A number of new spine procedures are being performed for treatment of pain of discogenic origin such as intradiscal electrothermy (IDET), vertebral fusion, and microdiscectomy. Most of these procedures require discography as a part of the preoperative work-up to identify the disc level that is the source of pain and to identify intrinsic disc pathology. We describe a simplified technique for cervical, thoracic, and lumbar discography using bony landmarks identified easily on fluoroscopy.
is a Resident,
are Staff/Attending Physicians in the Division of Neuroradiology,
Department of Radiology, University of Pittsburgh Medical Center,
A number of new spine procedures are being performed for
treatment of pain of discogenic origin such as intradiscal
electrothermy (IDET), vertebral fusion, and microdiscectomy. Most
of these procedures require discography as a part of the
preoperative work-up to identify the disc level that is the source
of pain and to identify intrinsic disc pathology. Magnetic
resonance imaging (MRI) is widely used in evaluating structural
integrity of the intervertebral disc; however, MR imaging is not
reliable in detecting internal disc pathology, especially in the
Often surgeons request discography preoperatively to accurately
assess 1) the culprit disc responsible for pain; and 2) the
probability of successful outcome of the operation. The surgical
and nonsurgical treatment outcomes of discogenic pain are
significantly improved by discography.
Discography is technically challenging, and thorough knowledge
of the spinal anatomy is a must for performing the procedure safely
and accurately. Among other reasons, faulty technique not only
increases patient discomfort, but may also confound examination
reliability by leading to false-positive results.
Different techniques for performing discography have been described
by various authors.
These techniques vary with the patients in the sitting, prone, or
lateral decubitus positions; using the paravertebral approach or
transdural approach; and using 22-gauge straight needles, 21-gauge
and 26-gauge co-axial needles, needles with single end-holes, and
multiholed needles. We describe a simplified technique for
cervical, thoracic, and lumbar discography using bony landmarks
identified easily on fluoroscopy.
All discography is performed on ambulatory outpatients using
C-arm fluoroscopy, strict aseptic technique, minimal conscious
sedation (intravenous [IV] fentanyl and midazolam) and local
anesthesia (1% to 2% buffered lidocaine). Some authors advocate the
use of intradiscal antibiotic (cefazolin) routinely for all
discography to prevent discitis.
We only use intravenous antibiotics prior to cervical discography.
During injection of contrast, the patient's response is recorded,
ie, whether pain is concordant or discordant, as well as the level
of pain intensity on a scale of 0 to 10 (10 being the worst).
Subjective resistance to injection and/or adequate visual depiction
of the intervertebral disc and/or response of the patients to the
injection is used, singly or in combination, as the end point of
the injection. Following discography, all patients undergo a CT
scan of the injected discs. A normal disc should be injected prior
to study of the suspect disc as a baseline or control to improve
reliability of the examination.
Technique for cervical discography
The patient is placed in a supine position on the fluoroscopy
table. After prepping the neck, intravenous medications for
conscious sedation are administered. Skin and subcutaneous tissue
at the anticipated site of needle entry (as seen with oblique
fluoroscopy) are anesthesized with 1% buffered lidocaine. The X-ray
beam is angled 30š to 45š lateromedially to the cervical spine. The
beam is also angled craniocaudally so that it is tangential to the
intervertebral disc being studied. The needle entry is usually in
the right side of the neck. A "down-the-barrel" approach is used
with a 25-gauge, 8.89-cm spinal needle.
On oblique fluoroscopy, the target is the "uncinate-triangle"
formed by the uncinate process laterally; the superior end plate of
the lower vertebra inferiorly; and an imaginary line joining the
tip of the uncinate process and the superomedial tip of the
vertebral body (Figure 1).
An antibiotic (cefazolin) is administered intravenously while
the neck is being prepped. Following local anesthesia, the carotid
vessels are gently retracted laterally with the left hand and,
under intermittent C-arm fluoroscopy, a 25-gauge needle is guided
toward the uncinate-triangle described above. The needle passes
between the thyroid cartilage and trachea medially and the carotid
vessels laterally (Figure 2) and enters the intervertebral disc at
its anterolateral aspect (Figures 2 and 3).
By using this technique, we avoid the potential risk of
complications by injury to the vertebral artery that is protected
by the uncinate process (Figures 1 and 2). Figure 4 is an example
of a positive cervical discography.
Technique for thoracic discography
Using oblique fluoroscopy, with the patient prone, the X-ray
beam is angled 30š to 45š lateromedially to the thoracic spine. The
beam is also angled craniocaudally so that it is tangential to the
intervertebral disc being studied. A down-the-barrel approach is
used with a 25-gauge, 8.89-cm spinal needle. On oblique fluoroscopy
the target is a "box"--the vertical sides of this box are formed
medially, by a line joining the pedicles and laterally by a line
joining the head of the ribs (Figure 5). The horizontal margins of
this box are the superior and inferior vertebral end plates (Figure
5). The path of the needle as seen on cross-sectional imaging is
depicted in Figure 6.
Using aseptic technique, intermittent fluoroscopy is used to
guide a 25-gauge needle toward the box described above (Figure 7).
The needle passes between the superior articular facet medially and
the head of the rib laterally (Figure 5) and enters the
intervertebral disc at its posterolateral aspect. Figure 8 is an
example of a positive thoracic discography.
Co-axial technique for lumbar discography
The procedure is performed with the patient in the prone
position. The X-ray beam is angled 25š to 35š lateromedially to the
spine to get the "Scotty-dog" appearance of the vertebra. The beam
is also angled craniocaudally so that it is tangential to the
inferior end plate of the intervertebral disc being evaluated. This
view depicts the pedicle, superior articular facet, and lateral
margin of the disc (Figures 9 and 10). The needle entry is opposite
the side of usual back pain if the pain is predominant on one
A down-the-barrel approach is used with a co-axial needle
combination (an outer 20-gauge, 8.89-cm and an inner, curved
25-gauge, 15- to 20-cm needle). On oblique fluoroscopy the target
is the "safe-window" formed by the superior articular facet
medially, the superior end plate of the lower vertebra inferiorly
and an imaginary line joining the tip of the superior articular
facet and the superolateral tip of the vertebral body (Figure 10).
Under intermittent, biplane fluoroscopy, the 20-gauge outer needle
is guided into the back (Figure 11) so that its tip comes to lie at
the level of, or just anterior to, the superior articular facet as
seen on lateral fluoroscopy.
The 25-gauge needle is then hand-curved to approximately 30š to
45š, and advanced through the 20-gauge needle under intermittent
fluoroscopy into the posterior third of the intervertebral disc
(Figures 11 and 12). The entry point of needle into the lumbar disc
is at its posterolateral margin.
By using this technique, the needle will enter the disc
posterior to the nerve root exiting from the lumbar neural foramen
(Figure 9). In the lumbar region, a normal or "control" disc is
injected (Figure 13) prior to study of the suspect disc as a
baseline of the patient's pain.
In our experience, the safe windows described above in the
cervical, thoracic, and lumbar spine are easily identifiable
landmarks on oblique fluoroscopy and can be used reliably as a safe
and simple approach to discography.
The authors would like to thank Eric Jablonowski and Mike Purvis
for their help with the illustrations.