Does Prolonged Botulinum Toxin A Treatment Decrease its Duration of Action?


  • Muhammad Moin, Asif Manzoor



Purpose: To find out the results of prolonged Botulinum toxin A on its duration of action in patients with blepharospasm and hemifacial spasm.

Study Design: Prospective Case series.

Place and Duration of Study: Yaqin Vision center from 2010 to Dec 2016.

Material and Methods: All patients of both genders who were treated with Botulinum toxin for treatment of hemifacial spasm and blepharospasm were included in the study. Patients were divided into 2 groups, Group 1 included all patients who had 2-5 injection while group 2 included all patients who had 5-19 injections of botulinum toxin A. Patients with secondary blepharospasm due to drugs, ocular and neurological disorders were excluded from the study. Patients with blpharospasm were injected botulinum toxin A at 7 periocular sites on both sides while patients with hemifacial spasm were injected at 7 periocular and 6-7 perioral sites (orbicularis oris, levator labi, zygomaticus major, mentalis and platysma). Onset of effect of botulinum toxin A and duration of action was recorded for all patients.

Results: Total 257 injections were given to 40 patients with an average of 6.43 injections (range 2-19). The mean age of patients was 51 ± 12.1 years. Male to female ratio was 1:1.1. Mean onset of action in Group 1 was 3.81 ± 2.6 days and in Group 2 was 3.92 ± 3.4 days after injection. Average 51.13 units of botulinum toxin A were injected in each injection. Mean duration of botulinum toxin A efficacy in Group 1 was 3.43 ± 1.5 months and in Group 2 was 3.26 ± 1.6 months. Non-significant p-values of 0.41 for onset and

0.23 for duration were found.

Conclusion: After prolong use of botulinum injection mean duration of action remains almost same. Keywords: Blepharospasm, Hemifacial spasm, Botulinum toxin




How to Cite

Asif Manzoor MM. Does Prolonged Botulinum Toxin A Treatment Decrease its Duration of Action?. pak J Ophthalmol [Internet]. 2017 Jun. 1 [cited 2024 Jun. 23];33(2). Available from:



Review Articles