From the Research
A L4/5 subpedicular transforaminal epidural steroid injection primarily addresses the L5 nerve root. This is because the nerve root exits below the corresponding vertebral level, meaning the L5 nerve root exits through the L5/S1 neural foramen, but it also traverses the lateral recess at the L4/5 level. When performing a transforaminal approach at the L4/5 level, the medication is delivered into the epidural space near where the L5 nerve root begins its course through the lateral recess and foramen. The subpedicular technique specifically targets the superior aspect of the neuroforamen, just below the pedicle of L4, where the L5 nerve root is located. This approach allows the steroid medication to bathe the L5 nerve root as it courses through this region, reducing inflammation and providing pain relief for patients with L5 radiculopathy. The medication can also spread to affect adjacent levels to some degree, but the primary target is the L5 nerve root.
Key Points
- The L5 nerve root is the primary target for a L4/5 subpedicular transforaminal epidural steroid injection 1
- The subpedicular technique targets the superior aspect of the neuroforamen, just below the pedicle of L4, where the L5 nerve root is located
- The medication can spread to affect adjacent levels, but the primary target is the L5 nerve root
- Transforaminal epidural steroid injections have been shown to be effective in reducing pain and improving function in patients with lumbar radiculopathy 2, 3
Evidence Summary
The most recent and highest quality study on this topic is a prospective, randomized trial published in 2022 1. This study compared the effectiveness of the subpedicular and retrodiscal approaches for transforaminal epidural injections and found that both approaches were effective in reducing pain, but the retrodiscal approach showed a better contrast spreading pattern, especially in patients with severe central and foraminal spinal stenosis. Another study published in 2022 3 reviewed the efficacy and risks of epidural steroid injections, including transforaminal injections, and found that they can be an effective treatment for radicular pain.
Clinical Implications
In clinical practice, a L4/5 subpedicular transforaminal epidural steroid injection can be an effective treatment option for patients with L5 radiculopathy, especially those who have not responded to conservative treatments. The subpedicular technique allows for targeted delivery of steroid medication to the L5 nerve root, reducing inflammation and providing pain relief. However, it is essential to consider the individual patient's clinical presentation, pathology, anatomy, and unique risks and benefits of the technique when selecting an injection approach 3.