EPIDURAL STEROID INJECTIONS
The image below depicts a herniated disc that is impinging on the nerve root. Notice that there is a round sack or lining around the spinal canal. That protective shield is called the dura. The space between the dura and nerves within the spinal canal is called the epidural space. The epidural space is where the steroid injection is performed.
The procedure starts with a local numbing agent injection used to locally numb the skin. Using real-time x-ray for guidance, the doctor will guide a needle into the epidural space. Once the doctor is sure the needle is in the correct position, the steroid material is injected. Patients are typically monitored up to 30 minutes after the injection.
The patient may feel immediate pain relief and numbness in the local area for up to 6 hours. However, your pain may return after this short pain-free period or may even be a little worse for a day or two. This is normal. This increase in pain can be caused by needle irritation. Depending on the amount of inflammation, an injection could offer several months or pain relief. However, even if this procedure does not have the desired pain relief, it can be used as a diagnostic procedure to further narrow the cause of pain and subsequent treatment.
- The Epidural Injection (EI) is a procedure that anesthetizes the space around the spinal sac (dural sac).
- This procedure may be performed at any level of the spine, although is most commonly performed in the lumbar spine.
- As opposed to a selective nerve root block, or a facet injection, which target a specific nerve or joint on one side of the spine, the EI treats several consecutive levels on both sides of the spine.
- The EI procedure delivers a low volume of concentrated medication directly into a portion of the epidural space.
- The EI typically covers the epidural space of about 3-5 vertebral body levels.
II. The Epidural Space
- The epidural space is a continuous space that extends from the skull base to the sacrum, circumferentially enveloping the spinal sac.
- It is surrounded by the vertebral bodies of the spinal canal at all levels.
- All nerves going into or out of the spinal cord must traverse this space.
- This is the same space accessed for an ‘epidural’ during childbirth.
III. Back Pain
- Back pain may arise from any anatomic structure within or around the spine which has nerve endings and is capable of transmitting pain.
- These structures include discs, facet joints, muscle, nerves, ligaments and dura (the membrane lining of spinal canal).
- All of these structures are either directly touching or in close proximity to the epidural space.
- Pain may be either within the spine itself (‘axial’), or radiating from the spine (‘radicular’). Both of these types of pain are ideally alleviated with the EI.
IV. Patient Selection
- Back pain affects nearly everyone at some point in their adult life.
- Oftentimes the exact cause of pain is not readily apparent, as there are many factors which may be contribute to a patient’s back pain, including disc disease, referred pain, as well as psychological factors. This can make the exact site and level responsible for the back pain more challenging to localize and diagnose.
- Unfortunately, while imaging studies (X-RAYs, MRI and CT scans) are helpful in screening the spine for potential causes of back pain, sometimes they don’t demonstrate an exact cause for a patient’s pain.
- The epidural procedure in our Dardi pain clinic are explained to the patient, questions are answered and informed consent is obtained.
- An intravenous line is place to give a small amount of medication to relax the patient.
- The patient is placed prone (stomach down) on the fluoroscopic table, and the lower back is sterilely cleansed with povidone-iodine (Betadine) and alcohol.
- The exact level is located with the fluoroscope, and the skin overlying this area is anesthetized (numbed) with lidocaine. This is in the midline of the back.
- A needle is then sterilely advanced into the epidural space.
- Typically, as small amount of water-soluble contrast (dye) is injected to confirm proper needle tip position within the epidural space.
- Once this is confirmed, a mixture of anesthetic (lidocaine or bupivacaine) and anti-inflammatory medication (steroid) is injected.
- The needle is slowly withdrawn
- This procedure is usually performed with Fluoroscopic guidance.