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

Abstract

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.

Botulinum toxin type A attenuates hypertrophic scar formation via the inhibition of TGF‐β1/Smad and ERK pathways

“…In recent years, some studies have found that BTA also inhibits the release of cholinergic or noncholinergic neurotransmitter in smooth muscle and exocrine glands, 11‐13 which extends the application of BTA to more areas such as scar prevention and therapy for depression. Several studies have reported that BTA can improve the facial scar quality injected in the early postoperative period 14,15 .…”

The effect of botulinum toxin injections on bruxism: A systematic review

“…3 It has since been shown that BTA inhibits synaptosomal nerve-as- Different serotypes of botulinum neurotoxins act on different proteins involved in this process but the result is always inhibition of transmitter release. 5 As a commercial product, BTA is sold under different brand names where Botox® (Allergan) is one of the most known products. 1,2 After the purification of BTA into crystalline form, its use as a therapeutic drug began, especially as a transient relaxant of hyperactive muscle.…”

“…1 This trait has made BTA a drug used in the treatment of blepharospasm/hemifacial spasm, cervical dystonia, focal spasticity as part of juvenile cerebral palsy, upper and lower body spasticity as a result of stroke, chronic migraines, bladder hyperactivity, and primary hyperhidrosis in the axillary region. 5 As a commercial product, BTA is sold under different brand names where Botox® (Allergan) is one of the most known products. 6 The inhibition of ACh release and muscle excitability is progressive, and signs appear within a few days to 1 week, reaching a maximum peak after 5-6 weeks, after which the effect gradually wears off.…”

Role of botulinum neurotoxin–A in cerebral revascularization graft vasospasm prevention: current state of knowledge

“…15 Generalized side effects have been associated with retrograde axonal migration of BTX from the site of injection. [2][3][4] The proposed ex-vivo perivascular toxin application by soaking the graft in a reconstituted BTX-A solution intraoperatively during cerebral bypass does not involve injections. 63 Moreover, after approximately 30 minutes of soaking in BTX-A solution, the graft is thoroughly flushed and washed to remove any residual toxin, thus minimizing risks of local and systemic spread.…”