Two different types of botulinum toxins: Is there a difference in efficacy and longevity?

The significance of split-face studies and electromyography in forehead rejuvenation

BACKGROUND

Botulinum toxin is a neurotoxic substance with a wide range of uses, from the treatment of musculoskeletal spasms to antiaging regimens by improving wrinkles. Split-face studies in which drugs are injected in the right and left sides of the faces have been actively conducted in botulinum toxin studies. In this study, we aimed to investigate the reliability of a split-face study for determining the effectiveness of botulinum toxin based on eyebrow height and movement, and electromyography results.

METHODS

Thirty-one women aged 35 to 55 years were included in the study. Eyebrow height was measured as the distance from the eyebrows to the upper eyelid margin on the primary gaze, and eyebrow movement was measured as the distance when the forehead was wrinkled for 5 seconds. A noninvasive method was used for electromyography of the frontalis muscles.

RESULTS

No statistically significant differences in right and left eyebrow heights and movements, and electromyography findings (p= 0.256, p= 1.000, and p= 0.978, respectively) were found. Pearson correlation analysis showed that electromyography muscle activity is positively associated with eyebrow movement, respectively (p< 0.001).

CONCLUSION

We advocate the reliability of split-face study and the usefulness of electromyography of frontalis muscle in forehead rejuvenation research.

Addressing the Real-World Challenges of Immunoresistance to Botulinum Neurotoxin A in Aesthetic Practice: Insights and Recommendations from a Panel Discussion in Hong Kong

With increasing off-label aesthetic indications using higher botulinum neurotoxin A (BoNT-A) doses and individuals starting treatment at a younger age, particularly in Asia, there is a greater risk of developing immunoresistance to BoNT-A. This warrants more in-depth discussions by aesthetic practitioners to inform patients and guide shared decision-making. A panel comprising international experts and experienced aesthetic practitioners in Hong Kong discussed the implications and impact of immunoresistance to BoNT-A in contemporary aesthetic practice, along with practical strategies for risk management. Following discussions on a clinical case example and the results of an Asia-Pacific consumer study, the panel concurred that it is a priority to raise awareness of the possibility and long-term implications of secondary non-response due to immunoresistance to BoNT-A. Where efficacy and safety are comparable, a formulation with the lowest immunogenicity is preferred. The panel also strongly favored a thorough initial consultation to establish the patient's treatment history, explain treatment side effects, including the causes and consequences of immunoresistance, and discuss treatment goals. Patients look to aesthetic practitioners for guidance, placing an important responsibility on practitioners to adopt risk-mitigating strategies and adequately communicate important risks to patients to support informed and prudent BoNT-A treatment decisions.

Long-term Effects of Repeated Botulinum Toxin Injection in Cosmetic Therapeutics

BACKGROUND

Botulinum toxin (BT), a potent neurotoxin, has been used in clinical medicine since the 1970s for cosmetic and therapeutic purposes. Studies have consistently shown positive outcomes with a very limited adverse effect profile and a conventional understanding that results dissipate after 3 to 5 months. However, more recent evidence suggests that changes in muscle composition, function, and appearance persist for much longer, even years. To examine the potential implications of these findings on cosmetic use of BT injections in reduction of skin lines and wrinkles, we first needed to further our understanding of the current literature on long-term outcomes after repeated BT injections.

METHODS

A comprehensive review of the literature on long-term outcomes after repeated BT injections for cosmetic indications was performed. We evaluated the study designs, and results were compared.

RESULTS

A total of 22 publications met our inclusion criteria, of which 14 were clinical trials. Few studies extended outcome measurement past 6 months postinjection, and many were funded or supported by industry. However, the studies that extended follow-up saw persistent changes after BT injection, in some cases as far as 4 years postinjection.

CONCLUSION

The current body of knowledge on the long-term results after repeated cosmetic BT injections is very limited, and the available literature provides insufficient evidence on how prolonged effects could alter clinical use of BT. Further clinical studies with extended follow-up periods with inclusion of both subjective and objective measured outcomes of appearance and muscle function are required to better understand the long-term impacts of repeated BT injections.

A Double-Blind, Randomized Clinical Trial to Determine Effects of Increasing Doses and Dose-Response Relationship of IncobotulinumtoxinA in the Treatment of Glabellar Rhytids

BACKGROUND

IncobotulinumtoxinA is an effective neuromodulator for treating glabellar rhytids. The relationship between dose and reduction in rhytid severity is well established. However, the effects of escalating doses on the treatment duration response are less understood.

OBJECTIVES

The aim of this study was to assess the effects of increasing doses of incobotulinumtoxinA on the treatment duration for glabellar rhytids.

METHODS

A randomized, double-blind, Phase IV study was conducted at a fully accredited, outpatient surgical facility. Subjects (31 female, 7 male) with moderate to severe glabellar rhytids were randomized to 1 of 3 incobotulinumtoxinA dose groups: 20, 60, or 100 U. Effect duration was determined by calculating the time to return to baseline for dynamic glabellar lines during maximal contraction. Follow-up was completed through 1 year, and adverse events were monitored.

RESULTS

The median duration of effect was 120 days (95% confidence interval [CI] [90, 180 days]), 180 days (95% CI [180, 210 days]), and 270 days (95% CI [240, 330 days]) for the 20-, 60-, and 100-U groups, respectively. A Wald chi-square test from the Cox regression on the primary efficacy variable indicated a statistically significant effect of dose group on time to baseline (chi square = 54.63; df = 2; P < 0.001). Hazard ratios were HR = 0.21 (95% CI [0.10; 0.43] for the 60-U vs the 20-U group, and HR = 0.06 (95% CI [0.10; 0.43]) for the 100-U vs the 20-U group, indicating a statistically longer return to baseline for both the 60- and 100-U cohorts.

CONCLUSIONS

There is a dose-dependent relationship between incobotulinumtoxinA and duration of effect in the glabella.

LEVEL OF EVIDENCE: 2

Efficacy of Incobotulinum toxin-A for the treatment of masseter muscle hypertrophy in Asian Indian patients: A 2-year follow-up study

BACKGROUND

With the changing trends, more and more patients are opting for nonsurgical or minimally invasive options for reshaping the face. Noninvasive treatments such as incobotulinumtoxinA (Xeomin Cosmetic^® ; Merz Pharma Canada Ltd., Burlington, ON, Canada) are a preferred modality for reducing the volume of the muscle and therefore reducing the width of masseter.

AIMS

To evaluate the efficacy of Xeomin treatment in long-term management of bilateral masseter hypertrophy in Asian Indian patients.

PATIENTS/METHODS

A total of 30 patients were enrolled in the study and were injected with 30 U Xeomin on each side of face, at baseline. Fifteen patients received a second session of Xeomin injection at 12th week, and remaining 15 patients received an additional third session, at 12th and 24th weeks post the first injection, respectively. Follow-up was done at 4th-, 12th-, 24th-, and 36th-week and at first- and second-year follow-ups.

RESULTS

For the patients who received two injections, the maximum reduction of 26.85% was observed at 24th week, which was maintained as 20.04% reduction until second follow-up year. The patients who received three injections exhibited very high reduction of 43.12% of masseter volume at 36th week, which was maintained at 38.72 % until the second follow-up year. Three sessions of Xeomin injections were proved to be more effective in long-term maintenance of reduced masseter volume than 2 sessions of injections.

CONCLUSIONS

Xeomin injections were found to be effective in long-term management of bilateral masseter hypertrophy. This is the first of its kind paper, which evaluates the long-term effects of Xeomin injections for the treatment of masseter hypertrophy.