Selective Nerve Root Block Injection

Selective nerve root block (SNRB) injection is a pain-relief procedure. A doctor injects a long-lasting steroid (cortisone) around your nerve root as it exits your spinal column. The injection reduces the inflammation and pain caused by pressure on your nerve.

A doctor uses a selective nerve root injection to treat symptoms of a herniated (bulging) disc that causes sciatica (low back and leg pain). Doctors also use a root block as a diagnostic tool to determine if your nerve is irritated. If numbing your nerve removes your pain, they know the nerve is the problem.

UPMC experts use the latest, safest techniques to perform SNRB injections. Our goal is to relieve your symptoms and restore your quality of life.

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What Is Selective Nerve Root Block Injection?

SNRB injection is when a doctor injects a long-lasting steroid around the nerve root where it exits the spinal column. The injection reduces the inflammation in the area. This numbs the pain caused by pressure on your nerve.

It can also be a diagnostic tool to help doctors determine whether your nerve is irritated. The injection numbs your nerve, so if the pain stops, it is the likely cause.

One of the most common conditions to benefit from selective nerve root injections is a herniated (bulging) disc that causes low back and leg pain called sciatica.

This procedure is performed using fluoroscopy to help the physician place the needle in the correct place.

Types of selective nerve root block injections

Nerve root blocks can target different nerves, depending on where the doctor does the injection.

The most common type of nerve root block used in the spine is a lumbar sympathetic nerve block. This injection helps treat pain in the lower back or legs caused by a pinched nerve.

An SNRB in other areas of your spine can treat pain in other areas of your body.

Conditions we treat with selective nerve root block injection

Some of the spinal issues that cause nerve pain include:

• Complex regional pain syndrome.
• Critical limb ischemia.
• Hyperhidrosis.
• Nerve pain due to shingles.
• Neuropathy due to diabetes.
• Pain related to cancer or vascular conditions.
• Reynaud’s disease.
• Sciatica.
• Spinal conditions, including disc disease.

Why Would I Need A Selective Nerve Root Block Injection?

You may need an SNRB injection if you have pain or other symptoms from a pinched (compressed) nerve. If your symptoms do not respond to other, less-invasive treatments, an injection may be an option.

Who is a candidate for selective nerve root block injection?

You may be a candidate for SNRB injection if the pain caused by your pinched nerve has not improved after more conservative care. 

Alternatives to selective nerve root block injection

Alternatives to SNRB injection include:

• Heat or ice.
• Oral medications, such as pain medicine or muscle relaxers
• Physical therapy.
• Surgical procedures to treat the cause of your pain.

What Are the Risks and Complications of Selective Nerve Root Block Injection?

As with any medical procedure, SNRB injection has some risks.

Possible complications include:

• Bleeding or infection at your injection site.
• Medicine leaks into your bloodstream, other nerves, or your spinal canal.
• Nerve damage.

What Should I Expect From Selective Nerve Root Block Injection?

Before: How to prepare for selective nerve root block injection

Before your procedure, you will meet with your care team and have a physical exam.

Your care team may order tests, such as:

• Blood or urine tests — These studies ensure you are healthy enough for the procedure. They also check for signs of illness or infection.
• Electrocardiogram (EKG) — This test records the electrical activity of your heart. It shows abnormal rhythms (arrhythmias or dysrhythmias) and can sometimes detect heart muscle damage. EKGs are often performed before a procedure to check your heart health and identify potential problems.
• MRI — A diagnostic procedure that uses large magnets, radio frequencies, and a computer to take detailed images of organs and structures within your body.
• X-ray — Your doctor may order an x-ray to learn more about the condition of the bones and tissues in your spine.

Your doctor will explain the procedure to you and answer your questions. To prepare for the procedure, you should:

• Fast for a certain time before the procedure. Your doctor will tell you if you need to fast or how long to fast (usually overnight).
• Have any tests that your doctor requires. For example, your doctor may request a blood test before the procedure to determine how long it takes your blood to clot.
• Tell your doctor if you are sensitive or allergic to medicines, iodine, latex, tape, or anesthetic agents (local and general).
• Tell your doctor about all medicines (prescription and over-the-counter) and herbal or other supplements you are taking.
• Tell your doctor if you have any other health conditions. Your care team may need to take certain precautions during surgery for your safety.
• Tell your doctor if you have a history of bleeding disorders or if you are taking any medicines that affect blood clotting. You may need to stop some of the medications before the procedure.

On the day of your procedure, bring your photo ID and health insurance card(s). Leave valuables such as cash and jewelry at home.

Nerve blocks are usually outpatient procedures. The care team will send you home the same day. You must have someone to drive you home after the care team discharges you.

How long does selective nerve root block injection take?

SNRB injections usually take around 20 to 30 minutes.

During your selective nerve root block injection

When you arrive at the hospital, you will meet with your care team for final preparations.

Depending on your assessment, you may receive an IV, a mild sedative to help you relax, and an injection of local anesthesia to numb the treatment area.

If you receive local anesthesia, you will be awake and feel no pain. The surgical team will help position you on your stomach on a procedure table.

Your doctor will:

1. Use a special x-ray machine to find your compressed nerve.
2. Guide a needle into the area around your compressed nerve using x-ray guidance.
3. Inject dye that they can see on the x-ray to confirm that the medicine will go to the correct area.
4. Inject steroid medicine to reduce inflammation (swelling) of your nerve.

After your procedure, your surgeon will remove the needle, place a bandage over where they inserted it, and ensure your condition is stable.

Recovery after selective nerve root block injection

After your procedure, the care team will monitor you in recovery. You may feel warmth, numbness, or weakness, but this will go away soon.

Your doctor will let you know when it is safe to go home. You will need someone to drive you home from the hospital after the care team discharges you.

Before you go home, your doctor will tell you:

• How to care for your wound and watch for signs of infection or complications.
• What medicines you need to take.
• When or if you should begin physical therapy.
• When to call your doctor or 911 if you have certain symptoms.
• When you can return to your normal activities, such as driving.

How long does it take to recover from a selective nerve root block injection?

You should rest for about 24 hours after your procedure. You can resume normal activities the next day. 

When to call your doctor about post-op problems

You should let your surgeon know if you have:

• A fever of more than 100.0°F.
• Difficulty breathing.
• Difficulty with walking or keeping your balance.
• New or increasing shortness of breath.
• Numbness, tingling, pain, or weakness in your arms or legs.
• Pain, redness, bleeding, drainage, or increased swelling at your treatment site.
• Severe pain that does not respond to medicines.

What is the prognosis after selective nerve root block injection?

You should feel less pain within 3 to 7 days after your procedure. Most people experience pain relief that lasts for weeks or months, improving their quality of life and ability to do everyday activities.

The procedure helps heal damaged nerves in some people, so future injections may be unnecessary. Other people may need future injections to manage pain and other symptoms.

What is the success rate of selective nerve root block injection?

Although SNRB injections provide pain relief for most people, they do not work for everyone. If the first injection fails to relieve your pain and symptoms after 1 to 2 weeks, your doctor may recommend another injection.

Getting injections too often can increase your risk of medicine-related side effects. Your doctor will usually limit the number of injections you receive in 12 months to three.

Why Choose UPMC for Selective Nerve Root Block Injections?

UPMC surgeons use the least invasive, most effective approach to treat all types of spinal nerve disorders, including those caused by herniated discs.

Our team has pioneered some of the latest approaches to selective nerve root block injections. We use advanced devices and techniques. We aim to promote safer procedures, improved outcomes, and enhanced quality of life.

By UPMC Editorial Staff. Last reviewed on 2025-05-16.