Cervical facet pain, third occipital headache and medial branch RFA

Cervical facet pain is diagnosed by blocks, not imaging: a single medial branch block with at least 50% relief selects most patients for radiofrequency ablation, and C2–C3, via the third occipital nerve, is a key source of cervicogenic headache.

1. C2–C3 is innervated by the third occipital nerve. Headache from C2–C3 was historically called third occipital headache and is an accepted cause of cervicogenic headache ¹.
2. Third occipital headache is common after whiplash. Among 100 whiplash patients with chronic neck pain, blocks confirmed it in 27%, and in 53% when headache was the dominant symptom; cervical facet pain is a common problem after whiplash generally ¹².
3. One block, 50% relief, by default. The 2022 guideline recommends a single medial branch block to select patients for ablation (grade B) and a cut-off of at least 50% relief to maximize access to care (grade C) ¹.
4. Stricter selection trades sensitivity. Dual blocks or higher thresholds may raise ablation success but produce false negatives and a lower overall success rate; reserve them for selected cases ¹.
5. Imaging cannot find the painful joint. Radiographic changes cannot identify a painful facet, normal imaging does not exclude it, and CT shows facet arthritis in many people scanned for other reasons ¹.
6. Medial branch blocks beat intra-articular injections. Medial branch blocks are more predictive of ablation success, and therapeutic intra-articular injections should not be used routinely ¹.

ICHD-3 cervicogenic headache needs a cervical disorder plus at least two lines of causal evidence, such as abolition by diagnostic blockade; upper cervical imaging changes are common in people without headache ³.

• Tenderness over C2–C3 was 85% sensitive for a positive third occipital block ¹.
• The guideline recommends cervical medial branch block volumes of about 0.3 mL or less (grade C); 0.25–0.5 mL gave a 7% missed-nerve rate ¹.
• Keep cervical intra-articular volume to 1 mL or less ¹.
• Motor stimulation before ablation may benefit safety and efficacy (grade B) ¹.
• Conservative measures may prevent the need for blocks but do not preclude them after conservative failure (grade B) ¹.
• In the sham-controlled trial of cervical radiofrequency neurotomy, median time to pain returning to 50% was 263 days versus 8 days with sham ².
• Gait abnormalities, radicular or audiovisual symptoms are unlikely to arise from isolated atlanto-occipital or atlanto-axial joint dysfunction ¹.

• Requiring dual blocks for every patient ¹.
• Choosing the joint to treat from CT or MRI findings ¹³.
• Expecting history or examination to confirm third occipital headache; no unique feature correlated with a positive block ¹.
• Offering repeated intra-articular steroid as definitive therapy ¹.