Impact of Dysport on PMFF Donor Scar

This study will be a prospective randomized study to evaluate the effect of pre-operative injections of Abobotulinumtoxin-A to the forehead donor site on cosmetic appearance and patient satisfaction following paramedian forehead flap reconstruction (PMFF) of nasal Mohs micrographic surgery defects. Outcomes will include physician and patient graded cosmetic appearance of the forehead donor site and patient satisfaction following PMFF reconstruction.

The nose is the most common facial subsite affected by non-melanoma skin cancer (NMSC). Due to the high-risk nature of NMSC in this area, many patients undergo Mohs Micrographic Surgery (MMS) for tumor removal and require subsequent nasal reconstruction. A wide variety of flaps have been derived for nasal reconstruction depending on the subunits involved. However, the paramedian forehead flap (PMFF) has long been considered a workhorse for repair of nasal defects. The PMFF is a two-stage interpolated flap based on the supratrochlear artery. The flap is typically raised from the forehead contralateral to the nasal defect and based starting above the medial canthus. A flap with a width of 1.0 to 1.5 cm is designed, raised, and rotated for inset on the nasal defect. The resulting forehead donor site then requires undermining and advancement to the midline for closure.

Reconstruction of nasal defects following MMS may present a challenge due to the anatomic complexity and functional role of the nose. In PMMF reconstruction, it is important to consider not only functional outcomes but optimal aesthetic outcomes of both the nasal defect site and forehead donor site. Unsatisfactory facial scars are associated with decreased levels of satisfaction with facial appearance and greater appearance related distress. Excessive wound tension has been proven to be a key factor in the development of these unsatisfactory facial scars. Wound tension promotes inflammation, prolongs erythema, and may lead to scar hypertrophy and widening. Wounds located on the forehead are susceptible to increased tension and micro-trauma due to constant contraction of the muscles of facial expression.

Pre-operative BTX-A injections are not currently used at the investigator's institution prior to PMFF reconstruction. However, the impact of BTX-A injections on post-operative scar appearance and quality has been well demonstrated in the literature. The investigator's current practice allows access to a large, diverse patient population undergoing PMFF nasal reconstruction following MMS. This study will randomize patients undergoing PMFF reconstruction of MMS nasal defects, with their consent, to receive pre-operative Abobotulinumtoxin-A or saline injections. The investigators aim to demonstrate the impact of BTX-A injections to the donor site prior to PMFF reconstruction on post-operative cosmetic outcomes and patient satisfaction. The investigators anticipate collecting 40 patients over the course of two years. Outcomes will include scar color, scar width, scar height, presence of keloid/hypertrophic scar, and time to complete healing assessed by a blinded attending surgeon as well as physician graded outcome metrics including the Vancouver Scar Scale (VSS) and Visual Analog Scale (VAS). Patient reported outcomes will include the patient scored VAS, Patient Observer Scar Assessment Scale (POSAS), and Likert scales.

Weakening of muscles with neurotoxins such as botulinum type A (BTX-A) was first introduced by Scott in 1973. Since then, BTX-A has received approval from the Food and Drug Administration (FDA) for a variety of indications including treatment of strabismus, headache prophylaxis, and severe axillary hyperhidrosis. Previous in-vitro trials have demonstrated that BTX-A directly inhibits fibroblast-myofibroblast differentiation in scar formation, indicating that the neurotoxin may have potential in treating wounds and preventing hypertrophic scar formation.

The impact of BTX-A injections on post-operative scar appearance and quality has been well demonstrated in the literature. A recent systematic review of 17 randomized controlled trials (RCTs) and 633 patient cases demonstrated that injection of BTX-A before, during, or after wound closure resulted in significantly lower scores on the Vancouver Scar Assessment Scale (VSS) as well as increased cosmetic appearance on a patient Visual Analog Scale (VAS) and improved overall patient satisfaction. Much of the available literature for facial scars demonstrates outcomes following BTX-A injections in patients undergoing cleft lip scar revision. Two recent double-blinded RCTs found a significant reduction in VSS scores and scar width following injection of BTX-A into the subjacent orbicularis oris muscle immediately following cheiloplasty wound closure. An additional systematic review of 10 RCTs investigating the impact of BTX-A injection on the appearance of facial scars, also demonstrates overall improvement in patient VAS scores as well as decreased VSS scores and scar width.

Few studies have investigated the impact of BTX-A on forehead scars specifically. Kim et al recently conducted a double-blind RCT of patients undergoing closure of forehead lacerations. In 24 patients, improved VAS scale scores and Stony Brooke Scar Evaluation Scores (SBSES) were seen following BTX-A injections at the time of suture removal when compared to a saline control group. A single RCT has investigated the impact of BTX-A on donor site cosmetic outcomes following PMFF reconstruction. For 26 Asian patients, Zelken et al. injected 20 units of BTX-A 10 days prior to the first stage of PMFF reconstruction. The average patient VAS score of pre-treated scars was significantly higher than VAS score of those in the saline injection control group. Although BTX-A injections at the PMFF donor site have been proven to be feasible, no additional studies have investigated outcomes following BTX-A injections for a larger, more diverse, patient population.

Inclusion criteria

• Adults at least 18 years of age with a post-mohs micrographic surgery nasal defect requiring PMFF reconstruction in the operating room or clinic at our institution
• No other facial plastic surgery procedure or skin cancer reconstruction performed simultaneously
• Lack all the below Exclusion Criteria

Exclusion criteria

• Documented allergy to Abobotulinumtoxin-A
• Previous hypersensitivity to Abobotulinumtoxin-A
• Hypersensitivity to any botulinum toxin product or excipients
• Previous adverse reaction to any botulinum toxin product or excipients
• Allergy to cow's milk protein
• Infection at proposed injection site
• Previous scar or surgery at proposed injection site
• Inability to follow-up in clinic
• Inability to provide informed consent
• Patient currently on aminoglycoside or other agent interfering with neuromuscular transmission
• Patient on anticholinergic medication
• Pregnancy