Chapter 46 Facet Syndrome: Facet Joint Injections, Medial Branch Blocks, and Radiofrequency Denervation Flashcards
causes of neck and LBP
The etiology is usually multifactorial, including muscles, ligaments, discs, nerve roots, and zygapophysial
(facet) joints.
The zygapophysial joint (facet
joint) is a potential source of
neck, shoulder, mid back, low
back, and leg pain. It is also a potential source for headaches.
facet joints
paired structures that sit posterolaterally to the vertebral body, and along with the intervertebral disc, comprise the three-joint complex. Facet joints are true synovial joints formed from the superior articular process of one vertebra and the inferior articular process of the vertebra
above
Function of the facet joints
This complex works
together to stabilize the joint and allow for different movements depending on the level.
The volume capacity of the joints
1 to 1.5 ml and
0.5 to 1.0 ml in the lumbar and cervical regions, respectively.
The lumbar facets vary in angle but are aligned
lateral to the sagittal plane, with the inferior articular process facing anterolaterally and the superior articular process facing posteromedially
The upper lumbar
facet joints are oriented
more parallel to the sagittal plane
(26–34 degrees), while the lower lumbar facets tend to be
more closely aligned with the coronal plane.
The thoracic facets are oriented
the most vertically oriented joints, allowing for
lateral flexion without axial rotation.
The C2–C3 joint, the most frequent cervical facet pain generator, is aligned approximately
70 degrees from the sagittal plane and 45 degrees from the
axial plane, which inhibits rotation and anchors the C2 vertebra as a rotational pivot for the atlantoaxial joint (C1–C2
The area of greatest mobility in the cervical spine is at
C5–C6, the second most affected cervical facet joint,
which is where the cervical facets transition to their posterolateral position.
The medial branch
the terminal division of the posterior ramus that provides sensory innervation to the facet joint.
The medial branch divisions
This smaller posterior division of
the nerve root is divided into lateral, intermediate, and medial branches. The lateral branch in the lumbar region
provides innervation to the paraspinous muscles, skin, and
sacroiliac joint, while the small intermediate branch innervates
the longissimus muscle. The medial branch is the largest of the divisions.
medial branch division of the medial branch innervates
It innervates the facet joint, multifidus muscle, interspinal muscle and ligament, and the periosteum of the neural arch.
Each facet joint is innervated by
two medial branches, the medial branch at the same level and the level above (i.e., the L4–L5 facet joint is innervated by the L3 and L4 medial branches)
The position of the medial branch in the lumbar spine
It divides from the posterior primary ramus and wraps around the transverse process of the level below at the
junction of the transverse process and superior articular
process (i.e., the L3 medial branch lies on the transverse
process of L4). The nerve traverses the dorsal leaf of
the intertransverse ligament of the transverse process
and courses underneath the mamilloaccessory ligament,
splitting into multiple branches as it crosses the vertebral lamina
The mamilloaccessory ligament can
become calcified and be a source of
nerve entrapment, especially
at L5.
The main variation in the lumbar spine is at L5
where it is the primary dorsal ramus itself that is
amenable to blockade
in the thoracic spine the medial branches assume a courses
The nerve swing laterally to
circumvent the multifidus muscle, thereby removing
multifidus contraction as a means of needle confirmation
prior to denervation. The superolateral corner of the transverse process is the most consistent point for blockade
How many cervical nerve roots?
There are eight cervical nerve roots, which exit above the corresponding vertebral body
C3–C4 through the C7–T1 joints innervation from the medial
branches
the C3–C4 through
the C7–T1 joints receive innervation from the medial
branches at the same level and the level above. The
nerves curve around the waist of the articular pillars,
except at C7 and C8, where the anatomy is more variable.
The majority of the innervation of the C2–C3 joint comes from the
dorsal ramus of C3.
The C3 dorsal ramus divides into
two separate medial branches,
the larger of which is known as the third occipital nerve
The C2 dorsal ramus divides into
up to five branches, the
largest of which is the greater occipital nerve.
Pathology
involving branches of the C2 and C3 dorsal rami are a
common source of
occipital headaches
The facet joints contain
rich supply of encapsulated, unencapsulated, and free nerve endings. established the presence of Substance P and calcitonin gene-related peptide reactive nerve fibers in cadaveric facets. Inflammatory mediators, including prostaglandins, interleukin-6, and tumor necrosis factor-a, have been demonstrated in the facet cartilage
facet arthropathy and facet-mediated pain pathopyisiology
years of repetitive
strain, intervertebral disc degeneration, and minor trauma
are more commonly implicated.
the greatest degree of motion and strain in the
lumbar spine occurs in
the lowest two facet joints (L4–L5 and L5–S1). At these
joints, strain is maximized by forward flexion. In the most
caudad joints (L3–S1), the greatest degree of strain is
observed with contralateral bending, whereas the opposite
is seen at L1–L2 and L2–L3.
