Microneedling: A Comprehensive Review...Atrophic acne scars Leheta and colleagues16 2011 30 1C RCT of microneedling vs 20% TCA Atrophic acne scars Mohammed and colleagues27 2013 60
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BACKGROUND Microneedling is a minimally invasive procedure that uses fine needles to puncture theepidermis. The microwounds created stimulate the release of growth factors and induce collagen pro-duction. The epidermis remains relatively intact, therefore helping to limit adverse events. The indicationsfor microneedling therapy have grown significantly, and it is becoming a more widely used treatment indermatology.
OBJECTIVE A comprehensive review of microneedling in human subjects and its applications in dermatology.
METHODS AND MATERIALS A search was performed using PubMed/MEDLINE and Science Direct databases.Search terms included “microneedling,” “needling,” and “percutaneous collagen induction.” All available studiesinvolving human subjects were included in the discussion, with priority given to prospective, randomized trials.
RESULTS Studies demonstrate microneedling efficacy and safety for the treatment of scars, acne, melasma,photodamage, skin rejuvenation, hyperhidrosis and alopecia and for facilitation of transdermal drug delivery.While permanent adverse events are uncommon, transient erythema and postinflammatory hyperpigmenta-tion are more commonly reported.
CONCLUSION Microneedling appears to be an overall effective and safe therapeutic option for numerousdermatologic conditions. Larger and more randomized controlled trials are needed to provide greater data onthe use of microneedling for different dermatologic conditions in different skin types.
The authors have indicated no significant interest with commercial supporters.
Microneedling, also known as percutaneouscollagen induction (PCI), is a minimally
invasive technology used to treat numerousdermatologic conditions.1 In 1995, Orentreichand Orentreich coined the term “subcision” todescribe manual needling for the treatment of scars,while Camirand and Doucet used a tattoo gun totreat scars.2,3 These techniques used needles todisrupt dermal collagen that was tethering scars totrigger an inflammatory cascade, resulting indermal remodeling and skin resurfacing.1,4
Employing these principles, Fernandes developedPCI therapy with a dermaroller mounted with tinyneedles.1
Modern microneedling devices contain multiple fineneedles, typically 0.5 to 1.5 mm in length, located ona barrel and rolled onto the skin to create numerouspunctures into the stratum corneum and the papillarydermis.5 These microwounds initiate the release ofgrowth factors, triggering collagen and elastin for-mation in the dermis.6Microneedling can also be usedto augment transdermal drug delivery (TDD) throughthe creation of pores in the stratum corneum.7
The applications for microneedling have expanded overthe past few decades to include the treatment of acnevulgaris, scars, facial rejuvenation, dyspigmentation,alopecia, hyperhidrosis, and TDD. This review provides
*All authors are affiliated with the Ronald O. Perelman Department of Dermatology, New York University School ofMedicine, New York, New York
colleagues43Dermaroller MS4 1 Clinical assessment of
photographs by 2
independent
dermatologists.
AK clearance was 88.3%,
without significant
differences in clearance
rates between groups.
Patients treated with
microneedling also
demonstrated significant
improvements in coarse
wrinkles and erythema
Erythema, edema, and
crusting (“common”)
Bacterial superinfection
(10%)
Androgenic
alopecia
Dhurat and
colleagues49Dermaroller MS4 12 (1 wk) Hair count assessed by
macrophotographs
Hair count was
significantly greater in
patients treated with
microneedling and
minoxidil compared to
with minoxidil alone
(91.4 vs 22.2 mean
count).
None reported
Drug delivery
Fabbrocini and
colleagues55Dermaroller MS4 1 Visual analog scale (VAS)
pain scores
Microneedling prior to the
topical anesthetic
resulted in a significantly
reduced VAS pain score
compared to anesthetic
alone (p < 0.05)
None reported
*Level of Evidence: Based on recommendation from the Centre for Evidence-Based Medicine, Oxford (1a-5) (http://www.cebm.net/oxford-centre-evidence-based-medicine-levels-evidence-
march-2009/).
