Vikram B. Patel and Sukdeb Datta
INTRODUCTION
INTRA-ARTICULAR FACET JOINT INJECTIONS AND MEDIAL BRANCH BLOCKS
Indications
Common indications for diagnostic facet joint interventions include the following:
Traumatic or arthritic nonradicular low back pain.
Patients can experience pain radiating in to the buttock but rarely radiating beyond the level of the knee.
Pain on palpation is worse with extension of the lumbar spine and rotation or twisting of spine.
Traumatic or arthritic nonradicular upper back or posterior chest wall pain.
Typically the patient experiences pain on palpation and extension and rotation or twisting of thoracic spine.
Traumatic or arthritic neck pain, suboccipital headache, persistent and disabling axial neck and/or upper thoracic pain or suspected cervicogenic headache
Typically pain and/or headache with neck movements in flexion, extension, and rotations
CONTRAINDICATIONS
Common contraindications for facet joint interventions include the following:
RELEVANT ANATOMY
Lumbar Spine
Figure 23-1. Lumbar spine and facet joints. Note the varying angles of the facets from top to bottom.
Lumbar facet joints are formed by the articulation of the inferior articular process of the superior lumbar vertebra with the superior articular process of the inferior vertebra.
The lumbar joints exhibit features of typical synovial joints.
The articular facets are covered by articular cartilage, and the synovial membrane bridges the margins of the articular cartilage of the two facets in each joint.
Surrounding the synovial membrane is a joint capsule that attaches to the articular process, a short distance beyond the margins of the articular cartilage.
Ligaments connect spinous process, lamina, and bodies of the adjacent vertebrae.
Anterior and posterior longitudinal ligaments help stabilize the joints.
The articular capsule surrounds facets and allows gliding motions.
In the lumbar spine, L4-L5 permits most flexion.
The anterior longitudinal ligament attaches to the anterior bodies and the intervertebral disk. It is strong and prevents hyperextension.
The posterior longitudinal ligaments attaches to the posterior aspect of the vertebral bodies and intervertebral disks. It is weaker than the anterior longitudinal ligament and permits hyperflexion.
Ligamentum flavum connects adjacent laminae of vertebrae and limits flexion. Interspinous ligaments connect the spinous processes. These are weak ligaments. Intertransverse ligaments connect the transverse process and are also weak ligaments.
Figure 23-2. (A-E) Cervical, thoracic, and lumbar medial branches.
The capsules of the lumbar facet joints are richly innervated with encapsulated and unencapsulated free nerve endings.
Lumbar facet joints are appropriately equipped with sensory apparatus to transmit nociceptive and proprioceptive information.
Each lumbar facet joint has dual innervations being supplied by two medial branches of dorsal rami (Figure 23-2D).
Figure 23-3. Thoracic facet joints: Note the slanted angles at the middle levels and compare with the upper and lower facets. The interspinous opening for epidural access is minimal in the mid thoracic levels where the angles of the facets are most slanted.
The medial brunches of the L1-L4 dorsal rami have a constant and similar course.
Each nerve emerges from its intervertebral foramen and enters the posterior compartment of the back by coursing around the neck of the superior articular process.
Hugging the neck of the superior articular process, the medial branch passes caudally and slightly dorsally covered by mamillo-accessory ligament, hooking medially around the caudal aspect of the root of the superior articular process to enter the multifidus muscle.
Intermediate and lateral branches arise from the dorsal ramus at the same point as the medial branch.
The medial branch finally crosses the vertebral lamina where it divides into multiple branches that supply the multifidus muscle, the intraspinous ligament and muscle, and ligament and the two facet joints.
The medial branch of the L5 dorsal ramus has a different course and distribution than those of the L1-L4 dorsal rami. Instead of crossing a transverse process, the L5 dorsal ramus crosses the ala of the sacrum.
The L5 dorsal ramus is much longer than the typical lumbar levels.
