Dr. Koehler of Maastricht University has no relevant financial relationships to disclose.)
Percutaneous treatment of cervical and lumbar disc herniations involves several image-guided techniques meant to ablate protruding intervertebral discs. These techniques use a trocar so a variety of chemical, thermal, or mechanical ablative devices can be administered inside the nucleus pulposus. These procedures allow the surgeon to remove discs compressing over nerve roots. With these techniques, there is little damage to surrounding tissues. Tubular discectomy and percutaneous endoscopic discectomy are the 2 most commonly employed minimally invasive surgical techniques used, along with lumbar discectomy. Percutaneous intervertebral disc coagulation technique is a newer modality that is used for the treatment of lumbar and cervical disc hernias resistant to conservative therapy. Intradiscal injection of gelified ethanol has been found satisfactory in the management of both lumbar and cervical discs. The author explains the use of minimally invasive percutaneous thermal techniques, such as radiofrequency or laser nucleotomy, for the treatment of disc herniations. Indications, contraindications, and advantages of these technologies are described.
• Disc herniation is a common health problem with important social and economical consequences.
• Percutaneous disc decompression should be considered after 6 weeks of conservative management with antiinflammatories, physical therapy, and fluoroscopy-guided steroid infiltration.
• Radiofrequency nucleoplasty and laser decompression are less invasive than open surgery but can only be performed in contained disc herniations.
• Pain relief has been reported in up to 80% of selected patients treated with percutaneous disc decompression.
• Minimally invasive techniques, such as radiofrequency nucleoplasty and percutaneous laser disc decompression (PLDD), have challenged open surgical management of discogenic back pain. However, microdiscectomy is still considered the “gold standard” treatment.
Historical note and terminology
Percutaneous treatment of small- to medium-sized disc herniations aims to reduce the intradiscal pressure in the nucleus. The purpose of these techniques is to remove a small amount of central nucleus pulposus by using a variety of chemical, thermal, and mechanical approaches.
In 1934, William Jason Mixter and Joseph Barr elucidated the pathophysiological features of “lumbago” or “sciatica” (Mixter and Barr 1934). Since then, multiple therapeutic approaches have been developed. The historical mainstay in the treatment of disc herniation refractory to conservative management is discectomy; however, minimally invasive alternative procedures continue to evolve. In 1963, Smith and collaborators introduced chemonucleolysis with chymopapain to treat sciatica and proved the concept of disc decompression to relieve pain due to disc herniation (Smith et al 1963). Although the technique showed good results with a 70% to 80% success rate, it has been withdrawn because of the high rate of adverse reactions due to leakage toward the epidural space.
Parallel to the decreased used of chemonucleolysis, new percutaneous techniques evolved. In 1975, Hijikata and collaborators performed a percutaneous nucleotomy by inserting a 7-mm diameter tube into the disc annulus (Hijikata et al 1975). Open lumbar microdiscectomy was popularized 3 years later by Williams; technological advances allowed soft-tissue retraction through a small surgical corridor (Williams 1978). In 1983, Kambin and Gellman utilized forceps through a 6.5-mm outer diameter sheath to perform a posterolateral discectomy of the lumbar spine, which eventually represented a modified arthroscopic approach to discectomy (Kambin and Gellman 1983). Increased understanding of the arthroscopic anatomy of the foraminal and extraforaminal regions and the description of radiographic landmarks on the dorsolateral annulus combined with the availability of small-caliber fiber optic rods have led to the booming of arthroscopic spine surgery (Kambin et al 1998).
In 1985, Onik and collaborators reported the use of a 2-mm diameter suction and cutting probe for automated percutaneous nucleotomy (Onik et al 1985). Two years later, Onik reported the use of this technique in 20 patients with herniated discs (Maroon and Onik 1987). This new probe was similar to the automated vitrectomy instrumentation used by ophthalmic surgeons. Eighty percent of patients had good to excellent results in a short-term follow-up period of 6 months. Four patients subsequently required standard surgical excision of free disc fragments. The technique rapidly reached the same popularity as chemonucleolysis because of its safety and good results. However, the percentage of success with this procedure did not exceed 65%, similar to what has been obtained with conservative management. Therefore, the method has progressively been abandoned (Postacchini and Postacchini 2011). However, the concept of accessing the annulus fibrosus with a probe to relieve pressure has been adopted by new technologies like laser and radiofrequency.
The idea of using laser in the treatment of lumbar disc herniations arose in the early 1980s (Schenk et al 2006). Laser-assisted percutaneous discectomy was first reported in 1984, (Ascher and Heppner 1984). After a series of in vitro experiments, Choy and colleagues performed the first percutaneous laser disc decompression on a human patient in February1986 (Choy et al 1992). The United States Food and Drug Administration approved percutaneous laser disc decompression in 1991, and by 2002 over 35,000 percutaneous laser disc decompressions had been performed worldwide (Singh et al 2009).
Since 2002, new probes paved the way for intradiscal electrothermal annuloplasty for patients with chronic discogenic back pain. In 2004, Tsou and collaborators performed a posterolateral transforaminal selective endoscopic discectomy and thermal annuloplasty in a group of 113 patients (Tsou et al 2004). This technique allows direct visualization and targeting of the disc nucleus and annular fissures. The concept is that annular defects are the focal points of chronic exposure between neural sensory receptors in the defect and the nucleus pulposus. Therefore, radiofrequency thermal annuloplasty was used to interrupt the annular defect pain sensitization process. A total of 49 (43%) patients had good outcomes.
In 2010, Lee and Kang described favorable outcomes for carefully selected groups of patients with discogenic low back pain treated by percutaneous endoscopic laser annuloplasty (Lee and Kang 2010). The main benefit of this hybrid technique is that the procedure can provide decompression and thermal annuloplasty at the same time. A 90% success rate in pain reduction was reported in 30 patients treated at a single level. No procedure-related complications were reported.
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