Lasers in Surgery and Medicine 38:799–807 (2006)

Clinical InsightThe Role of Deep Heating for NoninvasiveSkin Rejuvenation

Christine C. Dierickx, MD*Skin and Laser Surgery Center, Boom, Antwerp, Belgium

Redundant facial, neck, or body laxity is a major feature ofaging. Just a few years ago, the choices for treatment of skinlaxity were only surgery. As technology continues to evolve,procedures that once required major surgical interventionare gradually being replaced by minimally invasivetechniques. Recently, monopolar radiofrequency (MRF)and infrared light sources have been introduced fornonablative tissue tightening by volumetric heating of thedeep dermis. Appropriate selection of patients and mana-ging realistic patients’ expectations of outcome are keyconsiderations to ensuring satisfaction with results. How-ever, controversy persists over the effectiveness of thesetreatments. Further development of the technologyand refinement of treatment protocols may allow formore dramatic modulation of the underlying deeperstructures, improving the consistency of results. LasersSurg. Med. 38:799–807, 2006. � 2006 Wiley-Liss, Inc.

Key words: fractional dermal heating; infrared lightsources; monopolar radiofrequency; noninvasive tighten-ing; volumetric dermal heating

MECHANISMS OF TISSUE HEATING

Only a deep penetrating method of heating the dermisand possibly the fibrous septae supporting the dermis andsubcutaneous fat to the underlying fascia, could possiblyhave an effect to tighten and contour nonsurgically, mildto moderate laxity of the skin. This novel method ofdistributing large energies evenly over a three-dimensionalvolume of tissue has been attempted by radiofrequency(RF) devices and infared light sources. Unlike themajority of lasers, which target specific absorption bandsof well-localized chromophores, the output of these devicesis transformed into heat mainly by tissue water. As a result,the energy is dispersed to three-dimensional volumes oftissue at controlled depths. Epidermal cooling is mandatorywith these techniques in order to assure preservation of thesuperficial skin layers. The depth and dimensions of theheated region can be manipulated by varying parameters ofthe energy source and cooling system.

Mechanism of Tissue Heating by MonopolarRadiofrequency

A monopolar radiofrequency (MRF) device (ThermaCoolTCTM System, Thermage, Inc., Hayward, CA) was the first

technology developed specifically to tighten deeper dermalstructures without epidermal damage. It was introducedabout 5 years ago and has an accumulation of publishedscientific data corroborating its unique tissue-tighteningeffect. The ThermaCool TC system heats tissue by couplingRF to the skin by a thin capacitive membrane thatdistributes RF energy over a volume of tissue beneath thesurface membrane. A cryogen system simultaneously coolsthe epidermis for protection. Like conventional RF tissuedevices, tissue heat is generated based on the tissue’snatural resistance to the movement of ions within an RFfield (Ohm’s law). The distinguishing tissue-heat feature ofthe device is the method of coupling the RF to the skin:instead of a standard RF conducting electrode, a capacitivecoupling membrane is used. This capacitive couplingmethod transforms RF to a volumetric tissue-heatingdevice, rather than a concentrated point heating sourceas characterized by standard RF electrode heatingdevices. This unique volumetric heating method allowslarge amounts of energy to be distributed over a three-dimensional volume of dermal tissue while protectingthe epidermis. Initial collagen denaturation within thesethermally modified deep tissues is thought to be themechanism for immediate tissue contraction. Subsequentneo-collagenesis further tightens the dermal tissue [1].

Mechanism of Tissue Heating by Infrared Light

Infrared light can also be used as an alternative source ofenergy for the purpose of skin tightening. A noncoherent,selectively filtered infrared device (Titan, Cutera, Brisbane,CA), emitting infrared light in multisecond cycles, has beendeveloped with the intention to provide dermal heating.Water, as the target chromophore, allows for uniform heatingof the targeted volume. A tailored spectrum from 1,100 to1,800 nm, including filtering of the strongly absorbingwavelengths in the 1,400–1,500 nm range, allows a penetra-tion depth of 1–2 mm, ideal for targeting the reticular dermis.

