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Post-stroke basal ganglia aphasia is an unusual and transient form of aphasia resulting from basal ganglia damage. It is commonly believed that the generation of language function primarily resides in regular language regions of the brain; however, recent findings indicate a prevalence of basal ganglia stroke aphasia as high as 22%. Subcortical structures (e.g., basal ganglia) also play an important role in language processing. Aphasia seriously affects the quality of life and functional outcomes of patients, and early diagnosis and intervention are important for the prognosis of and rehabilitation from aphasia after basal ganglia stroke. In recent years, the main diagnostic methods for basal ganglia aphasia include diffusion tensor imaging, diffusion spectral imaging, and functional magnetic resonance imaging, which explore the changes in patients with basal ganglia aphasia compared to those without from the perspectives of fiber tract imaging and brain function alteration, respectively, and are able to predict the recovery of patients before and after treatment. Treatment for post-stroke basal ganglia aphasia includes transcranial magnetic stimulation, a recent emerging therapeutic technique, in addition to conventional medications and speech rehabilitation. Consequently, understanding this condition is crucial. This review delves into its causes, imaging methods, and therapeutic interventions, offering a systematic and comprehensive analysis of these aspects., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Poststroke aphasia typically results from brain damage to the left-lateralized language network. The contribution of the right-lateralized homologues in aphasia recovery remains equivocal. In this longitudinal observational study, we specifically investigated the role of right hemisphere structural connectome in aphasia recovery. Twenty-two patients with aphasia after a left hemispheric stroke underwent comprehensive language assessment at the early subacute and chronic stages. A novel structural connectometry approach, using multi-shell diffusion-weighted MRI data collected at the early subacute stage, was used to evaluate the relationship between right hemisphere white matter connectome and language production and comprehension abilities at early subacute stage. Moreover, we evaluated the relationship between early subacute right hemisphere white matter connectome and longitudinal change in language production and comprehension abilities. All results were corrected for multiple comparisons. Connectometry analyses revealed negative associations between early subacute stage right hemisphere structural connectivity and language production, both cross-sectionally and longitudinally (p FDR  < .0125). In turn, only positive associations between right hemisphere structural connectivity and language comprehension were observed, both cross-sectionally and longitudinally (p FDR  < .0125). Interhemispheric connectivity was highly associated with comprehension scores. Our results shed light on the discordant interpretations of previous findings, by providing evidence that while some right hemisphere white matter pathways may make a maladaptive contribution to the recovery of language, other pathways support the recovery of language, especially comprehension abilities., (© 2023 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.)

Purpose: Aphasia-acquired loss of the ability to understand or express language-is a common and debilitating neurological consequence of stroke. Evidence suggests that transcranial magnetic stimulation (TMS) can significantly improve language outcomes in patients with aphasia. Repetitive transcranial magnetic stimulation (rTMS) has been reported to improve naming in chronic stroke patients with nonfluent aphasia since 2005., Methods: We conducted a systematic review and meta-analyses of TMS treatment studies in patients with aphasia. Eight electronic databases (PubMed, Medline, Embase, Scopus, ScienceDirect, Cochrane Central Register of Controlled Trials, Journals@Ovid, and clinicaltrials.gov) were searched for articles. Relevant studies were further evaluated, and studies that met inclusion criteria were reviewed. The searches were limited to human studies written in English and published between January 1960 and January 2020. In keeping with the main objective of this review, we included all studies that carried out treatment using rTMS in stroke patients with aphasia, regardless of the trial (or experimental) design of the study. Studies that implemented between-subject or randomized controlled (RCT) design, cross-over trials, and within-subject or pre-post trials were all included. Standard mean difference (SMD) for changes in picture naming accuracy was estimated., Results: The literature search yielded 423 studies. Fifty articles were further evaluated to be included. Eleven met all inclusion criteria and were chosen for review. Eleven eligible studies involving 242 stroke patients were identified in this meta-analysis. Further analyses demonstrated prominent effects for the naming subtest (SMD = 1.26, 95% CI = 0.80 to 1.71, p = 0.01), with heterogeneity (I 2  = 69.101%). The meta-analysis continued to show that there was a statistically significant effect of rTMS compared with sham rTMS on the severity of aphasia. None of the patients from the 11 included articles reported adverse effects from rTMS., Conclusions: There are some strong studies evaluating the efficacy of rTMS in stroke patients but further research is required to fully establish the usefulness of this treatment. This meta-analysis indicates a clinically positive effect of rTMS with or without speech and language therapy (SLT) for patients with aphasia following stroke in overall language function and expressive language, including naming, repetition, writing, and comprehension. Low-frequency (1 Hz) rTMS over the unaffected hemisphere is effective and compatible with the concept of interhemispheric inhibition. Moreover, the treatment of 1 Hz rTMS for patients with aphasia after stroke was safe., (© 2022. Fondazione Società Italiana di Neurologia.)

