Single-fiber Electromyography Examination in Patients Treated with Botulinum Toxin

Abstract

Objective: The aim of this study is to evaluate the neuromuscular junction functions of toxin-treated and non-administered muscles in patients who received botulinum toxin therapy.

Materials and Methods: Patients treated with botulinum toxin in our hospital’s movement disorders outpatient clinic were examined in this study. With a 25 mm concentric needle and a lower cut filter 1 kHz, the average and the individual jitter values were recorded during the voluntary muscle contraction in the frontalis and extensor digitorum (ED) muscles. The relation between the demographic characteristics of the patients, dose of botulinum toxin, the duration of treatment, and the jitter values was researched.

Results: Including 14 patients with hemifacial spasm (HFS) and seven patients with cervical dystonia (SD), 21 patients treated with botulinum toxin (female/ male: 12/9) were examined. The mean age was 52.19±10.2 years; there was no difference between the disease groups in terms of age (p=0.714). The mean followup time was 3.2±1.3 years; there was no difference between the disease groups in terms of follow-up time (p=0.188). The average jitter value of toxin injected to frontalis muscle in the HFS group was 55.6±10.6 microns, and the average high jitter value was 8.4±3.1. The average jitter value of ED muscle without toxin injection was 23.5±3.2 μs and no individual high jitter was detected. In the SD group, the average jitter values in the frontalis and ED muscles were 22.7±2.8 and 27±1.7 μs, respectively. The individual high jitter value was 42 microns only in one patient. However, the only individual high jitter value detected in one patient was not considered pathologic.

Conclusion: In patients treated with botulinum toxin, neuromuscular junction defects were not detected in the muscles in which the toxin was not injected directly.