Effect of Synchronized Radiofrequency and High-Intensity Facial Electrical Stimulation (HIFES) of the Upper Face (2025)

Konstantin Frank, MD ,

Article history

Abstract

Signs of aging in the upper face include but are not limited to the formation of static and dynamic rhytids of the forehead, glabella, and lateral canthal region, temporal volume loss, and eyebrow and eyelid ptosis.^1-3 The underlying mechanism is unfortunately still poorly understood, but it can be related to changes of the underlying bones and to soft tissue volume loss.^4,5 The latter predisposes the fascial layers to lose their foundation and stability, and by following the effects of gravity they start to sag caudally. To suspend the caudal movement of the upper facial soft tissues, muscles like the frontalis muscle are being reeducated to suspend the soft tissues in their original position, resulting in static skin rhytids rather than dynamic rhytids.⁶

Although the formation of horizontal forehead lines can be effectively reduced by relaxing the frontalis muscle with neuromodulators, this often comes at the cost of eyebrow ptosis, because the frontalis muscle is the only elevator for the eyebrow.⁷ Injection of hyaluronic acid–based soft tissue fillers into the deep plane of the frontal soft tissues has limited efficacy in ameliorating static forehead lines, and at the same time, due to proximity to the extensive arterial network located in the glabellar region, is not risk free.^8-10

A relatively novel procedure for reducing the signs of upper facial aging is the combined administration of synchronized radiofrequency (sRF) and high-intensity facial electrical stimulation (HIFES). In the porcine model, this combined treatment showed a muscle mass density increase of 19%, an increase of 21% in numbers of myonuclei, and an increase in individual muscle fibers.¹¹ Additionally, in a cohort of 21 human patients, 4 application cycles of synchronized RF and HIFES caused favorable volumetric changes of the cheek, alongside lower facial soft tissue repositioning.¹²

The concept of applying energy to the subcutaneous biomechanical unit comprised of facial muscle, the 3-dimensional connective tissue network, and skin is a novel anatomic concept aiming to safely and effectively rejuvenate the face. However, precise clinical evidence is currently absent in the scientific literature that connects this anatomic concept with the clinical benefit of the application of sRF and HIFES. Therefore, the objective of this study was to apply sRF and HIFES to the upper face and measure the clinical efficacy of this novel anatomic concept.

METHODS

Study Design

This was a nonrandomized, prospective, single-center investigation of sRF and HIFES for the treatment of facial aging. The clinical investigation plan (CIP), CIP amendments, informed consent forms, and all other appropriate study-related documents were reviewed and approved by the ethical committee of the medical chamber of Málaga on July 6, 2023. The investigation was performed in accordance with the International Standards Organization ISO14155:2011, the principles of the Declaration of Helsinki, and the applicable sections of the respective national laws, between July 2023 and March 2024.¹³

The interventional phase of the study included a total of 4 treatments conducted at an interval of 7 days (± 3 days), applying sRF and HIFES to the patient’s upper face. The evaluation phase of the study started after completion of the 4 cycles and relied on the clinical outcome measurements conducted at 4, 16, and 24 weeks (Figures 1-3).

Study Cohort

Each patient received the treatment after screening for eligibility. Patients were required to be 18 years of age or older upon enrollment, presenting with at least very mild static forehead and lateral canthal lines according to the modified Fitzpatrick Wrinkle Scale and healthy skin of the upper face, and be willing to abstain from additional aesthetic and/or surgical procedures for the face for the duration of the study (6 months).¹⁴ Patients with an impaired immune system, skin-related autoimmune diseases, scarring in the treatment area, metal implants, pacemakers, or internal defibrillators, or a history of or current skin cancer were excluded.

Treatment

Before treatment, the patient's forehead was disinfected with 95% alcohol solution to remove any kind of grease that could interfere with the EMFACE applicators’ positioning (BTL Industries, Boston, MA). The applicators are disposable items and intended to be utilized only once on the patient. After correct positioning on the forehead, a neutral electrode was placed on the patient's abdomen. The treatment consisted of 20 minutes of sRF and HIFES. The intensity of the treatment, which can be set from 0% to 100%, was set to 100% after a short period of 20 seconds for accommodation to the sensation of the sRF and HIFES tissue effects. After termination of the treatment, the applicators were removed, and the patient was discharged. The treatment was performed for the 4 sessions only. No sessions were repeated after 24 weeks.