From the L5-S1 intervertebral foramen, the medial branch of the L5 dorsal ramus runs along the groove by the junction of the ala and the root of the superior articular process of the sacrum before hooking medially around the base of the lumbosacral facet joint (Figure 23-2D).
Thoracic Spine (Figure 23-3)
The thoracic spine has unique features that differentiate it from the lumbar spine.
Each thoracic vertebra is distinguished by costal facets on the side of the body, and all but the last 2 or 3 segments by articular facets on the transverse process, articulating respectively with the heads and tubercles of the ribs.
The laminae are short, thick, broad, and overlap each other like roof tiles from above downward.
The typical spinous process slants posteriorly and downward overlapping between T5 and T8 and being less oblique above and below this level.
Projecting upward at the junction of the lamina and pedicles are the superior articular processes facing backward, upward, and laterally.
The articular processes of adjoining thoracic vertebrae form synovial joints, which permit a limited degree of movement, primarily facilitating axial rotation.
The primary axis of rotation for the mid-thoracic segments is located close to the anterior region of the thoracic intervertebral disk.
The lower thoracic zygapophysial joints (facets) provide specialized features with the characteristics of this region. There is greater developmental of the mamillary processes, which originate as extension of the superior articular process.
The mamillary process provides attachment for the multifidus muscle as it covers this medially to attach onto the spinous process of the segments above.
Small intra-articular synovial folds may be found within the thoracic facet joints. Intra-articular synovial folds originate medially from tissues adjacent to the ligamentum flavum and extend varying distances into the medial joint cavity filling spaces within the joint with fibrofatty tissue.
The articular surface of the thoracic facet joint is inclined to 60 degrees from the horizontal to the frontal plane and rotated 20 degrees from the frontal to the sagittal plane in a medial direction.
The lateral aspect of the thoracic joint is placed anterior and the medial aspect of the joint is placed posterior.
The superior articular facet from the inferior vertebrae is almost flat and faces posterior, superior, and slightly lateral.
The inferior articular facet is oriented in a reciprocal manner. There is variation in the inclination of the joints by region with the mid-thoracic level approximately 60 degrees off the horizontal plane while the upper segment has a more vertical orientation.
In contrast to the lumbar spine, the superior and inferior articular processes of the thoracic spine cannot be identified separately because the joints are mostly in the frontal plane and do not face sideward.
The articular pillar is wider in the thoracic level, and it extends further laterally in relation to the vertebral bodies.
The articular facets are covered by articular cartilage, and the synovial membrane bridges the margins of the articular cartilage of the 2 facets in each joints.
Fluoroscopic visualization is more difficult.
There is no fibrous capsule on the ventral aspect of the joint. Within interspace, the ligamentum flavum is in direct contact with the synovial membrane.
The thoracic facet joints receive bisegmental innervations from the medial branch of the dorsal ramus of the upper segment and one more cephalad level.
The medial branches of the thoracic dorsal rami were found to have a reasonably constant course except at mid-thoracic level (T5-T8).
The medial branches of the thoracic dorsal rami at mid-thoracic levels do not run on bone. Instead, they are suspended in the intertransverse space.
Thoracic medial branches are not that close to the facet joint as they swing laterally to circumvent the multifidus muscle.
The dorsal ramus is separated from the ventral ramus (that is, the intercostal nerves) by the anterior part of the superior costotransverse ligament.
In the thoracic region, the dorsal ramus is short, common trunk of 3 mm to 5 mm, which bifurcates immediately dorsal to the superior costotransverse ligament into a medial and lateral branch.
The medial branches supply the adjacent intrinsic muscles of the back, the facet joints and skin in the upper thoracic region; the lateral branches supply intrinsic muscles, costotransverse joint, and the skin in the lower thoracic spine.
Spinous processes of T1-T3 and T11-T12 are located approximately at the level of the facet joint of adjoining level and the one below; T2 spinous process relates to T2-T3 facet joint level.
