The proposed study aimed to determine if tDCS can help post-stroke patients with
dysarthria.

Non-invasive Brain Stimulation as a Treatment for Dysarthria Post-stroke

Dysarthria

Stroke

A total of 9 Cantonese-speaking chronic post-stroke patients who are suffering from
dysarthria was recruited and randomly divided into treatment group and sham group. For
the treatment group, an anodal high-definition tDCS of 2 milliampere (mA) lasting for 15
minutes was delivered to the primary motor cortex (SM1) in 10 daily sessions during a
2-week period. For the sham tDCS group, the same setting of tDCS electrodes was applied
on the scalp, but the stimulation only lasted for 30 sec in order to cause similar
sensation on the scalp as the other group. Simultaneous to the tDCS stimulation, both
groups will receive speech and voice therapy for 30 minutes.

An array of outcome measures reflecting speech production ability including acoustic,
kinematic, perceptual and self-perceptual qualities was obtained before and after
stimulation. It was anticipated that post-stroke dysarthric patients will see improvement
in speech production after stimulation. The results provided important insights into the
effects of tDCS on articulatory movement in individuals with dysarthria post-stroke.

Real tDCS

Sham tDCS

A Randomized Controlled Trial Study of the Use of Transcranial Direct Current Stimulation (tDCS) in Treating Dysarthria Post-stroke

All participants were required to produce a sustained vowel /a/, repeated some syllables
(i.e., /pa/, /ta/, /ka/ and /pataka/), produce some single words, read a standard
paragraph in Cantonese and had a two-minute conversation with the investigator. A
professional grade microphone (SM58, Shure, USA) was used to record the speech
production. Experienced speech-language pathologists blinded to the neurological
condition and history of each participant analyzed the speech samples independently using
a perceptual rating scale including 21 speech dimensions covering eight categories,
including pitch, loudness, voice quality, resonance, rate, articulation, tone, and
general impression. The speech samples were rated using a seven-point equal-appearing
interval scale, with a "1" indicating within typical limit performance and a "7" severely
deviated from the normal.

Fundamental frequency (F0) was obtained from sustained vowel phonation.

Frequency perturbation (jitter %) was obtained from sustained vowel phonation.

Intensity perturbation (shimmer %) was obtained from sustained vowel phonation.

Noise to harmonic ratio (NHR) was obtained from sustained vowel phonation.

Harmonic to noise ratio (HNR) was obtained from sustained vowel phonation.

Associate Professor

The lip and tongue function during speech production were traced real time and
objectively measured using an electromagnetic articulography. All participants were
required to produce single-syllable real words of consonant-vowel (CV) construction at
high level tone embedded in a carrier phrase and repeat some syllables (i.e., /pa/, /ta/,
/ka/ and /pataka/). A custom-written analysis programme was used to annotate and
calculate the kinematic measures, including duration (ms), distance (mm), maximum
velocity (mm/s), maximum acceleration (m/s2) and maximum deceleration (m/s2) in the
approach (movement towards the upper lip/palate) and release (movement away from the
upper lip/palate) phases along the z-axis, i.e., along the mid-sagittal plane.

Group 1 (n = 5) received anodal tDCS stimulation and intensive speech and voice therapy;
tDCS and speech therapy was applied in 10 daily sessions during a 2-week period,
administered on Monday to Friday. The anodal stimulation was delivered to the primary
motor cortex (SM1) of the orofacial area.

Group 2 (n = 4) received sham tDCS stimulation and intensive speech and voice therapy.
For the sham tDCS group, the same setting of tDCS electrodes was applied on the scalp,
but the stimulation only lasted for 30 sec in order to cause a similar sensation on the
scalp. tDCS and speech therapy was applied in 10 daily sessions during a 2-week period,
administered on Monday to Friday.

Non-invasive Brain Stimulation as a Treatment for Dysarthria Post-stroke

About this trial

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Placebo

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