What is a selective nerve root block?

Each spinal nerve is prone to compression and irritation as it leaves the spine. It is purely a diagnostic, not a therapeutic, procedure. It is used typically to localize a pain problem prior to further treatment such as surgery. Local anesthetic is injected around the nerve as it eaves the spine. If numbing the nerve helps the pain, then the assumption is made that it is the source of the pain.  In the illustration, a target nerve is colored red while the foramen is blue.

What will happen during the procedure?

You will lie on your stomach and be made as comfortable as possible. The skin will be numbed with local anesthetic. Using an X-ray machine for guidance, Dr. Harries will position a needle correctly then inject a small amount of X-ray dye. If everything appears satisfactory, the numbing medication will then be injected. This procedure will then be repeated for each nerve.  After the procedure, you will be taken to the recovery area and observed for about 20 minutes. Your pain score will be recorded. After the procedure, it is important that you maintain a pain diary for 48 hours.

Can I be sedated for the procedure?

Sedation may significantly increase the risks of the procedure and make interpretation of the results less certain.

What are the risks of the procedure?

This is a very safe procedure. Feeling faint is the most common problem patients experience. Numbness in the affected nerve is usually a welcome sensation and is to be expected. Short lasting weakness may also occur in the muscles that the nerve supplies. This usually resolves within hours. Allergic reaction to medications, bruising and infection are all very rare complications. Increase in pain is always a possibility with any procedure.

Are there any rare but serious risks with this procedure?

A very rare but serious complication can occur when a similar procedure transforaminal epidural is performed, particularly in the neck. It is felt that the cause of this is inadvertent injection of steroid into a blood vessel supplying the spinal cord. Paralysis has resulted in a small number of patients. As no steroid is injected during this procedure, the risk of serious complications is clearly far lower than for a transforaminal epidural. When Dr. Harries performs this procedure, he uses a special X-ray technique (Digital Subtraction Angiography) to look for any abnormal blood vessels. If there are any abnormal blood vessels present, the procedure is stopped. It should be emphasized that serious complications from this procedure are extremely uncommon particularly in the lumbar area.
Dr. Harries does occasionally see abnormal blood vessels that may supply the spinal cord. The above illustration is an example of one such patient. Whenever Dr. Harries sees such an abnormality he abandons the procedure. None of Dr. Harries patients with an abnormal blood vessel have suffered any harm.

How long does the pain relief last?

There is enormous variation in this regard depending upon how quickly your blood removes the numbing medication from the area of the nerve.

How long does it take for the procedure to work?

The benefits from local anesthetic, if injected are felt within 1 hour.

When can I return to work?

Most patients can return to work the following day. After any procedure it is possible to develop an increase in pain particularly from muscle spasms.

When can I drive?

You should not drive until the next day.

What research is there on the effectiveness of this procedure?

Research studies demonstrate that this is a more effective treatment than conventional epidurals when performed for nerve pain.

How does a selective nerve root block differ from a transforaminal epidural?

A selective nerve root block is very similar to a transforaminal epidural except for the following

1) A smaller volume of local anesthetic is injected around the nerve

2) No steroid is injected.

3) It is purely a diagnostic not a therapeutic procedure. It is used typically to localize a problem prior to further treatment such as surgery.