Selective Nerve Root Block

Selective nerve root block · St. Louis

Selective Nerve Root Block Injection

A selective nerve root block places short-acting numbing medicine and anti-inflammatory medicine over one or two spinal nerve roots. That can be in the neck, mid-back or low back. If your main pain gets better, that nerve is the likely source. So the block both confirms the cause and treats it.

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Selective Nerve Root Block

What is a selective nerve root block?

Nerve roots exit your spinal cord and form nerves that travel into your arms or legs. These nerves allow you to move your arms, chest wall, and legs. These nerve roots may become inflamed and painful when something irritates them, like a damaged disc or a bone spur.

A selective nerve root block gives your doctor key facts. It is not a main treatment. It proves which nerve is causing your pain. It does that by placing short-acting numbing medicine over the nerve root in question. If your main pain gets better after the shot, that nerve is most likely the cause. If your pain stays the same, that nerve probably is not the cause.

By ruling your exact pain source in or out, it points to the right treatment. That may include more nerve blocks and/or surgery at one level. Selective nerve root blocks are like epidurals. But an epidural covers all of the nerve roots. A selective block covers just one or two nerve roots.

Dermatomes Radic

The thin layer that covers the spinal cord and nerve roots is called the dura membrane. The space around the dura is the epidural space. Nerves pass through the epidural space. Then they form the nerves that run down your arms, along your ribs and into your legs. These nerve roots may become inflamed. A damaged disc or the bones of the spine rubbing on them can cause this. A selective epidural injection puts anti-inflammatory medicine over the nerve root and into the epidural space. That calms the inflamed nerve roots, which cuts your pain. By reducing inflammation, the epidural injection may help the injury heal. It may give permanent relief. Or it may give several months of relief while the injury/cause of your pain heals.

The selective nerve root block (SNRB) numbs one nerve root that we think is causing the pain. It can be in the neck (‘cervical’), or in the back (‘thoracic’ or ‘lumbar’). The covering of the nerve root is injected and numbed to relieve this pain. This procedure is sometimes called a ‘Foraminal Block.’ The SNRB puts a small amount of strong medicine right into the sleeve around the problem nerve root.

Back Pain often has many causes and is hard to pin down. That is because its symptoms overlap a lot with other wear-and-tear problems of the spine. The SNRB helps both find and treat back pain. So it is both a test and a treatment.

In other words, say we inject medicine into the nerve root sleeve we suspect, and the pain gets better. Then we are fairly sure this nerve root is causing the pain. If we inject medicine and the pain is no better, this nerve root is likely not the cause.

What causes nerve root pain?

Patients with pain from an irritated nerve root often have a physical cause. Usually something nearby is pushing or pressing on the nerve, and that irritates it.

The most common causes are a disc problem or a bone spur next to the nerve. Either one, when it sits close to the nerve, can irritate it. That causes pain along the path of that nerve.

Selective Nerve Root Block

Radicular Pain

An irritated nerve in the back or neck can cause pain. Usually the pain is in the part of the body that nerve serves.

Selective Nerve Root Block

Who is a candidate for a selective nerve root block?

SNRB works best in patients with radicular pain (pain that shoots along a nerve). These patients should have recent scans (CT or MRI scan). Scans often help find the cause of pain. Not every patient will have a cause that shows on a scan. But all should have radicular symptoms. Nerve tests such as EMG help tell apart peripheral neuropathy, a trapped nerve and radiculopathy (a pinched nerve root).

Selective Nerve Root Block

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How is a selective nerve root block done?

We explain the procedure, answer your questions and get your signed consent.

You lie on the fluoroscopic (live X-ray) table. You lie prone (stomach down) for low back or mid-back shots, or supine (face up) for neck shots. The area is cleaned with povidone-iodine (Betadine) and alcohol.

The exact level is found with the fluoroscope (live X-ray). The skin over this area is anesthetized (numbed) with lidocaine. This is either to the right or left of the middle of the back.

A clean needle is moved along the nerve root sleeve. This usually sets off mild radicular pain along that nerve. We need to know whether that pain is like your usual pain (concordant response), or not like it (discordant response).