Spinous processes T4-T10 are located halfway between the adjacent facet joints and the joints below.
Cervical Spine (Figure 23-4)
Figure 23-4. Cervical spine and facets.
The atlanto-occipital and the atlanto-axial synovial joints are also present in the cervical spine as two paired joints, but are not considered to be facet joints as they are anterior rather than posterior spinal structures. (See Chapters 14 and 15.)
The cervical facet joints are formed by the inferior articular process of the superior vertebral segment and the superior articular process of the inferior vertebral segment.
The superior aspect of the facet joint faces forward and downward at 45 degrees, whereas the inferior aspect of the facet joint faces backward and upward at 45 degrees.
The facet joints in the cervical spine form paired vertebral column or “pillar” which together with a discovertebral unit provides the 3-prong structural support for this cervical segment.
The obliquity of the facet joints allows degrees of flexion, extension, and rotation.
The articular facets are covered by articular cartilage, and a synovial membrane bridges the margins of the articular cartilage of the 2 facets in each joint.
The cervical facet joints may contain a variety of intra-articular inclusions with fibroid-exposed meniscoid being the most common inclusions.
The average joint volume is >1 mL.
The cervical facet joints are well innervated by the medial branches of the dorsal rami. The fibrous joint capsule is richly innervated with mechanoreceptors as well as nociceptive receptors.
The innervation of the atlanto-occipital and atlanto-axial joints is derived from C1 and C2 root, respectively.
Cervical facet joints below C2-C3 are supplied by the medial branches of the cervical dorsal rami above and below the joint.
The C2-C3 joint is also supplied by the third occipital nerve.
Each C3-C7 dorsal ramus crosses the same segments, transverse process, and divides into lateral and medial branches.
The medial branch crosses around the waist of the articular processes of the same numbered vertebra.
The medial branches are bound by fascia, held against the articular pillar and covered by the tendinous slips of the origin of the semispinalis capitis.
Articular branches arise as the nerve approaches the posterior aspect of the articular pillar within ascending branch innervating the joint above and a descending branch innervating the joint below.
At C7, in contrast to C3-C6, the medial branches are located at the higher level due to the transverse process. At C7, the base of the transverse process occupies most of the lateral aspect of the articular pillar pushing the medial branch higher.
The course of the C4 and C5 medial branch nerves has been shown to be relatively constant crossing the waist of the respective articular pillars.
The C3, C6, and C7 medial branches show more variations compared to C4 and C5. The C3 medial branch nerve, with its more superior location at the upper thirds of the C3 articular pillar, often localize the third occipital nerve with the third occipital nerve being rostral through the C3 medial branch.
The C3 medial branch and the third occipital nerve have a common origin in the C3 dorsal ramus.
The C6 medial branch crosses around the waist of the articular pillar above it, between the waist and the superior articular process.
The majority (70%) of C7 medial branches are located high on the C7 articular pillar and across the C6-C7 facet joint. However, a few may be lower on the C7 transverse process.
The distance between the nerves and bone varies from close proximity to separation by 2 mm through 3 mm.
The C2-C3 facet joint is largely innervated from the third occipital nerve, which is the superficial medial branch of the C3 dorsal ramus. The deep medial branch of the C3 dorsal ramus is referred to as the C3 medial branch.
Articular branches may also arise from a communicating loop that crosses the back of the joint between the third occipital nerve and the C2 dorsal ramus.
The third occipital nerve (TON) continues around the lower lateral and dorsal surface of the C2-C3 joint embedded in connective tissue that invests the joint capsule.
PREOPERATIVE CONSIDERATIONS
Lumbar Facet Joint Interventions
Patient position
The patient is placed in the prone position on the fluoroscopic table.
A rolled towel or a pillow can be placed under the abdomen to facilitate easier entering the joint by reducing the lumbar lordosis.
