Spinal injections

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.

Type of medication is in the spinal injection

The spinal injection is usually comprised of either a local anesthetic alone, steroid alone, but commonly 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.

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
  • Sacroiliac joint pain.

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.

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 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.

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).

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.

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