Lumbar Procedural Application
BACKGROUND:
RF medial branch thermal neurotomy for proven and recalcitrant lumbar zygapophysial joint pain is a very common neuroablative procedure performed in pain management practices. The RF electrode conventionally used for this procedure is an 18 – 20 gauge single lumen monopolar cannula. The lesion produced by this electrode requires placing the active tip of the electrode parallel and adjacent to the medial branch or dorsal ramus to achieve the desired length of neurotomy. Even if the ideal angle of incidence is accomplished, a challenging task in the most experienced of hands, multiple lesions are required to create a lesion matrix sufficient to ensure disruption of the pain-transmitting pathway. Over the past decades extensive efforts have been made to develop and teach techniques to compensate for the limitations of the traditional electrode technology. These techniques are time and x-ray exposure-intensive, and may be impossible in obese patients or those with advanced arthropathy or abnormal anatomy.
The Nimbus MEE is a fundamental improvement in electrode technology. By design, Nimbus will create a lesion of such size and shape that a straightforward “down-the-beam” approach results in the desired neurotomy. The Nimbus MEE may be used with the classic “pillar view” technique, but offers the additional flexibility of a “down-the-beam” approach fashioned after the standard medial branch block technique familiar to all practitioners.
L1-L4 Medial Branches - Down the Beam Technique
1. Identify segment of interest and align superior endplate (e.g., superior endplate of
L4 aligned for lesioning of the L3 MB on the L4 transverse process).
2. Rotate fluoroscopy 15-30 degrees ipsilateral oblique to visualize the pedicle shadow
and juncture of superior articular process (SAP) with the transverse process. A
minimal amount of rotation will ensure the active tip rests adjacent to SAP. In cases
of arthropathy more rotation will be needed.
3. Identify a desired target position at the mid of the base of SAP or slightly cranial. In
a more caudal position the mamillo-accessory ligament may protect the medial
branch from lesion.
4. Infiltrate skin and deep tissues with local anesthetic.
5. Gripping the central hub (colored), advance the cannula over bone target “down the beam” until
bony contact.
6. Return to AP to confirm placement at the juncture of the SAP and TP (ensure that cannula tip is
sufficiently medial).
7. Obtain a caudocranial decline view adequate to visualize the tip of tip of central cannula at base
of SAP in sulcus between SAP/TP.
8. Orient the cannula to project tines away from the midline. (Directional stripe on main hub will
point 90 degrees away from spine.)
L1-L4 Medial Branches - Down the Beam Technique
1. Identify segment of interest and align superior endplate (e.g., superior endplate of L4 aligned for lesioning of the L3 MB on the L4 transverse process).
2. Rotate fluoroscopy 15-30 degrees ipsilateral oblique to visualize the pedicle shadow and juncture of superior articular process (SAP) with the transverse process. A minimal amount of rotation will ensure the active tip rests adjacent to SAP. In cases of arthropathy more rotation will be needed.
3. Identify a desired target position at the mid of the base of SAP or slightly cranial. In a more caudal position the mamillo-accessory ligament may protect the medial branch from lesion.
4. Infiltrate skin and deep tissues with local anesthetic.
5. Gripping the central hub (colored), advance the cannula over bone target “down the beam” until bony contact.
6. Return to AP to confirm placement at the juncture of the SAP and TP (ensure that cannula tip is sufficiently medial).
7. Obtain a caudocranial decline view adequate to visualize the tip of tip of central cannula at base of SAP in sulcus between SAP/TP.
8. Orient the cannula to project tines away from the midline. (Directional stripe on main hub will point 90 degrees away from spine.)
Figure 13 – Down the beam approach lumbar medial branch neurotomy.
Figure 14 – AD view confirming active tip placement at medial aspect of transverse process.
Figure 13 – Down the beam approach lumbar medial branch neurotomy.
Figure 14 – AD view confirming active tip placement at medial aspect of transverse process.
Figure 15 – Caudal decline view to visualize active tip in succus.
Figure 16 – Lateral view, tines deployed – posterior to neural foramen.
Figure 15 – Caudal decline view to visualize active tip in succus.
Figure 16 – Lateral view, tines deployed – posterior to neural foramen.
L5 Dorsal Ramus
1. Obtain AP view through the L5S1 disc space.
2. Rotate ipsilateral oblique or ipsilateral oblique combined with caudal decline to optimize
visualization of groove at the base of the S1 SAP.
3. Starting medial to the iliac crest shadow and over groove advance the cannula to the base of
the S1 SAP.
4. Slide cannula into groove.
5. Adjust cranial placement using AP view through L5/S1 disc, advancing active tip to cranial edge
of sacral ala.
6. Rotate helical spin collar clockwise until fully advanced. A distinct tactile click will be
appreciated with full engagement. In general tines are positioned along sacral ala to account for
any lateral variability in primary location of the L5 dorsal ramus.
a. The directional heating bias of the electrode is intended to provide the operator with the
ability to fine-tune target coverage and minimize unnecessary collateral tissue injury.
b. If device needs to be repositioned tines must always be retracted fully before
cannula is manipulated.
7. Check lateral and adjust as necessary for active tip and tines to be approximately
halfway across the L5/S1 facet complex and posterior to the L5/S1 neural foramen.
8. Motor stimulation: a 2 Hz frequency at 1.5 – 2.0 volts is recommended to rule out
ventral ramus activation.
9. With tines fully deployed, inject local anesthetic if desired.
10. Recommended heat cycle: 30-second ramp and 80 seconds at 80 C.
11. Consider withdrawing 10 mm and repeating heat cycle.
12. Retract tines and remove cannula.
1. Obtain AP view through the L5S1 disc space.
2. Rotate ipsilateral oblique or ipsilateral oblique combined with caudal decline to optimize visualization of groove at the base of the S1 SAP.
3. Starting medial to the iliac crest shadow and over groove advance the cannula to the base of the S1 SAP.
4. Slide cannula into groove.
5. Adjust cranial placement using AP view through L5/S1 disc, advancing active tip to cranial edge of sacral ala.
6. Rotate helical spin collar clockwise until fully advanced. A distinct tactile click will be appreciated with full engagement. In general tines are positioned along sacral ala to account for any lateral variability in primary location of the L5 dorsal ramus.
a. The directional heating bias of the electrode is intended to provide the operator
with the ability to fine-tune target coverage and minimize unnecessary collateral tissue injury.
b. If device needs to be repositioned tines must always be retracted fully before cannula is manipulated.
7. Check lateral and adjust as necessary for active tip and tines to be approximately
halfway across the L5/S1 facet complex and posterior to the L5/S1 neural foramen.
8. Motor stimulation: a 2 Hz frequency at 1.5 – 2.0 volts is recommended to rule out ventral ramus activation.
9. With tines fully deployed, inject local anesthetic if desired.
10. Recommended heat cycle: 30-second ramp and 80 seconds at 80 C.
11. Consider withdrawing 10 mm and repeating heat cycle.
12. Retract tines and remove cannula.
Figure 17 – L5 dorsal ramus – initial cannula trajectory using slight oblique rotation with caudal decline.
Figure 18 – AP L5, showing active tip in the L5 dorsal ramus groove.
Figure 17 – L5 dorsal ramus – initial cannula trajectory using slight oblique rotation with caudal decline.
Figure 18 – AP L5, showing active tip in the L5 dorsal ramus groove.
Figure 19 – Lateral view L5 dorsal ramus. Active tip/tines posterior to neural foramen.
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