Overview
A selective nerve root block (SNRB) places a small amount of numbing medicine, often with a steroid, next to a single spinal nerve root where it exits the spine.
It can help confirm which nerve is causing arm or leg symptoms and may relieve pain from an inflamed nerve. The results can also help with surgical planning.
How it works
Using X-ray guidance and contrast dye, the physician places a needle at the opening where the target nerve exits the spine (the foramen) and injects medication.
Who it may be for
- Arm or leg pain thought to come from a specific nerve root
- Patients whose imaging shows more than one possible source
- Candidates for surgery who need diagnostic clarity
Your exam and imaging decide whether this treatment is appropriate for you.
What to expect
- Before: we review your medications (especially blood thinners), allergies and imaging. You may need a driver.
- During: you lie on a procedure table, the skin is cleaned and numbed, and the physician uses X-ray (fluoroscopy) or ultrasound guidance to place the needle.
- After: you are monitored briefly and usually go home the same day. Keep a pain diary so we can judge the response.
Recovery
The arm or leg may feel numb or weak for a few hours. Arrange a driver. Your instructions may differ.
Risks and side effects
Every procedure has risks. Your physician will review them with you, including:
- Temporary soreness at the injection site
- Temporary increase in pain
- Bleeding or bruising
- Infection (uncommon)
- Allergic reaction (rare)
- Temporary rise in blood sugar if a steroid is used
- Temporary numbness or weakness in the limb
- Nerve injury (rare)
Insurance and cost
Many plans, including Medicare, may cover this treatment when criteria are met. We verify benefits before scheduling. See accepted insurance.
Frequently asked questions
How is a nerve root block different from an epidural?
A nerve root block targets one specific nerve. An epidural spreads medication more widely in the epidural space.
Why is it used before surgery?
It can help confirm which nerve level is responsible for symptoms.
How long does it last?
Relief varies from hours (numbing medicine only) to weeks or months when a steroid is used.
This page is general patient education and does not replace advice from your own clinician. Individual results vary.