Ultrasound Measurements

Ultrasound imaging was be performed with an LG Logiq E10 (LG, Seoul, Democratic Republic of Korea). The probe was placed on the lateral forehead in the midpupillary line at a middle distance between eyebrows and hairline. The thickness of the superficial fatty layer and of the frontalis muscle were evaluated.

Electromyography Measurements

Surface-derived noninvasive electromyography was performed of the forehead to measure the motor unit action potential (MUAP) of the frontalis muscle with noninvasive surface adherent wireless sensors (Avanti Trigno Quattro; Delsys, Natick, MA) at standardized positions, as published in previous protocols.^15,16 In brief, the sensors were attached to the frontal skin bilaterally in the midpupillary line after disinfecting and degreasing with 95% alcohol. The patient was then asked to raise the eyebrows as strongly as possible (to activate the frontalis muscle). The signals were then captured and transmitted to the EMG workstation (Trigno Avanti Platform; Delsys) for further analysis.

Modified Fitzpatrick Wrinkle Scale

The modified Fitzpatrick Wrinkle Scale was applied to assess the severity of static horizontal forehead and lateral canthal lines. The scale utilized scale was an adaptation of the original Fitzpatrick Wrinkle Scale, designed to allow for more accurate evaluations in both clinical and research settings. It categorized wrinkle severity on a scale from 0 to 4, for which 0 indicated no visible wrinkles; 1 very mild wrinkles, barely perceptible; 2 mild wrinkles that were visible but not prominent; 3 moderate wrinkles clearly visible and prominent; and 4, severe wrinkles that were deeply etched and very prominent.¹⁴ Assessments were made at baseline and after 4, 16, and 24 weeks, ensuring consistent and repeatable evaluations of changes in wrinkle severity throughout the study period by a blinded evaluator.

Three-Dimensional Surface Imaging

A Vectra H2 (Canfield Scientific., Fairfield, NJ) camera system created 3-dimensional surface imaging photographs of the patient at baseline and at all follow-up appointments. The software for image analysis was the Vectra Software Suite (Canfield Scientific). The distances between the horizontal level of the midpupillary line and the eyebrow at the level of the medial limbus, midpupil, and lateral canthus were measured. To ensure consistency and accuracy, all measurements were performed by the same investigator (K.F.).

Statistical Analysis

Comparisons between the baseline values and the 24-week follow-up measurements were considered the primary endpoint of the analysis. The difference of the other time points (4 weeks and 16 weeks) and baseline were considered additional outcome parameters. The Wilcoxon signed-rank test (due to nonnormal data distribution) was performed, and the mean value and respective 1 × standard deviation were provided. All statistical analyses were performed with SPSS version 27 (IBM, Armonk, NY). The results were considered statistically significant when P values were less than .05.

RESULTS

Patients

A total of n = 37 patients (7 males, 30 females) with a mean age of 45.46 ± 13.2 years (range: 24-74) and a mean BMI of 21.84 ± 1.9 kg/m² (range: 17.8-25.7) were enrolled in this study. Three (8.1%) of the enrolled patients were smokers. Fitzpatrick skin type distribution was as follows: 7 patients with Type II (18.9%), 24 patients with Type III (64.9%), and 6 patients with Type IV (16.2%). All patients completed the 24-week follow-up (100%). The mean follow-up was 24.0 ± 0.0 weeks.

Forehead Wrinkle Scale

At baseline, 19 patients (51.4%) presented with very mild static forehead lines, 13 patients (35.1%) with mild static forehead lines, and 5 patients (13.5%) with moderate static forehead lines. When comparing to baseline, all changes observed, including those at 24 weeks, represented a statistically significant improvement, with P < .001 for all follow-up visits. For detailed scoring see Figure 4.

Lateral Canthal Wrinkle Scale

At baseline, 15 patients (40.5%) presented with very mild lateral canthal lines, 13 patients (35.1%) with mild lateral canthal lines, and 9 patients (24.3%) with moderate static lateral canthal lines. When comparing to baseline, all changes observed, including those at 24 weeks, represented a statistically significant improvement, with P < .001 for all follow-up visits. For detailed scoring see Figure 5.

Ultrasound Measurements

Frontalis Muscle Thickness

The average thickness of the frontalis muscle at baseline was 0.96 ± 0.27 mm, at 4 weeks 0.76 ± 0.19 mm, at 16 weeks 0.76 ± 0.17 mm, and at 24 weeks 0.92 ± 0.19 mm. When compared to baseline, the difference at 24 weeks displayed no statistical difference, with P = .939, whereas the differences at 4 weeks and 16 weeks were both statistically significant, with P < .001 (Figure 6).

