Intradiscal electrothermal therapy in the treatment of discogenic low back pain

Abstract

Chronic low back pain is a common but challenging problem for the spine specialist. Although not completely understood, the concept of a discogenic pain mechanism as a source of low back pain has been described. Discogenic low back pain may be refractory to conservative measures. This pain is typically characterized by low back pain, which is usually exacerbated by axial loading such as prolonged standing or sitting. Concurrent leg pain or lateralizing pain may likewise be present but is typically less severe than the low back pain and does not possess the typical radicular pattern of pain distribution. A discogenic etiology is suggested by a combination of this clinical presentation and a positive discogram. The pain mechanism is believed to be caused by pathologic tears of the disc annulus with subsequent irritation of nerve fibers that innervate the annulus fibrosus. 1,2 Substance P, vasoactive intestinal peptide, and calcitonin have also been identified as nociceptive neurotransmitters within these annular nerve fibers. 3 The sinuvertebral nerve and the dorsal ramus mediate the mechanical or chemical stimulation of these nociceptive fibers. Granulation tissue and neural tissue have been demonstrated within these annular tears on histopathologic specimens and thus may also play a role in discogenic pain. 4 The traditional management of discogenic low back pain has relied on conservative measures including rest, physical therapy, and oral or locally administered medications. For those patients who fail to respond to a 6-month course of these conservative measures, surgical intervention with discectomy and fusion is often considered. Surgery is expensive and is associated with a long recovery period. Spine surgery is not without complications and requires anesthesia. Disc surgery is not always successful, and repeat operations are not uncommon. Ultimately, the spinal fusion itself may not succeed in alleviating the patient’s symptoms, and nonunion may be observed. 5 An alternative treatment to spinal fusion for the management of discogenic back pain is intradiscal electrothermal therapy (IDET). 6,7 This minimally invasive procedure involves the application of thermal energy to damaged disc tissue by a percutaneously placed catheter that contains a thermal resistive coil. Thermal energy shrinks and reorients collagen fibrils and cauterizes neural and granulation tissue within the torn annulus. This promotes healing of the annulus fibrosus. Coagulation of the irritated and damage nerve fibers promotes annular denervation and contributes to pain reduction. IDET is a relatively new procedure; it received Food & Drug Administration (FDA) clearance in 1998. Preliminary results with this procedure seem to indicate reasonable safety and efficacy in properly selected patients.