Lumbar Zygapophysial Joint Nerve (Medial Branch) Radiofrequency Neurotomy—Posterior Approach: Fluoroscopic Guidance

Abstract

Often-used synonyms for “neurotomy” include “ablation,” “denervation,” and “lesion.” We do not recommend the term “rhizotomy” because it implies lesioning of nerve roots.

Keywords

ablation, lesion, low back pain, lumbar, lumbar facet joint syndrome, lumbosacral, neurotomy, radiofrequency, spondylosis

Note: Please see pages ii , iii for a list of anatomic terms/abbreviations used throughout this book.

Often-used synonyms for “neurotomy” include “ablation,” “denervation,” and “lesion.” We do not recommend the term “rhizotomy” because it implies lesioning of nerve roots.

The lumbar radiofrequency neurotomy approach is described as needle placement using a trajectory view and advancement using multiplanar imaging, with an emphasis on safety using the lateral and ipsilateral oblique views to confirm the depth and radiofrequency electrode tip placement parallel to the targeted nerve. Before neurotomy, sensory, and motor stimulation confirm nonradicular stimulation and prior to neurotomy, 0.5 to 1 cc volume of local anesthetic is typically administered for patient comfort. The time and duration of the denervation vary between practitioners (e.g., up to three 90-second cycles at 80°C–85°C).

Trajectory View

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Confirm the level with the targeted medial branch nerve (with the anteroposterior [AP] view).
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Oblique and tilt the C-arm image intensifier to obtain an optimal AP view with the spinous process (SP) at midline and squaring off the superior end plate (SEP) of the vertebral body.
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Oblique the C-arm image intensifier about 20 degrees toward the symptomatic side (the right side, in this case) (do NOT oblique for the L5 dorsal ramus as noted below).
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Tilt the C-arm image intensifier about 40 to 45 degrees caudally from the squared SEP.
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  Note that this is one of the few procedures where we recommend specific angles.
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An alternate method to estimate the tilt angle is to mark the immediately inferior target and tilt that point as demonstrated in .
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This angle is used for entry and to approximate the trajectory of the target nerve for a “parallel placement” along the nerve.
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The electrode tip destination is the lateral border of the superior articular process (SAP) and the very small concavity that is formed by the junction of SAP and the transverse process.
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At the L5 level, there is only a rudimentary mamillo-accessory ligament (MAL), and the iliac crest will interfere with oblique needle positioning. Therefore, the oblique trajectory angle will be close to 0 degrees.
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As this is the trajectory view, the needle entry position should be parallel to the C-arm beam ( Fig. 15C.1 ).

Fig. 15C.1

A, Fluoroscopic image of a trajectory view with the radiofrequency electrode tip in position over the right L3 medial branch nerve. B, Radiopaque structures, trajectory view. C, Radiolucent structures, trajectory view. Please see above for setup details. The electrode is placed so that it lies parallel to the trajectory of the target nerve.

After approaching the target, advance the needle safely using the other views and respecting their safety considerations.

Optimal Needle Position in Multiplanar Imaging

For radiofrequency denervation, after the needle tip has reached its target via the trajectory view, three other views—ipsilateral oblique, anteroposterior, and lateral—are obtained for the final confirmation of the electrode tip position before neurotomy.

Optimal Needle Positioning in the Ipsilateral Oblique View ( Fig. 15C.2 )

When the needle is placed in the trajectory view, oblique the C-arm image intensifier further toward the symptomatic side to confirm that the needle tip is placed at the lateral border of SAP and the concavity that is formed by the junction of SAP and the transverse process. Stay along the base of SAP to remain superior to MAL ( Fig. 15C.2C ) for the L1 to L4 medial branches. Note that MAL at the L5 segment is rudimentary and, thus, permits a more sagittal approach for the L5 dorsal ramus. This oblique view is different from the trajectory view because the length of the needle is visualized in the oblique view to confirm the proper position of the needle tip.

Ipsilateral Oblique Safety View Considerations