Spinal Injections and Nerve Blocks Treat Neck and Back Pain

10 common questions about spinal injections answered

Spinal injections, also referred to as spinal blocks, is the administration of a medicine directly into a specific area of the spine. They can be used to treat a variety of conditions that affect the spine anywhere from the upper cervical spine to the sacrum.

Injection treatments can help diagnose and relieve neck or back pain that may radiate into the patient’s arms and legs (eg, cervical radiculopathy, lumbar radiculopathy). A spinal injection for diagnostic or treatment purposes may be included as part of your multidisciplinary treatment plan that could include medication and physical therapy.

lumbar axial anatomy, nerve structuresSpinal injections require precise placement of the needle using x-ray guidance; the close proximity of key nerve structures is seen in this anatomical illustration of an axial lumbar level. Photo Source: 123RF.com.

Q1. What type of medication is in the spinal injection?

The spinal injection is usually comprised of either a local anesthetic alone, steroid alone, or a combination of a local anesthetic and steroid. Another name for steroid is corticosteroid; a powerful anti-inflammatory medication. Sometimes a contrast medium (x-ray dye) is added to the injection mixture to help guide accurate placement of the needle using image guidance.

Q2. What types of spinal disorders may benefit from an injection?

There are a wide range of spinal disorders that may benefit from an injection. The decision to proceed with an injection is based on a variety of factors and should be made after consultation with a physician. Most physicians recommend a period of conservative treatment, usually 4-6 weeks, prior to recommending an injection as many cases of neck or back pain will improve within that time frame.

  • Common conditions where an injection might be appropriate, include spinal stenosis, disc herniation, failed back syndrome, sciatica, facet joint pain, and sacroiliac joint pain.

Q3. What is the difference between a spinal injection and nerve block?

Spinal injections are a broad term that refer to any type of injection that involves the spine. Nerve blocks are a subtype of spinal injections that target a specific nerve. When the medicine is injected onto the target nerve, it can “block” the transmission of pain signals that travel from the pain generator (eg, lumbar herniated disc) to the brain.

  • In summary, all nerve blocks are spinal injections, but not all spinal injections are nerve blocks.

Q4. What are the different types of spinal injections?

Epidural Injection
The prefix “epi” is Greek for “upon” or “on.” The dura is the outermost layer of a three-layer soft tissue sac that encloses the spinal cord and cauda equina. Therefore, an epidural injection refers to an injection of medicine onto the dura.

There are 3 types of epidural injections. They are named based on the approach the needle takes to get to the dura.

  • Caudal epidural injection: The spinal canal terminates through an opening at the end of the sacrum called the spinal hiatus. The medicine is injected into the epidural space via the sacral hiatus. This is the same approach that is used to provide anesthesia to pregnant women during labor.
  • Transforaminal epidural injection: Nerve roots exit the spinal canal at each spinal level through a bony opening in the spine called the neural or intervertebral foramen or neuroforamen. The medicine is injected into the epidural space via these foramen.
  • Interlaminar epidural injection: The lamina is a section of bone that forms the posterior arch of each vertebral level and together form the spinal canal. Like shingles on a house, the lamina from the vertebral level above, lays on top of the lamina immediately below it. The tip of needle enters in between the lamina to allow delivery of the medicine into the epidural space.

Selective Nerve Root Block(SNRB)/injection
SNRB’s involve injection of a local anesthetic onto a specific nerve root. They are typically used in a diagnostic manner. In patients with multiple areas of spinal compression, SNRBs—in conjunction with the patient’s history, physical exam, and MRI—can help identify to identify the pain generator (eg, spinal stenosis).

Medial Branch Block (MBB)/Injection
The facet joints are a pair of bony projections that connect a vertebral level to the vertebral level directly above and below it. Like any joint in the body, it can become arthritic over time and is responsible for some forms of back pain. An MBB is an injection of local anesthetic onto the medial branch nerves; the nerves that transmit pain signals from a facet joint. They can help determine whether the facet joint is the pain generator.

facet joint anatomyPainful facet joints may be treated using a nerve block that stops the joint's medial nerve from transmitting pain signals. Photo Source: Shutterstock.com.

Facet Joint Injection
Facet joint injections are injections directly in the facet joint itself, similar to injecting anti-inflammatory and/or pain-relieving medication(s) into an arthritic knee.

Sacroiliac Joint Injection
There are 2 sacroiliac joints. They help connect either side of the sacrum to the ilium; a part of the hip joint. They are the link from the axial skeleton (eg, skull, vertebral column) to the rest of the body and, like most joints, can become painful in certain cases. A sacroiliac joint injection is an injection directly into one or both of the sacroiliac joints.

Q5. What medical specialists perform spinal injections and nerve blocks?

Injections are technically demanding procedures that should only be performed by physicians trained specifically in spinal injections. In most cases, injections are usually performed by an anesthesiologist, radiologist, physiatrist, orthopaedic surgeon, neurosurgeon, or neurologists.

Q6. What is the role of these procedures in the treatment of neck and back pain?

There are three reasons why an injection might be used:

  1. Help identify the pain generator (diagnostic)
  2. Provide pain relief (therapeutic)
  3. Predict the relief the patient might expect from a subsequent intervention—a more invasive procedure such as nerve ablation (prognostic).

Q7. How often can I have a nerve block or spinal injection?

A maximum of 6 injections in a 1-year period is recommended. There is no evidence to support a series of 3 injections. The decision to have a second injection should be based on the effect of the first injection.

Q8. What are the potential benefits of these injection procedures?

The primary benefit of spinal injection is to provide relief of pain and disability.

Q9. What are the potential risks of these spinal injection procedures?

Spinal injections are typically well tolerated and safe with an extremely low rate of complications. The most common risks include small amounts of bleeding, headache, and facial flushing. More major complications include puncture of the dura, infection, and nerve damage. These major complications occur in less than 1% of people undergoing spine injections. People with diabetes may note a temporary elevation of their blood sugars.

Q10. Typically, how long do the effects of injection treatment last?

It is difficult to predict how long an injection will last given the many variables at play—such as the type of injection, type of pathology (eg, diagnosis, cause), and/or how long symptoms last. Most people can expect to receive 1.5 to 3 months of pain relief. In some cases, an injection may provide minimal or only a few days of pain relief, while other patients may see symptom improvement up to a year after receiving an injection.

Updated on: 03/17/20
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Spine Injections: What You Need to Know
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Spine Injections: What You Need to Know

Spine injection questions? We've got answers about how it works, how to prepare, how it feels and much more. Learn more from our expert, Dr. William Mosenthal.
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