Melodic Intonation Therapy for Post-stroke Non-fluent Aphasia: Systematic Review and Meta-Analysis

Research trends and hotspots in post-stroke speech rehabilitation: A bibliometric analysis

BACKGROUND

With the global population aging, the incidence of stroke is rising, often resulting in motor dysfunction, speech disorders, and swallowing difficulties, significantly affecting daily life and social participation. Speech and language disorders notably impair communication and restrict social engagement, making speech rehabilitation a critical intervention. However, comprehensive bibliometric analyses on post-stroke language rehabilitation are limited, restricting understanding of progress in this field.

OBJECTIVE

This study aimed to identify hotspots and trends in post-stroke speech rehabilitation research from 2003 to 2023 to guide future studies.

METHODS

Articles on post-stroke speech rehabilitation from 2003 to 2023 were retrieved from the Web of Science Core Collection. Analyses included annual publications, key authors, countries, institutions, journals, co-citations, and keywords.

RESULTS

Among 1077 articles, publication volume showed an upward trend, with the United States leading in contributions. The Aphasiology journal published the most articles, and prominent institutions like the University of Queensland demonstrated significant publication and citation impact. Key trends included "communication disorders," "functional connectivity," and "melodic intonation therapy," with "stroke" and "aphasia" emerging as central keywords.

CONCLUSION

Research in post-stroke speech rehabilitation is increasing, with significant contributions from the United States and key institutions. Trends highlight the importance of communication-focused therapies and innovative techniques like melodic intonation therapy. This study provides insights into research directions.

The role of the right hemispheric homologous language pathways in recovery from post-stroke aphasia: A systematic review

The involvement of the right hemisphere, mainly the activation of the right cerebral regions, in recovery from post-stroke aphasia has been widely recognized. In contrast, the role of the right white matter pathways in the recovery from post-stroke aphasia is rarely understood. In this study, we aimed to provide a primary overview of the correlation between the structural integrity of the right hemispheric neural tracts based on the dual-stream model of language organization and recovery from post-stroke aphasia by systematically reviewing prior longitudinal interventional studies. By searching electronic databases for relevant studies according to a standard protocol, a total of 10 records (seven group studies and three case studies) including 79 participants were finally included. After comprehensively analyzing these studies and reviewing the literature, although no definite correlation was found between the right hemispheric neural tracts and recovery from post-stroke aphasia, our review provideds a new perspective for investigating the linguistic role of the right hemispheric neural tracts. This suggests that the involvement of the right hemispheric neural tracts in recovery from post-stroke aphasia may be mediated by multiple factors; thus, this topic should be comprehensively investigated in the future.

Neurologic music therapy for non-fluent aphasia: a systematic review and meta-analysis of randomized controlled trials

Introduction

The efficacy of neurologic music therapy (NMT) techniques for the treatment of non-fluent aphasia has been widely accepted by the rehabilitation medical community. However, consensus on which dimensions of speech function can be improved by NMT techniques and standardized intervention dosage remains elusive. This study aimed to provide evidence regarding the efficacy of NMT in improving speech function and explore the optimal intervention dose. A systematic review and meta-analysis were conducted to search for randomized clinical trials and open-label trials that evaluated speech functions after NMT.

Methods

We searched all papers and reviews published from database inception to July 2023, including PubMed, Cochrane Library, Web of Science, Embase, and CNKI. Statistical analyses were mainly carried out on RevManV5.4.1 and pooled using a random-effects model. The primary outcome was the standardized mean difference (SMD) in speech functions, determined by calculating the change in speech functions score from baseline to the primary endpoint in the NMT group versus the control arm.

Results

A total of 11 studies with 329 patients were included. NMT had a positive effect on repetition ability (SMD = 0.37, 95%CI [0.12, 0.62], p  < 0.05), but did not lead to significant differences in naming, comprehension, spontaneous speech, or communication. When the intervention time was >20 h, NMT exhibited a significant advantage at improving repetition ability (SMD = 0.43, 95%CI [0.06, 0.79], p  < 0.05).

Discussion

This study provides evidence supporting the NMT enhancement of repetition ability in patients with non-fluent aphasia. Future large-sample studies are required to determine the optimal intervention dose of music therapy for different subtypes of non-fluent aphasia.

Systematic review registration

PROSPERO, identifier CRD42023470313.

Repetitive transcranial magnetic stimulation for post-stroke non-fluent aphasia: a systematic review and meta-analysis of randomized controlled trials

Objective

To systematically evaluate the efficacy and safety of repetitive transcranial magnetic stimulation (rTMS) on language function in patients with non-fluent aphasia post-stroke.