Superficial Fatty Layer Thickness

The thickness of the fatty layer overlying the frontalis muscle at baseline was 1.31 ± 0.29 mm, at 4 weeks 1.12 ± 0.34 mm, at 16 weeks 1.00 ± 0.29 mm, and at 24 weeks 1.18 ± 0.40 mm. When compared to baseline, the difference at week 24 displayed no statistical difference, with P = .120 (Figure 7).

EMG Measurements

Mean signal of the frontalis muscle at baseline was 87.72 ± 14.9 µV, at week 4 it was 95.48 ± 23.9 µV, at week 16 97.70 ± 26.0 µV, and at week 24 121.48 ± 18.5 µV. When compared to the baseline value, none of the follow-up values displayed a statistically significant difference, with all P ≥ .109 (Figure 8).

Eyebrow Positioning

At baseline, the mean distances between the horizontal midpupillary line and the medial/central/lateral eyebrow were 15.98 ± 2.03 mm/16.94 ± 1.97 mm/19.95 ± 2.73 mm respectively. At 4 weeks the distances were 16.72 ± 2.10 mm/17.59 ± 2.03 mm/20.18 ± 2.62 mm, at 16 weeks the distances were 17.24 ± 2.19 mm/17.97 ± 2.25 mm/20.64 ± 2.42 mm, and at 24 weeks the distances were 19.13 ± 2.07 mm/19.88 ± 2.17 mm/22.17 ± 2.13 mm, respectively. Compared to the baseline values, all follow-up measurements displayed a statistically significant increase, with P < .001 (except 4-week lateral canthus measurement, P = .577) (Figure 9).

DISCUSSION

In this single-center interventional study we evaluated the clinical effects of a series of 4 sRF and HIFES treatments of the forehead with regard to rhytid reduction and eyebrow positioning. The follow-up evaluation included ultrasound imaging, 3D skin vector displacement measurements, noninvasive electromyography, and rhytid classification at 4, 16, and 24 weeks after the last cycle of the treatment. The results revealed that after a period of 24 weeks a statistically significant reduction in horizontal forehead lines and in lateral canthal lines was observed, with both at P < .001. It is interesting to note that already at week 4 an improvement was noted, and it is questionable how long after the end of this study the effect will be clinically identifiable. When evaluating eyebrow positioning, it was revealed that at 24 weeks the position of the medial/central/lateral eyebrow changed, with a measured increase in eyebrow height of 3.18/3.02/2.27 mm when compared to baseline, with all at P < .001. Except for the lateral eyebrow at 4 weeks, all aspects of the eyebrow increased at every follow-up evaluation, starting at 4 weeks, with P < .001.

When measuring the thickness of the frontalis muscle following the sRF and HIFES treatment, it was observed that the thickness of the frontalis muscle temporarily decreased at 4 and 16 weeks but was regained at 24 weeks, with P = .939. A similar trend was detected for the thickness of the superficial fatty layer overlying the frontalis muscle in the treatment zone: a decrease in thickness that was not observed at 24 weeks, with P = .120. Despite a slight increase in the MUAP of the frontalis muscle, the changes, when compared to baseline, failed to reach statistical significance at any follow-up time point, with P ≥ .109.

The effectiveness of radiofrequency (RF) and electrical stimulation on the frontalis muscle, specifically in lifting the eyebrows and diminishing forehead lines, can be explained by the interplay of increased muscle strength and collagen production. Electrical stimulation works by contracting the muscle fibers, which, over time, leads to enhanced muscle tone and strength. In the case of the frontalis muscle, which is suspended by the inferior, middle, and superior frontal septa rather than directly attaching to bone, stimulation can still activate the muscle. As the muscle becomes stronger, it better resists the effects of gravity, contributing to the visible lifting of the eyebrows. This increased muscle tone also plays a crucial role in reducing forehead lines, because the strengthened frontalis muscle helps keep the skin taut, reducing the formation of dynamic wrinkles during facial expressions and forehead line formation at rest.

