When, How, and Why to Use Epidural Corticosteroid Injections: An Overview
Acknowledgements: Dr. Kaplan wishes to extend special thanks to Dr Paul Dreyfuss of Tyler Texas, for his assistance in literature review and for his scholarly mentorship. "I follow your teachings, ‘Always check three radiographic views’ and ‘Remember that only the needle knows.’"
Spinal epidural steroid injections are commonly utilized in the treatment of acute and chronic neck, thoracic, and low back pain, as well as radicular pain in the arms or legs (Fig. 1). They are a valuable treatment modality in a number of spinal conditions but should primarily be used as a component of a comprehensive treatment plan, including medications and physical therapy, but never as a treatment in isolation (14). These injections can provide analgesic and anti-inflammatory effects, reduce stiffness, restore range of motion, and facilitate active therapy. They may also provide diagnostic confirmation of a specific "pain generator" when performed selectively at a target nerve or site.
Fig 1. Lumbar epidural blocks performed under fluoroscopy are most commonly performed using a paramedian approach. With this approach, the interlaminar space is visualized with AP fluoroscopy. Typically either a Tuohy or Crawford needle is used. The needle gauge can range from 22-gauge (generally for more experienced injectionists) to 18-gauge (for novice injectionists). The needle is advanced through the ligamentum flavum under direct fluoroscopic vision and the epidural space is identified by loss of resistance to either normal saline or Xylocaine. It is easier to feel the resistance of the ligamentum flavum using larger gauge needles. The exact depth of the ligamentum flavum can be estimated by first hitting the lamina and then advancing the needle 4 to 5 millimeters until firm resistance is felt.
Injection of corticosteroids into the epidural space for treatment of lumbosacral radicular pain was first recorded in 1952. Since that time there have been several reports and case studies on the subject, but few controlled clinical trials (some of which will be referenced in this review). Despite the lack of universal acceptance, the majority of the medical literature supports the use of epidural steroid injections for the treatment of radicular pain caused by common structural abnormalities such as lumbar disc herniation and spinal stenosis (3, 5, 18). Some of the controversies over epidural steroid injections in the literature center around such issues as the use of fluoroscopic guidance, the ideal site of administration of medication (translaminar, transforaminal, or caudal), the mechanism of action of the injectate, the inherent risks of the procedure, and even the absolute indications (8, 13). These will be addressed in this overview discussion.