Contract grant sponsor: Thermage, Palomar.*Correspondence to: Dr. Christine C. Dierickx, MD, Director,

Beukenlaan 52, 2850 Boom, Belgium. E-mail: mail@cdierickx.beAccepted 25 September 2006Published online 23 October 2006 in Wiley InterScience(www.interscience.wiley.com).DOI 10.1002/lsm.20446

� 2006 Wiley-Liss, Inc.

A multisecond exposure is used with sufficient energy tocreate the desired combination of time and temperature forcollagen contraction, according to the Arrhenius equation[2,3]. The epidermis is protected through contact cooling. Thisallows for heating of the treated tissue without epidermalablation. Infrared lasers (long-pulsed Nd:YAG laser and900 nm diode laser combined with bipolar radiofrequency)have also been used for the purpose of skin tightening [4,5].Since the author is not experienced with these devices,further elaboration is lacking.

Mechanism of Tissue Heating by FractionatedInfrared Light

An attempt was made to deliver a patterned irradiationprofile into the deeper layers of dermis and hypodermiswith an infrared lamp (Lux-IR FractionalTM, PalomarMedical, Inc., Burlington, MA). The rationale behind usingthe fractional, rather than the uniform delivery of infraredradiation, is threefold:

* A higher irradiance at the ‘‘islets’’ in comparison touniform illumination at a fixed total power. Thus, astronger effect can be achieved at the islets withoutincreasing the output power of the optical source.

* A faster healing response of the body due to increasedsurface-to-volume ratio of the microwounds. Neo-collagen formation is part of the healing response ofthe body to an inflicted wound. The rate of this process islargely determined by the intensity of expression ofevent-specific biomolecular markers. Literature datasuggest that the intensity of this process is maximal atthe boundary layer between the injured and intact tissue[6]. The volume of this layer is, in turn, proportional tothe internal surface of the wound. Thus, at a given totalvolume of the wound, fractional damage should healfaster and more efficiently than the bulk one.

* A larger safety margin. Fractional delivery shouldprovide higher ratio of maximally acceptable (in termsof discomfort and side effects) fluence to minimallyeffective fluence [7]. Thus, the fractional treatment has abigger room for error and is, therefore, safer.

DEVICES

ThermaCoolTM Device

The major component of the device includes (1) a MRFgenerator producing a 6 MHz alternating current RFsignal, (2) a handpiece for directing the RF energy to the

skin, (3) a disposable electrode treatment tip for transferr-ing RF energy to the skin and serving as a membrane forcooling, and (4) a cooling module that feeds cryogen througha controlled valve on the handpiece to the tip’s contactcooling membrane. During treatment, temperature, pres-sure, and RF feedback is monitored by sophisticatedcomputer-controlled sensors in the treatment tip andenergy delivery is immediately aborted if uniform contactwith the skin is not maintained or if the temperature at theskin surface rises above the set threshold. The size andstrength of the electric field is dependent on the geometry ofthe electrode and the power delivered through the tip.Because the treatment tips come in different sizes (0.25, 1,1.5, and 3 cm2), it is possible to change the depth oftreatment by changing the geometry of the electrode(Fig. 1). Smaller tips are better suited for treatment of theperi-orbital area, while the large 3-cm2 tip makes treat-ment of larger surface area (arms, thighs, and abdomen)feasible (Table 1).

Titan Device

The Titan device (Cutera) is a broadband infrared lamp.Its tailored spectrum ranges from 1,100 to 1,800 nm andincludes filtering of the more absorbing wavelengths in the1,400–1,500 nm range. This allows for a penetration depthof 1–2 mm, ideal for targeting the reticular dermis. Light isemitted in multisecond cycles and can therefore, thor-oughly heat the dermis over a period of seconds (up to 9.5seconds). Pre-, parallel-, and post-cooling takes place via atemperature-regulated sapphire crystal window. One canchoose from different spot sizes (1�1.5 and 1�3.0 cm),according to the treatment area (Fig. 2 and Tables 1, 2).

