Erbium:YAG laser treatment of post-burn scars: potentials and limitations Aletta Eberlein
Transcription
Erbium:YAG laser treatment of post-burn scars: potentials and limitations Aletta Eberlein
Burns 31 (2005) 15–24 www.elsevier.com/locate/burns Erbium:YAG laser treatment of post-burn scars: potentials and limitations Aletta Eberleina,*, Hadrian Scheplerb, Gerald Spilkera, Peter Altmeyerc, Bernd Hartmannd a Department of Plastic Surgery and Burn Center, Cologne City Hospital, Teaching Hospital of University of Witten-Herdecke, Ostmerheimer Str. 200, 51109 Cologne, Germany b Department of Hand and Plastic Surgery, Klinikum Lu¨denscheid, Teaching Hospital of University of Bonn, Paulmannsho¨her Str. 14, 58515 Lu¨denscheid, Germany c Department of Dermatology, Ruhr-University of Bochum, St. Josef-Hospital, Gudrunstr. 56, 44791 Bochum, Germany d Department of Plastic Surgery and Burn Center, Unfallkrankenhaus Berlin, Warener Str. 7, 12683 Berlin, Germany Accepted 1 June 2004 Abstract Erbium:YAG lasers are successfully used to treat a variety of epidermal and dermal lesions, including rhytides, dyschromias, and certain types of scars. To date, however, no report has focused on the experiences with this laser in reconstructive burn surgery. Since 2001, the Erbium:YAG laser has become an integral part of the treatment of postburn scars at the Berlin Burn Center. This paper presents the techniques applied and clinical experiences obtained. In addition, a new stripe technique is introduced, which avoids healing disturbances in scars following deep burns. In conclusion, the Erbium:YAG laser has proven to be a valuable supplementary tool for the improvement of cosmetically disturbing mild postburn scars. It is particularly handy in areas difficult to treat, such as the eyes, nose, lips, and fingers. The individual advantages of the Erbium:YAG laser, other laser systems, and dermabrasion for the treatment of burn scars are compared in a brief survey. # 2004 Published by Elsevier Ltd and ISBI. Keywords: Erbium:YAG laser; Scars; Burns; Wound-healing; Review 1. Introduction The classic procedure for improving the superficial appearance of scars is dermabrasion. In addition, advancements in laser technology have provided several new tools for scar revision [1–5]. Ablative laser systems like the Erbium:YAG laser and the pulsed CO2 laser deepithelialize similarly to dermabrasion without direct wound contact. The laser energy is mainly absorbed by water and proteins of tissue cells. High-peak power and short-pulse durations are used to optimize vaporization of targeted tissue with minimal surrounding damage [6,7]. Both lasers are successfully used in cosmetic * Corresponding author. 0305-4179/$30.00 # 2004 Published by Elsevier Ltd and ISBI. doi:10.1016/j.burns.2004.06.004 surgery and for a large variety of dermatologic indications [7–12]. The erbium:YAG laser in its traditional configuration emits infrared light with a wave length of 2.94 mm and uses 250–350 ms pulse durations in laser skin resurfacing. As a rule, a single pulse of the Er:YAG laser at 5 J/cm2 will ablate about 20–25 mm of tissue with an additional 5–10 mm zone of thermal necrosis [6,13,14]. The necrotic layer is completely removed during each new pass, and even after multiple passes, the residual necrotic layer does not exceed 10–50 mm [7,12,15] (Fig. 1). The defined depth of ablation and constantly low thermal necrosis are two favourable conditions considering the often-impaired healing potential of burn scars. While normal skin will reepithelialize quickly and evenly from hair follicles and dermal glands after dermabrasion or laser 16 A. Eberlein et al. / Burns 31 (2005) 15–24 Fig. 1. Histological finding after application of 600 mJ three times on the same 3 mm spot = 25.5 J/cm2. The epidermis is completely ablated and a very narrow zone of thermal necrosis is apparent in the papillary dermis. ablation, burn scars are often partially or completely deprived of their epidermal appendages, especially after deep burns [3]. During resurfacing of such scars, it is advisable to save spots of intact epidermal basal layer, which can serve as islands for reepithelialization. As the Erbium:YAG laser provides ideal options to maintain such calculated procedures, this laser was added to the equipment in our burn center in May 2001. 