Objective: To investigate two targeting techniques for onabotulinum toxin-A (BoNT) injection for the treatment of focal hand dystonia and upper limb spasticity: guidance with electrical stimulation (Estim) and ultrasound (US).

Background: BoNT injection therapy is effective established therapy for focal spasticity of the upper limb and is commonly used for upper limb focal dystonia. BoNT limb injections may be performed using anatomical landmarks, EMG, E-stim, and US guidance. A limited number of studies have attempted to compare these injection guidance techniques with inconclusive results.

Method: Two center, randomized, cross-over, assessor-blinded trial. Patients with focal hand dystonia or upper limb spasticity, on stable BoNT therapy for at least 2 previous injection cycles, were enrolled. Patients were randomized to either e-stim or US, with assessment of procedure-related discomfort at the end of the procedure, and assessment of efficacy and adverse effects at one month after the procedure. At 3 months after the first procedure, the patients crossed over to the other guidance method, with similar repeat assessments. ANCOVA test was used in SAS statistical suite.

Results: Twenty subjects were enrolled, 12 males, 10 with upper limb spasticity and 10 with dystonia. There was no difference between the two localization techniques in benefit or focal weakness after injection, as measured by both patient-reported visual analog scale (VAS, 0-100) or clinician global impression of change (CGI). There was a significant difference in perceived discomfort, with E-stim perceived as more uncomfortable by patients, VAS LS mean 34.5 vs 19.9 for E-stim and US, respectively (p<0.05).

Conclusion: E-stim and US guidance procedures yield similar benefit and focal weakness. E-stim is perceived as more uncomfortable by patients. Additional analyses, including the effects of each guidance method on procedure duration, correlation between muscle weakness and efficacy, and subgroup analyses by condition, are ongoing.

References: ALTER, K. E. 2010. High-frequency ultrasound guidance for neurotoxin injections. Phys Med Rehabil Clin N Am, 21, 607-30. SCHNITZLER, A., ROCHE, N., DENORMANDIE, P., LAUTRIDOU, C., PARRATTE, B. & GENET, F. 2012. Manual needle placement: accuracy of botulinum toxin A injections. Muscle Nerve, 46, 531-4.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-of-electrophysiologic-and-ultrasound-guidance-for-onabotulinum-toxin-a-injections-in-focal-upper-extremity-spasticity-and-dystonia/