Ultrasound-Guided Botulinum Toxin Infiltrations in Essential Tremor Patients: A 36-week Follow Up.

Background: Essential tremor (ET) presents therapeutic challenges as oral therapies, are often partially effective and carry adverse effects. Deep Brain Stimulation and High-intensity Focused Ultrasound targeting the ventral intermediate thalamic nucleus show efficacy in managing ET; however, their cost and invasiveness deter some patients. Botulinum toxin infiltrations for ET in the upper limbs have been limited by adverse effects. Most studies used manual or electromyography guidance, while ultrasound guidance has been less explored. The purpose of the present study was to investigate the potential long-term improvement in tremor and quality of life among ET patients following ultrasound-guided IncobotulinumtoxinA (IncoBoNT) infiltrations.

Methods: We present 18 ET patients who received IncoBoNT injections guided by ultrasounds. We also propose an anatomo-physiological paradigm for targeting muscles in ET patients based on two different tremor patterns.

Results: Eighteen ET patients (mean age 68.2 years) were followed over 12 months. After 36 weeks, patients with supination/pronation (SPP) and flexion/extension (FEP) patterns showed significant TETRAS score improvements: 46.4% in SPP (p = 0.0022) and 48.2% in FEP (p = 0.0021). The QUEST-QOL score also improved (65% in SPP, p = 0.0018; 62.7% in FEP, p = 0.0018). All patients presented notable improvements in mean scores on the self-evaluating spiral test and neurophysiological measures (p < 0.01 for all). Treatment effects lasted 8-12 weeks, with temporary numbness and pain reported, and no cumulative effects observed.

Discussion: Ultrasound-guided IncoBoNT infiltrations show promise for oral treatment-resistant ET patients with minimal adverse effects. The anatomophysiological paradigm utilized proved beneficial for our patients, although tremor pattern variability remains a consideration.

Highlights: Essential tremor patients often face limited options, as oral therapies often yield only partial efficacy, and invasive interventions, like Deep Brain Stimulation, may not always be viable. In this open-label study, 18 patients received ultrasound-guided IncobotulinumtoxinA injections, showing significant tremor improvement and enhanced quality of life, with minimal adverse events reported.