Lux-IR Device

A newly developed near infrared lamp device (Lux-IRFractionalTM, Palomar Medical, Inc.) delivers multiple,spatially confined thermal lesions in the dermis andhypodermis without epidermal damage (Table 1). Thisdevice employs a near infrared halogen lamp with anoptimally filtered emission spectrum spanning approxi-mately from 850 to 1,350 nm. The handpiece has a spotsizeof 12�28 mm with skin surface cooling (down to 58C) and apatterned optical window (Fig. 3). The window includes adielectric mirror mask with an array of 21 apertures, each3 mm in diameter, allowing a patterned irradiation profile(Fig. 4). A contact sensor, when depressed against the skin,will only allow delivery of infrared light when the skin is infull contact with the sapphire contact cooling tip. The

Fig. 1. Different sizes of the treatment tips of the Thermacool device (ThermaTipsTM).

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device delivers pulses with up to 10-second duration andrespective total fluence up to 200 J/cm2.

SELECTION OF PATIENTS ANDINDICATIONS/APPLICATIONS

Noninvasive tightening techniques are intended totighten and lift skin without surgical incisions, complica-tions, and recovery time. The technique is best suited forpatients with mild to moderate laxity of the skin withoutsignificant underlying structural ptosis. Patients withtremendous skin redundancy will have very limitedcontour improvement.

This treatment modality can cause softening of thenasolabial lines, tightening of the jowl, improvingthe definition of the cervicomental angle, and improve thecreepiness of skin, all without significant recovery time orcomplications.

As for any cosmetic procedure, appropriate selection ofpatients and managing realistic expectations are key toensuring satisfaction with results. It is imperative that onecommunicates to the patient in clear terms that thisnoninvasive alternative to surgery provides comparativelymodest tightening compared to with invasive surgicaltechniques. Patients, who require more dramatic results,should be counseled to consider surgery.

TREATMENT TECHNIQUES

As with any other recently introduced technology,treatment algorithms and techniques have evolved over

time and will still evolve over time. Initial protocolsinvolved providing the maximum amount of energytolerated by the patient in an effort to achieve the greatestimprovement with single-pass treatment. With the work ofZelickson et al. [8], it has become clear that an equivalent orgreater amount of collagen denaturation can be inducedwith multiple passes at a lower energy level. Developmentof faster or larger treatment tips, has allowed for theapplication of multiple-pass treatment algorithms withoutadding to the total treatment time.

Anesthesia

With the lower energy levels required with multiple-passtreatment algorithms, patients’ discomfort has greatlydecreased but has certainly not been eliminated. Eachtreatment cycle invokes a brief burst of deep dermal heat asthe energy penetrates and then the quenching postcoolingwith the completion of cooling cycle. In appropriatelydisposed patients, localized procedures (such as peri-orbitalbrow treatment) may be tolerated without anesthesia.Complete treatment of large surface areas (like full face andneck) may require many repeated sequential applicationsof MRF or IR energy, and these longer procedures warrantuse of some type of anesthesia to ensure patients’ comfort.

During treatment, the patient is asked to grade thediscomfort level on a four-point scale (0¼no heat,1¼warm, 2¼hot, 3¼ very hot, and 4¼ intense). Energylevels are titrated to a comfort goal for the patient of 2–2.5,ensuring a safe level of energy delivery. Current treatmentalgorithms discourage providers from using systemic(general anesthesia or intravenous sedation), and injectionor topical anesthesia that may blunt the patient’s painresponse [9]. Topical anesthetics may also exacerbatediscomfort by selectively numbing the epidermis, blockingthe cooling relief of the topical cooling method (cryogenspray on Thermacool, contact sapphire on Titan andLux-IR) while not alleviating the heat sensation, whichpenetrates deeper to the dermis. Extra pre-cooling of thetreatment area (e.g., by use of the Sheer Cool RollerTM,Palomar) provides limited but controlled bulk cooling toalleviate the discomfort of deep heating. Tumescent or localinfiltration anesthesia can alter skin resistance and impairappropriate MRF energy delivery [10,11], and should beavoided. Therefore, oral analgesics and short-acting anxio-lytics (benzodiazepines) taken an hour before the procedure

