If you have discogenic low back pain (that's pain specifically related to your
intervertebral discs), IDET—or intradiscal electrothermic (or electrothermal)
therapy—may be a good treatment option for you. Because it's relatively
new, there are lots of questions about it, including the most basic: How does
it work?
Dr. Lawrence Kamhi, an interventional pain management specialist, answers some
of the most important questions you may have about IDET.
To learn more about why some doctors consider IDET an experimental procedure,
you can read IDET
Controversy: Answers from a Pain Management Specialist.
Q: What conditions is IDET used for? Who does it help most? Who will
it not help?
A: IDET is used in the patient with documented discogenic low back pain where
the disc itself is known to be the patient's principle pain generator.
The intervertebral disc—whether healthy or diseased—contains small
nerves sensitive to pain. When the intervertebral disc is diseased, these nerves
amplify in number, and they become very sensitized to pain. The synapses, which
are tiny gaps between nerves where nerve impulses are transmitted, also increase
in strength and number with discogenic low back pain. Essentially, the synapses
transmit more message of more pain, and this is one mechanism
felt to be responsible for chronic low back pain.
Diseased intervertebral discs are abnormal in three main ways:
- reduced disc height
- loss of normal water content
- rents and tears in the outer, tougher annulus fibrosus through which portions
of the inner, softer nucleus pulposus may herniate
IDET is used for patients with diagnosed discogenic low back pain. Not all
spine pain is discogenic; IDET would be inappropriate, for example, for a patient
whose low back pain is due to a serious spondylolisthesis, or due to severe
arthritic disease of the lumbosacral facet joints.
Q: How does IDET work?
A: During IDET, the doctor inserts a small needle through the skin, just to
the side of the spine, at the level of the diseased disc. The doctor advances
the needle until the tip is within the center of the diseased disc (the nucleus
pulposus).
Then, a special catheter is passed through the needle and advanced through
the disc "between" the nucleus pulposus and the outer layer, the annulus fibrosis.
Specialized opaque markers enable the doctor to place the IDET catheter in precisely
the desired location. Then, wires inside the IDET catheter heat the disc to
a point that denatures (or "melts") the disc tissue immediately adjacent to
the catheter tip. This accomplishes two therapeutic aims:
- It deactivates the nerve tissue within the disc.
- It seals the rents and tears in the outer annulus fibrosus adjacent to the
heating portion of the IDET catheter.
Q: What results do you get with IDET?
A: One hoped-for result is a denervated diseased intervertebral disc, where
the nerve fibers have been essentially killed—and thus are no longer painful.
Another possible result is that a disc that has been repaired mechanically,
much like a "patched tire," may not be as likely to re-herniate. No doubt, there
will be further improvements in this technology in the future that may allow
us to do even a bit more in the treatment of discogenic disc pain.
Q: What are the benefits of IDET (over more traditional treatments
such as surgery)?
A: There are two main advantages to IDET. First, it is considered minimally
invasive, so it's not a "big" surgery. The second advantage is that the recuperation
period is very short, especially when compared to traditional open spine surgery.
Q: What are the risks involved in IDET?
A: All spine procedures, whether performed "open" (through a large incision)
or minimally invasively (through small incisions), are surgical in nature. It
doesn't matter if the procedure is performed with a needle and a catheter under
x-ray guidance (as in IDET), or if it is involves making an incision with a
scalpel and drilling into the bony spine (as in traditional surgery). Although
IDET is minimally invasive, it still carries the possibility of introducing
infection into the intervertebral disc if there is a breach of proper sterile
technique.
Unfortunately, IDET has resulted in at least one reported case of intra-operative
injury to the spinal nerves.
There are ways to safeguard against the risks of infection and nerve injury.
While it is considered a fairly safe surgical procedure, IDET still requires
considerable training and experience on the part of the doctor performing it.
Also, the entire operating team must pay the utmost attention to sterile technique
so infection isn't introduced into the disc.
For IDET, it's also important for the physician to use special imaging equipment
(called C-arm fluoroscopes) because that helps the team guide the catheter.
Finally, and most important of all, the operating doctor must carefully select
the patient and make sure that he or she is a good candidate for IDET. As one
of my professors in medical school would say to us, time and time again: "There
is never any point in doing the wrong operation for the patient very well."
Q: What would you say to a patient considering IDET?
A: I would first ask the patient whether he or she has had one or more visits
to a spine specialist. I'd want to know if the spine specialist conducted a
detailed history and physical examination to diagnose the patient's problem.
Then, I would ask the patient if his or her doctor performed confirmatory tests.
At minimum, I would expect that the doctor had done high-quality plain x-rays
and a high-quality MRI scan.
I would also ask the patient whether he or she had undergone a reasonable course
of conservative therapy for their spine pain, including appropriate oral medications,
physical therapy, and less invasive injection procedures including, but not
limited to, epidural steroids.
I would need to find out if the patient had discussed with their doctor why
he or she is suggesting IDET. They should also have discussed whether a different
surgical spine procedure might produce an equivalent—or perhaps even better—result
for them. Before trying any treatment option, patients need to be fully informed
about what is going to happen and why it's being suggested. Then
they'll be better able to help make the decision about how best to treat their
pain.