ALA, Aminolevulenic acid; DermaFRAC, 0.25 mm tip cap, Pressure, 10 mmHg; Dermaroller C8, 196 needles, length 0.15 mm; Dermaroller CIT8, device 192 needles, Length, 0.5 mm, Width, 0.02
spanning 10 mm2 Depth, 0.5–3.5 mm, 1 MHz of radiofrequency current); INTRAcel device, 49 microneedles, Depth, 1.5 mm, Spot size, 10 mm; MAL, Methylaminolaevulinate; MASI, Melasma
Area Severity Index; Medical Roll-CIT, 1 mm needles; MRF, Microneeding with Radiofrequency; MTS Roller CR10, 1 mm needles; MTS Roller CR20, 2 mm needles; PDT, Photodynamic therapy;
PIH, Postinflammatory Hyperpigmentation; PRP, Platelet Rich Plasma; RCT, Randomized Controlled Trial; TA, Tranexamic acid; TCA, Trichloroacetic acid; VAC, Vitamin A and C; VC, Vitamin C.
a comprehensive overview of the available literatureregarding the efficacy and safety of microneedling per-formed for dermatologic conditions in human subjects(Table 1). A search was performed using PubMed/MEDLINE and Science Direct databases. Search termsincluded “microneedling,” “needling,” and “percutane-ous collagen induction.” All available studies involvinghuman subjects were included in the discussion,with priority given to prospective, randomizedtrials (Figure 1).
Acne Scars
Microneedling has been most extensively studied foracne scar treatment. A recent review concluded thatalthough studies analyzed were heterogeneous indesign, there is moderate evidence supporting the useof PCI for acne scarring.8 Eight studies were examinedmicroneedling asmonotherapy for acne scars.8–16 Onestudy was a split-face trial involving 20 patients withFitzpatrick Skin Type (FST) I to V randomized toeither microneedling with a topical anesthetic or top-ical anesthetic alone.9 Three sessions at 2-week inter-vals were performed, with 2 blinded dermatologistsrating the photographs based on the Goodman andBaron grading system (GBGS). At the 6-month follow-up, there was a statistically significant decrease in themean scores of the treatment group compared to the
control group (3.4 vs 0.4). No adverse effects (AE)were reported.9
A randomized controlled trial (RCT) divided 60patients based on FST and assessed improvementusing the Global Aesthetic Improvement Scale (GAIS),as well as computerized analysis of silicone replicas toquantify skin irregularity.10 After 3 treatment sessions,there was a significant reduction in the acne scarseverity, as well as an average decrease in the degree ofskin surface irregularity by 31% in all skin types.10
One case series examined 32 patients with rolling acnescars.11 Each patient received 2 microneedling treat-ments and outcomes were evaluated by GBGS. Theseverity grade of rolling scars in all patients was sig-nificantly reduced (p < 0.05). Microrelief impressionsof the scars cast as an objective measurement of theskin’s topography showed a 25% decrease in irregu-larity and all samples showed decreased irregularity ofskin texture. No AE were noted.11
Another case series examined 36 patients (FST IV–V)after 5 microneedling sessions.12 After 5 sessions, pho-tograph assessment revealed a 50% to 75% averageimprovement. Adverse effects included pain andecchymosis, and5patientsdroppedoutof the studydueto postinflammatory hyperpigmentation (PIH) andtram-trak scarring12 Tram-trak scarring, a unique AE
of microneedling, was also described in a 25-year-oldfemale who underwent 2 sessions with a 2.0-mm-longmicroneedling device.13 The authors believed this wassecondary to excess pressure applied while using thedevice and the larger and longer needles used.6,13
Microneedling has been compared to other acne scartreatments, including subcision, cryorolling, andchemical reconstruction of skin scars (CROSS) withtrichloroacetic acid (TCA). An RCT of 70 subjectscompared patients receiving 3 sessions with eithermicroneedling alone or microneedling with subcisionwith a 20-gauge cataract blade.14 Efficacy (>25%improvement) was demonstrated in 77% of patientswho receivedmicroneedling alone compared to 100%of patients receiving microneedling and subcision.Adverse effects included transient erythema, edema,andmild scabbing for 2 to 3 days.14 Another split-facestudy compared subcision with either microneedlingor cryorolling, which consists of dipping the device inliquid nitrogen prior to use.15 Thirty-seven patientswere randomly assigned a treatment modality oneither side of the face and assessed by a blindedobserver using GBGS. Subcision with cryoroller wasassociated with a significantly higher mean improve-ment compared with subcision plus dermaroller (57%vs 40%). However, 16.7% of patients developed PIHafter cryorolling, lasting amean duration of 4months.Microneedling treatment was associated only withtransient erythema.15
