Intradiscal Techniques دکتر مهرداد نوروزی دانشیار بیهوشی و فلوشیپ درد دانشگاه علوم پزشکی کرمان

It has long been postulated that annular disruption can be a source of low back pain (LBP). In normal disc anatomy, nociceptive fibers innervate only the outer third of the disc annulus, but in vitro and in vivo studies have shown nerve and blood vessel in growth into deeper layers of the annulus, with high expression of substance P and clinically severe discogenic LBP.

Traditionally, discogenic LBP, or pain from IDD, has been treated with conservative care: Activity modification, analgesic medication, physical therapy, steroidal spine injections, chiropractic care, manual therapy, acupuncture, and other modalities. Surgical arthrodesis or disc replacement may be performed when discogenic LBP remains unresponsive to conservative treatments. There is significant variability in outcome following arthrodesis or disc replacement, and complications can include infection and adjacent segmental instability.

Radiofrequency ablation or thermal neurolytic treatment of the posterior annulus is in theory a plausible technique to ablate nociceptors and modify collagen of the annulus fibrosus of painful discs. Several percutaneous intradiscal techniques have been developed to attempt effective treatment of lumbar discogenic pain.

Options for treatment of discogenic pain • Intradiscal injections. Chemonucleolysis. Ozone injection. • Annuloplasty. Intradiscal electrothermal therapy (IDET). RF posterior annuloplasty (RFA). Biacuplasty. • Percutaneous disc decompression. Laser discectomy. RF coblation (plasma discectomy). Mechanical disc decompression (Dekompressor®). Manual percutaneous lumbar discectomy (PLD). • Endoscopic percutaneous discectomy.

In the late 1990s, intradiscal electrothermal therapy (IDET) was developed on the theory that thermal heating of the posterior and posterolateral disc annulus results in collagen fiber contraction and neurolysis of nociceptors within a painful or sensitized intervertebral disc in addition to enhancement or stimulation of chondrocytes promoting disc repair.

In practice, IDET uses a thermal resistive catheter placed intradiscally at the site of a radial or circumferential annular fissure to deliver RF energy to the posterior intervertebral disc. This RF energy is converted into heat, resulting in a thermal lesion of the disc annulus and neurolysis of upregulated nociceptors. Temperatures at or above 65°C result in consistent shrinkage of unwound triple-helix collagen fibers. Clinically this has been verified by disc shrinkage or resolution of disc displacement on MRI occurs following IDET.

After IDET, the intranuclear pressures decreased by 6% to 13 further supporting a biomechanical hypothesis for IDET efficacy. Although post-IDET annular contraction, thermally induced healing, sealing of annular tears, neurolysis of nociceptors and decreased intradiscal disorder are proposed mechanisms of pain reduction. The exact mechanism of intradiscal RF procedures effecting pain relief remains unclear .

INTRADISCAL ELECTROTHERMAL THERAPY TECHNIQUE The IDET procedure is performed percutaneously, similar to standard disc puncture techniques like discography . Conscious sedation is used to ensure patient comfort, though patients must be able to respond to commands and accurately report feelings of dysesthesias or radicular pain during needle placement, catheter placement, and disc heating, if these occur.

Most patients experience their typical LBP during the heating protocol, often with vague aching into the buttocks or legs. This must be differentiated from true radicular pain, specifically if these symptoms are severe and occur early during disc heating.

Following the procedure, back bracing is recommended for several weeks, followed by a lumbar stabilization and reconditioning program.

COMPLICATIONS Rare complications of IDET have been reported : -Catheter breakage, -post-IDET disc herniation, -cauda equina syndrome, -vertebral end plate osteonecrosis, - radiculopathy -foot drop,- decreased sphincter tone,- fecal incontinence, and discitis. In a meta-analysis of 17 reports on IDET, the complication rate was found to be 0.8%.

Mean improvement in the visual analog scale (VAS) after IDET was 3 in one review and in another, IDET was described as “modestly effective in the treatment of lumbosacral discogenic pain in carefully selected patients. Patients not likely to benefit from IDET include those with multilevel degenerative disc disease, overweight patients, and patients receiving worker compensation .

