Retrospective evaluation of the effectiveness of ultrasonography-guided caudal epidural steroid injection in the treatment of chronic low back pain

Objective: We aimed to retrospectively evaluate the effects, safety, and potential predictive factors of the caudal epidural steroid injection (CESI) performed under ultrasonography (USG) guidance on pain, functional status, and safety in patients with chronic low back pain (LBP). Materials and Methods: We conducted a retrospective analysis of 69 patients who underwent caudal epidural steroid injection (CESI) under USG guidance for complaints of chronic LBP and radicular pain lasting more than 3 months at the Department of Physical Medicine and Rehabilitation, Farabi Hospital, Karadeniz Technical University Faculty of Medicine, between January 1, 2019, and January 1, 2020. Data were collected from files of patients including Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Straight Leg Raise (SLR) test, neurological examination findings, lumbar range of motion (ROM) goniometric measurements, taken before injection, at 3rd week, and at 6th week after injection. To assess treatment efficacy, primary outcome measures included changes in VAS and ODI scores from baseline to the 3rd week and 6th week post-injection follow-up visits. Secondary outcome measures included SLR test values, lumbar joint ROM measurements, muscle strength, and deep tendon reflex (DTR) changes. Post-injection adverse events were evaluated. As the potential predictor of effectiveness was assessed using subgroup comparisons of 16 factors based on changes in VAS, ODI, and SLR. Results: In the study involving 69 patients, statistically significant changes were observed in all values of VAS, ODI, SLR, and lumbar ROM measurements at the 3rd week and 6th -week follow-up compared to before injection (p<0.05). No serious adverse effects were observed. Transient paresthesia in the lower extremities was noted in two patients (2.9%), exacerbation of back pain in two (2.9%), hypotension in one (1.45%), and headache in one (1.45%), resulting in mild and transient adverse effects in a total of six patients (8.7%). These effects were managed with symptomatic treatment and resolved within 72 hours. No changes were observed in the neurological examinations of the patients. In all subgroups, statistically significant changes were observed in VAS and ODI at the 3rd week and 6th week follow-up compared to baseline (p<0.05). Patients with symptom duration of 12 months or less, muscle strength of 5/5, normal deep tendon reflex (DTR), pathology at the L4/L5 and L5/S1 levels, positive SLR test between 30-50 degrees showed statistically significantly better responses based on changes in VAS, ODI, and SLR at the 3rd week and 6th week follow-up (p<0.05). There was no statistically significant difference in changes in VAS, ODI, and SLR at the 3-week and 6-week follow-up between L4/L5 and L5/S1 pathology levels (p>0.05). In the lumbar disc herniation (LDH) group, statistically better responses were observed at the 3-week and 6-week follow-up in terms of ODI and SLR changes compared to the failed back surgery syndrome (FBSS) group (p<0.05).Age, gender, number of pathological levels, body mass index (BMI), comorbidities, smoking status, neuropathic medication use, educational status, did not show statistically significant relationships with the results of VAS and ODI at the 3-week and 6-week follow-up in intergroup comparisons (p>0.05). Conclusion: In conclusion, we observed that USG-guided CESI is safe and effective for the treatment of chronic low back pain, and this effectiveness persists up to 6 weeks. Furthermore, it was found to be more effective in patients without neurological deficits, with shorter symptom durations, lower positive Straight Leg Raise (SLR) test degrees, and pathology at the L4/L5 and L5/S1 levels. Keywords: Chronic low back pain, caudal epidural steroid injection, ultrasonography, predictive factors