2. Patients and methods 2.1. Laser and technique The laser in use was the Dermablate1 (Aesclepion, Jena, Germany). This laser provides pulse energies of 100–1000 mJ. The spot size on the skin can be varied between 1–6 mm using different spacers on the handpiece. A high-power smoke vacuum (Safe SystemTM, Edge Systems Corp., USA) is directly attached to the handpiece (Fig. 2). We mostly used the 3-mm spot size in a freehand mode. The single spots were placed slightly overlapping in circles, meander or any other pattern on the skin (Fig. 3), while a constant spot overlap of 30–40% was maintained. At a speed of 8 Hz, working with the laser beam is similar to working with a paint brush. The speed was reduced to 2–4 Hz in more delicate areas such as the periorbital region, or accelerated for larger areas such as the trunk. For an even subtotal deepithelialization of larger areas, we applied two passes of a fluency of about 11–12 J/cm2 as provided by the 3-mm spot, a single spot energy of 600 mJ and 30–40% spot overlap. In order to level down single nodules or prominent parts of larger scar areas, higher spot energies (800–1000 mJ), higher pulse repetition, and increased overlaps, close to the point of pulse stacking, were used depending on the individual clinical situation. In larger scar areas containing multiple prominent bands and lines, the elevations were first cleared away selectively using high power (Figs. 4 and 8b). Preoperative marking of the elevated scar lines and points using a sterile skin marker was often helpful during this procedure (Fig. 4b). In a second step, the whole scar area was subtotally deepithelialized using the above described energy mode in order to obtain an even regeneration and optical blending. In the face, complete aesthetical subunits were treated whenever possible. All procedures were performed under either local infiltration anaesthesia, regional nerve blocks or under general anaesthesia. In some cases, thicker scar boards needed to be thinned. In these cases, deep ablation was performed in a channellike manner, leaving narrow stripes of healthy epidermis in between (Fig. 8b). These provided rapid postoperative A. Eberlein et al. / Burns 31 (2005) 15–24 17 Fig. 2. Different spacers on the laser handpiece can be chosen for different spot sizes. The wide opening on the handpiece is part of the integrated smoke vacuum. healing. As soon as repigmentation was restored, the other still untreated stripe-like scar areas were selectively levelled down in a second step (Fig. 8d). 2.2. Patients and perioperative care During May 2001 and December 2002, a total of 96 scars were treated in 24 patients aged 16–55 years. The scars to be treated had developed either after spontaneously healed superficial burns or after autologous skin grafting secondary to burn injuries. Most of the scars were mature scars, only few scars showed prolonged redness, indicating persistent scar proliferation. No keloids were treated. Thirty-eight scars with irregular profiles were larger than 4 cm 4 cm or covered a complete aesthetic unit in the face. Thirty of these scars were located in the face, neck or low neckline, eight on the hands. Twenty-four additional scar areas were treated for hyperpigmentation, four of these cases contained deep spotted powder tattoos that had to be removed (Fig. 5). Thirty-four scars were single nodules or cords or transplant borders (Fig. 6). The results of treatment were evaluated for changes of skin texture and colour after a follow-up period of at least 6 months. All patients gave their informed consent before treatment. Patients treated for hyperpigmentation were informed about alternative treatments such as ruby lasers. Patients who had received blood transfusions or who presented other risk factors were asked to be screened for HIV and Hepatitis. As the intended clinical laser treatment was not a part of an approved study, a human studies committee was not involved. After full-face procedures, the entire face was covered by Silon-TSRTM (Bio Med Sciences Inc. Allentown, PA), which is a very thin and flexible perforated silicone sheet specially produced for laser-resurfacing. In all other cases, we chose MepitelTM (Mo¨ lnycke Health Care AB, Sweden), a different silicone wound dressing, which we use regularly for the treatment of superficial second-degree burn injuries. The dressings were changed first on postoperative days 2 or 3, and thereafter every 1 to 3 days depending on the individual healing progress. During the postoperative period, special attention was paid concerning the possibility of herpes reactivation by laser treatment. However, no perioral antivirals were given prophylactically, as none of the patients presented a positive history of herpes simplex in the area to be treated. After complete healing, patients switched to the application of a moisturizing sunscreen during daylight (SPF 30 or greater) and pathenol cream until complete resolution of erythema. 