MATERIALS AND METHODS from Oh & Shim
Participants for this study were recruited from a group of
patients who had chronic discogenic pain for more than 1 year.
Each had a history of failed conservative treatment of several
months duration, and IDET had been performed on them only
after confirming discogenic pain with provocative discography
at low pressurization. Concordancy was defined as reproduction
of the patients typical symptoms. For each patient, the
pressure-controlled provocative discography also determined
the symptomatic disc, established the location of annular tears,
and categorized the sensitivity of the disc annulus to pressurization.
From January 2001 to September 2001 we enrolled 49
patients who had no significant improvement in pain during
the 9 months following IDET. We had enrolled our first 137
consecutive patients who had undergone IDET from March to
November 2000 and patients satisfaction with the procedure
and its outcome were examined using the 4-point NASS Patient
Satisfaction Index (PSI). The PSI results indicated that
46% of the samples (63 patients) were not satisfied with their
outcome and would enroll in this study. These patients underwent
a diagnostic block of the ramus communicans nerve to
clarify the relationship between ramus communicans nerve
and discogenic pain. Only patients (49 patients) with at least
50% temporary pain relief were selected for the study. Patients
MRI scans did not demonstrate a herniated IVD, which
can compress the neural element. Patients with clinical radiculopathies
and other neurologic abnormalities, as well as those
with combined facet joint or myofascial pain, were excluded
from this study. Patients underwent a diagnostic block of the
medial branch of the primary dorsal rami of the segmental
nerves of L3, L4, and L5 first to exclude facet joint induced
pain, and patients with a positive response were excluded from
this study. In addition, plain spine AP, lateral, oblique x-ray
were examined to exclude facet joint abnormalities. Myofascial
pain, paraspinalis muscle spasm induced pain, with a positive
response to trigger point injection and physiotherapy was
also excluded. Other exclusion criteria were: (1) verbal decline,
(2) failure to provide written informed consent, (3) spinal
stenosis, (4) spinal instability, (5) a multilevel (2 or more)
disc lesions, (6) previous spinal surgery, (7) history of excessive
bleeding or coagulopathy, and (8) obvious psychologic
problems. We evaluated the patients with psychologic problems.
Firstly, we examined the study group with MMPI and
excluded the patients with psychologic factors, such as the
presence or severity of depression. If patients were found to
have serious psychologic problems, they were interviewed by
staff psychologists, then reevaluated and excluded from this
study. Secondly, the patients who took antidepressants or antianxiety
drugs were excluded. In addition, 9 women of childbearing
potential were excluded.
Diagnostic Block of the Ramus
Communicans Nerve
To confirm the correlation between ramus communicans
nerve and discogenic pain, a diagnostic local anesthetic block
of the ramus communicans nerve was conducted prior to performing
RF lesions.
Patients who were NPO on the day of the procedure were
transferred to the operating room after intravenous access was
obtained. No preoperative medications were given. Throughout
the procedure, the ECG, O2 saturation, and blood pressure
of the patients were monitored. Patients were given intravenous
sedation with midazolam, but consciousness was maintained
so they could provide accurate verbal responses during
the electrostimulation portion of the procedure. With the patient
prone on the operating table, C-arm fluoroscopy was directed
cranially or caudad so that the end plates of the intervertebral
disc and the vertebral body could be well visualized.
The fluoroscope was then positioned at a 15° to 25° oblique
angle, with the position adjusted until the lateral tip of the
transverse process and the anterior margin of the vertebral
body were in alignment. The skin and subcutaneous tissue
overlying the entry point were anesthetized with 2% lidocaine.
A 150 mm RF curved cannula (cannula 415/10 mm, Stryker
Leibinger GmbH & Co. KG, Freiburg, Germany) with a 10
mm active tip was introduced at the caudad third aspect of the
vertebral body, parallel to the fluoroscopic beam, and advanced
until the periosteum was contacted (Fig. 1). At this
point, the cannula was advanced until it was positioned at the
lateral third aspect of the vertebral body under lateral fluoroscopic
view (Fig. 2). With the needle in proper position, a mixture
of 2 mL 2% lidocaine and 1 mL contrast medium was
injected. After 30 minutes, pain relief was assessed at the recovery
room by using a 4 point Likert scale: no relief, <30%
pain relief; moderate relief, <3050% pain relief; good relief,
<50% pain relief; and no pain, 100% pain relief. A positive
response was estimated as good relief or no pain state, and
patients underwent RF lesioning of ramus communicans nerve
the next day.
Radiofrequency Lesioning Procedure
The approaching technique of the cannula for the RF lesioning
procedure was identical to the diagnostic block. With
the tip of the cannula in proper position, the stylet was replaced
by the RF probe (Stryker Leibinger GmbH & Co. KG,
Freiburg, Germany) and then connected to the RF thermoco-
Oh and Shim Clin J Pain Volume 20, Number 1, January/February 2004
56 © 2003 Lippincott Williams & Wilkins
agulator (Neuro N50, Stryker Leibinger GmbH & Co. KG,
Freiburg, Germany). Electro stimulation was applied at 50Hz,
0.81.0 volt. The location that provoked a deep aching pain
identical to the usual pain of the patient was confirmed. After a
point at which no motor stimulation of the lower extremity was
noted with a 2 Hz, 1.02.0 volt stimulation, 1% lidocaine was
injected followed by RF thermocoagulation at 65°C for 60 seconds.
If motor stimulation was seen, we adjusted the tip of the
RF cannula until there was no stimulation of the motor portion
of the lumbar nerves. RF cannula was gently redirected underneath
the pedicle to rest slightly anterior to the superior aspect
of the intervertebral foramen. The cannula should be 0.5 cm
anterior to the foramen. From the fluoroscopic anteroposterior
(AP) view, it should be at the lateral portion of the vertebral
body as evidenced by fluoroscopy. If the needle is guided carefully,
exactly under the inferior aspect of the pedicle, it will
less likely make contact with the somatic nerve root. In addition,
contrast medium was then injected to confirm the lack of
spinal nerve root. After RF thermocoagulation, 2 mL of preservative-
free 1% lidocaine (Xylocaine®, Astra Co., Korea)
was injected along with 40 mg of sterile triamcinolone acetonide
(Tamcetone®, Hanol Inc., Korea) for the purpose of preventing
postoperative neuritis. RF lesioning was performed
above and below the vertebrae of the affected disc, but, for
patients with bilateral discogenic low back pain, it was carried
out on both sides of the target vertebrae.
