Botox is a highly purified toxin produced by a particular strain of bacteria. It has a number of medical applications, including the treatment of facial spasms, migraines, squints, neck spasms, and spastic muscles in cerebral palsy children. In plastic surgery, it has found application in the treatment of facial wrinkles (mimetic or hyperkinetic lines) which are due to the underlying muscles of facial expression acting on the overlying skin to create a wrinkle. These are most obvious between the eyebrows (glabellar frown lines), at the sides of the eyes (crow’s feet), and across the forehead.
Minute amounts of toxin are injected into the offending muscles, causing temporary weakness of the muscle, and flattening the overlying wrinkle. The onset of action takes 3-7 days, and lasts for about 4-6 months, at which time it can be repeated if desired. More recently, Botox has been used in order to shape the eyebrows, allowing a slight lift of the outer one third of the eyebrow, without the need for surgery. This is also a temporary phenomenon, lasting some 4-6 months. It also has found a role in assisting scar revision surgery, by limiting tension on the wound.
The injection itself is only slightly painful (I tend to dilute it with local anaesthetic, so temporary numbness of the area will be experienced – this lasts about 1 hour). The injections are very safe, with few side effects being reported, principally slight pain on injection, and occasionally mild bruising. Rarely, the toxin may seep into adjacent muscles, causing an undesirable temporary weakness of the muscle – an example of this would be a droopy upper eyelid or eyebrow. All the above complications are very uncommon (and lessened, I believe, by the addition of local anaesthetic). Generally, Botox is popular, and very well tolerated.
In my practice, the overwhelming majority of cosmetic botox is used in the upper 1/3 of the face. I typically use 20 units per pair of muscles (10 units per muscle) and there are 3 possible muscle groups that are routinely injected:
1. Frown lines (corrigator muscle and occasionally procerus muscle)
2. Transverse forehead lines (Frontalis muscle)
3. Crow’s feet lines (orbicularis oculi muscle)
Each site typically uses 20 units, so a maximum of 60 units can be used – all 3 areas. I also occasionally inject small volumes of botox in to other related sites, eg so-called bunny lines (sides of nose), vertical upper lip lines (smoker’s lines), and sub-brow region (for outer eyebrow lift).
Botox is also useful to minimise sweating in the armpits, and is injected in to the armpit skin at a dose of 50 units per side (100 units total). This is very effective to lessen sweating in this region and the effects may last up to 8 months.