Facial cosmetic conditions in dermatology mainly refer to pigmentation, erythema, scars, and skin laxity caused by acne, dermatitis, and photoaging. These conditions not only have a great impact on the appearance of patients but also seriously affect the physical and mental health of patients, thereby reducing their quality of life; hence, it has attracted the attention of an increasing number of clinicians and patients [1
In recent years, facial cosmetic conditions have become a major concern in dermatology, and many medical methods have been used to treat them. These methods include topical agents, chemical peeling, botulinum toxin, hyaluronic acid, laser, radiofrequency (RF), and surgery [3
]. Recently, the microneedle fractional radiofrequency system (MFRS) has been widely used to improve facial cosmetic conditions [4
]. The MFRS is a new minimally invasive device in aesthetics that combines both RF and microneedles and delivers RF current through a microneedle electrode assembly. The needles are inserted vertically and rapidly. The RF emission time and the depth of the needle insertion can be changed easily at the operator’s discretion. Therefore, this device is suitable for superficial or deep skin therapy for various skin diseases [5
]. The MFRS is commonly used in dermatology to treat sagging skin, wrinkles, acne vulgaris, scars, and axillary hyperhidrosis [6
It has been found that ablative laser therapy is invasive and may impair skin barrier function, especially in the early post-treatment period, with an increased incidence of microbial infection and inflammatory lesions [7
]. However, the MFRS is also invasive. Previous studies did not report whether MFRS could cause epidermal thinning or skin barrier function impairment. These could increase skin sensitivity and exacerbate melasma.
Therefore, this study focused on whether the clinical application of MFRS might increase skin sensitivity or induce or aggravate the risk of melasma.
This prospective study was approved by the Ethics Committee of the Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine (SH9H-2019-T127-2). All the enrolled patients signed an informed consent form before treatment. This study complied with the ethical guidelines of the 1975 Declaration of Helsinki.
In this study, 20 patients (four men and 16 women) age 26–52 years, with Fitzpatrick skin types III or IV (skin laxity with melasma, n
= 9; post-inflammatory erythema and scars, n
= 5; and enlarged pores, n
= 6), and facial cosmetic conditions were randomly selected. All patients were screened using the Sensitive Scale 10-item version (SS-10) to determine baseline (BL) skin sensitivity [8
]. They were informed of the protocol and treatment risks, and they signed an informed consent form. The exclusion criteria were facial skin diseases such as eczema, psoriasis, herpes virus infection; history of keloids; pregnancy; photofacial treatments; botulinum toxin injections; any treatment that interfered with the study; or participation in other clinical trials within the past 6 months and during the follow-up.
Devices and Treatment Protocol
All patients received a full-face treatment with MFRS (INTRAcel, Jeisys, Korea). Before the treatment, superficial anesthesia with a 5% compound lidocaine cream (Tongfang Pharmaceutical Group Co., Ltd.) was applied to the patient’s face for 1 h, followed by disinfection with 75% alcohol. The skin in the forehead, orbital, and periorbital areas was treated with 1.5-mm penetration depth of the microneedles, density level 3, power of 12.5 W, and duration of 80 ms. Other areas such as the cheek, jaw, and nose, used a 2-mm penetration depth of the microneedles, level 4, power of 12.5 W, and duration of 100 ms. All the patients were treated twice, with an interval of 3 months. After the procedure, no wound care was prescribed except compression of the treated areas with an ice pack for 45 min. The skin care products could be reused on the first day after treatment.
