Effects of Octanoic Acid for Treatment of Essential Voice Tremor

Phase 1

Completed

Conditions: Essential Voice Tremor
Vocal Tremor
Voice Tremor
Essential Tremor of Voice

Brief Summary: Essential voice tremor is a neurological condition that produces a regular, shaking quality in the voice. One form of drug treatment that produces some improvement in tremor of the hands is octanoic acid, which is a food additive that is similar to alcohol. Research suggests that octanoic acid may reduce tremor in the hands/arms with few side effects and no intoxication effects. This study will determine whether octanoic acid may be useful for reducing tremor when it affects the voice. Researchers are hypothesizing that octanoic acid will reduce the effects of tremor on the voice.

Detailed Description: Background:

* Essential tremor of the voice produces regular shaking and hoarseness in the voice, making it difficult speech difficult to understand

* Several previous studies have found that octanoic acid and octanol, which are related to alcohol, can improve tremor in some people without producing many side effects and without producing intoxication

* Researchers are interested in determining whether octanoic acid can improve tremor that affects the voice

Objectives:

* To determine the effects of octanoic voice using voice recordings and listener ratings of voice

* To determine the effects of octanoic acid on level of voice disability experienced by people with essential voice tremor

Recruitment & Eligibility

Inclusion Criteria

Participants have a diagnosis of essential voice tremor and show signs of tremor during the endoscopy examination (when pictures of the voice box are obtained)during screening appointment
Participants show measurable voice tremor from recordings of the voice during screening appointment

Exclusion Criteria

Participants have a diagnosis or show signs of Parkinson's Disease or another non-essential tremor movement disorder
Participants have a diagnosis or show signs of spasmodic dysphonia (a different neurological voice disorder)
Participants have a diagnosis of a severe, non-stable medical condition, such as kidney or liver failure, severe heart disease, severe lung disease, severe metabolic disease, uncontrolled hyperthyroidism, or other life-threatening disease such as active cancer
Participants have a diagnosis of diabetes mellitus
Participants are unable to suspend/stop a medication that they are currently taking for tremor or voice disorder for 12 weeks to complete this study
Participants have a dependence on alcohol or allergy to alcohol
Participants are pregnant or lactating
Participants have an allergy to soy
Participants have Irritable Bowel Syndrome

Arm && Interventions

Group	Intervention	Description
Inactive capsule	Inactive capsule	Participants will receive a pill/capsule with an inactive ingredient during the placebo arm of this study.
Octanoic acid	Octanoic acid	Participants will receive a pill/capsule with octanoic acid (amount determined by the participant's weight) during the experimental arm of this study.

Primary Outcome Measures

Name	Time	Method
Magnitude of Acoustic Amplitude Tremor and Magnitude of Acoustic Frequency Tremor	Measured at baseline visits (1 & 2) and after 3 weeks of placebo or octanoic acid on post-test visits (1 & 2)	Voice recordings were used to measure the degree of tremor in the voice. Mean post-test values for each acoustic measure were compared after the octanoic acid and placebo conditions, with and without consideration of baseline values. Mean values represent the average of two testing days. Degree of amplitude tremor shows the extent of amplitude variation as a percent of the mean signal amplitude, with lower numbers indicating less amplitude tremor. Baseline values for magnitude of amplitude tremor across all participants and conditions ranged from 4.06 to 27.09, and post-test values ranged from 1.94 to 26.02. Degree of frequency tremor shows the extent of fundamental frequency variation as a percent of the mean signal frequency, with lower numbers indicating less frequency tremor. Baseline values for magnitude of frequency tremor across all participants and conditions ranged from 1.21 to 15.31, and post-test values ranged from 0.60 to 13.86.

Secondary Outcome Measures

Name	Time	Method
Auditory-perceptual Tremor Severity Ratings	Measured at baseline visits (1 & 2) and after 3 weeks of placebo or octanoic acid on post-test visits (1 & 2).	Three experienced listeners independently rated each participant's voice from paired sample recordings comparing the baseline to post-test samples in randomized order for each condition. Sustained vowel and sentence-level recordings were rated, with decoded samples later analyzed for 1=better for post-test compared to baseline, 0= no difference between post-test and baseline. Maximum score for each participant was 3 (post-test was better for each of three raters). The range of possible scores was the sum of each of three raters' scores (0 to 3), with 0 indicating no difference between baseline and post-test voice tremor severity rating, and 3 indicating better voice (less tremor severity) at post-testing compared to pre-testing. Mean post-test values for task were compared for the octanoic acid and placebo conditions, and all raters were blind to which sample was a baseline versus a post-test recording, and which samples were associated with the \[placebo or octanoic acid conditions.