Microneedling also called "percutaneous collagen production" is a form of developing therapy using instruments which contain rows of thin needles. When these instruments are rolled over the surface of the skin, they induce rapidly-healing micropunctures. Subsequently, collagen and elastin fiber production is stimulated resulting in skin remodeling. Microneedling was also proposed to enable the penetration of high molecular weight drugs by creating transient aqueous transport microchannels through the stratum corneum, thus increasing the transcutaneous permeability. This procedure is called transdermal drug delivery. A peculiar type of microneedling is fractional radiofrequency microneedling in which, insulated needles release radiofrequency waves to act deeper in the dermis, thus preventing epidermal damages.Microneedling was initially used for scars, but now there are many indications for use. However, strong evidence for the efficiency of microneedling is not evident in the literature.
Various indications of microneedling include:
Microneedling is contraindicated in:
The usual medical roller has a handle and a 2 cm wide barrel-shaped cylinder having 192 thin stainless steel needles, which are 0.5 mm to 3 mm in length and 0.1 mm to 0.25 mm in diameter. The microneedles are usually non-allergenic to humans.
The roller is pre-sterilized by gamma irradiation. Re-sterilization of the instrument using an autoclave or ultrasound is not indicated since needles may become less sharp and detach from the roller. Roller should always be maintained in isopropyl alcohol.
Other variations in microneedling devices include:
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 should be applied before the procedure begins.
The skin of the face is stretched by one hand while the other hand is used to roll the instrument over in a direction perpendicular to that of stretching force. The roller is rolled 15 to 20 times in horizontal, vertical, and both oblique directions. The base of the scar is to be treated. Pinpoint bleeding should occur from the base of the scar. Saline pads are kept over the treated area.
The topical antibiotic cream is applied. The procedure takes 15 to 20 minutes. Treatment is to be repeated after 4 to 6 weeks.
Pathophysiology of Collagen Induction Therapy
Rolling with a standard roller containing 192 needles of 2 mm length and 0.07 mm diameter over an area of skin for 15 times results in approximately 250 holes per square cm up to the papillary dermis depending on the pressure applied. Each pass produces 16 micropunctures in the stratum corneum per square cm. The needles are placed at an inclination of 15 degrees in relation to the surface of the derma roller to achieve a uniform depth of penetration, The depth of neocollagenesis was found to be average 5 micrometers to 600 micrometers with 1.5 mm length needle.
Microneedling aims to stimulate collagen production by producing micro wounds and initiating the normal post-inflammatory chemical cascade. There are three phases of the wound healing process which predictably follow each other as described by Falabella and Falanga.
Collagen fiber bundles qualitatively increase, thicken, and more loosely weave in both papillary and reticular dermis. It appears to lay more in a normal lattice pattern than in parallel bundles as in scar tissue. Neovascularization and neocollagenesis following treatment lead to the reduction of scars.
The treated area is swollen and superficially bruised. It should be covered with cool, damp swabs that are replaced for 2 hours to absorb the bleeding and serous discharge.
Topical antibiotic cream (mupirocin) is applied for few days to minimize the chance of bacterial infection.
Avoid sun exposure and harsh chemicals or any cosmetic procedure over the face for at least for 1 week.
Complications are almost negligible.
Poor quality needles of the roller device often result in bending at needle tips after repeated treatments, which results in more tissue damages and hemorrhage with linear hypertrophic scars or post inflammatory hyperpigmentation. Over-aggressive needling using a tattoo gun may also cause scarring, but not with the special barrel of needles.
Evidence-based recommendations for the use of microneedling could not be performed currently.
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