Another RCT compared the efficacy ofmicroneedling toTCACROSSby randomly assigning 30 patients (FST II–IV) to 4 sessions of either treatment.16Resultswere basedon overall disease severity score and global response totreatment. All patients experienced acne scar improve-ment, with no significant difference between micro-needling and TCA groups (68.3% vs 75.3%).16
Seven prospective studies have performed micro-needling in conjunction with topical treatments,including vitamin C (VC), platelet-rich plasma (PRP),and chemical peels.17–23 One study evaluated 49patients (FST III–V) using a regimen that alternatedbetween microneedling and 15% TCA peel at 2-weekintervals, with improvement based on GBGS.17 All 49patients had at least one grade improvement in their
acne scarring. Ice pick scars were more treatmentrefractory compared to rolling, boxcar, and lineartunnel-type scars. All 11 patients withGrade 2 scarringdemonstrated complete resolution. Three patientsdeveloped PIH, which subsided after 5 months of top-ical treatment.17 Another study randomly assigned 24patients to treatment with microneedling and 20%TCA or deep skin peeling with 60% phenol.18 Therewas no statistical difference between the 2 groups ona quartile grading scale (69% vs 75%). Adverse effectsincluded procedural pain, transient erythema, andswellingwithpeeling for 1week.18One study randomlyassigned 39 patients to either skin needling with 20%TCA (Group I), fractional thermolysis (Group II), ora combination of the two (Group III).19 Assessment bya blinded dermatologist showed mean improvement of60%, 62%, and 78%, respectively. The difference indegree of improvement was found to be significantbetween Groups I and III and Groups II and III, but nostatistical difference between Groups I and II. Adverseeffects included transient edema, erythema, and pain,along with desquamation 4 to 7 days after peels.19
Studies have also investigatedmicroneedling with PRP.A study with 12 patients concluded that 2 sessions ofmicroneedling with PRP was significantly more effica-cious thanmicroneedling alone although the study waslimited by the lack of randomization and blinding.20
Another study in which 45 patients were randomlyassigned to either intradermal PRP, topicalTCA100%,or microneedling with topical PRP showed that all 3groups had statistically significant improvement in theseverity of their acne scars on the GBGS, with no dif-ferences between groups.21 Another prospective studyevaluated the improvement of acne scars when micro-needling was combined with PRP or VC.22 Twenty-seven out of 30 patients completed 4 sessions ofmicroneedling and PRP on one side of the face andmicroneedling with VC on the contralateral side.Twenty-three patients demonstrated a one- to 2-gradereduction in scarring although one developed PIH anddropped out of the study. “Excellent” results (2-gradereduction) were more common with PRP compared toVC (18.5%vs7%,p<0.05) although“good” responserates (1-grade reduction) were similar. Improvementwas seen in boxcar and rolling scars, but there waslimited efficacy seen with ice pick scars.22
The efficacy of glycolic acid (GA) combined withmicroneedling has also been studied. In one trial, 30patients (FST III–V) with boxcar or rolling acne scarsreceived either microneedling combined with GA ormicroneedling alone.23Outcomeswere evaluatedwiththe Echelle d’Evaluation Clinique des Cicatricesd’acne (ECCA) grading system.23 Subjects treatedwithboth microneedling and GA demonstrated a signifi-cantly greater decrease in ECCA score compared tomicroneedling alone (62% vs 31.33%). Severalpatients developed milia and transienthyperpigmentation.23
