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What is a selective nerve root block?

A selective nerve root block is an injection of local anesthetic and steroid along a specific spinal nerve root. After the injection, the patient logs changes to pain levels at various intervals, to help determine which nerve is causing the pain.

What is the purpose of a selective nerve root block?

A selective nerve root block is a diagnostic and therapeutic procedure.


Chronic pain in the extremities is often caused by something compressing the nerve root along the spinal column, like a bulging or ruptured disk, bone spurs or misalignment of vertebrae.


Diagnostically, the selective nerve root block can isolate the problematic nerve so a treatment plan can be devised. Therapeutically, each injection will reduce swelling and pain along the spinal column.

How is a selective nerve block performed?

Patients remain awake throughout the procedure, with vitals constantly monitored.

The area of injection is sterilized and locally anesthetized. Using a fluoroscope (live X-ray), a needle is inserted and guided to the proper position. A small amount of dye is release to confirm that the anesthetic will spread to the appropriate area. Then the medication is injected gradually.

spine with bulging disc

After the procedure, the patient is monitored for a brief time before being allowed to return home.

Some patients require multiple selective nerve root blocks to properly isolate the problem.

What are the risks and side effects?

syringe for selective nerve root block

In general, a selective nerve root block is a very safe procedure with few side effects. Temporary pain at the site of the injection is common.


Less common, more serious side effects include:


• Inadvertent puncture of a spinal fluid sack

• Headaches

• Infection

• Bleeding

• Nerve damage

• Fluid retention/weight gain

• Increased blood sugar (primarily in diabetics)

• Elevated blood pressure

• Mood swings/irritability/insomnia

• Suppression of the natural production of cortisone

• Adverse reaction to the anesthetic or steroid 

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