Dermatologic Use of Botulinum Toxin Treatment & Management

The selected areas are treated by injecting either 2-4 units of BOTOX® or clinically equivalent amounts of Myobloc or Dysport into the thickest part of the muscle.

The injection can be a single-point injection or a skewered injection. With the latter method, which is used primarily in the platysma, the preferred injection site is identified with EMG. The needle is then inserted parallel to the plane of the muscle, and the injection is performed while the needle is carefully withdrawn.

Preoperative details include the following: identifying contraindications, if any; discussing the realistic expectations with the patient; identifying the areas to be treated; locating the targeted muscles; and preparing a plan of injection.

For later comparison, the patient's face should be photographed before treatment in both the resting position and in an exaggerated expression (eg, frowning, smiling).

Any makeup should be carefully removed, and the planned injection sites should be cleaned with isopropyl alcohol.

The patient should lie on his or her back, comfortably propped up.

To prevent the unwanted diffusion of botulinum toxin into the adjacent muscles, do not massage the injection site, and advise patients to avoid doing so as well. Female patients should not reapply their makeup in the office. All patients should avoid exertion on the day of treatment.

Follow up with the patient in 1-2 weeks, and photograph the patient's face with the same expressions as those in the preoperative pictures.

Re-treat the patient as needed after the effects diminish.

All unwanted local effects of botulinum toxin are generally transient and gradually wear off. However, some unwanted effects (eg, drooling) can seriously affect the patient's everyday activities. As with any injection, pain, mild bruising, and infection can occur. Diffusion of botulinum toxin can lead to weakness of the muscles adjacent to the injection site. Therefore, advising the patient not to massage the injected areas is important.

Ptosis can occur when injections above the brow are too lateral (past the midpupillary line) or too close to the brow. Some authors use phenylephrine apraclonidine (Iopidine) eye drops to minimize ptosis. Delayed eyelid closure, a decreased blink response, and excessive tearing can occur when injections into the orbicularis oculi muscle in the temporal region are too close to the eyelid. Asymmetry of the face can occur because of differences in injection techniques or doses between the 2 sides of the face. Drooling can occur when injections of the orbicularis oris muscle are too close to the lip.^[10]

Systemic complications are possible. Headache has been reported and is usually transient. Hypersensitivity reactions have not been described. Antibody development is described in patients receiving high doses of botulinum toxin (eg, for the treatment of torticollis or dysphonia); as a result, their muscles become resistant to further therapy.^[11] One case of necrotizing fasciitis occurred after botulinum toxin was injected into a patient who was immunocompromised.^[12]

During the treatment of hyperhidrosis, complications can result from the use of local anesthetics. Muscular paralysis and a temporary loss of manual functions are possible alarming complications.

Overdosing can theoretically occur by accidental injection or oral ingestion. The patient should be supervised medically for up to several weeks for signs or symptoms of paralysis or systemic weakness. If the overdose or inappropriate injection is immediately known, an antitoxin is available. However, this will not reverse the unwanted effects that were present at the time of antitoxin administration.

The use of unlicensed botulinum toxin product was documented in a series of 4 iatrogenic botulism cases in 2004. Laboratory tests suggested that by receiving injections of a highly concentrated unlicensed botulinum toxin A preparation, these patients might have received doses 2857 times the estimated human lethal dose by injection.^[13]

The effects of botulinum toxin injections are not immediately noticeable. The full effect is achieved approximately 3-7 days after treatment, with the peak at around 1 month. The results last for about 4-6 months with a gradual reappearance of the wrinkles.

The results are cumulative; repeated treatments tend to lead to longer-lasting effects. After several injections of botulinum toxin into the same anatomic region, the underlying muscles may become atrophied. This effect usually leads to the permanent resolution of the wrinkles.

For comparison, the patient's face should be photographed before treatment and at follow-up visits.

In the treatment of hyperhidrosis, the use of botulinum toxin results in dramatic improvement, which can be objectively documented by repeating the starch-iodine test. The treatment must be repeated every 4-6 months.

Botulinum toxin treatment of hyperhidrosis in persons with social anxiety disorder has led to improvement of social functioning and a reduction of overall disability.^[14]

Recent studies compared onabotulinumtoxinA (Botox) and abobotulinumtoxinA (Dysport) with split-face injections. In a randomized, double-blinded study of 10 U of onabotulinumtoxinA and 30 U of abobotulinumtoxinA for the treatment of lateral orbital rhytids, abobotulinumtoxinA showed a statistically significant advantage compared with onabotulinumtoxinA in the treatment of lateral orbital rhytids at maximal contraction.^[15]

Future

In addition to the treatment of glabellar lines, the number of FDA-approved indications for the use of botulinum toxin in cosmetic applications may increase.

The treatment of wrinkles with botulinum toxin is becoming more popular, and demand for it is expected to increase. The cosmetic use of botulinum toxin is essentially controlled by market forces because most health insurance does not cover it. Economic trends (especially trends in the amounts of disposable income) and social issues influence the number of people seeking treatment. Also, the limited number of products and suppliers affect the current prices of the treatment.

Controversies

What conditions should be treated with injections of botulinum toxin? Generally, treatment of the glabellar, frontal, and temporal frown lines is considered safe. Several authorities consider other uses around the mouth and on the neck risky.

Which preparation should be used? Each preparation is unique, and the products are not necessarily interchangeable. Different botulinum toxin serotypes significantly differ in their relative potencies and durations of action that affect the clinical outcome. Even different preparations of the same serotype can have marked differences. For instance, 1 U of BOTOX® has a potency that is approximately equal to 4 U of Dysport. From a clinical point of view, these preparations may be used interchangeably with appropriate dosage adjustments. However, the current data are insufficient to determine whether one product is superior to another.^[16]

Both products have advantages and disadvantages. BOTOX® (Allergan) has been widely used in the United States and Canada for more than a decade. Its safety is well established. The drawback is that once the contents of a vial are dissolved, the reconstituted product loses its potency. Therefore, dermatologists tend to schedule the treatments for several patients on the same day so that they can use the entire contents of the vial. This scheduling may be inconvenient for some patients, who may decide not to proceed.

Myobloc (Elan), when reconstituted, has a shelf life of more than 12 months. This feature is advantageous in terms of patient scheduling. However, larger volumes of Myobloc may be needed to obtain effects similar to those of BOTOX®. Antibody formation against this product may occur more often because of its higher protein content.

Studies with botulinum toxin type B (Myobloc, Neurobloc) showed safety and efficacy in the treatment of axillary hyperhidrosis.^{[17, 18]}

Comparative studies of BOTOX ®, Dysport, and Myobloc are relatively rare. A 2007 review analyzed these products in patients with cervical dystonia. Differences were noted in the rates of adverse events.^[19] Another study found that Dysport had a greater area of diffusion than BOTOX ®.^[20]