Evaluation of Paraspinal Muscle Degeneration on Pain Relief after Percutaneous Epidural Adhesiolysis in Patients with Degenerative Lumbar Spinal Disease

Background and Objectives: The analgesic effectiveness of epidural adhesiolysis may be influenced by morphological changes in the paraspinal muscles, particularly in elderly patients. The objective of this study was to assess whether the cross-sectional area or fatty infiltration of the paraspinal muscles impacts the treatment outcomes of epidural adhesiolysis. Materials and Methods: The analysis included a total of 183 patients with degenerative lumbar disease who underwent epidural adhesiolysis. Good analgesia was defined as a reduction in pain score of ≥30% at the 6-month follow up. We measured the cross-sectional area and fatty infiltration rate of the paraspinal muscles and divided the study population into age groups (≥65 years and <65 years). Variables were compared between the good and poor analgesia groups. Results: The results revealed that elderly patients experienced poorer analgesic outcomes as the rate of fatty infiltration in the paraspinal muscles increased (p = 0.029), predominantly in female patients. However, there was no correlation between the cross-sectional area and the analgesic outcome in patients younger than or older than 65 years (p = 0.397 and p = 0.349, respectively). Multivariable logistic regression analysis indicated that baseline pain scores < 7 (Odds Ratio (OR) = 4.039, 95% Confidence Interval (CI) = 1.594–10.233, p = 0.003), spondylolisthesis (OR = 4.074, 95% CI = 1.144–14.511, p = 0.030), and ≥ 50% fatty infiltration of the paraspinal muscles (OR = 6.576, 95% CI = 1.300–33.268, p = 0.023) were significantly associated with poor outcomes after adhesiolysis in elderly patients. Conclusions: Fatty degeneration of paraspinal muscles is correlated with inferior analgesic outcomes following epidural adhesiolysis in elderly patients, but not in young and middle-aged patients. The cross-sectional area of the paraspinal muscles is not associated with pain relief after the procedure.