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Procedure: Selective Nerve Root Block


What is a selective nerve root block (SNRB) injection?                                                                             

It is an injection of long lasting steroid medication into the area around specific nerve roots – that is the area in which the nerves exit the spinal column.  This is done when a specific nerve needs to be targeted, unlike an epidural, which targets all nerves in the area. 

What is the purpose of it?

The steroid injected reduces the inflammation and/or swelling of nerve roots in the epidural space caused by a torn or bulging disc, bone spurs or pinched nerve. This may in turn reduce pain, tingling/numbness and other symptoms caused by nerve inflammation/irritation and swelling.


How long does the injection take?

The actual injection only takes a few minutes, but plan to be in the office for one to two hours.  This allows for the patient's pre-op and recovery time as well.  The driver must remain in the building during the procedure.


What is actually injected?

The injection consists of a mixture of local anesthetic (like lidocaine or bupivicaine) and the steroid medication (triamcinolone or methylprednisolone).


Will the injection hurt?

The procedure involves inserting a needle through the skin and deeper tissue (like a tetanus shot). So, there is some discomfort involved. However, we numb the skin and deeper tissues with a local anesthetic using a very thin needle just prior to inserting the epidural needle. You may feel discomfort if the needle brushes against the nerve, similar to hitting your funny bone.  Most patients opt to receive IV sedation, which makes the procedure easy to tolerate.


How is the injection performed?

The procedure is done with the patient lying on their stomach unless you are having cervical then you will be sitting up in a chair. The Patients may be monitored with EKG, blood pressure cuff, and blood oxygen monitoring device. The area to be injected is cleaned with antiseptic solution and then the injection is carried out.


What should I expect after the injection?

Immediately after the injection, the patient's extremities may feel heavier and possibly numb. Due to the local anesthetic injected during the procedure, patient might notice their pain may be gone or quite less. The patient may also feel sore for two to three days due to the mechanical process of needle insertion as well as initial irritation from the steroid itself.  Patient should start to notice pain relief within three to seven days.

What should I do after the injection?

The patient should have a driver take them home. Coastal Bend Pain Management advises patients to take it easy for a day or two after the procedure, Normal activities, such as returning to work, can be resumed the day after the procedure.


How long does the effect of the medication last?

The steroid starts to work in about five to seven days and can last several days to a few months.


How many injections do I have to have?

If the first injection does not relieve patient's symptoms in about a week or two, they may be recommended to come in for an office visit to discuss further options or have one more injection. Generally we do not repeat injections that do not help patient's symptoms. Patients can only have three to six injections a year.


Will the epidural steroid injection help me?

It is very difficult to predict if the injection will indeed help or not. Generally speaking, the patients who have “radicular symptoms” (like sciatica) respond better to the injections than the patients who only have back pain.  Similarly, the patients with a recent onset of pain may respond better than the ones with a long standing history of pain.


What are the risks and side effects?

Generally speaking, this procedure is safe. However, with any procedure there are risks, side effects, and possibility of complications. The most common side effect is pain – which is temporary. The other risks involved are spinal puncture with headaches, infection, bleeding inside the epidural space with nerve damage, worsening of symptoms, etc. The other side effects are related to the use of steroids; these include increase in blood sugar (mainly in diabetics), water retention, suppression of body’s own natural production of steroid, etc.


Who should not have this injection?

If the patient is allergic to any of the medications to be injected, if they are on a blood thinning medication (ex: Coumadin, Plavix or Aspirin), if they have an active infection going on, if they are pregnant or suspect they might be pregnant, you should not have the injection.

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