TABLE 1. Overview of the Discussed Devices

Device

Mechanism of tissue

heating

Frequency* or

wavelength range Handpiece Cooling

ThermaCool

(Thermage)

Monopolar

radiofrequency (MRF)

6 MHz* 0.25, 1, 1.5, and 3 cm2 Cryogen spray

Titan (Cutera) Infrared light 1,100–1,800 nm with

filtering in 1,400–1,500

range

1� 1.5 cm, 1� 3.0 cm Contact cooling

Lux-IR (Palomar) Infrared light 850–1,350 nm 1.2� 2.8 cm Contact cooling

Fig. 2. Different treatment tips of the Titan device.

DEEP HEATING FOR NONINVASIVE SKIN REJUVENATION 801

for maximal effect are suggested as method of minimizingthe patients’ discomfort while allowing the provider togauge the patients’ response to each treatment pulse.

Procedure

It is essential to take standardized pictures prior totreatment. Pre- and post-operative pictures should matchin color, positioning, and lighting in order to be ofvalue. Pre-operative pictures often need to be comparedwith post-operative ones to detect the changes, given thatthey are subtle and may go undetected by the patient.Monopolar radiofrequency (ThermaCoolTM). Pa-

tients are instructed to remove make-up and metaljewellery and to cleanse the face with water and soap.Prior to treatment, the patient is grounded. An easilyremovable ink grid of contiguous squares with each squareslightly larger than the selected treatment tip is applied tothe treatment area. The MRF generator is initiated andcalibrated for each patient with a test pulse. A couplingfluid is applied liberally to the treatment site to ensureuniform conduction of the MRF energy from the electrode tothe skin. Care is taken to place the treatment tip in goodcontact with the skin to allow protective cooling throughoutthe treatment cycle and to enable volumetric distribution ofMRF energy in the treatment area. If during the treatmentcycle, the temperature at the skin surface rises above the

set threshold or contact with the skin is not maintained, theenergy delivery will immediately be aborted. However,patients’ reports of extreme discomfort in a given areashould be interpreted as an indication of excessiveheat production, regardless of the joules indicated on thesetting.

Each ink grid square of the treatment area is treatedwith a separate application from the RF tip, resulting in40–80 RF applications for the peri-orbital area up to600 sequential applications for treatment of full face andneck. Each application consists of three continuous andautomatic phases: (1) cryogen pre-cooling, (2) simultaneousRF heating and cryogen cooling, and (3) cryogen post-cooling. The choice of setting is determined by the locationand thickness of skin within each treatment grid square.Lower energy levels are required in areas of thinner skin,over vulnerable subcutaneous fat pads (temporal, malar),over nerves (greater auricular, supraorbital, infraorbital,mental), and in the neck. In addition, the RF levels areadjusted according to the upper limits of the subjects’ paintolerance during the procedure.

When treating a full face, the face is usually divided intoseveral treatment sections (for instance forehead, lowerface, submandibular area, and neck). Two initial passes areperformed throughout the entire indicated treatmentsection, using the ink grid to ensure complete coverage.Stacking of pulses within less than 2 minutes is avoided toallow appropriate cooling of the skin in between treatmentcycles. Additional passes are then performed over areas ofnoticeable skin laxity, typically superior to the nasolabialfold, over the jowls, and in the submental area, in thedirection of the vectors, that allow maximal lifting of theskin, and definition of the contours of the face [12]. Finalpasses are made to promote contraction of the subdermalfibrous septa, providing shrinkage of tissue in areas ofexcess fullness. Treatment with multiple passes is con-tinued as tolerated until visible tightening is observed ornoticeable erythema is evident.Infrared light source (Titan). Patients are directed

to wash their face with water and soap to remove anycosmetic residue. For treatment of the face, the areas ofneed are first assessed while the patient is sitting up.Adequate protective goggles are worn by the patient and

TABLE 2. Specifications of the Different Hand Pieces

of the Titan Device

Name Titan S Titan V Titan XL

Window size 10� 15 mm 10� 15 mm 10� 30 mm

Tip proudness 1 mm 5 mm 3 mm

Features Higher visibility Large areas

Fig. 3. Lux-IR handpiece with contact sensor and cooling

window.

