IDET: an alternative to invasive surgery for chronic low back pain
IDET introduction
Intradiscal Electrothermal Annuloplasty (IDET)
is a minimally invasive treatment for chronic low back pain that results
from certain types of painful degenerative disc disease or contained
disc herniation. Successful
IDET treatment may allow some patients to experience
good or excellent pain relief without having to undergo major spinal
surgery for disc removal and spinal fusion, or disc replacement.
The IDET treatment was first introduced in 1997 and has been performed
extensively since then. The procedure involves inserting a catheter
into the disc and heating it up. It takes about an hour and can
be readily performed on an outpatient basis (with no overnight hospital
stay). Several disc levels may be treated in a single session.
The exact mechanism by which IDET reduces disc pain is still under investigation. Proposed
mechanisms include: thermal destruction of pain sensitive nerve endings
in the posterior disc wall; heat induced contraction of collagen tissue
within the disc wall that may seal up painful tears; stimulation of new
collagen formation, and; destruction or alteration of inflammatory or
pain mediators within the disc tissue.
The IDET procedure
Prior to undergoing an IDET procedure, patients
usually have a preliminary discogram test in which the lumbar disc or
discs that are abnormal (as seen on an MRI scan) and thought to be the
cause of a patient’s
back pain are injected with dye. Discogram tests that reproduce
the patient’s pain and demonstrate tears or small herniations on
the posterior wall (in the back of the disc) may signify a disc that
may respond to IDET treatment. Recent improvements in the discogram
test utilizing pressure controlled injection equipment
have allowed physicians to more accurately identify truly symptomatic
disc levels.
Once the symptomatic disc or discs have been identified, the patient
is brought to the procedure suite and placed face down on the operative
table. Intravenous sedation is usually given to relax the patient
and relieve any discomfort during the procedure. A flexible catheter
is inserted into the target disc under x-ray guidance and navigated into
the proper position. The terminal portion of the catheter is placed
along the posterior disc wall (the area of the disc that is thought to
be painful), and then slowly heated to 90 degrees Celsius for 15 to 16
minutes. The catheter is then removed and the disc is injected
with a small amount of antibiotic and anesthetic medication to lessen
discomfort and the risk of infection. If the catheter cannot be
fully advanced along the entire posterior disc wall, the thermal treatment
is performed and then a second catheter is inserted from the opposite
side and a second thermal treatment is carried out.
After the operation, patients are typically placed in a low back brace
and advised to avoid activities that stress the low back. Analgesic
medications may be given to control discomfort in the early recovery
period. After two months of low back protection, patients typically
undergo four weeks of physical therapy, emphasizing exercises that strengthen
the supporting musculature of the lower back, and are then encouraged
to resume their regular activities.
IDET success rates
Numerous studies have demonstrated that 50
to 60% of patients undergoing IDET experience good or excellent pain
relief. A recent blinded,
placebo-controlled study (the gold standard in medicine for determining
the unbiased success rate of a given treatment) by Pauza, Howel, Dreyfuss,
et al showed that 40% of patients undergoing IDET achieved greater than
50% relief of their pain. This was more than the 32% of patients
who experienced greater than 50% pain relief after
undergoing the sham treatment.
It is important to note that careful patient selection and meticulous
placement of the IDET catheter appear to lead to higher success rates.
Patients with less severe disc degeneration are thought to respond better
to the IDET procedure than those patients with severe disc degeneration.
Potential risks and complications with IDET
There are minimal
risks associated with IDET when it is performed by an experienced physician. Initially, it was thought that disc space
infection, nerve root injury, post treatment disc degeneration or herniation,
and post treatment increase in back pain were significant concerns. However,
most published studies of IDET therapy have not reported
any significant complications and the real risk of complications is now
felt to be quite low.
Contraindications to IDET
Patient factors or anatomical features that have been associated with
poor response to IDET treatment include:
Obesity
Significant reliance on narcotic pain medications
either before or after IDET treatment
Significant disc space narrowing
Large disc herniations
Diffuse disc degeneration
Three or more symptomatic discs
IDET summary
While the exact mechanism of pain relief achieved
by IDET therapy is still to be fully determined, and
the treatment is not successful in all patients, the
IDET treatment has been established as a safe, minimally
invasive treatment that may provide a select group of patients with painful
disc disorders pain relief without the risks of a major spinal surgery
(such as a spine fusion or disc replacement). Careful patient selection
and meticulous placement of the IDET catheter appear to lead to higher
success rates in providing pain relief for patients.
