Aphasia, Stroke
Conditions
Keywords
aphasia, stroke, rTMS, brain stimulation, speech and language therapy
Brief summary
This project aims to tailor repetitive Transcranial Magnetic Stimulation (rTMS) target to the clinical profile of post-stroke aphasia, specifically focusing on lexicosemantic impairments, to enhance recovery. Functional Magnetic Resonance Imaging (fMRI) will provide critical insights into the effects of facilitatory versus inhibitory stimulation on interhemispheric balance. Additionally, this study will generate new data on how lesion localization and brain connectivity influence individual responses to rTMS, explaining variability in treatment efficacy.
Detailed description
Background and aims In the United States, 18 to 66% of individuals who experience a stroke will suffer from language impairment, referred to as aphasia. Aphasia profoundly impacts quality of life by restricting participation in social, familial, and professional spheres. While the gold standard for aphasia rehabilitation is Speech and Language Therapy (SLT), it often does not lead to complete recovery. Repetitive Transcranial Magnetic Stimulation (rTMS) or Transcranial Direct Current Stimulation (tDCS) are non-invasive brain stimulation techniques that could enhance post-stroke aphasia recovery. Most rTMS and tDCS studies in post-stroke aphasia following left hemispheric strokes have applied inhibitory stimulation targeting the right Inferior Frontal Gyrus (IFG) or facilitatory stimulation targeting the left IFG (i.e., Broca's area and its right homologue). Aim 1: Focusing solely on the IFG for all participants with post-stroke aphasia may be inefficient, as the language system is widespread and complex, and involves large, interconnected networks also linked to non-linguistic cognitive functions such as working memory or executive functions. Previous research indicated that individuals with different language impairments may have varied recovery paths, and using the same cortical target for non-invasive brain stimulation might be ineffective or even impair recovery. Interestingly, rTMS targeting the motor cortex of the lips in people with phonological impairments improved accuracy and decreased phonological errors in a Picture Naming Task. This improvement likely resulted from rTMS modulating not only the targeted motor cortex but also the connected dorsal phonological stream via intra- and interhemispheric connections. Building on this principle, a pilot study was conducted using inhibitory rTMS targeting the right Anterior Temporal Lobe (ATL) in people with post-stroke aphasia suffering from lexicosemantic impairments, with improvement in Picture Naming for all participants. Lexicosemantic difficulties manifest as anomia and/or semantic errors (e.g., saying tea instead of coffee) and can result from deficits in lexical access or within the semantic system itself. Lexicosemantic processes involve a complex brain network. According to the hub-and-spokes theory, the ATL serves as a central amodal semantic hub that integrates information from various modalities. Other theories emphasize its multimodal and potentially lexical sensibility. This study hypothesizes that rTMS targeting the ATL will modulate the ventral stream of language, resulting in improvements in people with lexicosemantic impairments. This RCT aims to combine ATL stimulation with Semantic Feature Analysis (SFA) rehabilitation, which strengthens lexicosemantic links. This approach was expected to enhance the effect of rTMS on lexicosemantic processes. Aim 2 and 3.3: Furthermore, the facilitation of the left hemisphere and the inhibition of the right undamaged hemisphere are based on the theory of transcallosal interhemispheric imbalance, where brain lesion leads to hyperactivation of the undamaged hemisphere and hypoactivation of the damaged hemisphere. The undamaged right hemisphere could play a maladaptive role in post-stroke aphasia recovery. However, the role of right hemisphere activation in post-stroke aphasia recovery remains unclear, as it may support recovery in certain participants during both the subacute and chronic phases. More research is needed to better understand the underlying mechanisms of facilitatory and inhibitory stimulation targeting respectively the undamaged and damaged hemispheres. Aim 3: While non-invasive brain stimulation has been shown to be effective in post-stroke aphasia, certain people with post-stroke aphasia respond better than others. The previous sections highlighted the impact cortical target and stimulation parameters, but recent studies have also proposed that participant's aphasia type or lesion localization may influence their response. Further research, particularly using rTMS, is needed to clarify how lesion localization and disconnections contribute to recovery, as these factors may explain chronic post-stroke language impairments and predict rTMS efficacy. Since the ATL serves as a central hub in the ventral lexicosemantic stream, and rTMS modulates other brain areas through both inter- and intra-hemispheric connectivity, the hypothesis was as follow: a preserved connectivity between the ATL and the posterior temporal lobe will be a strong predictor of rTMS effectiveness. Study Intervention Participants will be randomly assigned to one of three groups: (1) the inhibitory continuous Theta Burst Stimulation (cTBS) targeting the right ATL, (2) the facilitatory intermittent Theta Burst Stimulation (iTBS) targeting the left ATL, or (3) the sham control TMS group, with sham stimulation targeting either the left or right ATL in half of the participants. The intervention will consist of two weeks of stimulation according to group assignment, five times per week (10 sessions total), followed by 30 minutes of Speech-Language Therapy using the Semantic Feature Analysis method.
Interventions
We will use continuous Theta Burst Stimulation (600 pulses, burst frequency at 5 Hz, burst of three pulses at 50Hz) targeting the right ATL
DEVICEintermittent Theta Burst Stimulation
We will use intermittent Theta Burst Stimulation (600 pulses, burst frequency at 5 Hz, burst of three pulses at 50Hz, interval intertrain of 8 sec, 10 pulses in train) targeting the left ATL
DEVICETranscranial Magnetic Stimulation Sham
We will use sham stimulation using the same coil but flipped over, with the left ATL targeted in half of the participant and the right ATL in the other half. The placebo coil will replicate the auditory sensations produced by active stimulation. In addition, we will use electrical stimulation of the scalp (via electrodes placed over specific muscles) in the Sham group to mimic the sensory effects of active stimulation. Participants will have no prior rTMS experience before inclusion in the protocol.
