Selective Nerve Root Block

Selective Nerve Root Block

What is a Selective Nerve Root Block (SNRB)?
A SNRB is primarily done to diagnose the specific nerve root pain source and for therapeutic relief of low back pain and/or leg pain.

How does it work?
When the nerve root becomes compressed and inflamed it produces back and/or leg pain.  Sometimes the MRI may not clearly show which nerve is causing the pain so an SNRB injection is done to help in isolating the source of pain.  It also can be used to treat far lateral disc hernia ion. (a disc that ruptures outside the spinal canal).

How long does the injection take?
The actual injection takes only a few minutes.

What medications are used for the injection?
The injection consists of a mixture of local anesthetic (lidocaine or bupivicaine) and the steroids (depo-medrol or betamethasone)

Does the injection hurt?
The procedure involves inserting a needle through the skin and deep tissue.  So, there is some discomfort involved.  But, we will numb the skin and deep tissues with a local anesthetic (lidocaine) before inserting the block needle.  Most of the patients also receive intravenous sedation and pain medication, which makes the procedure easier to tolerate.

Will I be “put to sleep” for this procedure?
No.  This procedure is done under local anesthesia.  Most of the patients also receive intravenous sedation and pain medication, which makes the procedure easier to tolerate.  The amount of sedation given usually depends upon the patient tolerance.

How is the injection done?
It is done with the patient lying on their stomach, under fluoroscopy (live x-ray).  All of our patients are monitored with EKG, blood pressure cuff and blood oxygen-monitoring device (pulse oximeter).  The skin on your back is cleaned with antiseptic solution and then the injection is done.

What should I expect after the injection?
Shortly after the injection, you may feel that your pain is gone or much less.  This is due to the local anesthetic that was injected. If the patient’s pain goes away after the injection, the source of the pain was probably the specific nerve root that was injected.  Following the injection, the steroid also helps reduce inflammation around the nerve root. Some common effects of the local anesthetic are temporary weakness, numbness or tingling on the affected side.  Since the injection is right next to the nerve root, sometimes an SNRB will temporarily worsen the patient’s leg pain.

What should I do after the procedure?
You need to have a ride home.  Make sure that you have something to eat or drink within an hour or two after the block.  We advise the patients to take it easy for a day or so after the procedure.  You may want to apply ice to the affected area.  Perform your normal daily activities as tolerated.

When can I go back to work?
Unless there are complications, you should be able to go back to work the next day.  The most common thing you may feel is a sore back.  Ice at the injection site will help with the soreness.  You may also take ibuprofen or acetaminophen for the discomfort.

How long will the block work?
The immediate effect is usually from the local anesthetic injected.  This wears off in a few hours.  The cortisone starts working in about 3 to 7 days and its effects can last for several days to a few months.  Success rates vary on the primary diagnosis and whether or not the injections are being done only for diagnosis.

How many injections will I need to have?
If the first injection does not relieve your symptoms in about a week to two weeks, you may be recommended to have one more injection. If you respond to the injections and still have residual pain, you may be recommended for a third injection.

Can I have more than three injections?
In a six-month period, we usually do not perform more than three injections.  If three injections have not helped you much, it is unlikely that you will get any benefit from more injections.  Also, giving more injections will increase the likelihood of side effects from cortisone.

Does the SNRB injection help everyone?
No.  It is very difficult to predict if the injection will help or not.  Usually, the patients who have recent onset of pain tend to do better than the ones with long standing pain.

What are the risks and side effects?
The procedure is safe. But, with any procedure there are risks, side effects and possibility of complications.   The most common side effect is pain- which is temporary.

Sometimes an SNRB will temporarily worsen the patient’s leg pain because the injection is right next to the nerve root.  The other risks involve infection, bleeding, worsening of symptoms, spinal block, epidural block etc.  The other risks are related to the side effects of cortisone:  these include weight gain, increase in blood sugar (mainly in diabetics), water retention, suppression of body’s own natural production of cortisone etc  Fortunately, the serious side effects and complications are rare.

Who should not have this injection?
If you are allergic to any of the medications to be injected, if you are on a blood thinning medication (i.e. Coumadin, Plavix, aspirin or aspirin containing medication, or if you have an active infection, you should not have the injection.

Be aware that herbs Ginseng, Garlic and Gingko Baloba and Vitamin E are blood thinning.

* DO NOT STOP ANY OF YOUR MEDICATIONS BEFORE CONSULTING WITH YOUR DOCTOR*