Chapter 65 Intradiscal Techniques: Intradiscal Electrothermal Therapy, Biacuplasty, Percutaneous Decompression Techniques Flashcards
normal disc anatomy
nociceptive fibers innervate only the outer third of the disc
annulus
internal disc disruption (IDD)
defined as a “biochemical, biophysical, and morphologic disruption of
the nucleous pulposis and annulus fibrosis of the disc,” typically characterized by radial or circumferential fissures
extending from the nucleus pulposis into the outer layers of the annulus. These fissures can create a chronic inflammatory response within the disc resulting in neoinnervation,
upregulation of nociceptors and overall disc sensitization.
Diagnostic Criteria for Internal Disc Disruption IDD
Disc stimulation is positive at low pressures (6/10 on visual analog scale.
Disc stimulation reproduces concordant pain.
Computed tomography discography shows a grade 3 or greater
annular tear (tear extends into the outer third of annulus)
Control disc stimulation is negative at one and preferably two
adjacent levels.
Traditionally, discogenic LBP, or pain from IDD, has been treated with conservative care:
activity modification, opiate and nonopiate analgesic medication, physical therapy, steroidal
spine injections, chiropractic care, manual therapy, acupuncture, and other modalities
when discogenic LBP
remains unresponsive to conservative treatments
Surgical arthrodesis or
disc replacement may be performed. complications can include infection,
pseudarthrosis and adjacent segmental instability
a plausible technique to
ablate nociceptors and modify collagen of the annulus fibrosus
of painful discs
Radiofrequency ablation or thermal neurolytic treatment of the posterior annulus
intradiscal electrothermal therapy (IDET)
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
proposed
mechanisms of pain reduction in IDET
post-IDET annular contraction, thermally
induced healing, sealing of annular tears, neurolysis of
nociceptors and decreased intradiscal disorder
INTRADISCAL ELECTROTHERMAL
THERAPY
TECHNIQUE
Setup
IDET procedure is performed percutaneously. using
fluoroscopic guidance, a radiolucent table, and strict sterile technique. Parenteral antibiotics are typically delivered
to the patient preprocedurally. With the patient positioned
prone, local anesthesia is used to anesthetize the skin, subcutaneous tissues, and periosteum at the level at which the IDET will be performed.
Sedation during IDET
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.
INTRADISCAL ELECTROTHERMAL
THERAPY
TECHNIQUE
Using an extrapedicular approach, an introducer needle is placed into the disc to be treated. Needle entry into the
disc is ventral to the superior articular process of the zygophyseal joint at the level IDET is to be performed. The introducer needle tip is precisely positioned halfway between the superior and inferior end plates of the adjacent vertebral bodies, just anterior to the midpoint of the disc on the lateral projection. A thermal resistive catheter is then navigated through
the introducer needle to the posterior annulus at the site of the previously diagnosed fissure or tear. The catheter is then heated to a maximum temperature
of 85° to 90° C. The avascular disc acts as a heat sink, allowing the disc to retain this delivered heat and effect collagen conformation distal to the catheter without causing nerve root or spinal cord damage
The countercurrent
blood flow in the epidural and perineural vessels appear to have a neuroprotective effect
by preventing heat from
building up within neural tissue when the catheter is appropriately
placed intradiscally
Most patients experience
their typical LBP during the heating protocol in IDET, 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
in IDET, A high index of suspicion should be maintained to prevent
thermal injury of the cauda equina or the exiting nerve roots within the neural foramen
If true radicular pain
occurs during the heating protocol in IDET
the intradiscal catheter
must be removed and/or repositioned
Complications of catheters in IDET
Catheter kinking is known to occur, as is catheter breakage. When breakage occurs, it is typically at the connection of the catheter to the catheter hub, but it can occur
along the body of the catheter from damage incurred at the introducer needle tip. Kinking of the catheter can occur when the tip becomes lodged within a radial fissure
or circumferential tear.
Management of Complications of catheters in IDET
The catheter should be withdrawn under these circumstances, and the introducer needle moved anteriorly or posteriorly prior to reinsertion
of the catheter more optimally. If a catheter is severely bent or kinked, it should be discarded and replaced. If removal of the catheter from the introducer needle is met
with resistance, the introducer and catheter should be removed en bloc and then positioned again separately. If the catheter cannot be navigated successfully across the length of a fissure, the introducer needle position can
be revised via a contralateral extrapedicular technique
with reattempts at optimal catheter placement.
Following the procedure (IDET)
back bracing is recommended
for several weeks, followed by a lumbar stabilization and
reconditioning program.
Possible Mechanisms of Action for Intradiscal
Radiofrequency Procedures
Alteration in spinal segment biomechanics via collagen modification
Thermal nociceptive fiber destruction
Biochemical mediation of inflammation
Stimulation of outer annulus healing process
Cauterization of vascular in-growth Induced healing of annular tears.
Rare complications of IDET
These include catheter breakage, post-IDET disc
herniation, cauda equina syndrome,vertebral end
plate osteonecrosis, radiculopathy, headache, foot drop, decreased sphincter tone, fecal incontinence, and discitis
Patients not
likely to benefit from IDET include those with
multilevel degenerative disc disease, overweight patients, and patients receiving worker compensation benefits
Biacuplasty
or intradiscal bipolar water-cooled RF. 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. it causes intradiscal temperature changes that would allow for thermal neurolysis without concomitant
heating of adjacent neural tissues and vascular structures.
Biacuplasty electrodes
electrodes are actively and internally cooled during the
ablation procedure with a peristaltic pump unit (Baylis
Medical Company, model TDA-PPU-1) that circulates
water through the probes to cool the electrodes,42 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.