Microneedling with fractional radiofrequency(MFR) has also been employed in the study of acnescars. This modified treatment modality createsradiofrequency thermal zones without epidermalinjury, leading to dermal remodeling and new col-lagen deposition.24 Chandrashekar and colleaguestreated 31 patients (FST III–V) with Grade 3 to 4atrophic acne scars with 4MFR treatmens.24 After 3months, 80.6% of patients showed improvement by2 grades, and 19.4% showed improvement by 1grade. Five out of 31 patients experienced transientPIH and 2 developed transient tram-trak marks.24
Another case series looked at acne scarring in Asianpatients (FST III–V).25 Twenty-six patients had 3treatments withMFR and the results were evaluatedby 2 blinded dermatologists using the globalimprovement scale (GIS). Objective evaluation wasobtained via an Ultraviolet-A camera to measureskin surface characteristics. After 1 month, skinsurface roughness improved significantly. At the 6-month follow-up, the improvement was judged as“excellent” in 8%, “good” in 23%, “fair” in 36.5%,and “slightly improved” in 32.5%. Punched out androlling acne scars responded better than ice pick andhypertrophic acne scars. Adverse effects includedmoderate pain, transient PIH for 1 month (4%), andscabbing for 2 to 7 days (46%).25 A separate caseseries assessed 30 patients with acne scars andenlarged facial pores after 2 sessions ofMFR.26 Acnescars were graded by 2 dermatologists, and pore sizewas evaluated using the Investigator GlobalAssessment (IGA). Transepidermal water loss(TEWL), sebum production, and dermal density ofthe right cheek were measured. After 2 sessions, the
grade of the acne scars improved in 22 of the 30patients (77.3%), was unchanged in 7 patients(23.3%), and worsened in 1 patient (3.3%).Enlarged pores improved in 21 patients (70%) andbecame aggravated in 2 patients (6.7%). While skinsurface roughness and dermal density improved,TEWL and sebum measurements did not change.Adverse effects were mild and transient.26
In another case series, microneedling was performedalong with targeted, pinpoint scar treatment with anablative carbon dioxide (CO2) laser.27 Sixty patientswere randomly assigned to either laser or laser withPCI. Patients were assessed by 3 blinded observersusing GBGS. There was a statistically significantimprovement after treatment in both groups with nodifference between the treatment groups.27
Acne
Microneedling with fractional radiofrequency hasalso been studied in the treatment of acne vulgaris.Two prospective studies showed significant decreasesin inflammatory acne count and suggested thatMFR issafe and effective for the treatment of active acne.28,29
The first was a case series that examined 18 patientswith FST IV and moderate-severe acne treated with 2sessions of MFR.28 Improvement was evaluated by 2blinded dermatologists using GIS. Among the 18patients treated, improvementwas >75% in 2, 50% to75% in 8, and 25% to 50% in 6 patients.28 A secondcase series examined 25 patients with moderate tosevere acne treated with MFR 3 times at monthlyintervals.29 Acne lesions were assessed by countinginflammatory and noninflammatory lesions, whilesebum production was measured using sebumeter (C-K Electronics, Cologne, Germany). Inflammatoryacne decreased significantly after every treatment andwas reduced by 90.11% at 3-month follow-up. Therewas a statistically significant reduction at each timepoint in noninflammatory lesions and amean decreaseof 36.9% in sebum excretion at the 3-month follow-up. No dyspigmentation, burns, or scarring werenoted.29
However, one case series found that while MFRreduced sebum production, it did not improve acne
severity.30 The study evaluated 20 patients (FST III–IV) with moderate to severe acne treated with onesession of MFR. The authors found that at 2-weekfollow-up after one MFR treatment, casual sebumlevels and sebum excretion rates were significantlyreduced by 30% to 60% and 70% to 80%, respec-tively, and both remained significantly below baselineafter 8 weeks. Acne lesion count and acne severityshowed temporary improvement with maximum effi-cacy at Week 2, but returned to baseline by Week 8.Two patients developed pustular eruptions that self-resolvedwithin aweek. The authors hypothesized thatthe temporary improvement of acne was due to ther-mal injury of the sebaceous glands or hyperkeratoticplug disruption in the follicular infundibula.30
