Epidural Corticosteroid Injection
Pain specialists have used epidural corticosteroid injection (ESI) for decades to treat back and neck pain. The procedure is further divided into cervical ESI, thoracic ESI and lumbar ESI (LESI) with the purpose of treating the pain originated from different spinal regions. By 1995, there were at least twelve so-called double-blind, placebo-controlled studies investigating the clinical efficacy of LESI for low back pain. Of these studies, only six yielded positive results, while the other studies did not support the use of LESI for low back pain. Actually several of these studies exhibited the critical flaw of treating “low back pain” as a single entity.
It is now realized that low back pain is a clinical syndrome that may be caused by a variety of pathologies in the lumbar spine and adjacent organs. It is not reasonable to treat low back pain with epidural corticosteroid injections regardless of the cause. More recent, well-designed, placebo-controlled studies have provided clinical evidence that LESI decreases lumbar radicular pain (nerve root pain) caused by lumbar disc herniation. The pain-relieving effect of LESI may last up to three months. Corticosteroids appear to speed the rate of recovery and return of function, allowing patients to reduce medication levels and increase activity while waiting for the natural improvement expected in most spinal disorders. Recent studies also support the use of LESI for pain relief in patients with spinal stenosis (narrowing of spinal canal).
Disc Herniation Pain
It is now believed that the pain in patients with disc herniation and associated radiculopathy is not simply due to mechanical compression, but is due to chemical inflammation of the nerve roots and nerve endings. Past the age of 60, more than 90 percent of the normal population has a variety of degenerative spine changes including disc herniation, spinal stenosis and foraminal stenosis. The majority of persons with these changes, however, do not have pain. Human discs contain high levels of phospholipase A2. This enzyme is responsible for the liberation of arachidonic acid from cell membranes, and has a theoretical inflammatory potential. It therefore appears that the primary function of a local corticosteroid injection is to suppress the function of phospholipase A2 and to decrease the inflammation around the nerve roots. It is reasonable to let patients have a trial of LESI before considering a surgical treatment for lumbar disc herniation. The procedure often prevents back surgeries. As long as pain is relieved and the patient is free of neurological deficits, a herniated disc should be left alone without further treatment.