A selective nerve root block (SNRB) is an injection that delivers medication into the space around spinal nerve roots. The goals of this treatment are to determine the location of a specific spinal nerve root that is the suspected cause of the pain and, secondarily,  to provide relieve back, leg or other pain caused by the irritated spinal nerves. A SNRB may also be used therapeutically for the treatment of specific types of disc herniations.

What to Expect During a Selective Nerve Root Block
An SNRB generally follows this process:

The patient lies face down on an x-ray table and the skin is well cleaned with an antiseptic.

The physician locates a specific spinal nerve root using fluoroscopy, a type of X-ray that provides real-time video imaging of your body.

Once the nerve root is located, the physician introduces a needle through the skin into the area adjacent to the spinal nerve

Medication — steroids (to decrease inflammation) and/or a local anesthetic (to numb the area) — is then injected into the area bathing the nerve root.

If the patient's pain subsides after the injection, the pain-generating nerve root is presumed to have been identified.

The procedure normally takes 30 to 60 minutes.

What Causes Spinal Nerve Inflammation?
Spinal nerves can become inflamed due to compression, for example from a damaged disc or from contact with a bone spur. Depending on the location of the inflamed nerves, pain and/or other symptoms (such as numbness, tingling) may be experienced in different areas of the body. Nerve irritation in the cervical spine can cause pain, tingling or numbness in the neck, arm or shoulder. Nerve irritation in the thoracic spine can produce upper back pain or pain along the ribs and chest wall. Irritation of lower back (lumbar) nerves can produce lower back pain, hip pain, buttock pain or pain, tingling or numbness in the leg.