3. Results 3.1. Clinical improvement All profile treatments of larger areas in the face, neck, lower neckline and hands showed improvement (Fig. 7). Grafted area could be smoothed in all cases (Fig. 6). Single nodes or cords, which were levelled down, showed partial recurrence of hypertrophy in 42% of the treatments. Some of these cases responded to a second treatment session. Results after treatment of hyperpigmented scars varied. Black powder tattoos could be cleared away in all cases (Fig. 5). Smaller dark spots or freckle-like lesions improved in 93% of the cases. One Russian patient who underwent multiple treatment sessions for large hyperpigmentation on both hands, returned to her country after healing and could not be further followed up. After treatment of nine other larger hyperpigmented areas on other patients, recurrence of 18 A. Eberlein et al. / Burns 31 (2005) 15–24 Fig. 3. Application of the laser beam on the skin: single spots may be lined up in circles creating round planes (a) or in meander-like patterns forming rectangular areas (b). hyperpigmentation occurred in five cases. The other four laser-treated areas remained hypopigmented, which, however, were intended and improved the overall appearance. 3.2. Complications No intraoperative complications occurred. None of the patients developed local infections or herpetic reactivation. Reepithelialization was completed after 7–14 days postoperatively in all cases where the technical treatment modalities described above were used. However, delayed healing-up to 5 weeks was observed in three other cases, where the applied laser energy exceeded the threshold of 25 J/cm2 in larger areas for other reasons. One of the latter patients showed local infection and subsequent hypertrophic scarring. The second patient developed long-lasting erythema and itching, and the third patient could not be followed up. Unwanted hypopigmentation was not seen, especially not in darker skin types. Hyperpigmentation was seen in one female patient of darker skin type III. As the healing process A. Eberlein et al. / Burns 31 (2005) 15–24 Fig. 4. Typical profile irregularities after mesh graft transplantation of the hand (a): elevated scar components are pen-marked prior to selective ablation (b) and subsequent superficial treatment of the complete region. was completely inconspicuous after the first two treatment sessions, this patient became less compliant regarding the use of her sun blocker after the third treatment. Shortly after reepithelialization, she developed blotchy hyperpigmentation, most of which resolved spontaneously within several months. 4. Discussion 4.1. Safety of the Erbium:YAG laser in burn scar treatment Reepithelialization of a large ablated skin surface depends on intact adnexal structures, such as hair follicles and dermal glands. However, in deeper second-degree and third-degree burns, those adnexal structures are partially or completely destroyed. In such cases, spontaneous healing can take place only from the surrounding healthy skin. This 19 Fig. 5. (a) Residual powder-tattoo secondary to superficial burn injury caused by a gunshot. (b) The pigmented spots were removed using the 1-mm spot size and short-pulse stacking. procedure usually goes along with delayed healing time depending on the wound size and wound contraction. In such spontaneously healed skin only the epidermis is restored without adnexal structures. In other burns, where the wound has been covered by thin split-thickness skin grafts, adnexal glands are lacking as well. In conclusion, areas with thin or atrophic skin, such as burn scars, must be treated with caution [3]. In such cases, the possibility of a highly controlled laser ablation as provided by the Er:YAG laser is a great advantage. In addition, this laser causes only minimal thermal necrosis, which even after multiple passes does not exceed 10–50 mm using ablative energy modes [7,12,15] (Fig. 1). As a single pulse of the Er:YAG laser at 5 J/cm2 will ablate about 20–25 mm of tissue, one would expect complete ablation of a thin epidermal layer of about 125 mm after delivering a fluence of 25 J/cm2 and more [13,14]. Our own previous clinical observations and histological findings in 20 A. Eberlein et al. / Burns 31 (2005) 15–24 Fig. 6. Full-thickness skin transplant at the lower eyelid before (a) and after laser treatment of the transplant borders and the small nodule at the medial border (b). discarded human dog-ear skin have shown that this treatment mode causes gross ablation into the dermal layer but leaves small islands of basal epidermis intact. Accordingly, for an even subtotal deepithelialization of larger areas, we usually applied no more than two passes of a fluency of 11–12 J/cm2 as provided by the 3-mm spot and a single spot energy of 600 mJ. In fact, in all cases where the above energy mode was used, we found a regular course of healing within 1–2 weeks postoperatively. In addition, all areas treated with higher energy flow according to the stripe technique proved regular healing time as well. Hence, we consider the Erbium:YAG laser as a safe tool for scar treatment in reconstructive burn surgery (Table 2). 