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Disc Annuloplasty
Andrea Trescot, MD, FIPP
DISCLOSUREAndrea Trescot, MD
Director of Education, WIP
Medical director: Pinnacle Lab Services (not relevant to this program)
Disc as a Source of Pain?
• Although reports of nerve fibers in the annulus fibrosis were seen as early as 1940, consideration of the discs as a source of pain (as apposed to HNP) did not come until 1970
Roofe PG. Innervation of the annulus fibrosus and posterior longitudinal ligament: fourth and fifth lumbar level. Arch Neurol Psychiat. Chicago, 1940;44;100.
Crock HV. A reappraisal of the intervertebral disc lesion. Med J Aust 1970;1:983-989
• Clues for painful, degenerative disc:– “dark” appearance on T2 weighted
image– loss of height– reactive changes of the end-plates
and high intensity zone (HIZ)
Imaging Correlation
Large Disc Herniation
Disc Annuloplasty
• The term intervertebral disc annuloplasty indicates any procedure aimed at repairing the annulus of a bulging intervertebral disc before it herniates.
• Potentially addresses a problem that is difficult to treat with standard surgical techniques
Abtruse Acronyms
TIPs - Thermal intradiscal proceduresIDET - Intradiscal electrothermal therapy IDEA - Intradiscal electrothermal annuloplastyIDTA - Intradiscal thermal annuloplastyIRFT - Intradiscal radiofrequency thermocoagulationPIRFT- Percutaneous intradiscal radiofrequency thermocoagulation
… and Confusing Semantics PIRFT is commonly used to designate two procedures where RF is directly aplied to the disc,The Intranuclear RF and the RF annuloplasty with the DiscTRODE
IDET is commonly used to designate the RF annuloplasty done with the SpineCath
discTRODE™
Percutaneous Intradiscal Radiofrequency Thermocoagulation (PIRFT)
• discTrode™ placed a heating element across the posterior annulus (within the lamelli) form one side, with a thermister from the other side
• Technically difficult and rarely performed any more
Intradiscal Electrotherapy
Intradiscal Electrothermal Annuloplasty (IDET)
• Also known as Intradiscal Thermal Annuloplasty (IDTA)– Placement of a thermal catheter within
the disc• between the annulus and the nucleus
L4
SAP
L3
L3-4= puncture target
ANESTHETICNEEDLE
PROCEDURENEEDLE
STYLETTE REMOVED
Complications
• catheter breakage• nerve root injuries • post-IDET disc herniation • cauda equina syndrome • infection • epidural abscess• spinal cord damage
Nerve root
Dura
Before IDET
Operatingwire probe
Adhesions
After IDET
IDET Conclusion
• Safe• Minimally invasive• Outpatient procedure• Effective for well-selected patients• May prevent or delay the need for fusion• May need follow-up adhesiolysis
Bipolar “Conventional” RF
• Attempts were made to place an RF needle at each side of the disc, using a bipolar energy to create a “heat strip”
The cannulae should be placed between 4 and 6 mm apart to maximize the surface area of the resultant lesion. Treatment duration of 120 to 150 seconds at 90°C is required to maximize the size of the strip lesion
Pino et al. Reg Anesth Pain Med 2005
Why Bipolar “Conventional” RF Can’t be Effective
Why Bipolar “Conventional” RF Can’t be Effective
“Cooled” Radio Frequency Lesioning
Probe
• Without cooling, the size of lesion is limited by the heat generated in the tissue adjacent to the electrode
• It is not desirable to raise tissue temperature above 95° C• Cooling the tissue adjacent to the electrode allows effective heating at a greater
distance
Non-cooledCooled
Temperature
Distance
80° C
45° C r
Ionic Heating Using Cooled RF
Internal cooling doubles the lesion radius and increases the lesion volume by a factor of 8
Standard RF Internally-Cooled RF
Cooled vs. Non-Cooled RF Lesions
(a) Single lesions (b) Strip lesion
Tissue
Tissue
Two electrodes of similar size are used. A grounding pad is not required.
If electrodes are not close together, separate lesions are made If electrodes are close enough, a “strip lesion” is made
TransDiscal BiacuplastyPhysics
Cooled RF Probe
• Radiofrequency current is concentrated between electrodes on two straight probes.
•The electrodes are internally cooled, allowing deep, even heating and eliminating tissue adherence.
• Temperature sensors allow monitoring at the electrode tips and disc periphery.
• Heating parameters can be adjusted to achieve a specific thermal dose.
TransDiscal BiacuplastyLogics
RF AnnuloplastyPhysics
Lesion in chicken breast
TransDiscal RF AnnuloplastyPhysics
Lesion in egg white
TransDiscal BiacuplastyProcedure
Conclusion
• Radiofrequency lesioning provides the potential for denervation as well as disc sealing, theoretically providing pain relief as well as pathology reversal
• RF techniques for the disc continue to evolve.
• Advances in imaging technology may speed up that evolutionary process
