Continuing Education Activity

Microneedling a relatively new procedural therapy used in clinical and aesthetic dermatology. This activity summarizes the role of microneedling in dermatologic practice and includes discussion on the physiology, indications, contraindications, various tools, technique, and complications of the procedure. This activity will prepare healthcare teams to care for patients who undergo microneedling for any of a wide variety of indications.

Objectives:

• Identify the indications for microneedling.
• Describe the technique of microneedling.
• Review the physiology of stimulation of collagen regrowth and reorganization that is initiated by microneedling.
• Understand the risks of, and contraindications to, microneedling.

Introduction

Microneedling is a form of therapy that utlilizes instruments containing rows of thin needles that penetrate the dermis to a uniform depth, creating a controlled skin injury. This controlled skin injury induces rapidly-healing micropunctures with subsequent stimulation of collagen and elastin fiber production, resulting in skin remodeling.[1]

Microneedling was initially developed as a tool for skin rejuvenation. However, it is now being used for a number of indications, which include: various forms of scars, alopecias, drug delivery, hyperhidrosis, stretch marks, and more.[1] It is occasionally combined with delivery of radiofrequency energy, which is thought to enhance dermal remodeling and clinical effects.[2]

Microneedling is a commonly-used procedure in dermatology. It is regarded as a safe and relatively inexpensive alternative to other forms of skin rejuvenation that is well-tolerated with minimal downtime. Despite its common use and wide variety of indications, strong evidence for the efficacy of microneedling is not evident in the literature.[3][4][5]

Anatomy and Physiology

Physiology of Collagen Induction Therapy

Micropunctures are created, which produce a controlled skin injury without causing any significant damaged to the epidermis. These microinjuries lead to minimal superficial bleeding and set up a wound healing cascade with release of various growth factors such as platelet derived growth factor, transforming growth factor alpha and beta, connective tissue activating protein, connective tissue growth factor, and fibroblast growth factor.[6]

In the treatment of scars, the needles breakdown the scar strands and allow it to revascularize. Neovascularization and neocollagenesis is initiated by migration and proliferation of fibroblasts and laying down of intercellular matrix.[7]

A fibronectin matrix forms after 5 days of injury that determines the deposition of collagen resulting in skin tightening persisting for 5–7 years in the form of collagen III. The depth of neocollagenesis has been found to be 5–600 µm when a 1.5 mm length needle is used for the procedure. Histological examination of the skin treated with 4 microneedling sessions 1 month apart shows up to 400% increase in collagen and elastin deposition at 6 months postoperatively, with a thickened stratum spinosum and normal rete ridges at 1 year postoperatively.[8]

Physiology of Drug Delivery

Microneedling enhances the delivery of various drugs across the skin barrier as it bypasses the stratum corneum and deposits the drug directly up to the vascularized dermis. It has also been shown to cause significant widening of the follicular infundibulum by 47%, which may contribute to the increased penetration of the medication across the skin barrier.[9]

Indications

Various indications for microneedling include:

• Pigmentary Disorders[1]
• Scars and Striae[1][10]:
  • Androgenetic Alopecia (in combination with 5% minoxidil)
  • Alopecia Areata (in combination with topical steroids)
• Skin rejuvenation (rhytides, etc)[1][10]
  • Acne scars (atrophic, boxcar, rolling, and ice-pick scars). Though deep boxcar scars, ice-pick scars, and linear scars are less likely to respond.[1]
  • Burn scars
  • Traumatic scars
  • Varicella scars
  • Hypertrophic scars
  • Striae distensae (stretch marks)
• Alopecia[1]
  • Melasma (in combination with topical application of skin-bleaching agents)
  • Periorbital Hypermelanosis (in combination with topical application of skin-bleaching agents)
• Primary Axillary Hyperhidrosis: using fractional radiofrequency microneedling[1]

Contraindications

Microneedling is generally a well-tolerated, safe procedure. Contraindications are limited, but include the following[1][10]:

1. Active acne, especially inflammatory lesions
2. Active herpes labialis or other localized infection in the treatment area, including warts.
3. Moderate-to-severe chronic skin diseases such as eczema or psoriasis
4. Patients with extreme keloidal tendencies
5. Immunosuppressed patients, including patients on chemotherapy
6. Care should also be taken in patients near concomitant chemodenervation (botulinum toxin) injection sites to avoid unwanted toxin diffusion

Equipment

There are a number of microneedling devices employed in medical and aesthetic offices. The most commonly used instruments, however, are fixed, needle rollers and electronically-powered pens with disposable tips.

