Effect of Fresh and Stored Botulinum Toxin A on Muscle and Nerve Ultrastructure

Treatment of Chin Retrusion With Botulinum Toxin Plus Hyaluronic Acid Filler in Comparison With Hyaluronic Acid Filler Alone: A Randomized, Evaluator-Blinded, Controlled Study

BACKGROUND

Hyaluronic acid (HA) has already been widely administered for chin augmentation. Patients with chin retrusion frequently present with increased chin hypertonia. Monotherapy with HA falls short in addressing the multifaceted cosmetic concerns associated with chin retrusion.

OBJECTIVES

This study aimed to investigate the clinical efficacy and safety of the combination therapy involving botulinum toxin (BTX) and HA in the treatment of chin retrusion.

METHODS

We enrolled patients with moderate to severe chin retrusion for 9 months of follow-up after they received either combined treatment with BTX plus HA or monotreatment with HA. We also calculated the surface-volume coefficient with 3-dimensional digital scanning technique, and evaluated outcomes based on the Allergan Chin Retrusion Scale (ACRS), the Global Aesthetic Improvement Scale (GAIS), and treatment-related adverse events (TRAEs).

RESULTS

A total of 50 patients were recruited and randomized to the treatment group (BTX plus HA) or control group (HA alone) in a 1:1 ratio. Patients in the treatment group exhibited significantly higher surface-volume coefficients during the first 6 months (P < .05). ACRS scores and responder rates in the 2 groups remained similar throughout the follow-up (P > .05). Within the initial 3 months, the GAIS responder rate in the treatment group was significantly higher than that in the control group (P < .05). Mild TRAEs were observed in both groups, and subsided within 7 days. There was no increase in adverse effects with the combined treatment.

CONCLUSIONS

In comparison to monotherapy, the combined treatment not only improved the surface-volume coefficient of hyaluronic acid but also achieved similar ACRS scores with less HA volume. Furthermore, the combination treatment yielded superior treatment outcomes for individuals with chin retrusion.

LEVEL OF EVIDENCE: 2

Botulinum Toxin Type A: Assessing The Effects on The Brain Stem

BACKGROUND

In this study, our aim is to investigate the possible effects of Botulinum toxin type A administrations in the early and late periods on the brain stem.

METHODS

Eighteen white New Zealand rabbits were used in this study with the subjects being divided into three groups. Group I received 0.05 mL sterile saline to the left anterior auricular muscles. Group II and III were injected with Botulinum toxin type A (Botox, Allergan) to the left anterior auricular muscles. Group II was sacrificed 5 days after application and Group III was sacrificed 12 weeks after application; brain stem tissues were then taken. The samples were examined with Caspase 3, 8, and 9 immunohistochemical stainings.

RESULTS

In the control group with Caspase-3 immune staining, moderate-to-strong immune reactivity was seen in a small number of neurons. In the Caspase-8 and 9 immune stainings, the immune reactive neurons were seen in greater numbers when compared with the Caspase-3 immune reactive neurons. In the early and late period, groups with Caspase-8 and 9 immune stainings, the immune reactive neurons were seen in greater numbers and in the wider area when compared with the Caspase-3 immune reactive neurons. No significant differences were recognized in the Caspase immune stainings between the early and late period groups. The results were statistically supported.

CONCLUSION

It was concluded that Botulinum toxin type A application did not trigger apoptosis in stem cell tissues.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Assessing adverse effects of intra-articular botulinum toxin A in healthy Beagle dogs: A placebo-controlled, blinded, randomized trial

OBJECTIVE

To investigate the clinical, cytological, and histopathological adverse effects of intra-articularly injected botulinum toxin A in dogs and to study whether the toxin spreads from the joint after the injection.

METHODS

A longitudinal, placebo-controlled, randomized clinical trial was conducted with six healthy laboratory Beagle dogs. Stifle joints were randomized to receive either 30 IU of onabotulinum toxin A or placebo in a 1:1 ratio. Adverse effects and spread of the toxin were examined by evaluating dynamic and static weight-bearing of the injected limbs, by assessing painless range of motion and pain on palpation of joints, and by performing synovial fluid analysis, neurological examination, and electrophysiological recordings at different examination time-points in a 12-week period after the injections. The dogs were then euthanized and autopsy and histopathological examination of joint structures and adjacent muscles and nerves were performed.

RESULTS

Intra-articular botulinum toxin A did not cause local weakness or injection site pain. Instead, static weight-bearing and painless range of motion of stifle joints decreased in the placebo limbs. No clinically significant abnormalities associated with intra-articular botulinum toxin A were detected in the neurological examinations. Electrophysiological recordings showed low compound muscle action potentials in two dogs in the botulinum toxin A-injected limb. No significant changes were detected in the synovial fluid. Autopsy and histopathological examination of the joint and adjacent muscles and nerves did not reveal histopathological adverse effects of the toxin.

CONCLUSION

Intra-articular botulinum toxin A does not produce significant clinical, cytological, or histopathological adverse effects in healthy dogs. Based on the electrophysiological recordings, the toxin may spread from the joint, but its clinical impact seems to be low.

