Clinical comparison of botulinum toxin in motor and autonomic disorders: Similarities and differences

Current practice trends for lacrimal gland neurotoxin in the management of epiphora-a BOPSS survey

PURPOSE

Injection of botulinum neurotoxin A (BoNTA) to the lacrimal gland (LG) offers a simple and effective treatment in the management of epiphora. However, there is little data on current practice trends or uptake as an alternative to surgery. This study assesses current practice trends of such treatment amongst BOPSS (British Oculoplastic Surgery Society) members.

METHODS

All consultant BOPSS members were invited to participate in a web-based survey which consisted of 5 questions, with a reminder invitation to participate. The role, dose, potential side effects, use as an alternative to surgical intervention, and impact on service delivery were assessed.

RESULTS

Fifty-one BOPSS consultants (43% uptake) completed the survey. Ninety percent of respondents were regularly using LG BoNTA in their management of epiphora. The main indicators for considering BoNTA use were medical comorbidities and elderly patients. The mean first treatment dose of Botox® was 3.6 units (SD 1.5). Diplopia and ptosis complications were always discussed in the consent for treatment in addition to dry eye. Twenty-five percent of surgeons reported doing less conjunctivo-dacryocystorhinostomies (cDCR) due to the availability of LG BoNTA. No respondents felt that the requirement for repeated BoNTA treatments was impacting on their service delivery.

CONCLUSION

Uptake of LG BoNTA in the management of epiphora is at a similar rate to all other available treatments. As a result, respondents are performing less surgical procedures, particularly cDCR in patients at higher surgical morbidity.

Clinical duration of action of different botulinum toxin types in humans

The Botulinum NeuroToxin (BoNT) comprises several serotypes with distinct properties, mechanisms of action, sensitivity and duration of effect in different species. The serotype A (BoNT/A) is the prevalent neurotoxin applied in human's disease. In this paper we present an overview of the current knowledge regarding the duration of effect and the neuromuscular sprouting of different BoNT serotypes in humans. Then, we report the original results of a study in healthy subjects treated with BoNT/A, B, C and F using different neurophysiological techniques. Twelve healthy volunteers (7 men, 5 women) are treated with BoNT/A, B, C and F or placebo in Abductor digiti minimi (ADM) muscle of the hand. Before and after injections, an extensive neurophysiological study is performed with the CMAP amplitude variation, Multi-Motor Unit Action Potentials (MUAPs) analysis, the Turns/Amplitude ratio of interference pattern (IP) and determination of jitter and Fiber Density (FD) at single-fiber electromyography (SFEMG), at week 2 (w2), 4 (w4), 6 (w6) and 8 (w8). A maximal neuromuscular block is obtained at w2 for all the serotypes. Afterwards, the CMAP trend appear similar for BoNT/A, B, and C while, BoNT/F shows a faster recover. Multi-MUAPs analysis and IP detect mild changes at w2 for all serotypes, except for BoNT/F that shows a greater change since w4. SFEMG have minimal changes in FD while, Jitter increase at w2 with a slower decrease over the time for all BoNTs. In conclusion, BoNT/F has earlier sprouting and complete recovery at w8. Other serotypes present a slower and similar profile. The EMG appear useful to study the functional recovery in humans, and these results should provide new evidence for assessing different serotypes. These findings improve our knowledge regarding the methods to evaluate duration of effects and dose equivalents in different serotypes, that in the future could change the clinicians strategy for disease-tailored BoNT therapies.