The Effect of Octanoic Acid on Essential Voice Tremor: A Double‐Blind, Placebo‐Controlled Study

Objectives/Hypothesis

The purpose of this study was to determine the effects of octanoic acid on acoustic, perceptual, and functional aspects of essential voice tremor (EVT).

Study Design

Prospective, double‐blind, placebo‐controlled, crossover study.

Methods

Sixteen participants with a diagnosis of EVT were randomized to a 3‐week dosing condition of octanoic acid or placebo, followed by a 2‐week washout period and crossover to the other condition for an additional 3 weeks. Baseline and post‐testing sessions were completed before and at the completion of each condition. Primary outcome measures were the magnitude of amplitude and frequency tremor, measured from the acoustic signal. Secondary outcomes were auditory‐perceptual ratings of tremor severity and self‐ratings of voice handicap.

Results

Magnitude of amplitude and frequency tremor were significantly lower after 3 weeks of octanoic acid dosing as compared to the placebo condition. Auditory‐perceptual ratings of tremor severity did not show significant differences between conditions. A trend toward better voice was seen for the sustained vowel ratings, but not the sentence‐level ratings. No significant differences between conditions were seen on self‐reported voice disability as assessed on the Voice Handicap Index‐10.

Conclusions

The results of this controlled investigation support the potential utility of octanoic acid for reducing the magnitude of tremor in people with EVT. Further research is needed to determine whether different dosing or treatment combinations can improve functional communication in EVT.

Level of Evidence

1 Laryngoscope, 2018

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