Selective Nerve Root Blocks

and Transforaminal Epidural Steroid Injections

A precise injection at a single spinal nerve to find, and often calm, the nerve causing pain that travels down your leg or arm.

Mountain Home870-706-2557
Harrison870-233-9960

What is a selective nerve root block?

Pain that shoots down a leg (sciatica) or an arm usually comes from an irritated spinal nerve root, often from a disc herniation or narrowing where the nerve exits the spine. This is called radicular pain.

Sometimes imaging shows changes at several levels, or doesn’t quite match your symptoms. A selective nerve root block (SNRB) places a small amount of numbing medicine along one nerve root to see whether it is the one causing your pain.1

Most SNRBs also include a steroid to calm inflammation around the nerve, so the same injection can help treat your pain as well as identify its source.2

Illustration of a needle delivering medication near an inflamed spinal nerve root
Medicine is placed right where one nerve root exits the spine.

How it works

  1. Pinpoint the nerve

    Your symptoms, exam, and MRI or CT point to the nerve root most likely involved.

  2. Guided by X-ray

    After numbing the skin, a thin needle is guided by live X-ray, and contrast dye confirms the medicine will reach that one nerve.

  3. Numbing medicine and steroid

    Local anesthetic gives quick, short-term relief. A steroid, if used, calms inflammation over several days.

  4. Track your relief

    You note how your usual pain changes over the next several hours and the following week.

Is this the same as an epidural steroid injection? They are closely related. An SNRB is a very targeted type of transforaminal epidural steroid injection, aimed at a single nerve root. Its results can help your physician, or a spine surgeon, decide which level needs treatment.

  • Same-day outpatientMost injections take 15 to 30 minutes, and you go home the same day.
  • PreciseX-ray and contrast dye help deliver medicine to one nerve, not the whole area.
  • Answers a questionA strong short-term response helps confirm which nerve is causing your pain.
  • Can also treatThe steroid may relieve pain for weeks to months while the nerve settles down.
  • Local numbingMost patients need only skin numbing. Light sedation is available if needed.
  • Guides next stepsResults can help plan further care, including surgery when it is being considered.

What to expect

Before your injection

Tell us about all of your medications, especially blood thinners, and whether you have diabetes or an allergy to contrast dye. We’ll tell you whether any medication should be paused. Please don’t stop one on your own.3

During your injection

You lie on your stomach, or on your back for a neck injection. The skin is numbed, and you may feel pressure or a brief reproduction of your usual leg or arm pain as the medicine reaches the nerve.

After your injection

Your leg or arm may feel numb or heavy for a few hours, so plan on a driver. Track your pain as instructed. A steroid usually starts working in 3 to 7 days and can raise blood sugar, cause flushing, or disturb sleep for a few days.

Is a selective nerve root block right for you?

It may be an option if

  • Pain travels down one leg or arm, often with numbness or tingling
  • Imaging shows possible nerve irritation at more than one level
  • Your symptoms and imaging don’t clearly match
  • Physical therapy and medications haven’t provided enough relief

Another approach may fit better if

  • Your pain is mainly in the back or neck, without shooting pain, which may point to the facet joints or another source
  • You have new or rapidly worsening weakness, or trouble controlling your bladder or bowels. These need urgent evaluation, so call 911 or go to an emergency room
  • You have an active infection or a bleeding problem that can’t be managed safely

Common questions

How long will relief last?

The numbing medicine wears off within hours. If a steroid is used, relief can last weeks to months, and for some people the nerve settles down for good. Results vary, and your physician will use your response to plan the next step.

Why does my physician want to know how I felt in the first few hours?

That window shows the effect of the numbing medicine alone. Strong relief then suggests the blocked nerve is the source of your pain, which is the diagnostic part of the test.

Can I have more than one?

Yes, when they help. Because steroids can affect blood sugar, bones, and other parts of the body, we space injections out and limit how often steroids are given.

I have diabetes. Is that a problem?

Not usually, but steroids can raise blood sugar for several days. Check your sugar more often after the injection, and let the clinician who manages your diabetes know.

Will insurance cover it?

Most plans, including Medicare, cover nerve root injections when symptoms and imaging support the diagnosis and conservative care hasn’t helped enough. Our staff will check your benefits and request any required prior authorization.

Talk with a specialist about leg or arm pain

Our physicians will review your symptoms, exam, and imaging to decide whether a selective nerve root block, or another treatment, is the right next step.

Schedule a consultation

New pain management patients need a referral. Your provider can fax it to 870-706-2428.

Risks

Possible side effects include soreness at the injection site, temporary numbness or weakness, headache, increased pain for a day or two, bleeding, infection, and steroid side effects such as temporary high blood sugar, flushing, or trouble sleeping. Rarely, serious complications such as nerve or spinal cord injury can occur; the FDA requires a warning about these rare events on injectable steroids.4 Your physician will review the risks with you before your procedure. Individual results vary.

Sources

  1. Beynon R, et al. The diagnostic utility and cost-effectiveness of selective nerve root blocks in patients considered for lumbar decompression surgery: a systematic review and economic model. Health Technol Assess. 2013;17(19):1-88. doi:10.3310/hta17190
  2. Sayed D, et al. The American Society of Pain and Neuroscience (ASPN) evidence-based clinical guideline of interventional treatments for low back pain. J Pain Res. 2022;15:3729-3832. doi:10.2147/JPR.S386879
  3. Narouze S, et al. Interventional spine and pain procedures in patients on antiplatelet and anticoagulant medications (second edition). Reg Anesth Pain Med. 2018;43(3):225-262. doi:10.1097/AAP.0000000000000700
  4. U.S. Food and Drug Administration. FDA Drug Safety Communication: FDA requires label changes to warn of rare but serious neurologic problems after epidural corticosteroid injections for pain. 2014. fda.gov

Illustration: Blausen.com staff, “Medical gallery of Blausen Medical 2014,” WikiJournal of Medicine, CC BY 3.0, cropped.