Patient follow up

PATIENT FOLLOW-UP AND BOTULINUM TOXIN TYPE A ADJUSTMENTS 

As with any other procedure, injection records should be kept allowing reproducible future treatments. Especially after an anatomic area is treated the first time, patients should be seen 2 weeks after toxin injections to assess the outcome, consider additional injections, and make adjustments for future treatments.

IMMUNOGENICITY

 As with any foreign substance, the toxin is recognized by the body’s immune system and trigger a humoral response. Antibody formation can block the therapeutic action of toxins, resulting in partial secondary therapy failure or complete secondary therapy failure. Most cases of therapy failure have been documented in patients receiving large  doses of toxins or treatment of spasticity and dystonia; however, several reports of therapy failure in patients receiving aesthetic treatments have been published.  Various factors have been implicated in promoting the formation of antibodies against BTA, including large single doses, short injection intervals, and booster treatments closely following initial treatment; the preparation used for injection; and the individual characteristics of a patient’s immune system. An accurate determination of the incidence of therapy failure is difficult, as patient behaviours (receiving treatment from more than 1 practitioner, irregular  follow-up), and physician practices (injection technique, dosing, frequency of administration) are non-standardized. Similarly, we do not currently understand which patients may progress to secondary therapy failure. The available data suggest that the frequency of antibody conversion after onabotulinumtoxin A treatment is low and infrequently leads to loss of clinical efficacy.  The complexing proteins that accompany injectable botulinum toxin have been implicated as adjuvants in stimulating the immune response.  Commercial preparations devoid of any complexing proteins (Xeomin) are available and may reduce antibody formation.  In non-aesthetic indications, there is evidence that switching from complexed toxin preparations (Botox, Azzalure) to purified neurotoxin (Bocouture) may be efficacious in secondary nonresponders. Furthermore, although botulinum toxin types A and B are found to be equally effective in treatment of cervical dystonia, botulinum toxin type B shows high levels of immunogenicity than type A. The primary indication for type B botulinum toxins may, therefore, be in treating patients who have shown immunologic resistance to botulinum toxin type A preparations.

SUMMARY

Although there is extensive clinical experience with all of the commercially available types of injectable toxins dose equivalencies have not been established; variations in patient anatomy, behaviors, and injection patterns can have an impact on dosing. Therefore, although clinical guidelines are presented here, each patient should be considered individually when selecting a product, the treatment areas, and the appropriate dosing.