Fluoroscopy
As with any lumbar interventions, a baseline AP fluoroscopic view of the lumbar spine is obtained, and the fluoroscopy is oriented.
Fluoroscopy beam is rotated from the anteroposterior view toward the oblique view until the posterior borders of the target facet joint are visible.
The upper lumbar face joints are typically aligned toward the sagittal plane and may be visible on AP imaging, whereas the lower facet joints are typically oriented toward the coronal planes so that oblique imaging is necessary to identify the joint lines.
Procedural steps
The target joint is then visualized under fluoroscopic guidance, and the skin may be marked.
A 22-25-gauge 3.5-inch spinal needle (depending on body habitus) is then inserted through anesthetized area (Figure 23-5A, B).
The needle is directed downward and obliquely (from lateral to medial) toward the selected joint under direct fluoroscopic visualization, and contact is then made with the inferior articular process (Figure 23-5A, B).
The needle is then withdrawn slightly and redirected to the target facet joint. As the needle is felt to penetrate the joint, advancement is stopped to prevent any potential damage to the articular cartilage.
If there is difficulty in obtaining capsular penetration, one may try to access the articular recess by redirection of the needle just off the margins of the inferior articular process.
Another method of getting intracapsular entry is to redirect a needle slightly medial or lateral to the posterior joint line so that the needle gains access via its medial placement through the insertion of the capsule on the articular process.
Once the needle is in an appropriate position, 0.2 to 0.25 mL of contrast can be injected under low pressure into the joint to confirm proper placement (Figure 23-6A, B). An arthrographic image can then be visualized.
During contrast injection, outline of the oval shape joint capsule should be visualized without any vascular uptake and/or epidural spread.
After contrast confirmation of intra-articular needle replacement, the joint is injected with anesthetic agent to complete a diagnostic block, or in combination with the steroid for a therapeutic injection.
Figure 23-5. (A, B) Proper alignment of the lumbar facet joint posterior borders. Note that the best view may not be the best entry point as that would represent the middle portion of the joint rather than the posterior borders which would be visible at lesser oblique angles, especially at the lower levels. Note the higher obliquity of the lower levels.
Figure 23-6. (A, B) Intra-articular injection. Not the contrast pattern within the joint. The upper and lower poles of the capsule for the “S” shape of the contrast pattern. Occasional capsular foramen may be seen with contrast spread within the epidural space.
Lumbar Medial Branch Blocks (Figure 23-7A, B)
Figure 23-7. (A, B) Lumbar medial branch blocks. The contrast pattern for the upper levels is often described as a “blind fold” over the “Scotie dog’s” eyes (left image). The L5 medial branch is blocked at the junction of the ala of the sacrum with its superior articular process. In this case (right image), a common anomaly is seen. This is the winged transverse process of the L5 vertebral body which may mimic the sacral ala.
To block the sensory innervation to the lumbar facet joint, it is necessary to block the 2 medial branch nerves which supply the joint.
Technique for L1 to L4 Medial Branch Block
Prone position (oblique [posterolateral] approach)
The patient is positioned in the prone position with pillow under the abdomen if needed. C-arm is adjusted to an oblique position.
To optimally visualize the landmarks for this “Scotty dog” configuration, an approximately 25 to 30 degree angle is necessary depending on the specific level from L1-L4 medial branches.
The needle is advanced toward the dorsal aspect of the root of the transverse process to ensure safe needle depth away from the ventral ramus.
Needle placed down to contact bony endpoint utilizing oblique fluoroscopic imaging. Prior to injection, final needle depth position should be confirmed using both AP and lateral imaging to ensure that the needle tip is neither too deep nor too medial or by orthography.
On AP imaging, the tip of the needle should be at least in line with the lateral margin of the silhouette of the superior articular process and if possible medial to this margin.
On lateral imaging, the needle tip should be within the confines of the shadow of the dorsal elements and not protruding into the foramen.
