A major part of a patients treatment consists of correct diagnosis which will guide a logical decision making process leading to a prompt recovery. Since the spine has a complex biological and mechanical properties, finding the location of pain generators are not always an easy task. This process requires judgment, knowledge, and experience. In order to pin point the site of pain, a specific nerve can be blocked by a Selective Nerve Root Block (SNRB).
Using current advanced technology, we have the ability to anesthetize specific nerve roots or deliver local high concentrations of steroidal anti-inflammatory medication. This process can be used as a diagnostic as well as a therapeutic injection. It is performed under flouroscopic guidance. Flouroscopy allows the physician to obtain immediate X-ray images on a television screen which allows needle placement at specific anatomic locations. This system is shown to the bottom right of this page.
From information gathered by research studies, we now know that dysfunction is produced by mechanical pressure on a nerve, and pain is produced by the inflammation caused by this pressure. Placing an anesthetic solution around the nerve should alleviate the radicular pain temporarily and the steroidal medication will reduce inflammation, which will inurn, reduce the symptoms for a longer period.
SNRB is used more commonly for a far lateral disc herniation (herniated disc outside of the spinal canal). Since diagnosis of far lateral disc herniation is more difficult, this injection is very helpful in these cases. Once the diagnosis is confirmed, proper steps can be taken to treat the symptoms.
The procedure is performed under sterile conditions usually in an operating room under fluoroscopy (as seen in the bottom right picture). The surrounding skin is anesthetized and a needle is placed deeper next to the spine at specific anatomic locations. The needle is placed next to the affected nerve as it exists the spine. The picture to the right depicts such a situation. A herniated disc is placing pressure on the exiting nerve root causing dysfunction and pain. The needle is placed in the exit zone and anesthetic along with steroidal anti-inflammatory medications are injected in that area. After injection of the anesthetic solution, the patient is questioned regarding their familiar pain. If the pain has resolved, steroid medication is injected as well to decrease the inflammation for a longer period of time. This process could be repeated three times in a year period to achieve highest clinical value. SNRB is more difficult to perform than Epidural steroid injections and should be performed by physicians knowledgeable of the pertinent anatomy.
The results of these testings are only part of the workup for a specific spine condition. More commonly and MRI would have been performed prior to this procedure and the information obtained from all studies will dictate the course of action by your spine surgeon.
As with any procedure, risks, benefits, and alternatives should be discussed in advance. Risks are uncommonly encountered but include infection, and nerve root injury. Since the needle is placed in close proximity to the nerve root, patients may experience a transient increase in symptoms.
