Microneedling

Anatomy and Physiology

Physiology of Collagen Induction Therapy

Micropunctures are created, producing a controlled skin injury without causing significant damage to the epidermis. These microinjuries lead to minimal superficial bleeding and set up a wound healing cascade with the 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 treating scars, the needles break down the scar strands, allowing them to revascularize. Neovascularization and neocollagenesis are initiated by the migration and proliferation of fibroblasts and the laying down of the intercellular matrix.[7]

A fibronectin matrix forms after 5 days of injury that determines collagen deposition, resulting in skin tightening and persisting for 5 to 7 years in the form of collagen III. The depth of neocollagenesis is 5 to 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 a 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 it directly to the vascularized dermis. It has also been shown to cause a 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:
  • Androgenetic Alopecia (in combination with 5% minoxidil)
  • Alopecia Areata (in combination with topical steroids) [1][10]
• Skin rejuvenation (rhytides, etc)
  • Acne scars (atrophic, boxcar, rolling, and ice-pick scars); 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) [1][10]
• Alopecia
  • Melasma (in combination with topical application of skin-bleaching agents)
  • Periorbital Hypermelanosis (in combination with topical application of skin-bleaching agents) [1]
• 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 [1][10]

Equipment

Several microneedling devices are employed in medical and aesthetic offices. However, the most commonly used instruments are fixed needle rollers and electronically powered pens with disposable tips.

The size of the needles should be selected appropriately based on the treatment indication and the treatment location. For treating scars, for instance, longer needle lengths of 1.5 to 2.0 mm may be used. However, smaller needle lengths of 0.5 to 1.0 mm are generally recommended to treat aging skin and rhytides.[1] Furthermore, thick, sebaceous skin, like 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 antiaging 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 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

One hand is used to stretch the skin of the face while the other hand rolls or glides the instrument in a direction perpendicular to the stretching force. If using a needle roller, the device is rolled 15 to 20 times in horizontal, vertical, and oblique directions. The treatment endpoint is uniform, with pinpoint bleeding. Once the treatment endpoint has been reached, saline pads should be kept over treated face areas. Full facial treatment generally takes 15 to 20 minutes.

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

Postoperative Care

The procedure is typically well-tolerated with no posttreatment sequelae besides some erythema, mild edema, and exfoliative scaling lasting 2 to 3 days. There is no downtime, and patients can resume their 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 1 week.

Patients should be advised that they may observe some serous drainage in the hours following the procedure, in the earliest stages of wound healing. Damp gauze can effectively be used to collect the excess fluid. Patients should also be advised that final results cannot be viewed immediately as neocollagenesis continues for approximately 3 to 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. Pain during the procedure (minimal when topical anesthetics are used appropriately)
2. Erythema, irritation, and mild edema (which generally subsides in hours-to-days)

Other less commonly observed adverse effects can include the following:

1. Hyperpigmentation, though the risk is significantly 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 [1][16]

Clinical Significance

Like other procedures, microneedling has advantages and disadvantages.

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)
• It can be combined with other acne scars treatments like subcision, chemical peeling, microdermabrasion, and fractional resurfacing, maximum-giving benefits

Disadvantages

• Evidence-based recommendations for using microneedling are lacking; most recommendations 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 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 expensive, 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, many anecdotal reports and small case-series have demonstrated significant improvement when used for many dermatologic conditions.