Other Scars
Microneedling has been studied for the treatment ofa variety of scars including burns, striae, and otheratrophic scars.4,31–38 One retrospective study exam-ined 480 patients who received microneedling treat-ment for fine wrinkles (Group I), acne or burn scars(Group II), and lax skin/striae (Group III).4 Patientswere treatedwith vitamin A andC (VAC) for at least 1month prior to microneedling treatment. Histologicexamination of 20 patients showed a significantincrease in collagen deposition 6 months post-operatively, the collagen exhibited a normal latticedesign instead of the parallel bundle arrangement seenin scar tissue. Elastic fiber staining showed an increasein elastin at 6 months postoperatively. Further, epi-dermal thickening was observed and attributed toa 40% thickening of the stratum granulosum andnormalization of rete ridges.4 Two patients developedherpes simplex infections, no additional AE werereported.4
Schwarz and Laaff studied microneedling in 11patients with acne and other post-traumatic scars,with punch biopsies before and 6 to 8 weeks aftermicroneedling. Ten patients completed the study andall were satisfied with the results and willing toundergo another treatment. Histologic examinationrevealed an increase in collagen, dermal thickness, andelastic fibers subepidermally, with no change in epi-dermal thickness. No AE were noted.31
One case series examined the effects of 3 to 4 micro-needling sessions on patients with GBGS Grade 2 to 4atrophic scars of various etiologies, including 32patients with acne scars, 2 with postvaricella scars, 2with post-traumatic scars, and 1 patient with post-herpetic scars.32 Thirty-four patients had a reductionin severity by 1 or 2 grades. Rolling and boxcar scarsresponded best, pitted scars showed moderateimprovement, while deep tunnels and complicatedscars had minimal response.32 The patient with post-herpetic scarring saw an improvement of 2 gradeswhile the post-traumatic and postvaricella patientshad 1-grade improvements.32 Another case study ofa 15-year-old girl (FST V) with varicella scars whounderwent 3 sessions of PCI showed significantimprovement of her scarring.33
Three studies have also noted significant improvementin patientswith striae distensae.34–36A case series of 22female subjects with striae noted improved skin tex-ture and skin tightening without dyspigmentation 6months after a single microneedling treatment.34 Asecond case series studied 16patients (FST III–IV)withstriae distensae treated with 3 sessions of micro-needling.35 Seven patients had 51% to 100%improvement, while the remaining 9 showed 1% to50% improvement. Post-treatment biopsies showedepidermal thickening and increased collagen andelastic fibers. Adverse effects included transient pain,erythema, bleeding, and pruritus.35 Lastly, a RCT of30 patients with FST IV were treated with fractionalCO2 laser only, MFR, or a combination of the two.36
Improvement was evaluated 6 months after treatmentusing a visual analog scale (VAS) ranging from 1 to 4.The mean VAS score in the laser only group was 2.4,1.9 in the MFR group, and 3.6 in the combinationgroup. Skin biopsies showed epidermal thickening andincreased collagen in the combination group. How-ever, these patients also had more AE, with 30% ofpatients developing PIH.36
There is interest in the use of microneedling forhypertrophic scars, as microneedling has been shownto normalize the extracellular collagen-elastin matrixin the reticular dermis of burn patients.37 In one pro-spective study, 16 patients with postburn scarringreceived one to 4 sessions ofmicroneedling and topical
VAC. Statistically significant improvements wereobserved on both the Patient and Observer ScaleAssessment Scales (POSAS, 27 vs 19) and VancouverScar Scale (VSS, 7.5 vs 4.8). In one case report, a 50-year-old Korean woman with a chin burn scar treatedwith 5 sessions of conventional ablative CO2 laserfollowed by microneedling showed relaxation of thecontracture and improvement in texture and color.38
However, the combination of treatments in onepatient renders it difficult to interpret the independenteffect of each treatment modality.
