Nerve blocks are also known as regional anesthesia. This is a set of techniques developed by injection anesthesiologists as diagnostic and therapeutic tools. Some blocks are performed in and around the spinal nerves and spinal cord and are known as Spinal Blocks. Other blocks are done on more peripheral nerves or sympathetic ganglia.

Diagnostically blocks can help to pinpoint and differentiate a lesion. For instance, in a patient with lancinating pain radiating to a leg, allodynia of the foot and lower leg and temperature changes a selective nerve root block and a sympathetic block can help determine whether the pain is coming from an injured nerve root (CRPS 2) or activation of the sympathetic nervous system (CRPS 1). Blocks can often determined if the pain is coming from a local site or is referred from a more distant location. At other times there may be obvious pathology noted on imaging studies, but doing provocative procedures may show that the pain is actually coming from a more subtle injury. An example of this would be concordant pain evoked by a discogram done on a mildly degenerative or normal looking L4-5 disc, with an obvious herniation at the L5-S1 disc on MRI.

Therapeutic blocks can make a dramatic difference in acute and chronically painful conditions. Examples of this include the following. Serial sympathetic blocks can eliminate Complex Regional Pain Syndrome 1 (CRPS 1) in many patients, especially if caught early. This can be effective even later in the evolution of the condition. At times a continuous epidural infusion can be used to dramatically decrease symptoms from painful degenerative discs. Celiac plexus blocks can help dramatically decrease the pain of pancreatic cancer. Opioids delivered in an epidural catheter can provide excellent post operative analgesia. Therapeutic blocks can be short lived in their effectiveness or may have long lasting effects.

Blocks may also point out the value of other procedures. Discograms can show the need for fusion surgery or IDET procedures. Selective Nerve Root Blocks can confirm the efficacy of trying spinal cord stimulator implants. Opioid epidural infusions can point to the utility of using an intrathecal narcotic pump. Blocks of the facet joints and medial ramus of the nerve root can predict whether facet joint rhizotomies are likely to help.

Blocks are a very important aspect of diagnosing and treating pain disorders. Although invasive treatments are generally reserved for failure of more conservative measures, diagnostic and therapeutic blocks are an exception to this rule. In general they can be very effective early on in dealing with acute and chronic pain.