Neurophysiological Measures of Efficacy and Safety for Botulinum Toxin Injection in Facial and Bulbar Muscles: Special Considerations

Botulinum toxin (BoNT) injections into facial and bulbar muscles are widely and increasingly used as medical treatments for cervical and facial dystonia, facial hemispasm, correction of facial palsy, hyperhidrosis, as well as cosmetic treatment of glabellar lines associated with grief and anger. Although BoNT treatment is generally considered safe, the diffusion of the toxin to surrounding muscles may result in complications, including difficulties swallowing, in a dose-dependent manner. The sensitivity of clinical examination for detecting adverse events after BoNT treatment is limited. Few reports have highlighted the potential effects on other muscles in the facial area due to the spreading of the toxin. The possibilities of spreading and thus unknown pharmacological BoNT effects in non-targeted muscles emphasise the importance of correct administration of BoNT in terms of dose selection, injection points, and appropriate effect surveillance. In this review article, we will focus on novel objective measures of efficacy and safety regarding BoNT treatment of facial muscles and the reasons why this is important.

Consensus statement regarding storage and reuse of previously reconstituted neuromodulators

BACKGROUND

Legacy recommendations suggest that vials of botulinum toxin be used within 24 hours of reconstitution and in a single patient. Current standard of care is consistent with storage after reconstitution and use of a single vial for several patients.

OBJECTIVE

To develop expert consensus regarding the effectiveness and safety of storage and reuse of botulinum toxin.

MATERIALS AND METHODS

The American Society for Dermatologic Surgery authorized a task force of content experts to review the literature and provide guidance. Data extraction was followed by clinical question review, a consensus Delphi process, and validation of the results by peer review.

RESULTS

After 2 rounds of Delphi process, the task force concluded by unanimous consensus and with the highest level of confidence that a vial of toxin reconstituted appropriately can, for facial muscle indications, be (1) refrigerated or refrozen for at least 4 weeks before injection without significant risk for contamination or decreased effectiveness and (2) used to treat multiple patients, assuming appropriate handling.

CONCLUSION

The standard of care, which allows for use of botulinum toxin more than 24 hours after reconstitution and in more than 1 patient per vial, is appropriate and consistent with the safe and effective practice of medicine.

The Inhibitory Effect of Platelet-Rich Plasma on Botulinum Toxin Type-A: An Experimental Study in Rabbits

BACKGROUND

Combination treatments of botulinum toxin type-A and other rejuvenation agents or instruments are gradually becoming more popular. After observing a high incidence of therapy failure following simultaneous applications of botulinum toxin type-A and platelet-rich plasma mesotherapy, we aimed to investigate whether PRP has an inhibitory effect on botulinum toxin type-A.

METHODS

Twenty-four New Zealand white rabbits were divided into 4 groups, and the anterior auricular muscle and overlying skin were used for injections. Groups I and II both received onabotulinumtoxinA intramuscular injections. In addition, autologous platelet-rich plasma mesotherapy was performed in Group I while Group II received saline mesotherapy. Group III was designed as the in vitro mixture group in which onabotulinumtoxinA and platelet-rich plasma were mixed and then administered intramuscularly. Group IV received saline within the mixture instead of platelet-rich plasma. The contralateral ears of all the rabbits served as control and were only treated with onabotulinumtoxinA. Visual evaluation of ear positions and electroneuromyographic studies were done prior to all procedures and at day 14. Anterior auricular muscles were harvested at day 14 and were evaluated with quantitative real-time PCR.

RESULTS

Visual and electroneuromyographic studies revealed less onabotulinumtoxinA activity in Groups I and III. When platelet-rich plasma was administered through skin mesotherapy, onabotulinumtoxinA activity failure was more severe in comparison with direct contact. No significant difference in SNAP-25 mRNA expression through quantitative real-time PCR was observed between groups.

CONCLUSION

Although we could not explain the exact mechanism underlying this interaction, platelet-rich plasma applications result in less onabotulinumtoxinA muscle paralysis activity.

Muscle biopsy substantiates long-term MRI alterations one year after a single dose of botulinum toxin injected into the lateral gastrocnemius muscle of healthy volunteers

Despite numerous clinical and experimental studies on botulinum toxin type A (BoNT/A), long-term alterations of muscle texture and fine structure following BoNT/A treatment have thus far not been studied in normal human skeletal muscle. After obtaining institutional review board approval, we performed a prospective, placebo-controlled, double-blinded follow-up study on two healthy adults using magnetic resonance imaging (MRI) and muscle biopsy to visualize long-term alterations after a single BoNT/A injection into the lateral head of the gastrocnemius muscle. MRI disclosed a high-signal-intensity pattern in short tau inversion recovery sequences, and a reduction of the cross-sectional area in the BoNT/A-injected, but not in the saline-injected contralateral control muscle (at 6 to 9 months in volunteer A: 73%, in B: 62%; at 12 months in A: 88%, and in B: 78%). Enzyme histochemistry, 12 months after injection, confirmed neurogenic atrophy of muscle fibers only in the BoNT/A-injected muscle. Electron microscopy revealed additional degenerative changes at the neuromuscular junction. The data confirm that MRI is a suitable tool to monitor the long-term effect of BoNT/A on skeletal muscle. Neurogenic muscle atrophy following a single BoNT/A injection should be taken into consideration when repeated BoNT/A injections into the same muscles are proposed.