Also known as discography, this refers to a diagnostic procedure that aims to identify discogenic pain, or pain that is related to the disc itself, and not from, for instance, the spinal nerves that lie in close proximity.
Epidural steroid injection refers to the instillation of a mixture of local anesthetic and anti-inflammatory medication to irritated nerve roots, generally in order to address radicular (leg or arm>back or neck) pain related to problems in the spine.
Facet injection refers either to injection into these joints themselves or injection of anesthetic in close proximity to the nerves that carry the signal from these joints in order to diagnose or treat axial low back or neck pain.
There are many applications of this technique, but most commonly, this term refers to the interruption of the nerves that carry the signal from the facet joints.
Sacroiliac joint injection refers to the injection of anesthetic and or anti-inflammatory medication into the joint in an effort to identify and potentially treat the sacroiliac joint as a potential pain generator.