The superior articular process frequently bulges laterally overlying the target point dorsally. If the needle appears lateral to this point, it has contacted a thick transverse process instead of the superior articular process. In this case, the needle usually needs to be adjusted dorsally until the correct position is obtained on both the AP, oblique, or lateral views.
Before injection, the bevel opening should be medial and slightly inferior to reduce lateral and superior flow to the intervertebral foramen, especially the needle is placed inadvertently higher than the target position.
L5 dorsal ramus blocks
The patient is positioned prone with a pillow under the abdomen.
Begin with an AP view of the L5-S1 segment. Rotate the fluoroscope approximately 10° to 15° oblique toward the site to be blocked to view the junctions of the sacral ala and the superior articular process of S1.
Further obliquity usually places the medial iliac crest in front of the trajectory to the target position. If the ilium obscures the view of the target point as the C-arm is rotated obliquely, cephalad tilt of C-arm would usually bring the target into clear view by moving the ilium caudad within the fluoroscopic image.
A curved needle tip will allow for adequate steering of the needle to the target despite a cephalad-to-caudad needle entry point.
Once a clear path to the target point for the L5 dorsal ramus is identified, a skin insertion point is chosen. The target point is recognized as a notch between the sacral ala and the superior articular process of S1. The target point lies opposite the middle of the base of the superior articular process and that is likely below the silhouette on top of the sacral ala.
Higher placement is associated with spread into L5-S1 epidural space and lower placement with spread through the S1 posterior sacral foramina.
The needle is advance directly “down the beam” to the target position.
Anteroposterior imaging is obtained to verify that the needle is placed at appropriately medial to the lateral silhouette of the S1 superior articular process.
Lateral imaging should confirm that the needle tip lies within the shadow of the posterior spinal elements and does not protrude into the L5-S1 neural foramina.
After the needle tip confirmed to be in the proper location, the bevel opening should be rotated medially. This has been shown to reduce the inadvertent spread to the S1 posterior foramen or the L5-S1 vertebral foramen.
Radiofrequency Ablation of Lumbar Medial Branches (Figure 23-8A, B)
Figure 23-8. (A, B). Needle placement for RF ablation of the lumbar medial branches. Note the tangential placement of the needle to maximize the contact with the medial branch.
Thoracic Facet Joint Interventions (Figure 23-9A, B)
Figure 23-9. (A, B) Thoracic facet joint injections.
Intra-Articular Injections
Thoracic facet joints are not clearly evident in AP view. The location is estimated from the location of the thoracic pedicles.
Thoracic Medial Branch Blocks (Figure 23-10)
Figure 23-10. Radiofrequency ablation. The medial branch can be lysed along its path from the junction of the transverse and superior articular process to the interior aspect of the joint traversing over the lamina. At this level it is not “plastered” to the lamina but rather freely floating above it. A medial to lateral angle is preferred.
To block the nerve supply in thoracic facet joint, two medial branches must be blocked due to dual innervation of each facet joint.
Radiofrequency Ablation of Thoracic Medial Branches
Cervical Facet Joint Interventions
Intra-Articular Cervical Facet Joint Injections (Figure 23-11)
Figure 23-11. Cervical intra-articular injection. A posterior approach is safer and preferred. Although recent evidence does not support this procedure (in favor of Radiofrequency ablations of the medial branches), many practitioners still prefer it for inflammatory facet syndrome. The upper part of the image shows the facets that are not aligned properly. The lower part of the image shows properly aligned facets and articular pillars with parallax removed.
Posterior approach
The posterior approach for cervical intra-articular facet joint blocks can be performed with the patient in a prone position, or if required in a sitting position. It involves introducing a 22- to 25-gauge needle into the target joint from behind, along an oblique trajectory that coincides with the plane of the joint.
The patient is placed in the prone position with a cushion under the chest with the head and neck completely prone; however, the neck may be rotated to the side opposite the needle insertion.