Fig. 4. Patterned optical window of the 12�28 mm Lux-IR

handpiece.

802 DIERICKX

the medical staff. Two initial passes are performed over theentire designated treatment area, with additional passesover the areas of concern. When treating the lower face, theflaccid areas of jowls, and lower cheeks are treatedadditionally. To soften the nasolabial fold, an extra stripof 2–3 cm in the pre-auricular area is treated. To obtaineyebrow elevation, extra passes on the upper portion of theforehead and temples are given. The neck is treated directlyin the submental area. Settings of 30 J/cm2 and between200 and 250 pulses for the mentioned areas of the face andneck are usually used. At these settings, the procedure isvery well tolerated. On certain more sensitive areas likethe temples, the fluence is usually lowered to 25 J/cm2 dueto discomfort. If patients can only tolerate 25 J/cm2

throughout, then the total number of pulses should beincreased to 300. If the patient mentions an immediateburning sensation after the pulse, ice is applied immedi-ately to prevent further tissue damage from a burn. This isusually the result of incomplete skin contact with thecooling sapphire crystal during pulses.Lux-IR. Treatment can be started after cleansing the

skin. Pre-cooling of the treatment area with SheerCoolRollerTM for 10–15 seconds will aid with comfort. Pulses areplaced individually. At the end of each pulse, the handpieceis lifted up and placed in close proximity to the previouspulse without any overlap. This is the so-called stampingtechnique. A treatment cycle consists of three consecutivephases: a pre-cooling period, a light pulse period, and a post-cooling period. Each phase of the treatment cycle has aunique audible tone. Good contact over the entire surface ofthe hand piece throughout the whole treatment cycle iscrucial for a safe treatment. Use caution when treatingpeople with a very boney facial structure since good contactcan be jeopardized by boney structures. If unable to insuregood contact, it is advised not to treat the area, due to risk ofoverheating the skin. During treatment, continuing, deepwarmth in the area being treated should be felt. This deepheating sensation will occur during the last 0.5–1 second ofthe treatment pulse and may intensify after the pulse iscompleted.

The treatment parameters are chosen by the feedback ofthe patient and are increased to a maximum tolerable level.The preferred range of settings for treatment of the face andneck are 2–3 seconds of pre-cooling, 3.5 second pulseduration, fluence range of 40–60 J/cm2 with not more thanmoderate discomfort, 2 seconds post-cooling, one to fourtotal passes over the treatment area, with a minimum delayof 2 minutes between passes over any given area.

If the patient feels any pain or a burning hot sensation,while the pulse of light is delivered, the treatment should beinterrupted immediately by releasing the foot pedal. It isvery important to keep the treatment window in contactwith the skin after the light pulse has stopped to allow forthe sapphire window to extract heat from the skin andminimize any possible side effects.

Lower fluences and fewer passes should be used on theneck. Treatments directly over the mandible are notrecommended. To treat the submandibular area, the skinshould be grasped above the mandible and pulled upward

so that the submandibular skin is stretched, and locatedabove, not over, the mandible. When treating the abdomen,thighs, or arms for skin laxity, the same treatmentguidelines apply: one starts with the lowest fluence andincrease based on tolerance. Fluences higher than thoseused to treat the face and neck may typically be used to treatthe abdomen or thighs. However, the determining factor isalways that there should never be more than moderatediscomfort during the treatment. The preferred rangeof settings for treatments of the abdomen or thighs are2–3 seconds of pre-cooling, 3.5 second pulse duration,fluence range of 40–80 J/cm2 with no more than moderatediscomfort, 2 seconds post-cooling, one to four total passesover the area, with a minimum delay of 2 minutes betweenpasses over any given area. For correction of laxity of thearms, the whole circumference of the upper arm is treated.The posterior arm, over the triceps, is the least painful totreat. The thighs and abdomen are generally treateddirectly over the areas of laxity. If there is an abundanceof lax skin present, the skin should be stretched to ensuregood contact.