Methods

We selected randomized clinical trials (RCT) that involved stroke patients with non-fluent aphasia, whose intervention was rTMS vs. no therapy or other therapy. Two researchers autonomously reviewed the literature based on the specified criteria for inclusion and exclusion and completed the process of data extraction, data verification, and quality evaluation. Meta-analysis was performed using RevMan 5.4 and Stata MP 17, while the assessment of risk of bias was carried out utilizing the Risk of Bias version 2 tool (RoB2).

Results

The meta-analysis involved 47 RCTs, encompassing 2,190 patients overall. The indexes indicated that rTMS has the potential to decrease the severity of non-fluent aphasia in stroke patients, including improvement of the capability of repetition, naming, and spontaneous language. The determination of BDNF in the serum of patients was also increased. In addition, rTMS reduced the likelihood of depression in stroke patients.

Conclusion

To summarize the relevant studies, rTMS has significant effects on improving the language abilities of stroke patients suffering from non-fluent aphasia, including the abilities of repetition, naming, and spontaneous language.

Remapping and Reconnecting the Language Network after Stroke

Here, we review the literature on neurotypical individuals and individuals with post-stroke aphasia showing that right-hemisphere regions homologous to language network and other regions, like the right cerebellum, are activated in language tasks and support language even in healthy people. We propose that language recovery in post-stroke aphasia occurs largely by potentiating the right hemisphere network homologous to the language network and other networks that previously supported language to a lesser degree and by modulating connection strength between nodes of the right-hemisphere language network and undamaged nodes of the left-hemisphere language network. Based on this premise (supported by evidence we review), we propose that interventions should be aimed at potentiating the right-hemisphere language network through Hebbian learning or by augmenting connections between network nodes through neuroplasticity, such as non-invasive brain stimulation and perhaps modulation of neurotransmitters involved in neuroplasticity. We review aphasia treatment studies that have taken this approach. We conclude that further aphasia rehabilitation with this aim is justified.

Effects of melodic intonation therapy in patients with chronic nonfluent aphasia

Patients with large left-hemisphere lesions and post-stroke aphasia often remain nonfluent. Melodic intonation therapy (MIT) may be an effective alternative to traditional speech therapy for facilitating recovery of fluency in those patients. In an open-label, proof-of-concept study, 14 subjects with nonfluent aphasia with large left-hemisphere lesions (171 ± 76 cc) underwent two speech/language assessments before, one at the midpoint, and two after the end of 75 sessions (1.5 h/session) of MIT. Functional MR imaging was done before and after therapy asking subjects to vocalize the same set of 10 bi-syllabic words. We found significant improvements in speech output after a period of intensive MIT (75 sessions for a total of 112.5 h) compared to two pre-therapy assessments. Therapy-induced gains were maintained 4 weeks post-treatment. Imaging changes were seen in a right-hemisphere network that included the posterior superior temporal and inferior frontal gyri, inferior pre- and postcentral gyri, pre-supplementary motor area, and supramarginal gyrus. Functional changes in the posterior right inferior frontal gyri significantly correlated with changes in a measure of fluency. Intense training of intonation-supported auditory-motor coupling and engaging feedforward/feedback control regions in the unaffected hemisphere improves speech-motor functions in subjects with nonfluent aphasia and large left-hemisphere lesions.

A Review on Music Interventions for Frontotemporal Aphasia and a Proposal for Alternative Treatments

Frontotemporal dementia (FTD) is a rare neurodegenerative disease, characterized by behavioral and language impairments. Primary progressive aphasia (PPA) is the linguistic variant of this heterogeneous disorder. To date, there is a lack of consensus about which interventions are effective in these patients. However, several studies show that music-based interventions are beneficial in neurological diseases. This study aims, primarily, to establish the state of the art of music-based interventions designed for PPA due to FTD and, secondarily, to inform the planning of PPA-dedicated future interventions for Italian neurological institutions. The first aim is fulfilled by a review which critically screens the neurological studies examining the effects of music- and/or rhythm-based interventions, especially, on language rehabilitation in aphasic FTD. We found that only two papers fulfilled our criteria and concerned specifically aphasic patients due to FTD. Of those, one paper reported a study conducted in an Italian institution. Most of the reviewed studies focused, instead, on aphasia in post-stroke patients. The results of our review invite further studies to investigate the role of music as a valuable support in the therapy for neurodegenerative patients with language problems and in particular to PPA due to FTD. Moreover, based on this initial work, we can delineate new music-based interventions dedicated to PPA for Italian institutions.

