Sarcopenia and Interlaminar Epidural Steroid Injection Outcomes in Lumbar Spinal Stenosis

Primary outcomes

• Change in Leg Pain Following Interlaminar Epidural Steroid Injection by Sarcopenia Status [Baseline, 3 weeks, and 3 months]: Leg pain intensity will be assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. NRS scores will be recorded at baseline, 3 weeks, and 3 months. Changes in leg pain intensity from baseline will be compared between patients with and without sarcopenia.

Secondary outcomes

• Change in Low Back Pain Following Interlaminar Epidural Steroid Injection by Sarcopenia Status [Baseline, 3 weeks, and 3 months]: Low back pain intensity will be assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. NRS scores will be recorded at baseline, 3 weeks, and 3 months. Changes in low back pain intensity from baseline will be compared between patients with and without sarcopenia.
• Change in Functional Disability Following Interlaminar Epidural Steroid Injection by Sarcopenia Status [Baseline, 3 weeks, and 3 months]: Functional disability will be assessed using the Istanbul Low Back Pain Disability Index (ILBPDI). The ILBPDI consists of 18 items and has a total score ranging from 0 to 90, with higher scores indicating greater disability. ILBPDI scores will be recorded at baseline, 3 weeks, and 3 months. Changes from baseline will be compared between patients with and without sarcopenia.
• Change in Health-Related Quality of Life Following Interlaminar Epidural Steroid Injection by Sarcopenia Status [Baseline, 3 weeks, and 3 months]: Health-related quality of life will be assessed using the 12-Item Short Form Health Survey (SF-12), which provides Physical Component Summary (PCS) and Mental Component Summary (MCS) scores. Both scores range from 0 to 100, with higher scores indicating better health-related quality of life. Scores will be recorded at baseline, 3 weeks, and 3 months. Changes from baseline will be compared between patients with and without sarcopenia.
• Correlation Between Erector Spinae Cross-Sectional Area and Leg Pain Outcome [Baseline Magnetic Resonance Imaging; leg pain at baseline, 3 weeks and 3 months]: Erector spinae cross-sectional area (CSA) will be measured on baseline lumbar magnetic resonance imaging (MRI) in square centimeters (cm²). Leg pain intensity will be assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, with higher scores indicating greater pain intensity. The correlation between baseline erector spinae CSA and change in leg pain NRS from baseline will be evaluated.

Sex: All, ages: 50 Years to 75 Years

Inclusion Criteria:

* Clinical and radiological diagnosis of lumbar spinal stenosis
* Persistent symptoms despite conservative treatment and scheduled to undergo interlaminar epidural steroid injection as part of routine clinical care
* Age between 50 and 75 years
* Low back and/or leg pain for at least 3 months
* Availability of lumbar magnetic resonance imaging (MRI)

Exclusion Criteria:

* History of lumbar fusion surgery
* Lumbar epidural steroid injection within the previous 3 months
* Prominent radiculopathy due to lumbar disc herniation
* Severe motor deficit or an indication for surgical treatment
* Polyneuropathy, neuromuscular disease, or neurological disease that may significantly affect muscle mass
* Active malignancy or systemic inflammatory disease
* Significant mobility limitation due to advanced hip or knee osteoarthritis
* Cognitive impairment or communication problems that may prevent completion of study assessments
* Coagulopathy or active infection constituting a contraindication to epidural injection
* Inflammatory rheumatic disease requiring chronic corticosteroid therapy