A Review of Epidural Glucocorticoid Injections
Epidural glucocorticoid injections may provide modest transient benefit for amelioration of back and leg pain in patients with acute lumbosacral radiculopathy. However, they provide no benefit beyond three months. Given the possible self-limited natural history of acute lumbosacral radiculopathy and the availability of alternatives, epidural glucocorticoid injections are not recommended during the acute phase of lumbosacral radiculopathy. After weighing risks and benefits, their use may be reasonable for selected patients with lumbosacral radiculopathy who have not improved with conservative treatment over six weeks.
Epidural glucocorticoid injections have been used for pain control in patients with radiculopathy, spinal stenosis, and nonspecific low back pain. However, the efficacy is unclear due to inconsistent results as well as heterogeneous populations and interventions in randomized trials. In 2014, the US Food and Drug Administration issued a drug safety communication about epidural injection of glucocorticoids, noting the potential for rare but serious adverse effects (loss of vision, stroke, paralysis, and death) and that effectiveness has not been established. The best evidence for benefit comes from trials for patients with radiculopathy due to a herniated disc and demonstrates short-term, but not long-term, benefit.
Epidural glucocorticoid injections involve the administration of steroids via a needle inserted in the space between the ligamentum flavum and the dura. Epidural injections can be performed by the translaminar approach (via the interlaminar space in the spine), the transforaminal approach (through the neuroforamen dorsal to the nerve root), or the caudal approach (through the sacral hiatus at the sacral canal). Injections are administered by a number of spine specialists, including anesthesiologists, physiatrists, and interventional radiologists.
The interval or number of injections, optimal steroid dose, technique or site of injection, and whether local anesthetic should also be injected have also not been firmly established in randomized trials. In general treatment is with one or a series of up to three injections at intervals of no less than one month. Additional injections are not indicated if the initial injection does not improve symptoms. More than three injections at the same site within 12 months are usually not recommended because of concerns about potential suppression of the hypothalamic-pituitary-adrenal axis, though there is little objective evidence to support these parameters.
Serious complications of epidural glucocorticoid injections are rare and may include dural puncture, infection, and bleeding. A systematic review found that methods for assessing harms in randomized trials were not well reported and harms data were sparse. Thirteen of 30 placebo-controlled trials did not report harms at all or reported no harms. In the randomized trials (2912 patients in total), one serious adverse event (a case of retroperitoneal hematoma in a patient receiving anticoagulation) was reported in one trial. One trial of 120 patients receiving epidural glucocorticoids reported the following frequency of adverse events: post-injection headache, 3.3 percent; postdural puncture headache, 0.8 percent; nausea, 1.7 percent; and other events, 4.2 percent. The systematic review also found serious adverse events to be rare in large observational studies, though minor adverse events such as local hematoma, bleeding, return of blood, and dural puncture were more common. The largest study reported no cases of nerve damage, infection, abscess, or epidural hematoma after 2760 fluoroscopically guided lumbar epidural injections. Rates of bleeding ranged from 0.2 to 0.8 percent and transient nerve root irritation ranged from 0 to 4.6 percent, depending on the approach used. In a retrospective database analysis including 3000 patients, each successive epidural glucocorticoid injection increased the five-year risk of vertebral body fracture compared with a matched cohort of noninjected patients by a factor of 1.21 (95% CI 1.08-1.30) after adjustment of covariates. Patients considering a trial of epidural glucocorticoids should be made aware of a possible modest increase in vertebral fracture risk associated with each injection due to the increased risk of bone fragility. Further complications include risks of development of cauda equina syndrome, arachnoiditis, and adhesive arachnoiditis, these are mostly reported in case reports; current patient outcome data exclude these diagnosis from research reporting at this time.
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