BEHAVIORALSemantic Feature Analysis
Participants will receive 30 minutes of Semantic Feature Analysis therapy administered by a Speech and Language Pathologist. On a computer screen, participants will see an image of an object and will be cued to retrieve the object's name by describing various features of the object, including its physical properties, typical location, personal associations, category, use and actions involving the object (Quique et al., 2019).
Sponsors
University of South Carolina
National Institute on Deafness and Other Communication Disorders (NIDCD)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Subject)
Intervention model description
We will conduct a superiority randomized controlled trial. Participants will be randomly assigned in a 1:1:1 ratio to one of three parallel groups: (1) inhibitory continuous Theta Burst Stimulation (cTBS) targeting the right ATL; (2) the facilitatory intermittent Theta Burst Stimulation (iTBS) targeting the left ATL; (3) sham stimulation, targeting either the left or right ATL with allocation balanced across participants. In all three groups, participants will receive rTMS five times per week for two consecutive weeks (10 sessions in total). Each rTMS session will be immediately followed by Speech and Language Therapy (SLT) using the Semantic Feature Analysis (SFA) protocol. Assessments will be conducted at baseline, immediately post-intervention, and at one-month follow-up. Participants will also undergo fMRI scanning at S1 and S2.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Right-handedness (assesed using the Edinburgh Handedness Inventory) * Native English speakers * Single left hemispheric stroke * Diagnosis of aphasia and lexicosemantic impairments (e.g., anomia, semantic errors in picture naming or spontaneous speech) confirmed by a Speech and Language Pathologist or Physician
Exclusion criteria
* Severely impaired auditory comprehension (WAB Comprehension score of 0 or 1) * Major phonological impairments (defined as \> 2 errors in non-word repetition of one- and two-syllable items on the PALPA, 2) * Contraindications to rTMS (e.g., uncontrolled epilepsy, history of seizures, intracranial ferromagnetic body, cochlear implant, or factors that lower seizure threshold (see Rossi et al., 2021) * Contraindication to MRI * Stroke involving the left ATL * Severe depression or psychiatric history * Illiteracy * Known neurodegenerative disorders * Severe uncorrected visual or hearing impairments
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Picture Naming task accuracy | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | The primary outcome is improvement in accuracy of the a Picture Naming task. Participants will complete a Picture Naming tasks based on the Older Adult Naming Test. Participants will name items from pictures as quickly and accurately as possible. Items will include mid-frequency words and 10 pictures of middle-to-late age-of-acquisition words (mean = 10.01 years, SD = 1.16). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Picture Naming Reaction time | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Reaction times will also be recorded for the picture naming task using E-Prime software (version 3.0). A decrease in reaction time for the picture naming task will be considered as an improvement. |
| Auditory Description Naming accuracy | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Participants will complete an Auditory Description Naming based on the Older Adult Naming Test. Participants will name items from verbal descriptions as quickly and accurately as possible. Items will include mid-frequency words supplemented with 10 descriptions of middle to high-frequency abstract words (mean frequency = 3.45, SD = 0.90). |
| Auditory Description Naming reaction time | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Reaction times will also be recorded using E-Prime software (version 3.0) for the auditory description naming task. A decrease in Reaction Time will be considered as improvement. |
| Comprehensive Aphasia Test - cognitive screening | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Online version of the Comprehensive Aphasia Test (CAT): cognitive screening score (scale /49, higher meaning better outcome) |
| Comprehensive Aphasia Test - language score | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Online version of the Comprehensive Aphasia Test (CAT): language comprehension (spoken and written words, sentences, and paragraphs) and expressive language (repetition, picture description, reading aloud, writing) (Total scale /402, higher meaning better outcome). |
| Comprehensive Aphasia Test - aphasia impact questionnaire | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Online version of the Comprehensive Aphasia Test (CAT): Aphasia Impact Questionnaire score (124-item scale; higher scores indicate a greater impact of aphasia on the participant's life, meaning worse outcome). |
| Similarity task Accuracy | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Participants will be asked whether pairs of items are similar or dissimilar in meaning (for example, coffee and tea are similar in meaning, whereas cat and cup are not). Accuracy will be recorded. |
| Similarity task - reaction time | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | We will also measure Reaction time for this task. |
| Verb naming task accuracy | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Verb naming will be assessed using video clips from the T-DAV 20. Only the number of correct answers will be recorded as an outcome measure. |
| Digit span | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Digit span (WAIS-IV) for the working memory and the total score will be reported. |
| Flanker task | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Using an E-Prime script, inhibitory processes will be measured with the Flanker task. Accuracy will be used as the outcome measure. |
| Flexibility - Trail Making Test | Baseline assessment conducted within 7 days prior to intervention Post-intervention assessment conducted within 3 days after the final intervention session Follow-up assessment conducted 1 month after the end of the intervention | Flexibility will be measured using the Trail Making Test, and the reaction time difference between Parts B and A will be used as the outcome measure. |
Countries
United States
Contacts
CONTACTSophie Arheix-Parras, PhD
Outcome results
None listed