The two most caudal facet joints are associated with the greatest degree of degenerative disc disease,
and are most commonly affected.
(L4–5 and L5–S1)
The most common presentation of trauma-induced facet pain is
whiplash injury
The most reliable method to determine
facetogenic pain is with
One limiting factor
in determining the true incidence of facet pain is that the diagnosis cannot be made by historical, physical exam, or radiologic findings. The most reliable method to determine facetogenic pain is with image-guided medial branch
or intra-articular facet joint blocks
In the lumbar region, the upper facet joints tend to refer pain into the
flank, hip and
upper lateral thigh
For lower levels, pain is generally experienced in the
posterolateral thigh and occasionally
the calf.
In the cervical spine, upper facet arthropathy usually
manifests as pain felt in the
posterior upper neck and occipital region.
Pathology involving middle cervical
facet joints tends to radiate into the
lower neck and supraclavicular region
lower cervical facetogenic pain
typically causes pain in the
base of the neck and scapular region.
limited utility in the diagnosis of
facet-mediated pain
radiologic examination
diagnostic MBBs
volumes as small as 0.5 ml cover 6 cm2 of tissue. Hence,
the intermediate and lateral branches are likely to be anesthetized with typical injection volumes, thereby blocking afferent transmission from portions of the paraspinous musculature and sacroiliac joint
excessive volumes of local anesthetic solution
can rupture the joint capsule, leading to spread into the intervertebral
foramen epidural space, and paraspinous musculature.
Both medial branch and intra-articular blocks are associated
with high rates of
false-positive results.
Potential causes of false-positive blocks include
placebo
response, sedation, excessive superficial local anesthesia,
and the spread of local anesthetic to other pain-generating
structures
the use of sedation for
diagnostic blocks should be limited
as even benzodiazepines
can lead to muscle relaxation and interfere with a
patient’s ability to assess pain relief.
Techniques to Reduce False-Positive Rates for
Lumbar Medial Branch Blocks
- Avoid the use of sedation and analgesics.
- Use injectate volumes of #0.5 ml.
- Limit volume of skin local anesthesia.
- Aim for lower target point on transverse process.
- Use a single-needle approach.
- Consider use of comparative local anesthetic blocks.
One of the principal causes of false-negative blocks is
thought to be vascular uptake. The most reliable means to detect vascular uptake is with real-time fluoroscopy. Other potential causes of false-negative blocks are failure to discern between baseline and procedure-related pain, and missing a target
nerve(s).
conservative management for spinal pain
There is strong evidence for
nonsteroidal anti-inflammatory drugs and acetaminophen. Antidepressants
and muscle relaxants have also been shown to be effective. physical activity and weight loss are likely to benefit BP patients. Spinal manipulation is superior to sham treatment for
acute and chronic spinal pain. Acupuncture also appears effective for
spinal pain,
The most commonly performed treatment for facetmediated
pain is
RF denervation
The medial branch is denervated by
placing the active
tip of a RF needle at the location of the nerve
The medial branch is denervated for the lumbar region
the active tip is optimally positioned at the junction
of the transverse process and lateral neck of the superior
articular process in an orientation parallel to the nerve
The medial branch is denervated In
the cervical region
the active tip should be placed along the
center of the articular pillar at most levels
Sensory stimulation
usually performed prior to denervation, with most experts recommending a threshold of no more than 0.5 volts.
Motor stimulation
considered a safety measure to ensure
adequate distance from motor fibers, though the elicitation
of multifidus muscle contraction has also been used to guide needle placement
Prior to denervation, local anesthetic
with or without steroid can be injected to
reduce procedure related pain, enhance lesion size, and prevent neuritis
The
duration of analgesia following RF denervation
varies widely
between studies, with most demonstrating between 6 months
and 1-year relief
Surgery is occasionally done for facet pain
inadvertently transect the medial
branch during pedicle screw placement, which can provide
some pain relief.
COMPLICATIONS FROM MINIMALLY
INVASIVE INTERVENTIONS
The most feared risk of RF denervation is thermal damage
to the ventral nerve root due to incorrect needle placement,
which is rare when motor stimulation is utilized. Post denervation
neuritis is the most common complication. Some patients describe transient numbness or dysesthesias, which are usually minor
and self-limting
Postdenervation
neuritis can be reduced even further with
prophylactic
corticosteroid administration
