A selective nerve root block is a precise spinal injection that is sometimes performed with fluoroscopic (X-ray) guidance for enhanced accuracy. During this procedure, a physician carefully delivers a mixture of a local anesthetic and a long-lasting steroid medication (cortisone) to a nerve root at the point where the nerve branches away from the spinal cord.

SNRB injections can be used for both diagnostic and therapeutic purposes. Because a single nerve root can be targeted and numbed, this procedure can help a physician pinpoint the specific nerve root that is causing a patient’s symptoms (if the patient experiences immediate relief due to the numbing effect of the anesthetic, the problematic nerve can be identified). Additionally, the cortisone can help reduce inflammation and pain that result from the compression or irritation of the nerve.

How soon will the injection take effect?

You can expect to see some of the effects of a selective nerve root block right away. Immediately after an injection, you may experience short-term pain relief due to the action of the local anesthetic. This will wear off within a few hours, after which your original pain may return — and possibly worsen — for a day or two. If your pain temporarily intensifies, it can likely be attributed to the mechanical process of needle insertion as well as initial irritation associated with the steroid medication. To manage this type of discomfort, you might find it helpful to apply an ice pack to your injection site. Within three to seven days, you may begin to experience meaningful pain relief as the steroid medications take effect.

Will further injections be necessary?

If an initial injection does not provide sufficient symptom relief within one to two weeks, a physician may recommend a second — and possibly third — injection to address residual pain. In general, however, most physicians advise against having any more than three injections within a 12-month period. This practice can help reduce the risk of side effects associated with the repeated use of cortisone, which can affect the body’s natural hormonal balance. What’s more, if three SNRB injections performed with fluoroscopic guidance result in little to no relief, it is unlikely that further injections will provide any significant benefits.

If you’d like to find out whether you could benefit from a selective nerve root block, you should schedule a personal consultation with a physician.