Morris Questionnaire. RESULTS Most analyzed structures had lower PPT values in patients with CLBP than in healthy individuals on both sides (bilaterally). PPT correlated positively with height and pain duration (P < 0.05) and negatively with body mass index in the suprainterspinous ligament between L2 and L3 and dermatomes L5 to S2 (P < 0.05). CONCLUSION Our results showed that individuals with CLBP have lower PPT values than healthy individuals in almost all assessed structures. We propose a simple approach that can differentiate patients with CLBP whose hyperalgesia in the painful area may be the result of several mechanisms that should be further investigated, such as sensitization of the central nervous system. LEVEL OF EVIDENCE N/A.