Download Musculoskeletal Imaging and Intervention Section Imaging

 Musculoskeletal Imaging and Intervention Section Imaging Procedures
LUMBAR AND SACRAL NERVE ROOT BLOCKS
INDICATIONS
Nerve Root blocks are commonly requested in patients with radicular symptoms for
two broad general indications:
1. Diagnostic Injections:
a. Imaging studies are normal do not show abnormality to explain the
distribution of symptoms).
b. Imaging studies show multiple levels of pathology so it is difficult to know
which level(s) is responsible for the symptoms.
c. Both hip and spine pathology are present and either or both may be the
cause of the leg symptoms.
2. Therapeutic Injections: The anesthetic and steroid injection is desired to treat the
pain generator. This will make the patient more comfortable and functional until the
symptoms resolve or surgery is necessary.
RISKS
•
Hematoma
•
Infection
•
Allergic reaction
•
Pain
•
Nerve injury
•
Reflex sympathetic dystrophy
•
Transient weakness or paresthesia
MATERIALS
•
4 x 4 gauze, alcohol, betadine, small steridrape • 5 cc syringe • 10 cc syringe
(2) • Short iv hep lock connecting tubing
•
1% lidocaine, preservative free • 25G 11⁄2” needle • 22G 31⁄2” needle •
Omnipaque 300
•
Celestone 6 mg/cc or Kenalog 40 mg/cc • Bupivacaine 0.5% preservative free
PREREQUISITES
• Patient must have driver to get home. • Review the patient’s cross sectional
imaging studies. • Check request and be certain of the exact nerve root the referring
clinician would like
injected. Correlate with MRI findings. • Discuss the procedure with the patient:
a. Explain that they will likely experience transient radicular pain as the inflamed
nerve root is approached.
b. Explain the diagnostic and therapeutic aspects of the procedure. c. Explain a “pain
diary” for the patient to keep for their doctor. d. Obtain signed consent.
TECHNIQUE - For Lumbar Nerve Blocks
1.
Place patient in the prone position, no bolster is required.
2.
Profile the disc at the level to be injected
3.
Roll the tube toward the side to be injected until the inferolateral corner of the
vertebral body is uncovered by the most lateral margin of the superior
articular facet. Target 2 mm above the inferior endplate and 4 mm medial to
the lateral cortical margin of the vertebral body (Figures 1 and 2)
4.
Prep alcohol, betadinex3), small steridrape and towels, local 1% lidocaine,
preservative free with 1 1⁄2” 25G needle.
5.
Insert a 3.5” 22 G needle at the site marked. Advance in the AP view
occasionally checking in the lateral view to determine depth and confirm proper
craniocaudal angulation.
6.
Once the needle tip reaches the posterior margin of the neural foramen, all
additional advancement will be in the lateral view.
7.
From this point the patient is asked to report any subsequent leg or buttock
pain. The needle is incrementally advanced in 1 mm steps until the patient
feels radicular pain. If the patient does not feel any pain, the end point on the
lateral view is approximately 2 mm within the posterior cortex of the vertebral
body.
8.
In the true AP projection, the stylet is removed and a 5 cc syringe of
Omnipaque 300 attached via short IV hep lock connecting tubing (capacity of
tubing is 0.2 cc). A small amount of contrast is injected producing a neurogram
extending inferolaterally from the neural foramen.
Image pending
Fig 1: Start position
Image pending
Fig 2: End position.
Fig 3: L4 neurogram, AP.
9. Disconnect the syringe with contrast from the tubing. This minimizes any
manipulation of the properly positioned needle tip. Shake the syringe with the
therapeutic solution to resuspend the particulate steroid component before
attaching to the tubing.
10.Inject 1.5 cc of equal parts Kenalog-40 and 0.5% preservative free Bupivacaine
and take a spot film. It is not uncommon for the patient to report increased pain
during the injection; this can usually be mitigated by a short waiting period or
decreasing the rate of injection. If no neurogram is produced by the contrast
injection, flood the area with 2.0 cc of the therapeutic solution for a perineural block.
11.Discuss a “pain diary” with the patient.
Alternative Methods for Lumbar Nerve Blocks
1. Oblique tube about 45° until the superior articular process is about in the middle of
the disc in the AP direction. Aim the needle with tower until tipis 2-3 mm inferior to
the eye of the Scotty dog at the 6 o’clock position.
Alternative method #1: 45o oblique. Direct needle directly down to the •, 2-3 mm
beneath the 6 o’clock position of the pedicle, until paresthesias occurs.
TECHNIQUE - Sacral Nerve Block
1.
The S1 nerve root is the most common sacral nerve root we are asked to
inject.
2.
After exiting the spinal canal, the nerve travels in a common neural foramen
which bifurcates into anterior and posterior branches. The portion of the nerve
we wish to block is the anterior division.
3.
Review the patient’s cross sectional study to see if it includes the S1 neural
foramen on the affected side. Make note of the angle of entry into the
posterior branch. Typically this will be between 10 – 20 degrees with 15
degrees being most common.
4.
Position the patient prone without a bolster.
5.
Roll the tube out to the predetermined angle and look for a faint circle just
below the S1 pedicle representing the posterior neuroforamen (Figure 4)
Fig 4: Sacral nerve block start position, slight larteral angulation
6.
This is usually accomplished without cranialcaudal angulation as the posterior
neuroforamen is oriented caudally but the upper sacrum is tipped dorsally
about the same amount.
7.
Target the center of the properly positioned neural foramen and place a 31⁄2”
22 G spinal needle.
8. On the lateral view the endpoint is 2-3 mm inside the anterior cortex of sacral
canal (Figure 5).
Fig 5: Sacral nerve block, lateral.
9. At this level, confirm positioning with a small injection of Omnipaque 300 in the
true AP projection and take a spot film (Figure 6).
Fig 6: Sacral nerve block, AP.
10.Flood the area with 1.5-2.0 cc of equal parts Kenalog-40 and 0.5% preservative
free Bupivacaine and take a spot film.
•
For a sacral nerve block, angle the tube towards head 25-45° until the anterior
and posterior aspects of the foramen form a well-defined circular lucency and
mark the skin over the foramen superiorly, 2-3 mm under the pedicle.