4.2. Technical advantages of the Erbium:YAG laser Working with the laser beam is similar to working with a paint brush if a 3–6 mm spot size and a medium speed like 4–8 Hz is chosen. For larger areas like the trunk, larger spot sizes may be preferable. For this special indication, Fig. 7. A 28-year-old female burn patient who had received mesh graft transplants in the entire face abroad 2 years before and who is in the multistep secondary reconstruction program in our clinic. Among others, she had received full-thickness skin grafts of the eyelid, upper cheeks, and upper lip in the meantime. (a) Presently, hypertrophic scar ropes lateral to the nasolabial fold are causing a bulky appearance of the midface. (b) Improved appearance after levelling prominent scars in the nasolabial fold and on the distal part of the nose. additional scanner devices, as promoted for cosmetic skin resurfacing, may also have a place in reconstructive burn surgery. Particularly fine parts of a scar can be revised using even smaller spot sizes so that the laser beam can be guided like a pen. In delicate areas like the periorbital region or the nose, the speed can be easily reduced to 2–4 Hz (Figs. 6 and 7). A. Eberlein et al. / Burns 31 (2005) 15–24 Table 1 Burn scars susceptible to Erbium:YAG laser treatment Table 3 Disadvantages of the Erbium:YAG laser Mildly prominent scars Mesh-graft pattern Overgrafting Edges of skin transplants Fine scar lines and filigree findings Pigmentation irregularities Traumatic dotted tattoos Selective levelling of elevated scar components necessary Time consuming treatment of larger areas Missing hemostasis (not relevant in scar tissue) Smoke development High costs 21 as well as higher costs for purchase, storage and service (Table 3). In conclusion, the Erbium:YAG laser is particularly handy for very small and fine scars (Table 1). In addition, in areas difficult to work on like the eye-lids, the nose, the lips or the fingers, the laser was found to be comparably safe, as it is not subject to the special risks of dermabrasion such as slipping or rolling up soft tissue like the eye-lid. Furthermore, the flexibility and handyness of this laser allow special applications like the stripe technique, as described above. 4.3. Disadvantages of ablative lasers in comparison to dermabrasion There is an important difference between dermabrasion and laser ablation of irregular scar surfaces like mesh-graft pattern. While dermabrasion first clears away the elevated layers of scars, the laser beam will level ‘‘hills’’ and ‘‘valleys’’ equally. Only some minor irregularities may smooth away secondarily due to new mild scarring. However, this secondary shrinking effect, which is desired in the so-called ‘‘laser lifting’’ of normal aged skin, may be unwanted in the face of burn patients, where the scarred skin is already contract. Therefore, we feel, that an even twodimensional lasering of a complete area should be advised only for very mild scar irregularities after spontanously healed superficial burns. In all other scars showing more prominent profile irregularities, single elevations must be levelled down selectively. In such cases, preoperative ink-marking of the elevated scar lines and points is helpful during the operation, especially in larger scar areas (Fig. 4). Nevertheless, clearing away elevations selectively remains time-consuming and exhausting, especially in mesh-graft pattern. This general disadvantage concerns all ablative laser systems such as the Erbium:YAG lasers and CO2 lasers. Other disadvantages of ablative lasers include the development of smoke and smell Table 2 Advantages of the Erbium:YAG laser in burn scars Minimal thermal necrosis (‘‘cold ablation’’) Predictability of ablation depth and healing time Variable spot sizes and speed Precise ablation of filigree scars No mechanical wound contact No risk of slipping or rolling up soft tissue Easy handling around eyes, nose, lips