Melasma and Melanosis
Microneedling has also been utilized in the manage-ment of melasma andmelanosis. In one RCT involving60 patients (FST IV–V) with moderate to severe mel-asma, treatment with tranexamic acid (TA) micro-injections was compared with microneedling followedby the application of topical TA.39 After 3 treatments,a mean improvement of 38% was observed in theMelasma Area Severity Index (MASI) in patients trea-tedwithTA injections, compared to 44% improvementin patients who received topical TA andmicroneedling.The authors attribute the improved outcome to theenhanced delivery of TA through the pores createdthrough the use of microneedling.39 A split-face trialwith 20 patients (FST III–V) with melasma examinedthe administrationof depigmentation serumcontainingrucinol and sophora-alpha with and without micro-needling to augment serum delivery.40 Combinationtherapy improved MASI scores from baseline signifi-cantly more than serum alone (10.1 vs 7.1, p < 0.05).40
Microneedling was reported to be effective for a 48-year-oldmale (FSTV)withsevere, idiopathicperiorbitalmelanosis who underwent treatment with the Derma-Frac device (Genesis Biosystems, Lewisville, TX),whichemploys PCI and a simultaneous infusion of anti-agingand lightening compounds.41 Physician global assess-ment revealed 50% to 75% and 75% to 90%improvement, after 4 and 12 sessions, respectively.41
Photodamage and Actinic Keratoses
Microneedling has been used to supplement photo-dynamic therapy (PDT) for the treatment of actinickeratoses (AK) and photodamage. Twenty-one
patients (FST II–III) were treated with microneedlingprior to the application of aminolevulenic acid (ALA)and irradiationwith 630 nm red light and broadband-pulsed light for the treatment of facial photoaging.42
MeanGlobal Photoaging score significantly decreasedfrom 3.57 to 2.24 after 3 months and 2.05 after 6months. Statistically significant reductions were alsoseen in the appearance of fine lines, sallowness, androughness. The authors hypothesize that micro-needling augments absorption and penetration ofALA.42
In another study, 10 patients (FST I–III) were treatedwith PDT with methyl aminolevulinate (MAL) aftereither pretreatment curettage or microneedling for thetreatment of AKs and photodamage.43 At 30-dayfollow-up, improvements were comparable betweengroups in regard to global score for photodamage,roughness, sallowness, and mottled pigmentation.Only patients treated with microneedling demon-strated significant improvements in coarse wrinklesand erythema. Overall, AK clearance was 88.3%,without significant differences in clearance ratesbetween groups. Adverse effects, including erythema,edema, and crusting, were more common in patientstreated with microneedling and one patient in themicroneedling groupdeveloped abacterial infection.43
Another uncontrolled study investigated the use ofmicroneedling combined with topical MAL-basedPDT for AK management in 12 organ-transplantrecipients.44 Patients underwent 3biweekly treatmentsand demonstrated complete resolution of all lesions.No new AKs were detected at 4-month follow-up and83% of patients remained free of relapse 9 monthsafter final treatment.44
Skin Rejuvenation
Percutaneous collagen induction has also demon-strated benefit for skin rejuvenation and improvementof rhytides. In one study, 10 female patients weretreated with microneedling for upper lip rhytides.45
Thirty weeks after the completion of 2 treatment ses-sions, patients demonstrated a mean 2.3-fold reduc-tion in wrinkle severity using the Wrinkle SeverityRating Scale (WSRS). This result was confirmed by
a 33% reduction in skin irregularity demonstrated bysilicon replicas. No prolonged AE were reported.45
In another study, 8 patients underwent 2 micro-needling sessions to treat aging neck skin.46 After 8months, 7 of the 8 participants demonstratedimprovements on the WSRS and the GAIS. Skin rep-licas from baseline and final follow-up demonstratedan average reduction of 29% in skin irregularity.Ultrasound demonstrated an average reduction of24% in rhytides depth and revealed that skin thicknessincreased an average of 0.45 mm after treatment.46
A split-face trial studied the use of MFR with orwithout a “stem cell conditioned medium” of growthfactors and cytokines for the purpose of skin rejuve-nation in 15 female patients (FST III–IV).47 Patientswere treated with MFR alone on one side of the faceand MFR plus stem cell medium on the contralateralside. After 3 treatment sessions, both sides showedimprovements in hydration, erythema index, and skinroughness. Microneedling with fractional radio-frequency plus medium had a moderate benefit inoverall appearance over MFR alone (2.06 vs 2.20).Histologic specimens demonstrated collagen andfibrillin-1 production.47
Hyperhidrosis
