The mechanism of action and side effects of epidural steroids

Immediate Pain Response Does Not Predict Long-Term Outcome of CT-Guided Cervical Transforaminal Epidural Steroid Injections

“…Though Mixter and Barr 11 demonstrated that sciatica was associated with disk herniation in 1934, recent research has demonstrated that radicular pain is not only caused by mechanical injury but also by chemical inflammatory factors. [12][13][14][15][16][17] These findings are substantiated by clinical findings such as asymptomatic prominent disk protrusions, radicular pain without mass effect on a nerve, and trials demonstrating improvement in pain without surgical decompression.…”

“…16 PLA2 initiates the arachidonic acid cascade that leads to the production of prostaglandins, thromboxanes, and leukotrienes, all inflammatory mediators. 12,22 Inflammatory mediators, in turn, cause a range of effects including recruitment of immune cells (leukocytes, lymphocytes, macrophages, platelets, and mast cells) and the subsequent activation of these cells, edema through effects on the vasculature, and production of inflammatory cytokines among oth- ers. The inflammatory response can cause additional tissue injury, including Wallerian degeneration.…”

“…Indeed, the antiinflammatory properties of steroids are a major rationale for these injections. 12,22 There are many mediators that can generate an inflammatory response. High levels of phospholipase A2 are found in the intervertebral disk, and elevated levels of PLA2 have been found in tissues from human radiculopathy patients 17 and animal models.…”

“…This cascade also can increase pain through hypersensitization of the neural roots to stimuli that may not normally be painful. 12,22 The transforaminal injection of steroids can be effective by interacting with the inflammatory response at several points. A primary target of the steroid is the inflammatory cascade, particularly the effects of phospholipase A2 and the lipoxygenase pathway, thus reducing the downstream production of inflammatory mediators.…”

Epidural Steroid Injections

“…As a modulator of arachidonic acid, phospholipase A2 has been postulated to play a major role in several pathological conditions resulting in back pain [29]. Phospholipase A2 has been found in high concentrations in intervertebral discs, which could explain why conditions causing pressure, inflammation, and rupture of these discs result in chronic back pain [30].…”