rTMS in Spasmodic Dysphonia

University of Minnesota20 enrolled

Overview

Focal dystonia is a neurological movement disorder characterized by excessive involuntary muscle contractions of any body part. Spasmodic dysphonia (SD) is a type of focal dystonia characterized by excessive contraction of intrinsic muscles in the larynx, leading to difficulty in speaking and affecting effective communication. The cause of SD is unknown and there are no treatments that produce long-term benefits. Previous studies have suggested that SD and other focal dystonias are associated with decreased inhibition in sensorimotor areas in the brain. However, no studies have investigated the effects of modulating excitability of the laryngeal motor cortex in healthy individuals or SD. The goal of this pilot project is to determine if brain excitability of the laryngeal motor cortex can be changed with low-frequency inhibitory repetitive transcranial magnetic stimulation (rTMS) in individuals with SD and healthy controls. Considering that rTMS at low frequencies (≤1 Hz) produces lasting inhibition in the brain, and that SD is associated with decreased cortical inhibition, the purpose of this pilot study is to determine safety, feasibility and response to 1Hz rTMS to the laryngeal motor cortex in individuals with SD and healthy people. The results will help understand changes associated with the disorder, as well as contribute to the development of future clinical interventions for SD.

Study Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Enrollment

Conditions

Spasmodic Dysphonia

Eligibility

Sex: ALLMin age: 21 YearsMax age: 75 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Primary inclusion for spasmodic dysphonia: 1. Diagnosis of adductor spasmodic dysphonia 2. Symptoms at worst severity if receiving regular botulinum injections * Primary inclusion for healthy participants (controls): 1. Absence of vocal fold pathology Exclusion Criteria: * Primary exclusion for participants with spasmodic dysphonia: 1. Other forms of dystonia 2. Vocal fold pathology or paralysis 3. Diagnosis of voice tremor 4. Laryngeal surgery 5. Laryngeal cancer or neurological condition other than dystonia 6. Contraindication to TMS 7. Medications with effect on central nervous system 8. Inability to complete tasks associated with study 9. Adult lacking ability to consent * Primary exclusion for healthy participants (controls): 1. Any health condition or disability that would interfere with participation 2. Contraindications to TMS 3. Medications with effect on central nervous system 4. Adult lacking ability to consent TMS contraindications: * The only absolute contraindication to TMS/rTMS is the presence of metallic hardware in close contact to the discharging coil (such as cochlear implants, deep brain stimulator, or medication pumps). In such instances there is a risk of inducing malfunctioning of the implanted devices. * Conditions classified as of increased or uncertain risk are listed below (Rossi et al., 2009; Rossini et al., 2015). Persons under those circumstances will be excluded from the study. 1. Pregnancy 2. Bipolar disorder 3. Epilepsy or history of seizure episodes in the past two years 4. Vascular, traumatic, tumoral, infectious, or metabolic lesion of the brain, even without history of seizure, and without anticonvulsant medication 5. Use of medications that potentially lower seizure threshold 6. Severe or recent heart disease

Outcomes

Primary Outcomes

Adverse Response to rTMS

Count of participants who experience and adverse response to rTMS treatment.

Time frame: 2.5 hours

Change in Duration of Cortical Silent Period (CSP)

The change from baseline in CSP duration will be reported. The CSP is an interruption of voluntary muscle contraction after single pulse transcranial stimulation. The duration of the period of silent muscle activity will be measured to test the effects of rTMS intervention. There is no known clinical relevance for this outcome measure.

Time frame: baseline and 2.5 hours

Secondary Outcomes

Change in Number of Voice Breaks

Changes from baseline in the number of voice breaks during speech will be reported. Voice breaks will be measured by asking subjects to repeat 10 sentences. The frequency of voice breaks in the recorded 10 sentences will be counted.

Time frame: baseline and 2.5 hours

Change in Voice Quality (Overall Severity) With the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V)

CAPE-V (overall severity) testing before and after rTMS consisted of the repetition of six sentences and two sustained vowels (/a/;/i/). A short sample of spontaneous speech (approximately 60s) was also collected for qualitative analysis of voice. The CAPE-V ratings were completed by three assessors who were blinded to group and pre/post-test. The assessors listened to the voice recordings for each participant and rated them for all six parameters listed above from 0 to 100, with higher values indicating worse severity. Ratings for each voice parameter were then averaged across the three assessors. We chose to analyze the change in the CAPE-V parameter for "Overall Severity" to represent an overall assessment of voice quality from pre- to post-rTMS (Post Score - Pre Score) as it had the greatest likelihood of detecting any small changes that may be perceived.

Time frame: baseline and 2.5 hours

Change in Cepstral Peak Prominence Smoothed (CPPS)

Quantitative assessment of voice quality was completed with acoustic analysis of each participant's production of the ten sentences from the Spasmodic Dysphonia Attribute Inventory (SDAI). A custom script in Praat (Boersma \& Weenink, 2018) was used to calculate cepstral peak prominence smoothed (CPPS) for each sentence production. CPPS is a relatively new measure that reflects vocal fold periodicity and noise components in the vocal spectrum. CPPS has been found to be correlated with perceived severity of voice symptoms and higher CPPS values represent a more normal vocal quality. CPPS values (in dB) were averaged across the ten sentences of the SDAI to derive an average CPPS for each participant before and after rTMS. Change for each participant was calculated as the average CPPS at post-rTMS minus average CPPS at pre-rTMS. The values for each group were then averaged to report the average change in CPPS for Controls and Spasmodic Dysphonia.

Time frame: baseline and 2.5 hours

rTMS in Spasmodic Dysphonia

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes