Transforaminal epidural steroid injection (TFESI) is a commonly used minimally invasive procedure for the treatment of lumbar radicular pain secondary to disc herniation. Although TFESI has been shown to provide significant pain relief in a substantial proportion of patients, the onset, duration, and temporal pattern of pain relief after the procedure vary considerably among individuals. The relationship between early pain response patterns and long-term treatment success remains poorly understood.

This prospective observational study aims to evaluate whether temporal changes in pain intensity following TFESI, particularly during the early post-procedural period, are associated with clinical treatment success at mid- and long-term follow-up. Pain intensity will be assessed using the Numeric Rating Scale (NRS) at predefined time points following the procedure, and treatment success will be defined as a ≥50% reduction in NRS score compared with baseline.

Transforaminal epidural steroid injection (TFESI) is widely utilized in patients with lumbar disc herniation-related radiculopathy who do not respond adequately to conservative treatment and are not immediate candidates for surgery. While previous studies have demonstrated the overall effectiveness of TFESI, there is limited evidence regarding the temporal characteristics of pain relief following the procedure and how these patterns influence long-term outcomes.

In routine clinical practice, patients may exhibit heterogeneous pain trajectories after TFESI, including early responders, delayed responders, transient responders, or those with minimal or no response. Identifying early pain response patterns that predict treatment success may help clinicians optimize patient counseling, follow-up strategies, and decisions regarding repeat interventions.

In this prospective observational cohort study, adult patients undergoing fluoroscopy-guided TFESI as part of routine clinical care will be followed longitudinally. Pain intensity will be assessed using the Numeric Rating Scale (NRS) before the procedure; at 1 hour post-procedure; every 72 hours during the first 21 days; and at 1, 3, and 6 months. Demographic data, clinical characteristics, and radiological findings from lumbar magnetic resonance imaging will be recorded.

The primary objective is to determine whether early temporal changes in pain intensity following TFESI are associated with treatment success at 3 months. Secondary objectives include evaluating treatment success at 6 months and identifying early pain response thresholds that predict favorable outcomes.

Inclusion Criteria:

• Age between 18 and 65 years
• Pre-procedural Numeric Rating Scale (NRS) pain score of 4 or higher
• Presence of segmental lumbar disc herniation demonstrated on magnetic resonance imaging (MRI) consistent with clinical findings
• Undergoing fluoroscopy-guided transforaminal epidural steroid injection due to insufficient response to conservative treatments, as determined by the algology clinic

Exclusion Criteria:

• Presence of spondylolisthesis, scoliosis, or lumbar spinal stenosis accompanying lumbar disc herniation
• Presence of malignancy
• History of lumbar spine surgery for disc herniation
• Transforaminal epidural steroid injection within the previous 6 months
• Requirement for repeat epidural steroid injection during the data collection or follow-up period
• Inability to be contacted for follow-up assessments by telephone

The study population consists of adult patients aged 18 to 65 years with lumbar disc herniation-related radiculopathy who are undergoing fluoroscopy-guided transforaminal epidural steroid injection as part of routine clinical care. All participants have clinically significant radicular pain with a pre-procedural Numeric Rating Scale (NRS) score of 4 or higher and lumbar disc herniation confirmed by magnetic resonance imaging (MRI) at a segmental level consistent with clinical findings.

Patients included in the study are those who have not achieved adequate symptom relief with conservative treatment modalities and are therefore referred for transforaminal epidural steroid injection by the algology clinic. Participants are prospectively followed after the procedure to evaluate temporal changes in pain intensity and their association with clinical treatment success.