Reducing Scar Formation after Lip Repair by Injecting Botulinum Toxin

Sir: We read with great interest the recent article “Intralesional Botulinum Toxin Type A Injection as a New Treatment Measure for Keloids.”1 We would like to take the opportunity to further expand on the topic, with injection of botulinum toxin to reduce scar formation after lip repair for cleft lip. One of 500 to 1000 babies is born with a cleft.2 Cleft lip, with or without cleft palate, is the most common of these facial clefts. Reconstruction of the upper lip and restoration of the continuity of the circular muscle in the lip are important steps in treatment. However, surgical intervention leads inevitably to scar formation. Scars are usually termed hypertrophic when they develop excessive redness, elevation, widening, and stiffness.3 The presence of serious scarring limits social interaction and affects self-esteem after lip repair.4 Surgeons have been focusing on how to make this scar less conspicuous and how to obtain a straighter and more natural-appearing suture line.5,6 Carefully designed incision lines, anatomically appropriate muscle reconstruction, and atraumatic suturing are essential for optimal scars.7 However, because of continuous muscle contraction and skin tension caused by infant crying and feeding, we have difficulty in achieving a satisfactory effect after lip repair. Surgeons have had to use a lip bumper to protect the wound and reduce continuous muscle contraction and skin tension. How can we further reduce scar formation after lip repair? Botulinum toxin is the universally accepted standard treatment for upper facial rejuvenation. Botulinum toxin use in the mid and lower face and neck has become an increasingly popular indication for facial aesthetic treatment.8 Botulinum toxin acts by inhibiting acetylcholine release at the neuromuscular junction.9 The toxin has an influence on muscular activity alone. When injected into hyperactive corrugator and/or procerus muscles that predominantly control frowning, botulinum toxin produces a localized muscle weakness, resulting in a temporary improvement in the glabellar frown line.10 On the basis of the above facts, we hypothesized a possible method of reducing scar formation after lip repair by injecting botulinum toxin. When skin and organs are damaged, the body naturally wants to heal itself. When the wound heals completely, it is known as a scar. Although scar tissue takes the place of damaged or destroyed tissue, it is limited in function, including movement, circulation, and sensation. Scars can never be completely removed. Cleft lip scars have a particularly serious impact on appearance. Many factors affect the formation of scar. However, continuous muscle contraction plays a key role in the formation of lip scar. The surrounding tissue is compressed because of muscle contraction. The skin tension will increase. In patients with reconstructed cleft lips, the expanding muscle is interrupted in the region where scar tissue is supposed to be present.11 After injection of botulinum toxin locally into lip muscles, the toxin enters the nerve terminal by means of endocytosis, interacts with intracellular proteins, and inhibits the vesicular release of the acetylcholine neurotransmitter at the neuromuscular junction. Inhibition of acetylcholine produces chemical denervation and paralysis of the lip muscles.12 Botulinum toxin will produce a localized muscle weakness. The method of local injection of botulinum toxin into lip muscles may reduce the continuous muscle contraction and skin tension and create good conditions for wound healing and reduction of the formation of lip scars after lip repair. Many surgeons prefer removing scars by means of surgery, but any operation will always create a new scar. The former scar may be less obvious, but there is the risk of recurrence and worse scarring. Botulinum toxin has been used for depressor upper lip wrinkles.13 It may have effective clinical applications for reducing scar formation after lip repair. Ren-kai Liu, M.D. State Key Laboratory of Oral Disease and Department of Orthodontics West China College of Stomatology Sichuan University Cheng-hao Li, M.D. State Key Laboratory of Oral Disease West China College of Stomatology Department of Cleft Lip and Palate Surgery West China Stomatological Hospital Sichuan University Shu-juan Zou, M.D., Ph.D.