American BTX-A injections are the most widely used cosmetic treatment, ideally suited for: women aged 40-60 with wrinkles caused by habitual muscle contractions;Its applications are extensive: functional wrinkles on the forehead, crow's feet, perioral area, and neck; facial asymmetry and muscle contractures; as well as strabismus, cervical muscle dysfunction, chronic pain or headaches, laryngeal spasm, temporomandibular joint disorders, and bruxism. This article primarily discusses botulinum toxin applications in the face and neck.
Operational Standards
Three botulinum toxins are approved by the U.S. FDA: Botox (onabotulinumtoxinA), Dysport (abobotulinumtoxinA), and Myobloc (rimabotulinumtoxinB). The first two are approved only for moderate to severe glabellar lines, while Myobloc is indicated solely for treating cervical dystonia.The potency ratios between Botox and Dysprotan (both BTX-A) differ, with a generally accepted conversion ratio of 1:2.5 to 1:3.
Dilution
BTX-A lyophilized powder should be stored between 2-8°C and used immediately after dilution.Botox is packaged in 50U/vial or 100U/vial. Using the 100U/vial as an example, it is recommended to dilute with saline to 2.5ml, yielding 4U per 0.1ml. The author prefers diluting to 4ml, resulting in 2.5U per 0.1ml, which facilitates bilateral symmetry and precise dose control.Dysport is packaged at 300U/vial. It is recommended to dilute it to 3ml, resulting in 10U per 0.1ml.
Anesthesia
Author's approach: Skin disinfected with alcohol swabs, followed by application of lidocaine and prilocaine ointment. Wiped off after approximately 20 minutes. Skin stretched taut by hand, avoiding superficial vessels. A 1ml syringe with a 30-gauge needle was used for slow intramuscular injection. No pre-injection local anesthesia was applied; target muscles were precisely identified during the procedure by inducing contraction.
Post-Treatment Requirements
Most experts recommend avoiding massage and muscle contraction post-injection to prevent diffusion beyond the target muscle. The author applies an ice pack immediately after injection to prevent bruising and advises avoiding strenuous activity and massage for 24 hours.
Clinical Applications
BTX-A was initially used solely for treating glabellar lines but has since expanded into new applications, making its use in emerging fields a research focus in plastic surgery. Facial aesthetic applications aim to reduce skin wrinkles or reposition adjacent structures (eyebrows, upper lip) by weakening the strength of facial expression muscles.All practitioners must thoroughly understand the facial contours in both static and maximum contraction states of the target muscles prior to treatment. This assessment guides the approximate botulinum toxin dosage required for correcting deformities. Additionally, attention should be paid to muscle volume and wrinkle depth (e.g., on the forehead). During injection, the relationship between elevating and depressing muscles must be understood, and injections should be administered when the muscle is at rest.
Complications and Contraindications
Intradermal or intramuscular injection of BTX-A is generally safe with rare complications, categorized as transient (e.g., headache, ecchymosis), injection site-related (pain, especially at repeated injection sites, incidence 3%), specific anatomical site-related (ptosis, brow drooping, incidence 1%), and functional complications (diplopia, dysphagia).
Since BTX-A is completely metabolized within 10-12 weeks post-injection, all complications are theoretically self-limiting.