Aftercare

Most patients are able to resume normal activities afterthe procedure. The patient may experience a mild lingeringdeep heating sensation after treatment that disappearsafter 1–2 hours. Some erythema and edema are presentafter treatment. This usually resolves within the first24 hours. A cooling gel may be used after treatment toenhance comfort and reduce erythema and edema. In therare event of a superficial burn, due to improper treatmenttechnique or excessive treatment, standard wound treat-ment procedures should be implemented at the operator’sdiscretion.

OUTCOME

Monopolar Radiofrequency

Patients are seen in the office at 4–6 weeks after theprocedure and then at 3 months intervals. Tighteningappears to continue for 4 months to 1 year after theprocedure [11,13–15]. If adequate treatment has beenperformed, generally a single procedure is sufficient,although Fritz et al. reported more improvement in thenasolabial fold with two treatments spaced 1 month apart[16]. Similarly, Koch found an increased percentageof patients with significant eyebrow lifting after fourtreatments (80% compared to 60% after a single treatment)[17].

It is of note that all publications to date evaluating theclinical efficacy of nonablative MRF treatment havedocumented overall improvement of skin study parameters[10–26]. In the lower face and neck, MRF treatments resultin softening of the nasolabial folds, lifting of the jowl skin,and accentuation of the cervicomental angle. Severalstudies have documented on average 1–4 mm of browframe height elevation, reduction of peri-orbital rhytids,and tightening of upper lid skin (Fig. 5) [11,13,14,17,21,25].In addition to skin tightening, other intrinsic skin

DEEP HEATING FOR NONINVASIVE SKIN REJUVENATION 803

characteristics appear improved with MRF treatment.Reduction of skin pore size [10,27] and acne reduction[11,28], presumably as a result of sebaceous gland atrophyand the antibacterial effect of heat generated in the dermisduring MRF treatment.

Titan

A recent report describes the results of a group of25 patients [29]. They were treated for eyebrow lifting,lower face tightening, or neck skin laxity (Fig. 6) at fluencesbelow pain levels (20–30 J/cm2). Immediate skin contrac-tion was obtained in 22 of 25 patients. The initialimprovement of eyebrow lifting or skin laxity improvementwas maintained during the whole follow-up period, up to12 months after the procedure. With the immediatecontraction, the degree of patient satisfaction was remark-able, while the low to moderate nature of pain contributedto further patient satisfaction.

Two patients were treated at 40 J/cm2 for eyebrow lifting.No changes were observed at these fluences. However, theyboth responded later to 20 J/cm2. It was hypothesizedthat the lower fluences heated up the dermis to the point of57–618C, the shrinkage temperature of collagen [2,3].Heating the collagen to a higher temperature woulddenature and damage the collagen beyond the point ofcontraction.

Lux-IR

To date, the technology of fractional heating withinfrared light is fairly new. The clinical outcome is thusfar limited. Pilot study reports promising results especiallyfor tightening of the laxity on abdominal skin (Fig. 7) or thecreepiness of arm skin [30]. Controlled clinical trials arerequired in the future to obtain more information.

