The purpose of this study is to compare two different approaches (midline and parasagittal) during interlaminar lumbar epidural steroid injection (LESI), and to verify the role of concordant pressure paresthesia occurring during the LESI in determining outcome.

The investigators are planning to include 100 patients, undergoing LESI for radicular low back pain. This will be single-blinded randomized study. Every patient will receive the same medication we would use regardless of participating in the study. The patients will be randomly assigned to one of two groups, based on the approach:

• Group I (50 patients) - will get LESI using midline (MIL) approach.
• Group II (50 patients) - will get LESI using parasagittal interlaminar (PIL) approach.

Inclusion Criteria:

• 18- 80 years old
• History of low back pain and unilateral lumbosacral radiculopathy pain
• Lumbar disk disease including disk herniations, bulging discs, and degenerated discs, where at least 50% of the disk height is preserved respective to contiguous levels

Exclusion Criteria:

• Discogenic pain without radiculopathy pain
• History of previous spinal surgery
• LESI(s) in the past year
• Allergy to methylprednisolone, or lidocaine, or iodine-based contrast
• Concurrent use of systemic steroid medications
• Opioid habituation
• Pregnancy