Session Information
Date: Tuesday, September 24, 2019
Session Title: Neurophysiology
Session Time: 1:45pm-3:15pm
Location: Les Muses Terrace, Level 3
Objective: We aimed to investigate effects of onabotulinum toxin (OnaBoNT) on clinical and neurophysiological findings of patients with hemifacial spasm (HFS).
Background: There is a general belief that the hyperexcitability of facial nerve or the facial nucleus responsible for HFS. Some studies showed that stimulation of the supraorbital nerve elicits a blink reflex in the orbicularis oris and other facial muscles in addition orbicularis oculi muscle. This finding is accepted as electrophysiologic evidence of synkinesis and reflexive activation of the facial nucleus which leads to a lateral spread at the nucleus level and more distally. Regarding the literature, in this study we evaluated effect of OnaBoNT on spreading of blink reflex.
Method: Sixteen patients with HFS and 30 healthy controls participated in this study. We recorded blink reflexes of orbicularis oculi (o. oculi) and oris muscles bilaterally. We also studied the compound muscle action potential (CMAP) of o. oculi muscle and repetitive nerve stimulation test (3c/s) on this muscle. Neurophysiological tests were held before treatment and one week, one and three month after OnaBoNT injection in patients group. We also evaluated HFS severity and HFS-7 quality of life scale at every visit.
Results: There was significant decrease in HFS severity and HFS-7 quality of life scale scores at follow up visits. CMAP amplitudes of o.oculi muscles were significantly low than basal values after OnaBoNT injection . Decremental responses at these muscles were observed after treatment. The latencies of the blink reflexes of the affected o. oculi and o. oris muscles were significantly prolonged at posttreatment first and thirth month. We also observed a correlation between HFS severity and synkinetic response amplitude and area of o. oris muscle.
Conclusion: This study shows that OnaBoNT has an effect on the brainstem circuits by suppressing the excitability of the facial nerve motor nucleus as well as its effect on transmission neuromuscular junction.
To cite this abstract in AMA style:
O. Kocak, A. Tokcaer. The effects of onabotulinum toxin on neurophysiological tests in patients with hemifacial spasm [abstract]. Mov Disord. 2019; 34 (suppl 2). https://www.mdsabstracts.org/abstract/the-effects-of-onabotulinum-toxin-on-neurophysiological-tests-in-patients-with-hemifacial-spasm/. Accessed June 14, 2025.« Back to 2019 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/the-effects-of-onabotulinum-toxin-on-neurophysiological-tests-in-patients-with-hemifacial-spasm/