Low rate of complications 4.4. Advantages and disadvantages of the Erbium:YAG laser in comparison to the CO2 laser The CO2 laser produces deeper thermal necrosis, which increases with each pass and may reach about 180 mm [11,16–18]. Therefore, the risk of wound healing disturbances and destruction of already atrophic dermis in burn scars by CO2 lasers is generally higher in comparison to the Erbium:YAG laser. However, in cosmetic resurfacing procedures for the aged skin, a deeper zone of necrosis and collagen shrinking is desired, as it is thought to be essential for wrinkle reduction and smoothed skin surface [17,19,20]. The more distinct thermal necrosis produced by CO2 lasers causes hemostasis, which simplifies cosmetic resurfacing procedures. The ‘‘cold’’ Erbium:YAG laser ablation, however, causes no coagulation, which is why ablation is normally stopped as soon as pinpoint bleeding from dermal vessels occurs and most of the laser energy is absorbed from the exuding blood. However, this is only true for healthy skin. Interestingly, pinpoint bleeding is not apparent in scar tissue and therefore, deep ablation using the Erbium:YAG laser is not limited by bleeding in burn scars (Fig. 8d). In conclusion, we consider the Erbium:YAG laser to be more suitable for the treatment of scars due to lesser thermal necrosis, while CO2 lasers seem to be more effective for smoothing aged skin. 4.5. Additional laser systems offering treatment options for burn scars Hypertrophic scars, which show prolonged redness and activity, can be improved by laser systems targeting treatment to the vascular component of the scar tissue. One of these lasers is the pulsed dye laser (585 nm), which has hemoglobin as target chromophore and thus penetrates the epidermis without deepithelialization. In several studies, it has been shown to be effective for longstanding hypertrophic and erythematous scars and for some cases of keloids [21–23]. In addition, itching of scars may be reduced [21,22]. Again, multiple treatment sessions in 8week-intervals are required. Early initiation of PDLtreatment for abnormally proliferative scars and concomitant administration of intralesional corticisteroids and silicone gel sheets are suggested. 22 A. Eberlein et al. / Burns 31 (2005) 15–24 Pigmented lesions caused by burn trauma may respond to treatment by the Q-switched Ruby laser [24]. Its 694 nm wavelength with a very short 20–40 ns pulse duration is selectively absorbed by melanosomes and other dark pigments, and its long wavelength allows penetration into the dermis. Like with all other lasers, the Ruby laser may cause unwanted pigmentation disturbances such as transient or permanent hypopigmentation or hyperpigmentation. However, the incidence of scarring or atrophy is comparatively low [25]. Unfortunately, postinflammatory hyperpigmentation, a frequent problem seen after second-degree burns and splitthickness skin grafting, is not consistently responsive to the ruby laser [26,27], but may be improved by the pigmented lesion dye laser (510 nm) [28–30]. Other laser systems, proven effective in the treatment of epidermal and dermal Fig. 8. Same patient as in Fig. 7. For deeper ablation of a thick scar board on the forehead (a) the two step stripe technique is applied (b–d). The first laser session was performed in supraorbital nerve block. The first pass of stripe-wise ablation (b) with single pulse energies of 800 mJ, 3 mm spot size and 80–90% spot overlap is followed by a second pass in the same lines. In between the laser-treated stripes, narrow bands of healthy skin are preserved as basis for a rapid and undisturbed reepithelialization, which is completed after 10 days (c). After 2 months, the still untreated skin bands are laser-treated selectively, while the formerly treated stripes are pen-marked and preserved (d). In addition, multiple scar bands in the nasal and nasolabial area were treated during the same operation. Note typical lack of bleeding within the scar tissue. (e) Clinical outcome on the forehead. There is some improvement of gross appearance. However, additional superficial dermabrasion or selective laser levelling of the numerous small scar elevations prior to stripe-wise treatment may have led to a better result. A. Eberlein et al. / Burns 31 (2005) 15–24 23 Fig. 8. (Continued ). pigmented lesions, are the Q-switched Alexandrite laser (755 nm) and the Q-switched Nd:YAG laser (1054 nm) [25,30]. 5. Conclusion In our experience, the Erbium:YAG laser is a valuable supplementary tool in reconstructive burn surgery. 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