Evaluating the Efficacy of an Ablative Fractional Carbon Dioxide Laser on Pathologic Symptoms in Pediatric Hypertrophic Scars: a Prospective Split-scar Controlled Trial

RATIONALE AND BACKGROUND:

Major strides in surgical care for traumatic injuries and burns over recent decades have enabled survival for wounds that would have previously been fatal. In the wake of these advancements, new challenges have emerged in managing the chronic aspects of these injuries. Among these, hypertrophic scarring remains one of our greatest unmet challenges. Hypertrophic scars are a type of pathological scar commonly formed after a traumatic injury, characterized by excessive collagen deposition during the wound-healing process that results in the appearance of an irregular, raised scar. These scars are the most common scar type formed after burn injuries with a reported incidence as high as 70%. In addition to their unpleasant appearance, hypertrophic scars can exhibit debilitating symptoms including pain, pruritus, and restricted movement in nearby joints. These symptoms often persist long after the initial wound has healed, with profound and lasting effects on patient quality of life. Stigmatization surrounding the appearance of hypertrophic scars further compounds their physical effects with psychosocial elements that are especially significant in the vulnerable pediatric population. A majority of affected children are subjected to bullying as a result of their scars and many experience increased rates of anxiety, depression, traumatic stress, and behavioral problems. Parents of affected children also experience elevated stress, depressive symptoms, and guilt. The profound, multidimensional impact of hypertrophic scarring necessitates improved treatment methods to preserve patient quality of life.

Current scar treatment modalities are limited, especially when it comes to improving the appearance of hypertrophic scars. This deficiency highlights a need to develop safe and effective new approaches that bridge the gap between conservative methods with limited efficacy and invasive measures with increased risk to patients such as surgery, laser treatment and corticosteroid injection. In recent years, the advent of ablative fractional laser (AFL) resurfacing technology has shown great promise in meeting this need with its unique combination of safety and efficacy. AFL technology fills the void between milder non-ablative lasers, which leave skin intact, and more aggressive fully ablative lasers which remove the epidermis of the entire treated surface area. While fully-ablative lasers can produce dramatic results, the large area of ablation leads to extended recovery times and increased risk of complications such as dyschromia, infection and scarring. By contrast, AFLs split the laser beam to target a dispersed pattern of the skin's surface, vaporizing precise discontinuous columns of tissue within numerous smaller areas referred to as microscopic treatment zones (MTZs). By injuring only a "fraction" of the skin, the healthy tissue surrounding the MTZs quickly regenerates and replaces the damaged tissue. Modern AFLs with ultra-pulsing technology achieve even greater efficacy by emitting the laser in rapid high-energy pulses to limit heating of adjacent tissue. By confining the treatment area to precise zones, AFLs can achieve much deeper tissue ablation than fully ablative lasers while minimizing collateral damage to surrounding tissue to maximize therapeutic effect.

Studies involving AFLs have reported a significantly diminished overall incidence of complications including those commonly associated with non-fractionated laser ablation: dyschromia, infection, and scarring. Dyschromia in the form of hyper- or hypopigmentation of the laser-treated skin is perhaps the most common side-effect that has been observed, especially in patients with darker skin types. Remarkably, using fractional ablation, the incidence of dyschromia is virtually avoided. , In addition to a reduction in overall complication rates, post-operative pain associated with AFL therapy is generally mild and well-managed even with non-opioid analgesics. General anesthesia remains the clinical consensus for avoiding intraoperative pain and thus will be implemented in this trial. Overall, AFLs are a powerful tool that can achieve a much more robust dermal remodeling response than non-ablative lasers while greatly reducing the risk of adverse effects and delayed healing seen with fully-ablative lasers and other more-invasive scar treatments.

Recent studies have examined the potential use of AFLs to treat hypertrophic scars with very promising results, documenting marked improvements in multiple aspects of scar pathology. In a large before-after cohort study, treatment of hypertrophic scars using an AFL resulted in substantial improvement of pigmentation, erythema, pliability, and thickness as measured by the gold standard Vancouver Scar Scale (VSS). The authors of this study reported a considerable reduction from 10.4 to 5.2 on the VSS within a diverse cohort of pediatric and adult patients. A more recent study that focused solely on treating pediatric burn scars with AFL also reported significant improvement with a 23% reduction in score from 89.6 to 69.2 on the Patient and Observer Scar Assessment Scale (POSAS). POSAS is similar to VSS but uniquely complements observer assessment of scars with patient-reported assessment including unprecedented assessment of pain and pruritus. The investigators will be using POSAS alongside SCAR-Q, a novel scar scale that was recently developed to provide more detailed patient-reported outcomes and unique assessment of the psychosocial impact of scars.