Skin entry point is carried out approximately two or more segments below the target joint. The skin entry is determined by identifying the lateral aspect of the facet joint: on prone fluoroscopic viewing.
The needle is directed upward and ventrally through the posterior neck muscles until it makes contact through the posterior surface of the articular pillar below the target joint. Following the above step, the needle may be readjusted until it enters the joint cavity.
This may require inferior, posterior, anterior, and lateral fluoroscopic visualization to ensure that the needle stays on course. Directing the needle medially toward the interlaminar space may result in epidural or intrathecal puncture and/or spinal cord trauma.
After satisfactory localization of the needle into the joint, water-soluble contrast medium is injected to obtain an arthrogram and verify accurate placement. Then, local anesthetic and/or corticosteroid is injected for diagnostic or therapeutic purposes.
Due to the risk of pneumothorax and proximity of other neurovascular structures, the posterior approach is often preferred for C7-T1 facet joints.
The C2-C3 joint may be technically more difficult to visualize and enter due to anatomic features. The C2-C3 joint is more angulated vertically and medially and not clearly evident on lateral views. For the C2-C3 joints, the posterior approach may be modified by rotating the patient’s head to bring the cavity of the C2-C3 joint into view as it rotates forward on the lateral access of the vertebral column.
Benefits of the posterior approach
The posterior approach is considered safe since the needle penetrates only the skin and partially posterior neck muscles with the deep cervical artery the only structure at risk of inadvertent puncture.
Posterior cervical artery poses minimal risk of morbidity as it supplies no major structures.
Risks of the posterior approach
Penetration of the anterior joint capsule moving into the neural foramen and into the vicinity of the dorsal root ganglion, the cervical radicular artery and/or vertebral artery, epidural space, and spinal cord.
Leakage of the local anesthetic and steroid into the dorsal root ganglion.
Lateral approach
Patient position
The patient is positioned lying on his or her side with the target side up. The shoulders are pulleddown to avoid obscuring the joints in the fluoroscopy and rotated slightly posterior, over 25% into the plane of the upper torso and shoulders. The target joint is identified on lateral imaging of the neck.
Fluoroscopy
Lateral fluoroscopic imaging must appropriately identify both joints so that the upper most target joint is differentiated from the downside contralateral joint. This can be done by precisely superimposing one joint over the other (true lateral view) or by offsetting the joints adequately to view them independently (oblique view).
Technical steps
The needle is introduced through the skin over the midpoint of the joint. Then, the needle is advanced deeply until it makes contact through the bone of either the superior or inferior articular process.
Once the correct joint is clearly identified, the needle is advanced until the superior articular process is contacted just above the joint line. The needle is then directed and advanced through the joint capsule. The needle may be felt to pierce the capsule and to enter the joint space. Only minimal penetration is required.
The appropriate position onto the joint is confirmed by injection of a small dose of a contrast medium to obtain an arthrogram.
The C2-C3 joint may be technically more difficult to visualize due to anatomic features. The C2-C3 joint is more angulated vertically and medially and is not clearly evident on lateral views.
Benefits of the lateral approach include: The lateral approach is considered technically less demanding. It is more comfortable for the patient because less soft tissue is encountered. The risk of morbidity is minimal.
Risks of lateral approach include: Aggressive maneuvering or over-penetration may enter the needle into the epidural space or spinal cord.
With the lateral approach, to ensure safety, needle must remain posterior to the ventral ramus and the vertebral and radicular arteries.
The C3-C4, C4-C5, and C6-C7 joint injections are easily performed using the lateral approach with no disadvantages compared to the posterior approach.
The C7-C1 joint injection may be more easily performed at the posterior approach.
In a patient with a large neck and shoulders, C7 and T1 may not be reached from a lateral approach and may require the posterior approach.
The C7-T1 may also require a much deeper superior to inferior approach than other mid-cervical levels to minimize the possibility of contacting more inferior neurovascular and pleural structures.