BIACUPLASTY Biacuplasty, or intradiscal bipolar water-cooled RF, is a more recent development in discogenic pain management and improves on some of the deficiencies of the IDET procedure. Similar to IDET, biacuplasty deploys thermal energy to the painful upregulated annulus, but in this case delivers bipolar RF energy via two stiff adjacent electrode probes placed intradiscally

Electrodes are actively and internally cooled during the ablation procedure with a peristaltic pump unit that circulates water through the probes to cool the electrodes, allowing bipolar RF energy to heat annular tissue adjacent to and between the two electrodes while the tissue in immediate contact with each electrode probe is actively cooled. Peak tissue temperatures are much lower with biacuplasty than those with IDET, offering an additional advantage of better procedural tolerability for patients. The electrode probes are typically placed with greater ease than the IDET coil, a technical advantage over IDET.

TECHNIQUE Needle tip placement is in the posterolateral nucleus–annulus junction, half-way between the superior and inferior end plates of the adjacent vertebral bodies. Electrode probes are then placed into the introducer needles. The temperature of the electrode remains at 45° C, while disc tissue temperature is heated to 55 to 60° C in the inner annulus and 45° C toward the edge of the annulus.

PERCUTANEOUS DISC DECOMPRESSION Percutaneous disc decompression (PDD) is based on the principle that small decreases in volume within an enclosed space will result in a disproportionately higher drop in pressure.

PERCUTANEOUS DISC DECOMPRESSION WITH NUCLEOPLASTY Nucleoplasty is a method of percutaneous intervertebral disc decompression approved by the U.S. Food and Drug Administration in 1999 for selected patients with persistent radicular pain due to small, contained herniated lumbar discs or contained disc bulges unresponsive to conservative, nonsurgical therapy.

This intradiscal transmission of energy excites the surrounding tissues, causing molecular bonds of the nucleus pulposis to break, vaporizing disc material into lowmolecular-weight gases (hydrogen, oxygen, carbon dioxide), which then exit the percutaneous needle. Thus, a small volume of the nucleus pulposis is removed, creating a profound decrease in intradiscal pressure. Decreased annular wall stress allows the intact annulus to retract from irritated neural tissue, thereby providing pain relief

TECHNIQUE Nucleoplasty is performed similar to other intradiscal techniques previously described. After an introducer needle is placed in the disc a nucleoplasty electrode is then placed through the introducer needle and advanced across the disc .

Patients should be awake and responsive during this procedure. Tissue ablation and coagulation is performed with each “pass” across the nucleus pulposis, creating a single channel within the disc. After making six channels within the disc, a total of 1 cc of intradiscal volume is removed via vaporization, with a significant decrease in intradiscal pressure. Patients should be awake and responsive during this procedure. Patients are typically able to resume normal activities within 1 to 2 weeks of the procedure.

OTHER METHODS OF PERCUTANEOUS DISC DECOMPRESSION Percutaneous disc decompression (PDD) can also be accomplished with a percutaneous disc probe (Dekompressor Stryker, Kalamazoo, MI). In contrast to nucleoplasty the Dekompressor probe mechanically removes nucleus pulposus material without RF energy or thermal heat

Intradiscal Ozone Chemonucleolysis As a result, an oxidative dehydration takes place in the nucleus; this is comparable with chemonucleolysis by means of chymopapain. In addition, upregulation of the intracellular antioxidant scavenger system occurs due to oxidative stress; this results in an increase endogenous anti inflammatory

Ozone nucleolysis may be done in most kinds of disc related pain. 1. It can be done in degenerated disc without any prolapse and nerve root irritation. This category is called discogenic back pain or back pain due to internal disc disruption.

2. It can be done in contained disc prolapse or disc bulge with root irritation. 3. It may be done in non-contained disc (extruded or sequestrated disc) as well

Directly inject to nucleus pulpusos Ozone dissolve in intradiscal nucleus pulposus water&react with macromolucular components such as PG. Oxidation of these substances break down the 3-D structure. Water will be reabsorbed . Decrease intradiscal pressure . Shrinkage of disc . Progressive disappearance of the herniated material . Reduce the pressure on nerve roots . Disappear the pain .

CONCLUSION Although there is a limited number of high-quality clinical trials of intradiscal procedures available in the literature, patients in prospective studies who meet strict selection criteria for these minimally invasive procedures appear to benefit with reduced pain, decreased analgesic requirements, and improved function