Technology in the field of aesthetic dermatology continues to advance over time. Microneedling, largely used to improve textural changes of the skin associated with photoaging and acne scarring, has evolved over time from the use of dermarollers and microneedling skin pens to energy-based devices that deliver radiofrequency (RF) energy though microneedles that are used today.
Unlike prior radiofrequency energy-based devices that deliver radiofrequency energy on the skin surface to allow bulk thermal energy (or heat) to stimulate collagen remodeling and tissue tightening, RF microneedling devices deliver the same RF or thermal energy via needles. RF, measured in Hertz (Hz) is part of the electromagnetic spectrum, with most devices delivering thermal energy at around 1-2 MHz, which is less than most typical RF only devices (at around 4-6 MHz), but with potentially more precise depth and delivery. For comparison, the RF of household electrical currents are around 60 Hz; traditional electrosurgical units, 50Hz -300 kHz; AM radio, 500 KHz; and microwaves, 2500 MHz.
When delivered to the skin, RF energy produces a change in the electrical charge of the skin, resulting in movement of electrons. The impedance (or resistance) of the tissue to the electron movement is what generates heat. Different factors, including tissue thickness, pressure applied to the tissue, hydration, bipolar versus monopolar delivery, and the number of needles are several factors than can affect the impedance.
Bipolar RF means that the current passes between two electrodes, whereas monopolar RF means that the electrical current is between an active treatment electrode and a passive grounding electrode (or grounding pad typically placed on the patient’s back). With bipolar RF, the current is limited to the area between the two electrodes. The depth of penetration is half of the distance between the electrodes, thus resulting in shallow (but potentially more aggressive) tissue heating. With monopolar RF, deeper tissue penetration occurs that is also often less uncomfortable to the patient.
The desired result of the energy delivery is collagen remodeling and strengthening of elastin. RF microneedling and microneedling in general may also have potential for use in enhancing topical product delivery.
Depending on the device, settings can be tailored to affect the energy delivery, including the type of needle (insulated vs. uninsulated vs. semi-insulated), Hz, number of needles, depth of needles, and time of exposure. In general, insulated needle tips provide less heat accumulation and potential injury to the skin surface, whereas uninsulated needles allow for more heat accumulation. Insulated needles, longer time of exposure, and lower energies (Hz) are safer options for darker skin types and those who hyperpigment easily.
Immediately after treatment, expected clinical endpoints can include erythema, edema, and possibly pinpoint bleeding that may last approximately several days to 2 weeks depending on the intensity of treatment. Potential side effects include infection, pigmentary alteration, folliculitis, prolonged grid marks, and scarring. Contraindications to treatment include having a pacemaker, history of keloid formation, active skin infections, prior gold threads in the treatment area, pregnancy and breastfeeding, metal implants in the treatment area, embedded electronic devices that cannot be turned off, isotretinoin use in the past 6 months, and allergy to any of the components of treatment.
Caution should be taken with tattoos in the treatment area or grounding pad (including cosmetic tattoos as tattoo ink may often contain metals that may absorb some of the heat, increasing the risk for injury or extrusion of the ink), a history of cold sores or herpes simplex virus in the treatment area (if so, a prophylactic antiviral would be indicated prior to treatment), use of topical retinoids in the past 7 days, having received neurotoxin or fillers in the prior 2 weeks, autoimmune disease, bleeding disorders, neuropathy, and history of poor healing.
Depending on the device and area being treated, most RF microneedling treatments require two to five treatments, typically 4-6 weeks apart. If improvement is seen, it may be noticeable after one to two treatments, and as with laser resurfacing, continued improvement may be noticeable over the following 6-12 months post treatment.
Dr. Wesley and Dr. Lily Talakoub are cocontributors to this column. Dr. Wesley practices dermatology in Beverly Hills, Calif. Dr. Talakoub is in private practice in McLean, Va. This month’s column is by Dr. Wesley. Write to them at firstname.lastname@example.org. Dr. Wesley has no relevant disclosures.