What type of burns can leave scars?
Second-degree or higher burns (i.e. those that affect the middle layer of the skin – dermis) – can cause scarring, as they affect the skin appendages (hair and glands), which are essential for the process of repairing a wound. First-degree burns, where the superficial layer of the skin (epidermis) is injured, do not leave a scar. Second-degree burns are usually the result of exposure to hot objects or liquids, or to caustic or acidic chemicals.
What are the physical characteristics of burn scars?
Since they produce a heterogeneous destruction of the noble structures of the skin (and deeper tissues, if applicable), they result in scars that are usually wide and with a huge tendency to hypertrophy and evolution towards keloid. Some studies show that up to 67% of burns evolve into a hypertrophic scar or a keloid. They usually have irregular edges, unlike surgical ones, and also present a retraction of the skin tissue, frequently hindering the movement or extension of the affected area. It is characteristic that the injured skin lacks hair follicles, in which case the skin appearance is waxy and shiny, pink or skin colored.
What treatments are available for burn scars?
Treatments depend on several factors. One of the most important is the time of evolution (more information here). Likewise, the colour, extension, location and symptomatology (pain, limitation of mobility) that they cause will also be key to determining which therapeutic option is the most appropriate at that time.
Below is a review of the therapeutic options for the treatment of burn scars:
MASSAGE. Manual massage or massage using medical devices is usually a standard treatment for burn scars. Although there is no scientific evidence of its usefulness, it seems appropriate to reduce the pain and itching caused by this type of scar, as well as to produce an increase in the mobility of the affected tissue. In meta-analyses evaluating its efficacy, it has been concluded that the treatment protocols are highly variable, the results very subjective, and the degree of evidence in their favor poor.
PRESSOTHERAPY WITH DRESSES. There are garments designed to apply pressure to the injured skin to try to prevent the damaged tissue from hypertrophying. It seems that pressive garments reduce the itching and pain of scars, although there is no study that objectively evaluates their real usefulness. Although there is not enough scientific evidence for its recommendation, the use of pressive garments is still the first therapeutic recommendation in burn scars, as long as the affected area allows the use of pressotherapy dresses. It seems that pressure reduces the supply of oxygen to the scar and reduces the probability of hypertrophy. It is recommended to wear the garments for a minimum of 23 hours a day, that they exert a pressure of 20 – 40 mmHg and that they are applied as early as possible, for a period of 6 – 24 months. The trunk and limbs are considered to be the locations where pressure garments are most effective. On the other hand, concave or flexion areas are the least benefited. The main drawback of pressotherapy is the low adherence to treatment by the patient, since it is uncomfortable to apply this type of fabric. In a meta-analysis, it was concluded that the costs and morbidity of this treatment outweigh the benefit to be obtained, which has not yet been reliably demonstrated.
OCCLUSION WITH SILICONE PATCHES. The hydration and occlusion provided by adhesive strips or silicone patches seem to be the main reasons why these therapeutic options are beneficial for the treatment of burn scars. It is recommended that the application begins two weeks after the scar forms and the treatment lasts up to three months, wearing the silicone patch or gel for 12-24 hours a day. It seems that in this way the tension forces to which the healing is subjected are reduced, reducing tissue hypertrophy. Silicone gels are useful for areas where the patch does not adhere, and should be applied every 12 hours. A Cochrane review of the usefulness of silicone on scars confirmed efficacy in improving the colouration and thickness of scars, although the studies analysed were not very robust.
CRYOTHERAPY. Cryotherapy consists of the application of liquid nitrogen at -196ºC. It has an anti-inflammatory effect and reduces the thickness of the scars. The combined use of cryotherapy and intralesional corticosteroids is considered to be the initial and basic treatment for hypertrophic and keloid scars, whether they are secondary to burns or that have a different origin.
