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Selective nerve root block injection (SNRB) is an injection of a long-lasting steroid (cortisone) around the nerve root as it exits the spinal column.
The injection reduces the inflammation and pain caused by pressure on the nerve. It can also be used as a diagnostic tool to help doctors determine whether the nerve is irritated by “numbing” the nerve. One of the most common conditions to benefit from selective nerve root injections is a herniated disc that causes low back and leg pain (sciatica).
UPMC neurosurgeons perform this procedure with the patient lying on the stomach on an x-ray table. The surgeon uses fluoroscopy (x-ray) to help locate the specific nerve root.
A needle is inserted into the area and the medication and an anesthetic are injected. The injection takes just several minutes. After the injection, the patient is monitored for 15-20 minutes and then released. Most patients start noticing pain relief after the third to seventh day, which can last weeks or months. If the first injection fails to relieve pain symptoms in one to two weeks, the doctor may recommend another injection. In a 12-month period, doctors usually limit injections to three.
Giving more than three injections in a year may increase the likelihood of side effects from cortisone.