It will be determined whether bihemispheric stimulation (anodal to the left IFG and cathodal to the right IFG) is used with fluency-facilitating conditions for 5 consecutive days in individuals with stuttering and whether there is a difference in terms of the effects seen in speech fluency compared to the sham condition.
Developmental stuttering is a fluency disorder that can negatively affect many aspects of an individual's life. Recent transcranial direct current stimulation (tDCS) studies with individuals with stuttering show that tDCS shows promise in increasing fluency when used in combination with situations that temporarily increase fluency. In this study, it was aimed to investigate the effect of bi-hemispheric tDCS on fluency in individuals with stuttering for 5 consecutive days. The hypothesis of the study is that bi-hemispheric stimulation, which includes anodal stimulation to the left hemisphere and cathodal stimulation to the right hemisphere, will be effective on reading and speech fluency when performed for 5 consecutive days. Thirty-six adults with developmental stuttering are expected to complete this double-blind, sham-controlled study. Participants will be divided into two groups by blocked randomization and one group will receive sham stimulation for 5 consecutive days and the other group will receive bihemispheric stimulation. Participants in the tDCS group will receive 20 minutes of tDCS stimulation accompanied by metronome-timed speech during the practice sessions. Reading and speaking fluency will be assessed immediately before, immediately after, and one week after the stimulation sessions. Data will be collected using the stuttering severity assessment instrument (SSI-4) Results will be compared both within and between groups in terms of percentage of stuttered syllables, stuttering severity, and evaluation of the speaker's experience of stuttering.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
36
TDCS involves applying a weak electrical current across the head through electrodes placed on the scalp and modulating the resting membrane potential of neurons in the underlying cortex.
Biruni University
Istanbul, Zeytinburnu, Turkey (Türkiye)
RECRUITINGDisfluent syllables
change in % disfluent syllables from baseline
Time frame: immediately before and immediately after the stimulation on each day of the 5-day intervention, and at 1 week after the end of the intervention.
Stuttering Severity Instrument- Fourth Edition (SSI-IV) score
It measures stuttering severity in the following four areas of speech behavior: (1) frequency, (2) duration, (3) physical concomitants, and (4) naturalness of the individual's speech. Frequency is expressed in percent syllables stuttered and converted to scale scores of 2-18. Duration is timed to the nearest one tenth of a second and converted to scale scores of 2-18. The four types of Physical Concomitants (Distracting Sounds, Facial Grimaces, Head Movements, and Movements of the Extremities) are converted to scale scores of 0-20. Naturalness is ranked on a scale from 1 (Highly Natural Sound Speech) to 9 (Highly Unnatural Sound Speech). Overall naturalness is ranked at the discretion of the clinician. Scaled scores of Frequency, Duration, and Physical Concomitants are added together to derive a Total Score, Percentile Rank, and Severity Equivalent.
Time frame: immediately before and immediately after the stimulation on each day of the 5-day intervention, and at 1 week after the end of the intervention.
The Overall Assessment of the Speaker's Experience of Stuttering (OASES) score
The instrument, which requires approximately 20 min to complete, is organized into four sections: (a) General Information, (b) Reactions to Stuttering, (c) Communication in Daily Situations, and (d) Quality of Life. OASES consists of 100 items, each scored on a Likert scale ranging from 1 to 5. For each item on the OASES, response scales are that higher scores indicate a greater degree of negative impact associated with stuttering and lower scores indicate less negative impact. All impact scores range from a minimum score of 20 (if the speaker answers 1 for every item within a section) up to a maximum of 100 (if the speaker answers 5 for every item within the section).
Time frame: baseline, after the 5-day stimulation and at the 1-week post-intervention time point
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