Summary

When comparing the use of the different devices, theauthor’s clinical experience thus far favors:

* The use of the MRF device (ThermaCool) with the small0.25-cm2 tip for the eyelid tightening because of theprecision of placing the handpiece on the eyelids, the

Fig. 5. Tightening of the upper eyelid skin after treatment

with the ThermaCool device. (Top left) before treatment, (top

middle) 4 months after treatment, (top right) 6 months after

treatment. This patient was treated with a combination of a

0.25- and 1.5-cm2 tips. The small 0.25-cm2 tip was used right

above the lash line up to the crease of the upper eyelid and from

the lower lash line for about two rows on the lower lid. The

larger 1.5-cm2 tip was used to treat the remaining intra-orbital

tissue up to the eyebrow and including the crow’s feet area. The

most frequently used setting level was 34 for the 0.25-cm2 tip

and 60.5 for the 1.5-cm2 tip. A total of 104 pulses were used for

both eyes. Photo courtesy of B. Biesman, MD.

Fig. 6. Result for lower face before (a) and 12 weeks (b) after a

single treatment with Titan. The treatment was performed

with a Titan S treatment tip. Three consecutive passes were

given at 36 J/cm2 with a total of 160 pulses. Photo courtesy of

L. Bunin, MD.

Fig. 7. Abdominal skin laxity, before (bottom left) and 6 weeks

after a single treatment (bottom right) with Lux-IR. A single

pass was used at 86 J/cm2 with 3 seconds pre-cooling, a 5-

second pulse, and 2 seconds post-cooling.

804 DIERICKX

proven, high eye safety profile of MRF, and the lack ofdiscomfort during treatment.

* The use of infrared light device (Titan) for softening ofthe nasolabial fold, tightening of the jowl line, andimproving the definition of the cervicomental anglebecause of the possibility of good contact cooling overall facial bony structures, and the relative lack ofdiscomfort during treatment.

* The use of Lux-IR for treatment of larger body surfaceareas like the arms, the abdomen, and the inner thighsbecause of the large spot size and minimal discomfortdue to fractionated delivery of the light.

Overall, good selection of the ideal candidate is key for theoutcome. In general, patients with minimal to moderateptosis of the underlying facial structures are the bestcandidates. For body-reshaping, it is key to choose nonover-weight patients with moderate laxity or creepiness of theirskin. Major ptosis or laxity of the skin cannot be improvedby this approach and still needs surgical intervention.

SIDE EFFECTS

Monopolar Radiofrequency

The incidence of complications with MRF treatment hasbeen extremely low [10,11,13–16,18–21]. Side effectsinclude some transient erythema and mild edema, whichtypically resolve in a day or 2. Persistent edema (lastingover a week) occasionally occurs and resolves after atapered dose of methylprednisolone. Numbness of skin,often in the distribution of the greater auricular nerve, canoccur, but resolves with time, as there is no anatomicaldisruption of the nerve. If higher energies are used in theneck, inflammation of the underlying platysma muscle cancause temporary ridging [9,26]. This phenomenon typicallyresolves over the course of a month and anecdotally appearsto predict better neck skin tightening. Despite the protec-tive mechanisms built in the treatment tips, incidents ofsmall superficial skin burns can occur, most likely as aresult of uneven contact of the treatment electrode with theskin, resulting in arcing of MRF energy, or if the patientmoves away prior to completion of the treatment cyclepossibly compromising completion of skin cooling [27]. Rareoccurrences of tissue irregularities related to tissue over-heating, with an estimated rate of 0.08% in more than161,000 uses, have been reported by the manufacturer.With the lower MRF energy levels now being used with themultiple pass treatment algorithm, ever fewer adverseevents were seen (rate 0.03%).

Infrared Light

Immediately after treatment, mild edema and erythemais seen in patients, but it usually fades within 1 hour.Occasionally, small superficial burns develop after treat-ment with infrared devices when proper contact with theskin is not made. With the appropriate aftercare,these superficial burns heal uneventfully [29]. Fullthickness third degree burns have been described as asignificant complication of deep heating infrared devices

[31]. Mechanisms include insufficient tissue cooling due tohandpiece positioning, the use of improper treatmentparameters or greater delivery of heat over bony structureswith subsequent nonselective bulk heating of the skin. Theclinician needs to be aware of these possible side effectswhen choosing appropriate treatment parameters withsuch kind of device.

