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Friday, April 17, 2020

Radiofrequency Ablation of Facial Venolymphatic Malformations: Assessment of Efficacy and Safety and the Role of Injectable Electrodes

Clinical questions

Is ultrasound-guided radiofrequency ablation safe and effective in treating facial microcystic lymphatic and venolymphatic malformations; and how does safety and efficacy compare when using a newer injectable electrode with induced-paralysis technique versus a standard noninjectable electrode?

Take-away point
US-guided RF ablation is effective and safe in the treatment of facial microcystic lymphatic and venolymphatic malformations. The induced-paralysis technique with an injectable electrode demonstrated noninferior safety and efficacy compared to noninjectable alternatives.

Cho, Se Jin. et al. Radiofrequency Ablation of Facial Venolymphatic Malformations: Assessment of Efficacy and Safety and the Role of Injectable Electrodes. Journal of Vascular and Interventional Radiology, Volume 31, Issue 4, 544 - 550.

Click here for abstract

Study design
Retrospective chart review

Funding source
Self-funded or unfunded 


Figure 2. Images from a 19-year-old woman with a mixed VLM. (a,b) Coronal contrast-enhanced CT (a) and fat-suppressed T2-weighted MR (b) images demonstrate a mixed VLM at the right sublingual and submandibular spaces. Note that the lesion is located close to the lower edge of the mandibular body, which is the location of the marginal mandibular branch of the facial nerve. (c) US image during RF ablation depicts the lesion (arrows) with an injectable electrode positioned at the center. (d) Coronal fat-suppressed T2-weighted image shows that the lesion is markedly decreased (volume reduction ratio, 79%) 11 months after a single-session ablation, without any complications.


Facial venolympathic malformations (VLMs) located in the head and neck can cause significant cosmetic disfigurement. Treatment has classically been accomplished with surgery, which can lead to scarring and neurovascular injury, ultimately leading to unsatisfying resolution. Ablation with sclerosing agent, however, has risen as an alternative therapy with investigations showing favorable efficacy. There is inadequate evidence of its utility in the treatment of microcystic lymphatic malformations (mLMs) and mixed VLMs, however, as sclerosing agent has not been shown to reduce mLM volume. RF ablation has been studied in mLM treatment with efficacy and safety, but the potential risk of thermal damage to functional nerve structures (e.g. cranial nerve branches) still exists. The authors proposed a novel technique for RF ablation for facial mLMs called “induced paralysis.” Using a novel electrode with multiple side holes at the non-insulated tip, the proceduralist can identify small motor and/or sensory nerves by injecting local anesthetic to the area around the tip prior to RF ablation, preventing inadvertent nerve damage.

In this retrospective chart review, 15 patients who had undergone RF ablation of a symptomatic facial VLM with ultrasound guidance within a 3-year period were identified. The group consisted of 3 males and a median age of 29 years. 6 patients were treated with the injectable electrode, while the remaining 9 were treated with the standard non-injectable electrode. The median number of treatments per patient was 1 (1-2 treatments). Median follow-up was 10 months (1-44 months). All patients underwent an initial cosmetic grading score (CGS) assessment as well as ultrasound and contrast-enhanced CT or MR imaging for initial volume assessment. Follow-up metrics included volume at 1 and 3 months with ultrasound and 6-month volume with CT or MRI. CGS and complications were also collected. Complete improvement was defined with a change of CGS from 4 to 1, whereas partial improvement was defined as a CGS of 4 to 2-4. Immediate and delayed procedure-related complications, including burns, bleeding, infection, necrosis, or sensory/motor nerve symptoms, parotid duct injury, and vascular damage were assessed with ultrasound.

Median CGS at final follow-up was 1 in all patients. This was not significantly different between injectable and noninjectable groups. 2 of 9 patients (22%) treated with the non-injectable probe experienced partial improvement versus 5 of 6 patients (83.3%) in the injectable probe group. Median volume decrease was 81% in the 13 patients with follow-up volume data. There was no significant difference between outcomes between non-injectable and injectable electrode groups despite similar incidence of a functional structure near the lesion on pre-procedure imaging (p<0.05). There was, however, a significant difference in outcomes between patients who had a nearby functional structure on imaging versus those without (p<0.05).

Two cases of nerve injury with partial improvement occurred in patients treated with the noninjectable electrode (22%). Specifically, 1 case of facial palsy with mild reduction of function (House-Brackmann grade II) and 1 case of hypoesthesia secondary to submental nerve injury were reported. Both of these patients experienced partial improvement of nerve injury symptoms. 1 case of intermittent sharp pain near the ablation zone was reported in a patient treated with the injectable probe (16.7%) which subsided after 1 month.


This study confirms previous findings demonstrating the efficacy of US-guided RF ablation of facial VLMs and mLMs. It also suggests non-inferiority of the induced-paralysis technique with an injectable RF ablation probe to avoid nerve injury. RF ablation therapy has shown significant potential as a safe and effective alternative to surgical therapy for facial vascular lesions, and is specifically associated with lesion volume reduction of mLMs while chemical ablation is not. The study is limited by its small sample size, discrepancy in lesion volumes between groups, retrospective design, and selection bias. These make the results inconclusive on their own. Future studies will be needed with larger patient groups in order to reduce heterogeneity of the study population and confirm the true potential of these modalities.

Post Author
Jared Edwards
4th Year Medical Student
Oregon Health & Science University School of Medicine, Portland, OR

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