Lumbar Radiofrequency Ablation (Neurotomy)

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Pre-Procedure0/2

Perform time-out: verify patient identity, procedure, levels, laterality, allergies, and anticoagulation status.

Confirm patient had at least 80% relief from dual comparative medial branch blocks before proceeding to RFA.

RFA is indicated only after positive dual comparative diagnostic medial branch blocks. Proceeding without adequate diagnostic confirmation leads to poor outcomes and unnecessary procedures.

Review prior MBB procedure notes to confirm exact levels and response. Plan corresponding RFA levels.

RFA levels must match the diagnostic MBB levels exactly. Do not add or subtract levels without additional diagnostic blocks.

The RFA target is the same anatomical location as the MBB: the junction of the SAP and TP for L1-L4, and the sacral ala-S1 SAP junction for L5.

Setup0/2

Position patient prone. Select appropriate RF cannulae: typically 18- or 20-gauge, 10 cm length with 10 mm active tip.

Larger active tips create larger lesions. Match the active tip length to the anatomy (10 mm for standard lumbar RFA).

The RF lesion extends laterally from the active tip, not beyond it. Proper needle placement parallel to the nerve maximizes the lesion length along the nerve course.

Set up C-arm in AP view with squared endplates. Identify target levels and plan needle trajectories.

RFA cannulae are larger than MBB needles. Use local anesthesia (lidocaine) at each skin entry point.

The RF cannula should be placed parallel to the medial branch nerve as it courses along the TP-SAP junction. This requires a slightly caudal-to-cephalad trajectory in most cases.

Procedure0/6

Advance RF cannula to the TP-SAP junction (L1-L4) or sacral ala (L5) using the same fluoroscopic technique as MBB.

Ensure bony contact before testing. The cannula should rest on the periosteum at the nerve target.

The goal is to place the active tip parallel to the medial branch nerve along the groove of the TP-SAP junction. A slightly oblique trajectory (ipsilateral oblique view) can help achieve parallel placement.

Perform sensory stimulation at 50 Hz, up to 0.5 V. The patient should report concordant pain or pressure at or below threshold.

If stimulation reproduces pain at less than 0.5 V, the cannula is near the target nerve. If no response at 0.5 V, reposition.

Sensory stimulation confirms proximity to the medial branch nerve. The patient should feel a deep, aching, or pressure sensation in the usual area of pain, confirming the correct nerve.

Perform motor stimulation at 2 Hz, up to 1.0 V. Observe for multifidus fasciculation (acceptable) and rule out lower extremity motor response.

If lower extremity motor response occurs at less than 2x the sensory threshold, the cannula may be near a ventral ramus. Reposition to avoid motor nerve injury.

Motor stimulation at 2 Hz should produce local multifidus twitching (visible or palpable paraspinal muscle contraction) but NOT limb movement. Limb movement indicates proximity to the ventral ramus or nerve root.

Anesthetize the target with 0.5-1 mL of 2% lidocaine through the cannula prior to lesioning.

Local anesthesia reduces procedural pain during the thermal lesion but may temporarily affect subsequent sensory testing at adjacent levels.

Pre-lesion local anesthesia is standard practice. Some practitioners complete all sensory and motor testing at all levels before anesthetizing any level to avoid cross-contamination.

Perform conventional thermal RF lesion at 80 degrees C for 90 seconds at each level. Monitor patient throughout.

The patient should not experience severe radiating limb pain during lesioning. If this occurs, abort and reposition.

Standard thermal RF creates an oblate spheroid lesion extending laterally from the active tip. At 80 degrees C for 90 seconds with a 10 mm active tip, the lesion is approximately 5-6 mm in diameter.

Consider creating a second lesion at each level by slightly repositioning the cannula (bipedicular technique or rotating the cannula) to increase lesion coverage.

Multiple lesions per level improve success rates but increase tissue disruption. Limit to 2-3 lesions per target.

Studies show that multi-lesion techniques improve denervation success rates from approximately 60% to 80%. The parallel placement technique and slight repositioning help capture anatomic variation in nerve position.

Post-Procedure0/2

Remove cannulae and apply bandages. Monitor patient for 20-30 minutes. Prescribe post-procedure analgesics for neuritis pain.

Warn patient about expected post-procedure soreness lasting 1-3 weeks (post-denervation neuritis). New radicular symptoms are NOT expected.

Post-RFA neuritis (localized back soreness and stiffness) is common and expected. It typically resolves within 2-3 weeks. Therapeutic benefit from RFA may take 3-6 weeks to fully manifest.

Schedule follow-up at 4-6 weeks. Document all levels treated, RF parameters, stimulation thresholds, and number of lesions per level.

Assess pain relief at follow-up. Successful RFA typically provides 6-12 months of relief before nerve regeneration.

Medial branch nerves regenerate over 6-18 months. When pain returns to pre-RFA levels, repeat diagnostic blocks may be performed, and RFA can be repeated with similar success rates.