It has been hypothesized that MFR, through thermalinjury to sweat glands, may benefit patients withhyperhidrosis. In one prospective study, 20 patientsunderwent 2 treatments with MFR.48 Statisticallysignificant decreases in hyperhidrosis disease severityscale (HDSS) scores from a baseline of 3.3 to 1.5 and1.8 were observed after 1 and 2 months, respectively.The starch–iodine reaction was also considerablyreduced in 95% of the patients post-treatment.48
Biopsies confirmed a decrease in the number and sizeof apocrine and eccrine glands 1 month after finaltreatment.48
Alopecia
Research has been conducted on treating androgeneticalopecia with microneedling. It is hypothesized thatPCI stimulates stem cells and induces growth factors,which are essential in the expression of hair growth
related genes.49 One prospective study considered 100men with androgenetic alopecia and randomized thepatients to either microneedling with 5% minoxidillotion or only minoxidil twice daily.49 After 12 weeksof treatment, the hair countwas significantly greater in80% of patients treated with both microneedlingand minoxidil, compared to no significant change inthe minoxidil only group.49 Microneedling has alsoshown promise in the treatment of alopecia areata.Two patients with alopecia areata treated with 3 ses-sions of microneedling followed by topical tri-amcinolone acetonide had excellent and durable hairgrowth over a 3-month follow-up period.50
Drug Delivery
Microneedling is also used to enhance TDD throughseveral methods including pore creation through theskin followed by topical drug application, drug-coatedmicroneedle arrays, and direct drug injection throughhollow microneedles.7 Animal studies confirm micro-needling creates pores through the stratum corneumand, through delayed pore closure, allows for effectiveintradermal and transdermal drug delivery fora number of drugs including insulin and protein vac-cines.51–53 Microneedling can also be synergisticallycombined with other procedures, such as iontopho-resis, electroporation, and sonophoresis.54
One prospective study examined the use of micro-needling for the delivery of topical anesthetics.55 Asmall patch on the forearm of 15 subjects was nee-dled followed by application of lidocaine-prilocaineanesthetic, while on the other forearm the anestheticwas applied without needling. After 60 minutes,a 27-G needle was introduced and the VAS painscores were compared. Microneedling prior to thetopical anesthetic resulted in a significantly reducedVAS pain score compared to lidocaine-prilocainealone (51.3 vs 20.1).55
Adverse Effects
Microneedling is associated with a low rate of AE.Histologic examination taken 24 hours after therapydemonstrates an intact epidermis and no change inmelanocyte number, resulting in limited downtimeandminimal risk of dyspigmentation.5 Adverse effects
are rare and temporary, with transient postprocedureerythema being most common.6 Tram-trak markingsare also rarely reported.8
One case study reported 2 sisters who developed sys-temic hypersensitivity reactions after microneedling,possibly to the needles themselves.56 In another caseseries, 3 patients developed biopsy confirmed, foreignbody-type facial granulomas after microneedling withtopical VC.57 In 2 patients, patch testing was reactiveto VC. The authors propose that channels created bymicroneedling may facilitate the deposition of immu-nogenic particles into the dermis.57
Conclusion
Over the past 20 years, the applications of micro-needling in dermatology have grown drastically. Theconcept of subcision for scars has progressed toautomated microneedling pens, MFR, and facilitationofTDD.This reviewhighlights the encouraging resultsand limitations that have been reported with micro-needling for a variety of conditions including scars,acne, melasma, photodamage, skin rejuvenation,hyperhidrosis, alopecia, and TDD. Current data showthat microneedling provides the advantage of epider-mal preservation while promoting production of der-mal collagen and elastin. Overall, its efficacy, safety,and ease of use, make microneedling a favorabletherapeutic alternative to consider.However, it shouldbe noted that the majority of microneedling studieshave been case series and small RCTs. Given thatmicroneedling, similar to lasers and other noninvasivedevices, is being used on an increasing basis by notonly physicians but also by physician extenders,nurses, aestheticians, and even patients using at homedevices, continued research on the safety and efficacyof microneedling is essential. In particular, there isa need for larger, double-blinded, RCTs, includingsubjects of all skin types in order to provide furtherinsight and evidence-based data on the utility of thispromising treatment modality.
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Address correspondence and reprint requests to: NadaElbuluk, MD, MSc, The Ronald O. Perelman Departmentof Dermatology, New York University School of Medicine,240 East 38th Street 11th floor, New York, NY 10016, ore-mail: [email protected]