- Interlaminar ESI. This method accesses the epidural space from the middle of the back under x-ray guidance. The needle is inserted between the two vertebrae directly through the numb skin overlying the ligaments and muscles. When the needle tip is in the correct place, the local anesthetic and steroid medication are injected to the epidural space. Medication is delivered to multiple nerve roots on both the right and left sides of the midline at the same time.
- Transforaminal ESI. This method accesses the epidural space from the left, right, or both sides of the midline of the back. It is indicated when pain is localized along the distribution of single nerve root or in patients who have undergone a previous spine surgery. The needle is placed under x-ray guidance to the side of the vertebra, just close to or in the exit opening for the nerve root. Use of a contrast dye indicates where the medication will flow when injected.
What to expect after ESI
The ESI contains a mixture of local anasthetic and a steroid medication.
The local anesthetic may provide partial pain relief within 10 to 15 minutes after the completion of the procedure but may last for a few hours only. Mild numbness or heaviness of an extremity can also be experienced, but most patients are able to stand and walk out without assistance.
The steroid will usually start working within 24 to 72 hours. The pain relief and improvement in function may last for days, weeks, or even several months after the single injection or a series of injections.
Although uncommon, some patients will experience an increase in their usual pain for a few days following the procedure.