Myelography

1. MYELOGRAM
2.5.2023
Presented by Dr. LT

2. A myelogram is a type of radiographic
examination that uses a contrast medium to
detect pathology of the spinal cord, including the
location of a spinal cord injury, cysts, and
tumors.

3. Indications
 Suspected spinal cord pathological or root compression.
 Demonstration of the site of a cerebrospinal fluid leak.
 Symptoms or signs of spontaneous intracranial hypotension.
 Surgical planning, especially in regard to the nerve roots.
 Evaluation of the bony and soft tissue components of spinal degenerative changes.
 Radiation therapy planning.

4.  Use of MRI precluded because of:
 Claustrophobia.
 Technical issues, e.g., patient size.
 Safety reasons, e.g., pacemaker.
 Surgical hardware.
 Delineation of congenital anomalies when MRI is insufficient.

5. Contraindications
■ Known space-occupying intracranial process with increased intracranial pressure.
■ Historical or laboratory evidence of bleeding disorder or coagulopathy.
■ Recent myelography performed within 1 week.
■ Generalized septicemia.
■ History of adverse reaction to iodinated contrast media.
■ Pregnancy

6. Contrast media used
■ Earlier - oil-based, air-contrast, Ionic contrast media.
■ Current - Non ionic, water soluble iodine-based media.
■ Nonionic water-soluble agents (e.g., Iohexol ( Omnipaque ) which are
significantly less neurotoxic than the ionic water-soluble agents are been used
instead for last two decades.
■ Many radiological contrast agents are neurotoxic and should not be administered
intrathecally.

7. Equipment
 Tilting X-ray table with a C-arm fluoroscopic facility for screening and
radiography in multiple planes.
Patient Preparation
 Mild sedation with oral diazepam is appropriate in anxious patients, but is
not essential.
 The skin puncture points is outside the hair line, and no hair is generally
needed, though the hair should be gathered into a paper cap.

9. Preliminary Images
AP and lateral projections of the region under study are taken. Preliminary
examination of radiographs is helpful to assess the anatomy of the spine, in order to
facilitate the lumbar puncture, and to assist in interpretation of the images. It is
important to draw the surgeon’s attention to any question of ambiguous segmentation,
either lumbarization or sacralization.

10. Anteroposterior lumbar radiographs.
Castellvi classification. (A) Type III
lumbarized S1. (B) Type III sacralized
L5. (C) Type II sacralized L5. (D) Type
IV mixed.
Anteroposterior lumbar radiographs
with diagrams overlaid to delineate the
anatomy of the lumbosacral transitional
vertebrae.

12. Lateral Cervical C1/2 Puncture Versus Lumbar Injection
Cervical myelography is therefore most easily, and safely, performed as a lumbar
injection, at the level of the cauda equina, and then running the contrast up into the
cervical region.Cervical puncture is indicated where there is severe lumbar disease,
which may restrict the flow of contrast medium and may make lumbar puncture
difficult, and when there is thoracic spinal canal stenosis. It may also be required for the
demonstration of the upper end of a spinal block. It is a relatively safe procedure but is
contraindicated in patients with suspected high cervical or cranio-cervical pathology,
and where the normal bony anatomy and landmarks are distorted or lost by anomalous
development or rheumatoid disease. Complications are rare but include vertebral artery
damage and inadvertent cord puncture.

13. Cervical Myelographic Technique
1. The patient lies prone with arms at the sides and chin resting on a soft pad, so that
the neck is in a neutral position or in slight extension. The patient must be
comfortable and able to breathe easily.
2. Using lateral fluoroscopy, the C1/2 space is identified. The aim is to puncture the
subarachnoid space between the laminae of C1 and C2, at the junction of the
middle and posterior thirds of the spinal canal. A 22G spinal needle is used.
Anaesthetizing the tract of the needle approach is only ever indicated if the
approach is to be followed by the passage of a wide gauge needle, such as a
biopsy needle.

14. 3. The sensation of the needle penetrating the dura is similar to that experienced
during a lumbar puncture, and the patient may experience slight discomfort at this
stage. A feature that indicates that the needle tip is close to the dura is the
appearance of venous blood at the needle hub as the epidural space is traversed.
Severe acute neck or radicular pain indicates that the needle has been directed too
far anteriorly and has come into contact with an exiting nerve root.
4. Following removal of the stilette, CSF will drip from the end of the needle, and a
sample may be collected if clinically required.

15. 5. Under fluoroscopy, a small amount of contrast medium is injected to verify correct
needle-tip placement. This will flow away from the needle tip and gravitate
anteriorly to layer behind the vertebral bodies. Transient visualization of the
dentate ligaments is obtained.
6. Injection is continued slowly until the required amount has been delivered. The
cervical canal should be opacified anteriorly from the foramen magnum to C7/T1.
If contrast tends to flow into the head before filling the lower cervical canal, tilt
the table feet down slightly, and vice versa if contrast is flowing into the thoracic
region without filling the upper cervical canal.

16. Radiographic Views
After needle withdrawal, two antero-posterior (AP) radiographs are obtained, with
the tube angulated cranially and caudally, in turn, along with both oblique views once
again with cranial and caudal tube tilt. Soft and penetrated lateral views are needed to
ensure full assessment of the cervico-thoracic junction. Lastly, a further lateral view of
the craniocervical junction is taken with mild neck flexion, because the extended neck
position may prevent full visualization of the upper cervical cord up to the foramen
magnum. CT is then performed with sagittal and cranial reformats, which provides
cross-sectional information equivalent to an MRI examination.