INTRALESIONAL INJECTION OF CORTICOSTEROIDS. It consists of injecting a corticosteroid into the scar. Corticosteroids are anti-inflammatory, reduce the proliferation of keratinocytes and fibroblasts, and have vasoconstrictor action. This technique improves the elasticity of the scar, reduces its volume, and improves itching and pain. Triamcinolone acetonide is usually used and injected every 1-4 weeks. Intralesional corticosteroid injection is considered to be the treatment of choice for keloids and hypertrophic scars. The positive response rate of intralesional corticosteroid injection varies between 50 and 100% of treated cases, with recurrence rates of 9-50%. Unfortunately, it is a painful technique for the patient and transient hypopigmentation and the appearance of telangiectasias (capillaries) in the treated area are very common. These capillaries can be removed later with laser if desired. The combination of corticosteroids plus 5-fluorouracil (a cytostatic that reduces cell proliferation) reduces the likelihood of adverse effects of corticosteroids and increases the effectiveness of the treatment. Intralesional injection of corticosteroids can be considered immediately after removal of the keloid, especially if it is repeated weekly for a period of up to 5 weeks. 5-fluorouracil can be used up to within the first five years of the appearance of the burn scar.
LASERS AND PULSED LIGHT. There are many studies that reflect the usefulness of CO2, erbium, pulsed dye, Nd:YAG or KTP lasers in the treatment of hypertrophic scars and keloids. Each of them has a specific mechanism of action, although in general terms we can accept that they either reduce the vascular system that feeds the scar, or modify the structure and formation of collagen in it.
Vascular lasers, which have the first mechanism of action (KTP, Nd:YAG and pulsed dye) have preventive action, especially on hypertrophic scars. They improve reddish coloration, texture and elasticity with an extraordinary safety profile. If you want more information about the KTP laser in the treatment of scars, click here. To obtain it from the Nd:YAG laser, click here. Vascular lasers can be combined with other techniques such as cryotherapy with liquid nitrogen or intralesional injection of corticosteroids with or without 5-fluorouracil. This type of combination is especially recommended in thick keloids (more than 1 cm), since the light from the lasers does not penetrate them completely.
Lasers that act on the collagen configuration can be ablative (CO2, erbium) or non-ablative (erbium). Ablative lasers are used to ‘burn’ in a controlled way, forming columns of heat in the wound that will allow the aberrant collagen in the scar to be reorganized. Non-ablative lasers simply heat the tissue deeply without burning it. Both have proven effective in reducing the volume and pigmentation of scars. If you want to learn more about the treatment of burn scars with CO2 lasers, click here. For the non-ablative erbium laser, click here.
For the treatment of burn scars, a therapeutic sequence with lasers is recommended. From 6 to 36 months after the burn, it is recommended to use vascular lasers. Subsequently, from one year after the burn, it is advisable to use the fractional CO2 laser. The first step tries to reduce the blood supply to the scarring area and reduce its red-purplish colour; the second step aims to soften and flatten the surface. Finally, it is possible to do a final treatment with pulsed light to improve the pigmentation of the scar (this option can be practiced up to years after the burn).
This scheme is only a generic guide that must be personalized in each case, depending on the type and area of burn, as well as the patient’s preferences.
Special mention should be made of burn scars located in the facial area. In this area, erythema (redness) can last for decades and it is recommended that the laser of choice to treat it, regardless of how old you have been burning, is pulsed dye, KTP or short-pulse YAG .
SURGERY. Surgery can be used in two circumstances. When the surgery increases the mobility of a joint or fold (e.g., by means of a Z-plasty) of retracted scars; and when the complete excision of the scar and subsequent application of a more intense treatment such as radiotherapy or bleomycin is considered to prevent cell proliferation of the new scar.
CONCLUSIONS
- Burn scars do not have a single treatment that is effective in all cases. Each patient requires a personal evaluation and their own therapeutic approach that must be agreed with their dermatólog@ at the first visit.
- It is advisable that the management of burn scars be carried out by dermatólog@s especializad@s in this area, since the range of therapeutic possibilities is extraordinarily wide and certain options (such as the KTP laser or the short-pulse Nd:YAG laser) can only be available to teams of sub-specialized professionals.
- In general, it is recommended to start with the combination of cryotherapy plus corticosteroid infiltration (with or without 5-FU), as it has an excellent risk/cost/benefit ratio.
- In generic terms, with cryotherapy plus corticosteroids and later a combination of lasers, notable aesthetic and functional improvements can be achieved.
REFERENCES
Arno AI, Gauglitz GG, Barret JP, Jeschke MG. Up-to-date approach to manage keloids and hypertrophic scars: a useful guide. Burns. 2014 Nov; 40(7):1255-66.
Click here for more information on treating burn scars with ablative fractional laser.
Click here to learn more about non-ablative laser treatment of burn scars.