Treatment of Pigmented Hypertrophic Scars with the 585 nm Pulsed Dye Laser and the 532 nm Frequency-Doubled Nd:YAG Laser in the Q-Switched and Variable Pulse Modes

Abstract

background. Pigmented hypertrophic scars are a difficult condition to treat. They may result from traumatic injuries or from surgical and cosmetic procedures. The 585 nm flashlamp‐pumped pulsed dye laser (FLPDL) has been used to treat this condition, with significant improvement of varying degrees. It remains to be determined whether other laser modalities may have a similar or even greater success in the treatment of pigmented hypertrophic scars. objective. To determine the efficacy of the 532 nm frequency‐doubled Nd:YAG laser in the treatment of pigmented hypertrophic scars as compared to the 585 nm FLPDL. methods. Six patients with pigmented hypertrophic scars and skin phototypes II–IV were chosen. A scar was selected for treatment in each patient and divided into four equal 2 cm segments. Three segments were each treated with a different laser modality and one was left untreated to serve as the control. A 585 nm FLPDL was used with an energy of 3.5 J, a pulse duration of 450 μsec, and a 10 mm spot size. A 532 nm Q‐switched frequency‐doubled Nd:YAG laser was set to an energy of 2.8 J, a 10‐nsec pulse, and a 3 mm spot size. The same 532 nm laser was set to the variable pulse mode to treat a 2 cm scar segment, with an energy of 9.5 J, a 10‐msec pulse, and a 4 mm spot size. An average of 3.3 treatments were performed on each scar segment, at intervals of 4–6 weeks and long‐term follow‐up at 22 weeks. Treatment outcome was graded by a blind observer using the Vancouver General Hospital (VGH) Burn Scar Assessment Scale. A SigmaStat t‐test was used to determine the statistical significance of the values obtained. results. Treatment of pigmented hypertrophic scars with the 532 nm Q‐switched Nd:YAG laser led to a significant improvement of 38% in the VGH scores when compared to baseline (P = .005). The 585 nm FLPDL also had a favorable effect on the scars, with an average improvement of 36.1% in the VGH scores. There was no significant difference noted between the outcome of treatment with either of these two lasers. Treatment with the 532 nm variable pulse Nd:YAG laser led to a 19% improvement in the VGH scores of scars, which did not differ significantly from the 16.1% improvement observed in control scars on the last follow‐up visit. No side effects or complications from treatment were noted or reported during the course of the study. At the conclusion of the study, five of six patients chose the segment treated with the 532 nm Q‐switched Nd:YAG laser as the best segment overall. conclusion. The 532 nm Q‐switched Nd:YAG laser and the 585 nm FLPDL offer comparable favorable results in the treatment of pigmented hypertrophic scars. The 532 nm Q‐switched Nd:YAG laser may be preferred by patients particularly distressed by the dark color of their scars.

Early Management of Scars Using a 532-nm Nd:YAG Laser

“…Scar hypertrophy also occurs as a result of continuous nourishment from the remaining capillary networks and collagen biosynthesis by fibroblasts. In addition, the excessive proliferation of melanin leads to hyperpigmentation [23].…”

“…A 532-nm Nd:YAG laser was used because the 532-nm wavelength is easily absorbed by hemoglobin and melanin, so that the laser can selectively destroy both of these substances. Bowes et al [23] published a research paper stating that they achieved improvements in pigmented hypertrophic scars after maturation with a 532-nm Nd:YAG laser.…”

“…Jang JY et al Early Scar Management Using Laser hyperpigmentation, and hypertrophy in scars [23]. Therefore, we selected the 532-nm frequency-doubled Q-switched Nd:YAG laser as our early treatment tool, hypothesizing that this laser might be effective for minimizing the redness, hyperpigmentation, and hypertrophy that occur early in scar formation.…”

“…Furthermore, microvessel injuries prevent fibroblasts from receiving nourishment and synthesizing excessive collagen, reducing the production of hypertrophic scars [8,9]. Moreover, absorption of the energy in melanocytes or melanosomes hinders the excessive proliferation of melanin and prevents hyperpigmentation [23].…”

Quantitative Assessment of Pulse Dye Laser Therapy in the Management of Hypertrophic Burn Scars

“…Both the Erbium: YAG and CO 2 lasers have been described for the treatment of more mature hypertrophic scars with noted improvement in texture and reduction of hypertrophy [19,33,34]. The Q switched, 532 nm, frequency doubled Nd: YAG laser has also shown potential for treatment of hyperpigmentation [35]. These may offer greater improvement when combined with PDL [36,37].…”