17. Lumber Myelographic Technique
1. The lumbar thecal sac is punctured at L2/3, L3/4 or L4/5. The higher levels tend to
be away from the most common sites of disc herniation and stenosis, and therefore
puncture may be easier. It is always advisable to introduce the needle into the spine
away from the site of previous surgery.
2. Lumbar puncture can technically be performed in the lateral decubitus position, in
the sitting position or in the prone position. Lumbar puncture is most easily
performed in the lateral decubitus position, as the interspinous space can be
maximally widened with as much spinal flexion as possible within the confines of
a narrow fluoroscopy table.

18. 3. Screening the patient AP will help ensure the needle does not drift off the midline,
whilst lateral screening ensures a clear path between the spinous processes, a position
that usually requires a slight degree of cranial angulation. Once the needle is well
embedded in the interspinous ligament, only the position of the bevel will influence its
direction. The bevel should be pointing either cranially or caudally to prevent
deflection of the needle from the midline. If the needle is drifting too far cranially with
risk of hitting the superior lamina, the bevel should be directed cranially, which will
deflect the needle away from the bone, and vice versa if the needle is drifting caudally.

19. 4. There is a characteristic sudden loss of resistance as the needle passes through the
ligamentum flavum into the epidural space. It is best at this point to make a brisk
advancement of the needle with one push of a centimetre or so; grasping the needle
at the required distance from the skin surface will prevent it being pushed in further
than intended. The position aimed for is within the centre of the spinal canal.
5. The central stylet is withdrawn and dripping of CSF from the needle confirms an
intradural position. If the needle has been inserted at a level of spinal stenosis,
crowding of nerve roots around the needle tip may prevent the flow of CSF, and
gently rotating the needle may result in CSF flow.

20. In any event, if the position of the tip appears satisfactory, cautious injection of
contrast under fluoroscopy is performed via a flexible connector, which reduces the
chance of disturbing the position of the needle and gets the injecting hand away from the
fluoroscopy beam. Flow of contrast away from the needle tip confirms an intradural
injection.
6. After the contrast medium has been injected, the patient turns to lie prone, and a
series of films is obtained. Before taking films, ensure that the relevant segment of the
spinal canal is adequately filled with the contrast medium. This usually requires some
degree of feet-down tilt of the table, and a footrest should be in place to support the
patient.

24. Radiographic Views
1. AP and oblique views are obtained. (About 25 degrees of obliquity is typical, but
this should be tailored in the individual case to profile the exit sleeves of the nerve
roots of the cauda equina.)
2. A lateral view with a horizontal beam is useful, but further laterals in the erect or
semierect position on flexion and extension add a dynamic dimension to the study.
Additional Technique
As with all myelography, the examination is followed immediately by computed
tomography thoracic myelography.

27. Thoracic Myelography
If the thoracic spine is the primary region of interest, the lumbar puncture injection is
made with the patient lying on one side, with the head of the table lowered and the
patient’s head supported on a bolster or pad to prevent contrast medium from running up
into the head. If an obstruction to flow is anticipated, about half the volume of contrast
medium may be injected and observed as it flows upward. If an obstruction is
encountered, the contrast medium is allowed to accumulate against it, and the remainder
of the contrast medium is then injected slowly. This manoeuvre will, in some cases, cause
a little of the contrast medium to flow past the obstructing lesion and demonstrate its
superior extent. If there is no obstruction, the full volume is injected. When the injection
is complete, lateral radiographs may be taken, and the patient is then turned to lie supine.
Further AP views are then taken.

28. Cervical myelography by lumber injection
The technique proceeds as for thoracic myelography, but the patient remains in the
lateral decubitus position until the contrast medium has entered the neck. With the head
raised on a pad or bolster, contrast will not flow past the foramen magnum. When all the
contrast has reached the neck, the patient is turned to lie prone, and the study is then
completed as for a cervical injection study.

29. CT Myelography
The CT scan takes place immediately after the injection, provided the patient is rotated a
few times to ensure an even distribution and reduce layering effects. The normal lumbar
lordosis can present difficulties if the CT scan is performed in the supine position, as the
contrast layers in the sacrum and thoracic spine away from the lumbar region. This can be
prevented by performing the lumbar CT in the prone position. If there is a complete block to
the contrast column, then delayed imaging should be performed, as the contrast will often
pass across through the block and show the full extent of the obstruction. If the block is
distal, patients can sit upright for a few hours, and if the block is proximal, they can lie head
down on a tilting trolley. Delayed CT is needed in suspected syringomyelia.

31. Aftercare
Most patients may be discharged home after being allowed to rest for a few hours
after the study. The practice of automatic hospitalization for myelography can no
longer be justified in light of improved contrast media with very low rates of serious
morbidity. A good fluid intake is generally advised, though its value is unproven..

32. Complications
1. Headache occurs in about 25% of cases, slightly more frequent in females.
2. Nausea and vomiting occur in about 5%.
3. Subdural injection of contrast medium. This occurs when only part of the needle bevel
is within the subarachnoid space. Contrast medium initially remains loculated near the
end of the needle, but can track freely in the subdural space to simulate intrathecal
flow. When in doubt, the injection should be stopped, and AP and lateral views
obtained with the needle in situ. The temptation of interpreting such an examination
should be resisted and the patient rebooked.
4. Extradural injection of contrast medium outlines the nerve roots well beyond the exit
foraminai.

33. 5. Intramedullary injection of contrast medium. This is a complication of lateral cervical
puncture or in a low-lying spinal cord, and is recognized as a slit-like collection of
contrast medium in the spinal canal. Small collections are without clinical
significance.
6. Infection with meningitis is a very rare complication that takes 2–3 days to develop
and therefore would present well after the patient has left the hospital, but is an
important complication to discuss with the patient during the consent for the
procedure.

36. T H A N K Y O U
Have A Nice
Day!