Low volumes must be injected into the cervical facet joints. A volume of >1 mL is injected or injection is carried out rapidly or forcefully. The joint capsule may rupture and/or medication may spread into neighboring structures.
A communicating pathway exists in 80% of subjects within the facet joint and the interlaminar space, the opposite facet joint, the extradural space and/or the interspinous space when volumes in excess of 1 mL are injected.
Even with smaller volumes, extra-articular leaks have been observed in about 7% of the cases.
Cervical Medial Branch Blocks (Figure 23-12A-C)
Figure 23-12. (A-C) Cervical medial branch blocks. The most important aspect of the procedure is proper alignment of the articular pillars and removal of parallax between the right and left side. The image on the left shows mal-aligned articular pillars which are then aligned (right image) by adjusting the C-arm. The medial branch is blocked at the midpoint of the articular pillar. Lateral (lower image) as well as posterior approaches are preformed.
Posterior approach
The patient is placed in prone position with a pillow under the chest. The head is maintained looking straight downward in a neutral position or it turns to the side opposite the needle insertion. A PA view is obtained to identify the posterior aspect of the waist of articular pillars from C3 through C7.
After the identification of the waist of articular pillars at the levels to be blocked, a 22- to 25-gauge, 2- to 3-in spinal needle is inserted through the skin.
Once the needle has made contact with the bone, it is readjusted laterally through the deepest point of the concavity where the C3-C7 medial branches lie.
Initially directing the needle medially to bone ensures that the needle is not placed too deeply. The needle is then directed laterally until the tip reaches the lateral margin of the waist of the articular pillar.
The needle should barely slip off the bone laterally in a ventral direction of the deepest point of the articular pillars concavity.
Lateral images may ensure that the needle tip rest at the centroid of the articular pillar.
Centroid is defined as an intersection of the two diagonals of the diamond shaped pillar.
The C8 medial branch is blocked by placing the needle on to the transverse process of T1 and then directing it until it lies at the superolateral border of the transverse process.
Lateral viewing of the needle tip, location may be difficult below C6.
Moving the C-arm to an oblique projection may help to identify needle depth by moving the shoulders out of the line of the fluoroscopic view.
Lateral approach
The lateral approach in the supine position is reported to allow for a much greater patient tolerance by the proponent.
The lateral approach is described as a fast well tolerated effective procedure.
The direction of the x-rays is used in the procedure as a technique to avoid contact with exiting segmental nerves.
The lateral approach may also be used with the patient’s target site.
Articular pillars are identified by lateral fluoroscopy.
The upper most articular pillar can be distinguished from the opposite side by moving the fluoroscope. The needle will be seen to travel with the upper most articular pillar as the two articular pillars separate on the fluoroscopic image.
This approach is suited for C3-C6 medial branches.
The needle is directed through the skin and posterolateral neck muscle toward the centroid of the articular pillar as seen on two lateral radiographs.
To block the C7 medial branch by the lateral approach, the needle is advanced so that it stays within the confines of the C7 articular process, which prevents excessive advancement into the C8 foramen and toward the vertebral artery.
Once the superior articular process is contacted, anteroposterior imaging should verify that the needle lies against the lateral aspect of the superior articular process.
With posterior and lateral approaches, contrast in doses of 0.1 to 0.2 mL may be injected to confirm a appropriate needle placement. However, contrast injection is not mandatory.
After confirmation of the medial placement, local anesthetic with or without steroid is injected incrementally around the nerve.
Radiofrequency Ablation of Cervical Medial Branches (Figure 23-13A-D)
Figure 23-13. (A, B) Cervical medial branch radiofrequency ablation using lateral approach. This approach is best for pulsed RF lesioning. (C, D) Cervical RF posterior approach. Note the optimized view with collimation.
SIDE EFFECTS AND COMPLICATIONS
Complications from facet joint nerve blocks or intra-articular injections in the lumbar spine are exceedingly rare.