Radiofrequency, on the other hand, is known for its ability to generate heat in the dermis, which stimulates collagen and elastin production. Collagen, a key structural protein, enhances the strength and elasticity of the skin and connective tissues. The collagen in the dermal insertions and the septa—middle, inferior, and superior—likely increased due to this stimulation, making the skin and underlying connective tissue firmer. This, in turn, helped to elevate the brows and smooth out forehead lines by providing additional structural support. Interestingly, no changes were observed in the thickness of the subcutaneous fat or the frontalis muscle, suggesting that the improvements were driven by functional enhancements (increased muscle tone and collagen production) rather than changes in tissue volume. The radiofrequency treatment did not reduce fat or alter muscle size but instead worked by strengthening the connective tissue through collagen stimulation and enhancing muscle tone through electrical stimulation. The reduction in forehead lines can therefore be attributed to both the increased muscle strength and enhanced collagen and elastin content. As the frontalis muscle became stronger, it held the skin more taut, preventing excessive wrinkling, while the improved collagen in the frontal septa increased the skin’s elasticity and firmness. The lifting effect of the eyebrow was a direct result of these combined factors, with the firmed connective tissue and toned muscle working synergistically to elevate the brow. Overall, the treatment effectively enhanced the structural integrity of the skin and the function of the muscle, leading to a noticeable lifting of the brows and a smoother forehead.

The clinical benefit of the conducted treatment has been demonstrated by eyebrow elevation and horizontal forehead and lateral canthal line severity reduction, which were observed up to 24 weeks following the initial treatment. Given the noninvasive nature of the procedure, sRF and HIFES may be regarded as a viable option for upper facial rejuvenation when neuromodulators or soft tissue fillers are not deemed suitable, or a longer-lasting effect is required (in this study, 24 weeks). Given that no adverse events were observed during the study period, the risk profile might be lower than that of frontal neuromodulator (eyebrow ptosis, eyelid ptosis, headaches, periosteal hematomas, etc.) or soft tissue filler (nodules, discolorations, product migration, skin necrosis, blindness, etc.) treatments; this again may support the use of combination treatments or a stand-alone treatment option.^17-19 Additionally, the conducted treatment (sRF and HIFES) can be performed in combination with neuromodulators and soft tissue fillers when aesthetic treatments of the glabella or other periorbital regions are requested.

However, there are limitations to the methodologies. The variability in the surface electromyography data is evident from the high standard deviations observed, suggesting fluctuations in muscle activity readings that could impact the precision of the results. Additionally, although ultrasound provides detailed insights into changes in tissue structure, its accuracy is highly dependent on the exact placement of the probe. Given that the structures being measured are extremely small, even minor deviations in probe positioning can significantly affect the reliability of the measurements. These factors introduce challenges to ensuring consistent and accurate data collection across all participants.

Future clinical studies will need to explore and confirm the results presented herein and, especially focusing on combination treatments, much more work will need to be done to assure patient safety (first) and optimal aesthetic outcomes (second).

CONCLUSIONS

The application of synchronized RF and HIFES to the frontal region reduced frontal and lateral canthal rhytids and elevated the position of the eyebrow until 24 weeks after the initial treatment. Based on the results obtained, this noninvasive energy-based treatment option may be a viable alternative to injectable treatments of the upper face when trying to ameliorate the signs of upper facial aging.

Acknowledgments

The authors want to thank Vanessa Garcia for her continuous support in the conduct of this investigation.

Disclosures

The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

This study was financially supported by BTL Industries (Marlborough, MA).

REFERENCES

Author notes

Dr Frank is a plastic surgery resident and Drs Brebant and Prantl are plastic surgeons, Department of Plastic, Hand, and Reconstructive Surgery, University Hospital Regensburg, Regensburg, Germany. Dr Frank is also an evidence-based medicine editor for Aesthetic Surgery Journal.

Dr Kaye is a plastic surgeon in private practice, Marbella, Spain.

Dr Casabona is a dermatologist in private practice, Marbella, Spain.

Dr Glaue is an ear, nose, and throat resident, Lithuanian University of Health Sciences, Kaunas, Lithuania.

Dr Zeng is a doctoral candidate and Dr Moellhoff is a plastic surgeon, Department for Hand, Plastic and Aesthetic Surgery, Ludwig–Maximilian University Munich, Germany.

Dr Alfertshofer is a maxillofacial surgery resident, Department of Plastic and Hand Surgery, Technical University Munich, Munich, Germany.

Dr Cotofana is a researcher, Department of Dermatology, Erasmus Medical Centre, Rotterdam, the Netherlands, and is an evidence-based medicine editor for Aesthetic Surgery Journal.

© The Author(s) 2025. Published by Oxford University Press on behalf of The Aesthetic Society.

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