Efficacy of a multicomponent singing intervention on communication and psychosocial functioning in chronic aphasia: a randomized controlled crossover trial

The ability to produce words through singing can be preserved in severe aphasia, but the benefits of group-based singing rehabilitation in aphasia are largely unknown. Our aim was to determine the efficacy of a multicomponent singing intervention on communication and speech production, emotional-social functioning and caregiver well-being in aphasia. Fifty-four patients with acquired brain injury and chronic aphasia and their family caregivers (n = 43) were recruited. Using a crossover randomized controlled trial design, participants were randomized to two groups who received a 4-month singing intervention either during the first or second half of the study in addition to standard care. The intervention comprised weekly group-based training (including choir singing and group-level melodic intonation therapy) and tablet-assisted singing training at home. At baseline, 5- and 9-month stages, patients were assessed with tests and questionnaires on communication and speech production, mood, social functioning, and quality of life and family caregivers with questionnaires on caregiver burden. All participants who participated in the baseline measurement (n = 50) were included in linear mixed model analyses. Compared with standard care, the singing intervention improved everyday communication and responsive speech production from baseline to 5-month stage, and these changes were sustained also longitudinally (baseline to 9-month stage). Additionally, the intervention enhanced patients' social participation and reduced caregiver burden. This study provides novel evidence that group-based multicomponent singing training can enhance communication and spoken language production in chronic aphasia as well as improve psychosocial wellbeing in patients and caregivers. https://www.clinicaltrials.gov, Unique identifier: NCT03501797.

Melodic Intonation Therapy for aphasia: A multi-level meta-analysis of randomized controlled trials and individual participant data

Melodic Intonation Therapy (MIT) is a prominent rehabilitation program for individuals with post-stroke aphasia. Our meta-analysis investigated the efficacy of MIT while considering quality of outcomes, experimental design, influence of spontaneous recovery, MIT protocol variant, and level of generalization. Extensive literature search identified 606 studies in major databases and trial registers; of those, 22 studies-overall 129 participants-met all eligibility criteria. Multi-level mixed- and random-effects models served to separately meta-analyze randomized controlled trial (RCT) and non-RCT data. RCT evidence on validated outcomes revealed a small-to-moderate standardized effect in noncommunicative language expression for MIT-with substantial uncertainty. Unvalidated outcomes attenuated MIT's effect size compared to validated tests. MIT's effect size was 5.7 times larger for non-RCT data compared to RCT data (g̅case report = 2.01 vs. g̅RCT = 0.35 for validated Non-Communicative Language Expression measures). Effect size for non-RCT data decreased with number of months post-stroke, suggesting confound through spontaneous recovery. Deviation from the original MIT protocol did not systematically alter benefit from treatment. Progress on validated tests arose mainly from gains in repetition tasks rather than other domains of verbal expression, such as everyday communication ability. Our results confirm the promising role of MIT in improving trained and untrained performance on unvalidated outcomes, alongside validated repetition tasks, and highlight possible limitations in promoting everyday communication ability.

Melodic Intonation Therapy in Post-Stroke Non-Fluent Aphasia and Its Effects on Brain Plasticity

Melodic Intonation Therapy (MIT) is one of the most well-known therapies for the rehabilitation of speech in patients with non-fluent aphasia and which is thought to promote right-hemisphere involvement in language processing. This review focuses on the study of language lateralization and/or neuroplastic reorganization with neuroimaging and/or neurophysiological techniques in non-fluent aphasic patients post-stroke during or after MIT. A systematic search was carried out according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) in databases (PubMed, Scopus, EMBASE, Dialnet, Web of Science, Cochrane) with the keywords melodic intonation therapy, neuroimaging, functional magnetic resonance, and positron emission tomography and the boolean operators AND and OR. Articles including patients of all ages and either sex with any type of aphasia post-stroke and in any language, which studied language lateralization and/or neuroplastic reorganization after or during MIT were included. Articles which did not achieve the objectives, revisions and conferences were excluded. Different results were obtained from the 16 studies included in the review: predominantly greater activation of the right hemisphere but also of the left hemisphere or both. MIT is an effective therapy to rehabilitate non-fluent aphasic patients post-stroke. It involves different neurobiological mechanisms and depends on multiple individual factors. Studies with larger samples are necessary.

Clinical and Neural Predictors of Treatment Response to Music Listening Intervention after Stroke

Patients with post-stroke impairments present often significant variation in response to therapeutic interventions. Recent studies have shown that daily music listening can aid post-stroke recovery of language and memory, but reliable predictors of treatment response are unknown. Utilizing data from the music intervention arms of a single-blind randomized controlled trial (RCT) on stroke patients (N = 31), we built regression models to predict the treatment response of a two-month music listening intervention on language skills and verbal memory with baseline demographic, clinical and musical data as well as fMRI data from a music listening task. Clinically, greater improvement in verbal memory and language skills after the music listening intervention were predicted by the severity of the initial deficit and educational level. Neurally, greater baseline fMRI activation during vocal music listening in the left parietal cortical and medial frontal areas predicted greater treatment-induced improvement in language skills and greater baseline engagement of the auditory network during instrumental music listening predicted improvement in both verbal memory and language skills. Our results suggest that clinical, demographic, and neuroimaging data predicts music listening treatment response. This data could be used clinically to target music-based treatments.