Are not a nerve block, but are a very important diagnostic injection procedure used to determine which intervertebral discs in the spine, if any, are causing pain ("pain generator"). Depending on where the pain is, the injection may be performed in the cervical (neck), thoracic (upper back), or lumbar (lower back) spine. This is a procedure requiring an experienced and skilled physician, as are available at CPMC. Because it is a highly technical test and there are increased risks of infection (discitis) associated with it. We always administer antibiotics prior to the procedure and also in the medication injected into the disc, which reliably prevent such infection. Discograms are also a procedure which is not routinely performed unless most other conservative treatments have failed to control the pain and spinal surgery is being contemplated. But the information provided by the discogram procedure is extremely valuable, actually essential, for the surgeon to determine precisely where to operate in order to relieve pain.