Usually, a small amount of water-soluble contrast (dye) is injected to confirm the needle tip is in the right spot.

Once this is confirmed, a mix of anesthetic (lidocaine or bupivacaine) and anti-inflammatory medicine (steroid) is injected.

The needle is slowly withdrawn.

This procedure may be performed with either CT or Fluoroscopic guidance.

What happens after a selective nerve root block?

Right after the procedure, you will get up and walk around. You will try to do something that normally sets off your usual pain. Then you will report how much of the pain is gone, as a percent. You will also track your relief over the next week.

You may not be able to drive the day of your procedure. Your legs or arms may feel weak or numb for a few hours. You may be referred to a physical therapist immediately afterward while the numbing medicine is still working.

You may have some weakness and/or numbness in your legs a few hours after the procedure. If so, do not do anything that needs lifting, balance or coordination.

Drink plenty of clear liquids after the procedure to help remove the dye from the kidneys.

General Pre/Post Instructions:

Eat a light meal within a few hours before your procedure. If you are a diabetic who uses insulin, do not change how you normally eat before the procedure. Take your usual medicines (i.e. blood pressure and diabetes medicines). Do not take pain medicines or anti-inflammatory medicines the day of your procedure. You need to be hurting before this procedure. Do not take any medicine that may ease your pain. You can restart these medicines after the procedure if you need them. If you are on Coumadin, Heparin, Plavix or any other blood thinners (including Aspirin), or the diabetes medicine Glucophage, you must tell this office. We will explain when to take them. You will be at our clinic for about 1-3 hours for your procedure. You will be awake under local anesthetic, with no sedation, so most patients drive themselves home. Arrange a driver only if your arm or leg feels weak or numb, and only until that wears off. Normal activity, including work, resumes within two to four hours.

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Selective Nerve Root Block FAQs

Both, but finding the cause is usually the point. Numbing one nerve root shows whether that nerve is causing your pain. Scans alone often cannot settle that.

An epidural covers a wider area around several nerve roots. A selective block aims at one root on purpose. So your response shows which level is the cause.

That still tells us something. Partial relief suggests the targeted nerve plays a part but is not the only source. That often points to more than one level being involved.

Usually, yes — we do not use sedation. The exception is short-term numbness or weakness in the arm or leg. That is possible for a few hours after the block. If it happens, wait until it is fully gone before you drive.

The test answer comes in the first few hours, while the numbing medicine is working. Keep a simple record of your pain during that window. It is truly useful, because it guides what we do next.

Your skin is numbed with lidocaine before the needle goes in. As the needle moves along the nerve root sleeve, it usually sets off a brief, mild flash of pain along that nerve. That moment matters: we need to know whether it matches your usual pain or feels different. We do not use sedation, so you stay awake to tell us, and then the numbing medicine takes over.

The effect to plan for is temporary weakness or numbness in your arm or leg for a few hours while the numbing medicine wears off. Until it clears, skip lifting and anything that needs balance or coordination, and do not drive. You may also feel a short flare of your usual nerve pain during the injection. Drink plenty of clear liquids afterward to help your kidneys clear the contrast dye.

It works in two stages. The numbing medicine lasts a few hours, and that window gives the test answer. The anti-inflammatory medicine calms the irritated nerve root more slowly. For some people that relief is permanent. For others it lasts several months while the disc or bone problem behind the pain heals. If relief fades, the block has still shown which nerve to treat next.

You can return to normal activities, including work, within two to four hours. Plan on one to three hours at our clinic. Most patients drive themselves home; arrange a driver only if your arm or leg feels weak or numb, and rest until that wears off. You may be sent straight to physical therapy while the numbing medicine is still working.

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Pain Conditions We Treat​

At Padda Institute, our pain management specialists & pain specialist doctors provide you the guidance and treatments tailored to your needs. We are best at what we do; we diagnose and evaluate to determine your best treatment plan, so that you can experience chronic pain relief like never before.

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Part of our complete guide to Interventional Pain Management in St. Louis.