Lumbar radicular pain is a condition that is very common The lifetime incidence of lumbar radicular pain is up to 43%. The most common cause of lumbar radicular pain is disc herniation. Other reasons; spinal stenosis, tumor, infection, spondylosis, spondylolisthesis, ligamentum flavum hypertrophy and synovial cyst. Lumbar disc herniation is most commonly located at L4-5 and L5-S1. Nerve compression due to disc herniation can occur in the spinal canal, lateral recess, neuroforaminal or extraforaminal region.

Inflammatory and mechanical reactions between the intervertebral disc, posterior longitudinal ligament and nerve roots play a role in the development of radicular pain. Chemical mediators released from the herniated disc increase the inflammatory response, and prostaglandin is released due to phospholipase A2 production. This situation results in radicular pain. Epidural steroid injections are frequently applied to patients in the treatment of radicular pain who do not benefit from medical treatment (non-steroidal anti-inflammatory analgesic, opioid, gabapentin, pregabalin) and physical medicine modalities. Epidural steroid injections can be administered via interlaminar, transforaminal or caudal routes. Epidural steroid injection inhibits the synthesis and release of pro-inflammatory substances that develop as a result of mechanical compression. In the transforaminal technique, the solution is administered to the anterior epidural space and spreads to the ipsilateral periradicular area. The applied solution does not cross the midline and there is no contralateral drug spread. In interlaminar epidural steroid injection, the solution crosses the midline and spreads bilaterally; but it remains in the posterior epidural area. Injection applied to the anterior epidural area adjacent to the nerve root via the transforaminal route is target-specific and a more effective form of treatment. In a study researchers reported that there was a greater decrease in pain intensity in patients with spinal stenosis with bilateral transforaminal epidural injection compared to interlaminar epidural injection. In another study, transforaminal injection was found to be superior in pain palliation compared to interlaminar injection in symptomatic lumbar disc herniation. Although there are studies in the literature comparing the advantages of epidural injection methods in lumbar disc herniation, there are no studies comparing the clinical effect of unilateral and bilateral transforaminal injection. Although bilateral transforaminal epidural steroid injection is recommended in unilateral lumbosacral disc herniation because the inflammation is bilateral, unilateral transforaminal steroid injection has been applied in most studies. (9- This study aims to evaluate the effects of unilateral and bilateral transforaminal epidural steroid injection on pain intensity, functionality and medication use in unilateral lumbosacral disc herniation and to observe whether they are superior to each other.

A single-center, prospective randomized controlled study will be conducted at Ankara University Faculty of Medicine, Department of Algology. Within the scope of the study, patients with radicular pain radiating to the unilateral lower extremities due to lumbosacral disc herniation will be evaluated with Magnetic Resonance Imaging (MRI) and physical examination between 1.6.2023 and 1.10.2023. The study included patients between the ages of 18 and 65, who had unilateral lumbosacral radicular pain for at least 3 months, whose MRI and physical examination confirmed lumbosacral disc herniation, who developed pain secondary to unilateral lumbosacral disc herniation, who did not respond to conservative treatment (medical and physical medicine modalities), and 128 patients with pain intensity of 4 and above measured using Numeric Rating Scala (NRS) will be included. Patients with previous lumbar surgery, patients with psychiatric illnesses who are unstable/not controlled by medical treatment, pregnant patients, patients with bleeding diathesis, patients who have received epidural steroid injection within the last year, patients who are exposed to substances given during the procedure (local anesthetic, steroid, contrast material). Patients with known allergies, scoliosis, spondylolisthesis, central canal stenosis, compression fracture, previous discitis, sequestered disc, and bilateral disc herniation will be excluded from the study.

Patients will receive epidural steroid injection through a unilateral or bilateral transforaminal approach. Within the scope of the study, patients with unilateral lumbosacral disc herniation and who are deemed suitable for transforaminal epidural steroid injection will be numbered in the order they are included in the study. Patients given an odd number will receive unilateral transforaminal epidural steroid injection, and patients given an even number will receive bilateral transforaminal epidural steroid injection. Transforaminal epidural steroid injections will be administered by Hanzade Aybüke Ünal. Pre-procedure and post-procedure evaluations of the patients will be recorded by Ahmet Basari, who is blind to the procedure performed. Demographic information of the patients, including age, gender, comorbidities, pain duration, and disc herniation level, will be recorded before the procedure. Before the procedure, pain intensity will be evaluated using the NRS 11 scale, and functionality will be evaluated using the ODI. The amount of medication used by the patients (non-steroidal anti-inflammatory analgesics, opioids, gabapentin, pregabalin) will also be noted. Patients will be contacted by phone at 1st week, 1st month and 3rd month to obtain information about NRS and ODI. During the specified time periods, pain intensity will be recorded using the NRS 11 scale, functionality will be recorded using the ODI, and medication use (non-steroidal anti-inflammatory analgesic, opioid, gabapentin, pregabalin) will be recorded. Additionally, possible complications in patients will also be recorded. A 50% or more reduction in pain intensity will be considered a response to treatment.