Subjective and Objective Evaluations
Twenty patients were treated with MFRS and assessed at BL and during seven follow-up sessions. Follow-up evaluations were performed on day one (D1), day three (D3), day five (D5), day seven (D7), month one (M1), month three (M3), and month six (M6) after the second treatment. At each visit, a dermatologist performed a clinical self-assessment of skin sensitivity using the SS-10 and objective testing. Images were captured by the same photographer using the VISIA Skin Analysis System (Canfield Scientific, USA) and a digital camera (Sony ILCE-7M3, Tokyo, Japan). The following equipment was used to evaluate different parameters: 7th Generation VISIA Skin Analysis System (Canfield Scientific, USA), Skintel™ Melanin Reader (Palomar Medical Technologies, Inc. Burlington, MA), and a high-frequency ultrasound imaging system (DUB SkinScanner V5.0, Germany). During the follow-up after the last treatment, all patients were evaluated using the SS-10. The Melasma Area and Severity Index (MASI) was used to evaluate the severity of nine patients with melasma before and after MFRS treatment.
To analyze the differences before and after the MFRS treatment at different time points, a one-way analysis of variance was used to test the effect of time and organize the different parameters investigated. SPSS version 17.0 (SPSS Inc., Chicago, IL, USA) was used for the statistical analysis. A p value < 0.05 was considered statistically significant.
Acne, scarring, enlarged pores, loose skin, and photoaging are the most common facial cosmetic skin conditions and are considered major aesthetic problems. Minimally invasive treatments with quick recovery that do not lead to pigmentation, scarring, skin infection, and other side effects are currently preferred.
MFRS is an emerging aesthetic technique for treating facial lesions, such as acne, scarring, photoaging, enlarged pores, and skin laxity [9
]. During wound healing, denatured collagen is replaced by new dermal tissue, elastin and collagen are increased, and new elastin and collagen are gradually remodeled [11
]. Hence, it can treat acne scars, enlarged pores, skin relaxation, and photoaging [12
Since ablative fractional CO2
laser treatment of acne scars may damage skin barrier function, resulting in adverse reactions such as pigmentation and flushing, the incidence of microbial infection and inflammatory injury also increases correspondingly [13
]. MFRS treatment has a quick recovery, short downtime, and it rarely causes pigmentation or skin infection.
In our study, according to photographic analysis, ultrasonography, and VISIA results, we found that facial cosmetic conditions improved significantly after MFRS treatment. Additionally, MFRS treatment did not affect skin sensitivity based on the SS-10. Based on the results of the MASI and the MI, the treatment did not irritate or aggravate melasma.
The MI and MASI score were used to objectively evaluate the melasma change process after MFRS treatment, and the results showed that there was no exacerbation of melasma in either the 1-week recovery period or the follow-up period. In the recovery period, the patients had different degrees of erythema, edema, or purpura, which returned to BL 1 week later. Kwon et al. found the combination of MFRS and Nd:YAG laser safe and effective for the treatment of melasma and has a significantly improved therapeutic effect [14
]. They also found that Nd:YAG laser alone may lead to an increase in the incidence of hyperpigmentation and hypopigmentation. The possible reason is that Nd:YAG laser can gradually reduce epidermal pigmentation, and MFRS can stabilize melanin activity by interfering with potential pathogenic targets.