The size of the needles should be selected appropriately based on both the treatment indication as well as the treatment location. For treatment of scars, for instance, longer needle lengths of 1.5-2.0mm may be used. For treatment of aging skin and rhytides, however, smaller needle lengths of 0.5-1.0mm are generally recommended.[1] Furthermore, thick, sebaceous skin such as that found on the nose, may require deeper penetration than delicate, periocular skin.[10]

Other variations in microneedling devices include:

1. Fractional radiofrequency microneedling 
2. Home-care rollers (needles of about 0.1 mm in length) are used for transcutaneous delivery of anti-aging agents
3. Devices combining microneedling and vacuum-assisted infusion
4. LED microneedling rollers

Preparation

Topical anesthesia with lidocaine and prilocaine cream (EMLA) is applied to the area to be treated and covered with a cellophane tape for 15 to 45 minutes. EMLA is then removed using normal saline. An antiseptic solution may be applied before the procedure begins.

Technique or Treatment

The skin of the face is stretched by one hand while the other hand is used to roll or glide the instrument over in a direction perpendicular to that of stretching force. If using a needle roller, then the device is rolled 15 to 20 times in horizontal, vertical, and both oblique directions. The treatment endpoint is uniform, pinpoint bleeding. Saline pads should be kept over treated areas of the face once the treatment endpoint has been reached. Full facial treatment generally takes 15-20 minutes.

Combining the microneedling treatment with immediate post-operative application of serums that include vitamins A and C enhances the regenerative-process of microneedling-induced wound healing and leads to greater clinical and histologic outcomes[11]. 

Postoperative Care

The procedure is typically well-tolerated with no post-treatment sequlae, besides some erythema, mild edema, and exfoliative scaling that can last for 2-3 days. There is no downtime and patients can resume usual daily activities starting the next day, with the caution to wear sunscreen with regular reapplication and to avoid sun exposure and harsh chemicals for at least for 1 week.

Patients should be advised that they may observe some serous drainage the hours following the procedure, in the earliest stages of wound healing. Damp gauze can effectively be used to collect the excess fluid. 

Advise patients that final results cannot be viewed immediately as the process of neocollagenesis continues for approximately 3-6 months following the treatment.[1]

Treatment can be repeated after a minimum of 3 weeks[1][12][13][14][15].

Complications

Complications are typically negligible. Common, expected complications include[1]:

1. Pain during the procedure (minimal when topical anesthetics are used appropriately)
2. Erythema, irritation, and mild edema (which generally susides in hours-to-days)

Other, less commonly observed adverse effects can include the following[1][16]:

1. Hyperpigmentation, though the risk is signficantly lower than when using energy-based devices (lasers)
2. Reactivation of herpes simplex
3. Localized superficial infections, such as impetigo
4. Allergic granulomatous reactions have been noted after application of serums in patients with hypersensitivity to serum ingredients
5. Allergic contact dermatitis to needle materials
6. Exposure to blood

Clinical Significance

Advantages

• Relatively short healing time compared to other rejuvenation modalities. 
• Relatively low-cost procedure.
• Simple technique that is easy to master
• Well tolerated by patients.
• Minimal risk of post-inflammatory hyperpigmentation (many alternative therapies used for the same indications such as CO2 laser resurfacing and deep chemical peels, ablate the epidermis with subsequent re-epithelialization. The epithelial damage in these procedures renders the skin more sensitive to photodamage and dyschromia)
• Can be combined with other acne scar treatment like subcision, chemical peeling, microdermabrasion and fractional resurfacing maximum-giving benefits

Disadvantages

• Evidence-based recommendations for the use of microneedling are lacking; most recommendations for its use are based on anecdotal reports and small studies.
• Head-to-head trials against the various other treatment options are sparse

Enhancing Healthcare Team Outcomes

Microneedling is a procedure used widely in dermatology, plastic surgery, and other aesthetic practices. In addition to its original intended use for skin rejuvenation, it is also gaining traction for novel uses such as transcutaneous medication delivery. Though the risks are minimal and the technique straightforward, it can be an expensive procedure and healthcare providers have an ethical responsibility to inform patients of the limited evidence regarding its efficacy. Despite the limited number of large, well-controlled studies there are many anecdotal reports and small case-series that have demonstrated significant improvement when used for a number of dermatologic conditions.