Lux-IR

Handpiece positioning to ensure good cooling of the skinis essential when using this infrared device with contactcooling. Due to inadequate tissue cooling, small superficialburns can occur. However, the patterned irradiationprofile that creates an inhomogeneous, periodic thermalprofile within the dermis might result in a better safetyprofile by leaving undamaged tissue between the thermallydenatured islands of tissue. These islands then serve asregeneration nidus.

LIMITATIONS

Currently, the amount of skin tightening achieved withnoninvasive tightening devices is not equivalent to thatwith a surgical procedure. For example, a browliftafter ThermaCoolTM treatment offers a lifting of 1–4 mmcompared with up to 1 cm seen with endoscopic surgicaltechniques [13,14,17,21,25]. The newer multiple-passtreatment algorithms have been reported to improvepredictability and extent of efficacy [24]. However, thesenoninvasive techniques have not yet approached thestandard of consistency and dramatic change associatedwith traditional surgery techniques. When the risks andbenefits of surgical and nonsurgical alternatives are fairlypresented to the patient, there are many who will choosethe more subtle tightening effect of noninvasive tissuetightening procedure with much less recovery time andchance of complications of surgery.

FUTURE DEVELOPMENTS

The ultimate goal would be the development of atechnology that allows for precise contouring and liftingof ptotic skin, and underlying structures, providing a trulynonsurgical lifting and tightening effect that may somedayapproach a surgical result. A further improvement of RFtechnology would be the development of a treatment tipthat can precisely determine individual patients’ resistanceat each treatment site (based on thickness, amongvariables) so that the exact amount of energy needed toachieve a predictable desired treatment endpoint can bedelivered with low risk of adverse effects [32]. A similartrend can be expected in the realm of infrared technologywith the development of ‘‘smart’’ devices, capable ofadjusting treatment parameters depending on character-istics of skin in the intended treatment area.

Several new approaches are furthermore under investi-gation. A 1,310 nm device with variable pulse duration andsurface cooling was recently developed to allow for variabledepth heating [33]. Research is currently being conductedusing an ultrasound device capable of delivering controlled

DEEP HEATING FOR NONINVASIVE SKIN REJUVENATION 805

thermal lesions at pre-set focus depths within the facial softtissue [34]. Another development of RF technology is an RFdevice with fine needle electrodes [35]. These electrodeshave an electrically isolated shaft and a fine, nonisolatedtip. A probe holder allows varying the distance between theelectrodes. In vitro work on human skin samples showedthat RF exposure with this device caused confined thermaldamage sufficient to cause marked collagen denaturationand shrinkage, of virtually any diameter at any depth asdetermined by the location of the probe. It maybe feasible inthe future that one of these new treatment concepts mightoffer distinct advantages for skin tightening.

CONCLUSION

The minimally invasive procedure trend has certainlybegun to sweep through facial plastic surgery with thegrowing popularity and acceptance of nonsurgical techni-ques such as office-based botox injections, the plethora ofinjectable filler materials, and the growing number ofnonablative lasers, and other modalities (IPL, RF, and IR)intended to rejuvenate the skin.

Noninvasive tissue tightening devices are currently notintended to replace the more dramatic effects of invasivesurgical techniques. Results are always subtle and are notremotely as dramatic or reliably produced as those obtainedfrom surgery. However, they are a good alternative to meetthe needs of the patients who are averse to any surgicalintervention, with no downtime and no incisions or scars.The skin contraction achieved is in the order of 1–3 mm.Although not dramatic, the changes are perceptible,especially when it comes to an eyebrow lift or softening ofthe nasolabial fold. The results have, therefore, a remark-able ‘‘natural look,’’ which plastic surgery rarely can match.With further refinement of the technology and treatmentalgorithms, nonablative tissue tightening may represent atool of growing importance to the future of facial rejuvena-tion procedures.

ACKNOWLEDGMENTS

The author thanks Pam Buckham and Bill Blaker fortheir scientific collaboration, Cutera for providing materialfor this manuscript, and Ilya Yaroslavsky for his invaluablecontribution. Loan of equipment was taken from Cutera.

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