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ARTICLE | TREATING SCARS |


Table 1 Current and novel approaches for the prevention and therapy of excessive scarring


PROPHYLAXIS OF EXCESSIVE SCARRING TREATMENT OF EXCESSIVE SCARRING Current treatment Pressure therapy


Current treatment


Silicone gel (sheeting)* Flavonoids/onion extract*


Novel options


Imiquimod 5% cream Botulinum toxin A* Recombinant TGF-β3


Intralesional corticosteroid Injections* Cryotherapy*


Surgical manipulation Radiotherapy Laser therapy (PDL)*


Novel options


5-fluorouracil (5-FU)* Bleomycin


Interferon (INF) Injections


Intralesional botulinum toxin A *very good results based on the experience of the author PDL=pulsed dye laser; TGF=transforming growth factor


Pressure therapy


Since the 1970s, pressure therapy has been the preferred conservative management for the prophylaxis and treatment of both hypertrophic scars and keloids. To date, pressure garments are mostly used for the prevention of burn scar formation. The mechanism of action of pressure therapy remains poorly understood. Decreased collagen synthesis by limiting the supply of blood, oxygen and nutrients to the scar tissue10–12 increased apoptosis13


and are under discussion. Recommendations for the amount of pressure and the


duration of the therapy are merely based on empirical observations and support continuous pressure of 15–40 mmHg for at least 23 hours per day for more than 6 months while the scar is still active11, 14


. Pressure therapy


may be limited by the ability to adequately fit the garment to the wounded area and by reduced compliance as a result of significant patient discomfort.


Silicone gel Topical silicone gel (sheeting) has been well-established for the management of scars since its introduction in the early 1980s, and its therapeutic effects on predominantly hypertrophic scars have been well documented in the literature15–19


Clinical


differentiation between hypertrophic and keloid scars is central before the initiation of any treatment, particularly before starting any surgical or laser-related manipulations.


Flavonoids Flavonoids (quercetin and kaempferol) are found in well-known topical scar creams. Quercetin, a dietary bioflavonoid, has been shown to inhibit fibroblast proliferation, collagen production, and contraction of keloid and hypertrophic scar-derived fibroblasts. Studies by Phan and others suggested that these inhibitory effects may be mediated through inhibition of SmAD classes 2, 3, and 4 expression by quercetin27, 28


. An increasing number of studies testing the ultimate


benefit of these flavonoid-containing (or ‘onion extract’) scar creams are available29–31


. A scar cream containing the


active substances extractum cepae and allantoin (and heparin) appears to be effective in improving scar appearance32–35


undergoing laser removal of tattoos36 or ultrasound38, 39


, and preventing scarring in patients . Its use has also


been proven successful in combination with intralesional TAC37


for the therapy of keloid and hypertrophic scars or mature scars, respectively.


Novel options for the prevention of hypertrophic and keloid scars Imiquimod 5% cream Imiquimod 5% cream, a topical immune response modifier, has been approved for the treatment of genital warts, superficial basal cell carcinoma, and actinic keratoses40


. Imiquimod stimulates interferon, a


pro-inflammatory cytokine, which increases collagen breakdown. Additionally, imiquimod alters the expression of apoptosis-associated genes41


. It has been


used in a number of trials and observational studies to reduce keloid recurrence after excision and was reported to have positive effects on the recurrence rate of keloids if applied post-surgery42–46


. However, additional studies with


a larger sample size and longer follow-up periods are necessary to further characterise its side-effect profile (e.g. persisting inflammation, erosion, depigmentation), and the role of this rather expensive approach for the reduction of recurrence rates after keloid surgery.


Botulinum toxin A . Current


opinion suggests that occlusion and hydration are likely the underlying mechanisms of the therapeutic action of silicone gel rather than an inherent anti-scarring property of silicone20, 21


. Silicone sheets


are recommended to be worn for 12 or more hours per day for at least 2 months beginning 2 weeks after wound healing. Increasing numbers of studies are supporting the use of silicone gel, particularly in areas of consistent movement where sheeting will not conform22–26


. Based on current data, silicone gels


can be recommended for excessive scar-prone patients or in specific anatomic locations, and should be applied twice daily beginning approximately 2 weeks after surgery or initial trauma. Nevertheless, convincing data for the effects of silicone gel on mature hypertrophic scars and keloids remains contradicting.


20 ❚ January/February 2012 | prime-journal.com


Botulinum toxin A immobilises local muscles, reduces skin tension caused by muscle pull, and thus decreases microtrauma and subsequent inflammation47


.


Reduction of the tensile force during the course of cicatrisation and effective regulation of the balance between fibroblast proliferation and cellular apoptosis48


may represent a novel therapeutic option


for the aesthetic improvement of post-surgical scars. Indeed, Gassner and colleagues demonstrated that injections of botulinum toxin into the musculature adjacent to the wound (15 U of botulinum toxin A (BOTOX® Cosmetic, Allergan) per 2 cm intraoperative length) within 24 hours after wound closure, resulted in enhanced wound healing and less noticeable scars compared with placebo49


. By injecting


botulinum toxin 4–7 days prior to surgery, similarly convincing results using a comparable dose regimen can be observed (depending on the respective anatomic location).


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