In a previous study of 27 patients with moderate facial photoaging, MFRS was effective in improving wrinkles, skin firmness, and skin tone. Most patients were satisfied with the treatment, but there were varying degrees of adverse effects, such as tolerable pain, mild bleeding, mild erythema, edema, and needle-like purpura. Throughout the procedure, none of the patients experienced significant or permanent adverse effects such as hyperpigmentation, hypopigmentation, or scarring [15
]. The reason is that MFRS energy is concentrated near the electrode tip located in the dermis. Therefore, the skin is not affected by a high temperature, and the energy is not diffracted or absorbed by the skin melanin, hence, there is only a small risk of damage to the activated epidermal melanocytes. Therefore, MFRS causes less hyperpigmentation and shows a lower burning rate compared to other treatment [16
A study comparing non-insulated microneedle radiofrequency alone with non-insulated microneedle radiofrequency in combination with polynucleotides for the treatment of melasma reported that the MI and erythema indices were lower than those at BL [17
]. The treatment was well tolerated by the patient. Similar to our study, no exacerbation or recurrence of melasma was observed. Moreover, invasive bipolar pulsed microneedle radiofrequency combined with polynucleotides was not superior to microneedle radiofrequency alone in the treatment of melasma. In our study, no reduction of melasma was observed, possibly because there were only two MFRS treatments in our study, which was less than those in other studies [18
Whether laser treatment induces skin sensitivity is also one of the key indicators observed in this prospective study. It has been documented that carbon dioxide laser resurfacing may induce skin sensitivity in sensitive areas of susceptible individuals, resulting in unpleasant sensations such as burning, pain, itching, or tingling. However, it has not been reported whether repeated use of ablative lasers increases skin sensitivity in real-world populations [19
]. It is currently believed that sensitive skin is related to impaired function of the epidermal barrier, which can lead to various kinds of discomfort [21
]. Studies have shown that TEWL, epidermal and dermal structures, and the red area of the face are related to barrier function [22
]. In this study, we measured TEWL values and the thickness and density of the epidermis and dermis to assess changes in the skin barrier function comprehensively. The results showed that facial water loss gradually increased from D1 to D3 after MFRS treatment. One week after treatment, TEWL gradually decreased to BL level, and at M6, there was no significant difference in TEWL compared with BL level. A possible reason is that, immediately after MFRS treatment, the epidermis is damaged to varying degrees, and the dermal tissue swells, leading to rapid water loss. Subsequently, with the gradual decrease in dermal swelling, the epidermis slowly returned to normal; thus, skin water loss was controlled and normalized. MFRS treatment might damage the skin barrier only in the early stage but resolves in 1 week without affecting skin sensitivity. Also, the sensitivity scale developed by Misery et al. (2014), a self-scoring questionnaire, was used to subjectively evaluate the sensitive skin condition of the participants before and after MFRS treatment. The results showed no difference in the sensitivity scores before and after treatment, suggesting that MFRS treatment did not irritate the skin barrier and did not cause skin sensitivity.
High-frequency ultrasonography was used to measure the thickness and density of the epidermis and dermis before and after the MFRS treatment, which showed no significant difference despite an observed increase in thickness and density of the dermis. On the contrary, Alavi et al. [9
] found that MFRS significantly increased the density and thickness of the epidermis and dermis, which may be due to radiofrequency affecting collagen synthesis in the dermis. The differing results between the two studies may be related to the number of MFRS treatments, courses of treatment, and follow-up intervals.
This study had some limitations. Facial histologic analysis is hardly conducted in patients on aesthetic consultation. Because of the relatively small sample size, we did not perform any correlations with the indices measured with each other or with demographic data of patients. In addition, the MFRS treatment data available are small due to the absence of a control group, relatively small sample size and insufficient follow-up period. The side effects of MFRS treatment require further follow-up studies with larger sample sizes and more treatment sessions.
We thank the patients who participated in the study. All patients have consented to publishing pictures and information.
This work was supported by the Major Project of Shanghai Xuhui District Medical Research Fund (grant number SHXH202002). The study sponsor is also funding the journal’s Rapid Service Fee.
All authors meet the International Committee of Medical Journal Editors’ criteria for authorship, take responsibility for the integrity of the work, and have given their approval for this version to be published.
Xiujuan Wu, Zhen Zhang, and Zongfeng Zhao contributed to the study design. Xianglei Wu, Jian Zhu, and Sheng Lu contributed to the experiments, analyzed the data, and drafted the manuscript. Xue Wang and Chen Chen confirmed the authenticity of all raw data. All authors have read and approved the final manuscript.
Xiujuan Wu, Zhen Zhang, Jian Zhu, Sheng Lu, Chen Chen, Xianglei Wu, Xue Wang and Zongfeng Zhao have nothing to disclose.
Compliance with Ethics Guidelines
This study was approved by the Ethics Committee of the Ninth People’s Hospital affiliated with Shanghai Jiao Tong University (SH9H-2019-T127-2). All the enrolled patients signed an informed consent form before treatment and for the publication of figures. This study complied with the ethical guidelines of the 1975 Declaration of Helsinki.
The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.