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    Botulinum toxin intraoperatively may reduce hypertrophic scars on the face

    Hunt Valley, Md. — Botulinum toxin is an excellent tool to apply intraoperatively to improve the appearance of scars down the road, according to a leading dermatologic surgeon.

    "Scars on the face can be very visible and disfiguring," says Yelena Frankel, M.D., a dermatologic surgeon at Maryland Laser, Skin and Vein Institute, Hunt Valley, Md. "Their appearance can be improved by judiciously using botulinum toxin intraoperatively as well as an adjunct in treating already established scars. We have so much experience using Botox (onabotulinumtoxinA, Allergan) on the face for cosmetic applications, so we are very familiar with its effects."

    A valuable surgical application for botulinum toxin is during reconstruction following skin cancer surgeries on the face, where nonmelanoma skin cancers are common, Dr. Frankel says.

    Botulinum toxin studies
    In addition to anecdotal case reports, more formal retrospective and prospective studies on the effectiveness of this tool have appeared in the literature. In one retrospective study published in Dermatologic Surgery in 2009, botulinum toxin, type A or B, was applied intraoperatively after Mohs micrographic surgery was performed to treat skin cancer. Investigators observed patients had superior apposition of wound edges and smooth skin overlying soft tissue. There were no serious adverse events. They also concluded that botulinum toxin type A and botulinum toxin type B were equally efficacious.

    Botulinum toxin has also been reported to be useful in cleft palate repairs, skin graft survival, urethral stricture repairs and knee cartilage surgery.

    "An ideal time to use a neurotoxin in skin cancer surgery is intraoperatively, right after the tumor is excised and the wound repaired," Dr. Frankel says, but, she notes, it could also be used for more cosmetic indications, such as blepharoplasty.

    While there is not an indication from the Food and Drug Administration to use botulinum toxin for postsurgical wounds, many dermatologic surgeons and plastic surgeons are injecting it during surgery to aid healing and reduce the potential for hypertrophic scars, according to Dr. Frankel.

    "The first several months following surgery are most critical in trying to prevent a disfiguring scar," she says. "As the wound healing and remodeling process takes place, the fact that you have a scar in a location perpendicular to skin tension line, leads to a constant force acting on the new scar. The muscles are kind of pulling the scar apart.

    “To a lesser extent, dynamic forces are present even if the scar is aligned to be parallel to skin tension lines. It takes almost a year for collagen remodeling to be completed."

    Problem solving
    Spread, dehisced, hypertrophic and disfiguring scars have always been a problem faced by dermatologic surgeons. They have traditionally attempted surgical approaches to minimize tension and inflammation, thereby reducing the risk of these scars from developing, Dr. Frankel says.

    "Dermatologic surgeons have developed ways to change the direction of the scar," she says, referring to Z-plasty. "Flaps can change the direction and location of the scar such that it is not subject to repeated dynamic forces as much, but some movement still exists. Particularly when doing surgery on the face, we are limited by the cosmetic units such as the nose, the eyes and the lips.

    "People have found that if you inject a small amount of botulinum toxin — near the wound edges, usually right after closing the wound during surgery, because that is the easiest time — it relaxes the muscles acting on the lesion for several months," Dr. Frankel says. She notes that depending on the location of the lesion and preference of the surgeon, the muscles acting on the incision are immobilized with the appropriate, standard dose, or about one to three units of botulinum toxin at 1 cm to 3 cm intervals around the edges of the incision can be administered for more localized action.

    During the months after injection of botulinum toxin, wound healing and remodeling take place undisturbed, and the collagen can mature without tension on it.

    "When there is constant pulling while the scar is healing, you don't end up with an optimal response," says Dr. Frankel, citing examples of lesions on the back, which commonly result in a wide, hypertrophic scar because of constant dynamic pulling of muscles.

    Ideal sites
    Good sites for the injection of botulinum toxin to aid in postsurgical wound healing are the forehead, some areas around the eyes, and the lower face. Sites that are not ideal include the cheek or lateral supraorbital rim. If used in the cheek, surgeons must inject botulinum toxin superficially to avoid affecting underlying cheek muscles, Dr. Frankel says. It's important not to immobilize deeper muscles because they are required for functioning, she adds.

    Dr. Frankel says clinicians who are not as familiar with botulinum toxin and do not have much experience with it may have some reluctance to use it intraoperatively in the goal to improve the appearance of postsurgical scars.

    "Someone might be resistant to do it, thinking they will cause a side effect such as lid ptosis or paralysis," she says. "As long as you thoroughly understand facial musculature and enervation, a neurotoxin can be a safe and effective tool."

    The beneficial effect of neuromodulators on scar appearance is well documented, but the complete mechanism of action is still unknown. Preliminary research suggests that other effects may act synergistically with relaxing the muscles, Dr. Frankel says.

    Disclosures: Dr. Frankel reports no relevant financial interests.

    Louise Gagnon
    Louise Gagnon is a medical writer and editor based in Oakville, Ontario, Canada.

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