With a transforaminal epidural steroid injection (ESI), often referred to as a 'nerve block', the needle is placed alongside the nerve as it exits the spine, and medication is placed into the 'nerve sleeve'. The medication then travels up the sleeve and into the epidural space from the side. This allows for a more concentrated delivery of steroid into one affected area (usually one segment and one side). Transforaminal ESIs can also be modified slightly to allow for more specific coverage of a single nerve and can provide diagnostic benefit, in addition to improved pain and function.
An epidural steroid injection involves bathing an inflamed nerve root in steroids (potent anti-inflammation medicine) in order to decrease the irritation of the nerve root that is causing pain. Epidural steroid injections are most commonly used in situations of radicular pain, which is a radiating pain that is transmitted away from the spine by an irritated spinal nerve. Irritation of a spinal nerve in the low back (lumbar radiculopathy) causes pain that goes down the leg. Epidural injections also are used to treat nerve compression in the neck (cervical spine), referred to as cervical radiculopathy.