RESUMO
INTRODUCTION: Microneedling (MN) is a minimally invasive procedure involving the induction of percutaneous wounds with medical-grade needles. In this literature review, we investigate clinical data on MN for the treatment of hair loss disorders. METHODS: A literature search was conducted through PubMed up to November 2021 to identify original articles evaluating the use of MN on hair loss disorders. The database was searched using the following keywords: "microneedling," "micro needling," "micro needle," "microneedle," "needle," "dermaroller" and "alopecia," "hair loss," "alopecia," "areata," "cicatricial," or "effluvium," RESULTS: A total of 22 clinical studies featuring 1127 subjects met our criteria for inclusion. Jadad scores ranged from 1 to 3, with a mean of 2. As an adjunct therapy, MN improved hair parameters across genders and a range of hair loss types, severities, needling devices, needling depths of 0.50-2.50 mm, and session frequencies from once weekly to monthly. Across 17 investigations totaling 911 androgenic alopecia (AGA) subjects, MN improved hair parameters when paired with 5% minoxidil, growth factor solutions, and/or platelet-rich plasma (PRP) topicals, or when introduced to subjects whose hair count changes had plateaued for ≥ 6 months on other treatments. Across four investigations on 201 alopecia areata (AA) subjects, MN improved hair parameters as a standalone therapy versus cryotherapy, as an adjunct to 5-aminolevulinic acid and photodynamic therapy, and equivalently when paired with topical PRP versus carbon dioxide laser therapy with topical PRP. Across 657 subjects receiving MN, no serious adverse events were reported. CONCLUSIONS: Clinical studies demonstrate generally favorable results for MN as an adjunct therapy for AGA and AA. However, data are of relatively low quality. Significant heterogeneity exists across interventions, comparators, and MN procedures. Large-scale randomized controlled trials are recommended to discern the effects of MN as a standalone and adjunct therapy, determine best practices, and establish long-term safety.