Selective Nerve Root Block

A selective nerve root block (SNRB) is a test performed to determine if a specific spinal nerve is the source of your arm or leg or radiating chest pain. Often patients with spine issues have multilevel MRI abnormalities often close together.   If we treat your problem with conservative care and it fails to respond, then surgery for your radiating pain may be an option. However, due to the above issue identifying which abnormality on the MRI is the cause of the actual radiating pain can be a challenge.   In most cases pain that radiates in a radicular fashion as above is caused by just one nerve root regardless of the number of abnormalities on the MRI. Therefore, we are trying, like an electrician would do in your house to find the short circuit, to isolate the responsible nerve that is the source of the pain.

A SNRB is performed to diagnose the specific nerve root of origin of your cervical (neck), thoracic (mid back) or lumbar (low back) radiculopathy (pain in the distribution of a particular nerve root off the spine due to compression, irritation and/or inflammation of a nerve root). A selective nerve root block is an injection of a local anesthetic that lasts hours to a few days very close to a specific nerve root. Along the spine, there are several exit “holes” or “foramina” through which nerve roots emerge. If these foramina are partially closed due to either bony overgrowth from degenerative changes, bulging disks, misalignment of vertebrae, etc., the nerve root can also be pinched. This typically causes a shooting or radiating pain along that nerve root. In a selective nerve root block, a small needle is placed in the foramen alongside the nerve root, and the medication is injected. The goal of a diagnostic injection is twofold:

1. We want to see if the needle adjacent to the nerve creates radiating pain that closely replicates your typical radiating pain for which you are seeking relief.
2. To see if, while the nerve that we injected adjacent to is “asleep” or effectively blocked by the local anesthetic, your normal radiating pain is gone or improved during any period of time while the block is effective. Your feedback helps to identify the cause of radiating pain.

A selective nerve root block is performed in a sterile setting, such as an operating room or ambulatory surgery center suite.  You change into a gown.  An intravenous line is started, and medication is administered through the IV to keep you comfortable.  You may be awake or in a twilight state.

In the surgical suite, you are positioned to give the doctor access to either your neck or low back.  The skin area is cleansed using a sterile soap.  A local anesthetic is injected to numb the area.  A special imaging machine called a C-arm (fluoroscopy) is positioned to enable your doctor to view your spine during the procedure.  The needle is advanced just outside the neuroforamen adjacent to the suspect nerve root.  A small amount of contrast (dye) is injected to confirm needle placement and material flow.  Your doctor may ask you to describe what you feel.  Next, the lidocaine is injected into the area.  Lidocaine is a local anesthetic.  A corticosteroid may be added.  A corticosteroid is a slow-releasing and long-lasting anti-inflammatory medication that effectively reduces inflammation.  As the medication is injected, it flows around and coats local nerve roots.

A selective nerve root block (SNRB) is a diagnostic test your doctor performs to determine if a specific spinal nerve root is the source of neck or back pain.  Depending on where you feel pain, your doctor may perform one or more diagnostic injections in your cervical (neck) or lumbar (low back) spine.

If the SNRB reduces your pain and related symptoms, then that particular nerve or nerves are identified as a pain source.

Selective nerve root blocks:

• Provides important diagnostic information to your doctor; gives evidence that a particular nerve root is causing pain
• May relieve pain and nerve related symptoms