Temporal Associations Between Pain-Related Factors and Abnormal Muscle Activities in a Patient with Chronic Low Back Pain: A Cross-Lag Correlation Analysis of a Single Case

• Published in: Journal of pain research 2020-01, Vol.13, p.3247-3256
• Main Authors: Shigetoh, Hayato, Nishi, Yuki, Osumi, Michihiro, Morioka, Shu
• Format: Article
• Language: English
• Subjects: abnormal muscle activities; Analysis; Back pain; Backache; Case Report; chronic low back pain; cross-lag correlation; Electrodes; Muscle function; Nervous system; pain-related factors; Patient education; Patients; Physical therapy; Questionnaires; Self image; Tension tests; Therapeutics, Physiological
• ISSN: 1178-7090; 1178-7090
• DOI: 10.2147/JPR.S286280

The cross-sectional and longitudinal associations between pain-related factors and muscle activity in patients with chronic low back pain (CLBP) are unclear. This study aimed to examine the temporal associations between them in a CLBP patient using a single-case analysis to account for an individual course. A patient with a history of lower back pain lasting more than 3 months was studied from March 16, 2020 to May 30, 2020. Surface electromyographic signals were recorded from over the bilateral lumbar erector spinae in the patient while performing a standing trunk flexion and re-extension task. The average value for muscle activity during each movement phase was estimated, and the flexion relaxation ratio (FRR) of all channels was subsequently calculated. Pain-related factors and disability were assessed using questionnaires. All assessments were performed nine times, along with 2-3 months of intervention. Once or twice per week, the patient received physical therapy that consisted of soft tissue mobilization, joint mobilization, nerve mobilization, and patient education. A cross-lag correlation analysis of this single case was conducted. Pain-related factors showed a trend toward improvements in all variables when compared to those in the first assessment; however, there was no general change (increase) in FRR over time. The cross-lag correlation analysis revealed that improvements in FRR were associated with improvements in body perception disturbance ( = -0.78, p < 0.01), and that improvements in muscle activity during the extension phase were associated with improvements in pain ( = 0.75), psychological factors ( = 0.57), and disability ( = 0.67) (p < 0.05). Our findings suggest that improvements in body perception were temporally associated with improvements in FRR, and improvements in pain, psychological factors, and disability were temporally associated with a reduction in muscle activity during the trunk extension phase in this patient with CLBP.