Background: There is high variability in post-stroke aphasia severity and predicting recovery remains imprecise. Standard prognostics do not include neurophysiological indicators or genetic biomarkers of neuroplasticity, which may be critical sources of variability., Objective: To evaluate whether a common polymorphism (Val 66 Met) in the gene for brain-derived neurotrophic factor (BDNF) contributes to variability in post-stroke aphasia, and to assess whether BDNF polymorphism interacts with neurophysiological indicators of neuroplasticity (cortical excitability and stimulation-induced neuroplasticity) to improve estimates of aphasia severity., Methods: Saliva samples and motor-evoked potentials (MEPs) were collected from participants with chronic aphasia subsequent to left-hemisphere stroke. MEPs were collected prior to continuous theta burst stimulation (cTBS; index for cortical excitability) and 10 minutes following cTBS (index for stimulation-induced neuroplasticity) to the right primary motor cortex. Analyses assessed the extent to which BDNF polymorphism interacted with cortical excitability and stimulation-induced neuroplasticity to predict aphasia severity beyond established predictors., Results: Val 66 Val carriers showed less aphasia severity than Val 66 Met carriers, after controlling for lesion volume and time post-stroke. Furthermore, Val 66 Val carriers showed expected effects of age on aphasia severity, and positive associations between severity and both cortical excitability and stimulation-induced neuroplasticity. In contrast, Val 66 Met carriers showed weaker effects of age and negative associations between cortical excitability, stimulation-induced neuroplasticity and aphasia severity., Conclusions: Neurophysiological indicators and genetic biomarkers of neuroplasticity improved aphasia severity predictions. Furthermore, BDNF polymorphism interacted with cortical excitability and stimulation-induced neuroplasticity to improve predictions. These findings provide novel insights into mechanisms of variability in stroke recovery and may improve aphasia prognostics.

In this chapter, we review fMRI evidence for language reorganization in individuals with poststroke aphasia. Several studies in the current literature have utilized fMRI as a tool to understand patterns of functional reorganization in poststroke aphasia. Consistent with previous models that have been proposed to explain the trajectory of language recovery, differential patterns of language processing and language recovery have been identified across individuals with poststroke aphasia in different stages of recovery. Overall, a global network breakdown typically occurs in the early stages of aphasia recovery, followed by normalization in "traditional" left hemisphere language networks. Depending on individual characteristics, right hemisphere regions and bilateral domain-general regions may be further recruited. The main takeaway of this chapter is that poststroke aphasia recovery does not depend on individual neural regions, but rather involves a complex interaction among regions in larger networks. Many of the unresolved issues and contrastive findings in the literature warrant further research with larger groups of participants and standard protocols of fMRI implementation., (Copyright © 2022 Elsevier B.V. All rights reserved.)

To date, new advances in technology have already shown the effectiveness of non-invasive brain stimulation and, in particular, of transcranial direct current stimulation (tDCS), in enhancing language recovery in post-stroke aphasia. More recently, it has been suggested that the stimulation over the spinal cord improves the production of words associated to sensorimotor schemata, such as action verbs. Here, for the first time, we present evidence that transpinal direct current stimulation (tsDCS) combined with a language training is efficacious for the recovery from speech apraxia, a motor speech disorder which might co-occur with aphasia. In a randomized-double blind experiment, ten aphasics underwent five days of tsDCS with concomitant treatment for their articulatory deficits in two different conditions: anodal and sham. In all patients, language measures were collected before (T0), at the end (T5) and one week after the end of treatment (F/U). Results showed that only after anodal tsDCS patients exhibited a better accuracy in repeating the treated items. Moreover, these effects persisted at F/U and generalized to other oral language tasks (i.e. picture description, noun and verb naming, word repetition and reading). A further analysis, which compared the tsDCS results with those collected in a matched group of patients who underwent the same language treatment but combined with tDCS, revealed no differences between the two groups. Given the persistency and severity of articulatory deficits in aphasia and the ease of use of tsDCS, we believe that spinal stimulation might result a new innovative approach for language rehabilitation., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Brain imaging methods such as functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI) have already been used to decipher the functional and structural brain changes occurring during normal language development. However, little is known about the differentiation of the language network after an early lesion. While in adults, stroke over the left hemisphere generally induces post-stroke aphasia, it is not always the case when a stroke occurs in the perinatal period, thus revealing a remarkable plastic power of the language network during early development. In particular, the role of perilesional tissues, as opposed to undamaged brain areas in the functional recovery of language functions after an early insult, remains unclear. In this review article, we provide an overview of the extant literature using functional and structural neuroimaging data revealing the signatures of brain plasticity underlying near-normal language development., (Copyright © 2020. Published by Elsevier Inc.)

Understanding the processes underlying normal, impaired, and recovered language performance has been a long-standing goal for cognitive and clinical neuroscience. Many verbally described hypotheses about language lateralization and recovery have been generated. However, they have not been considered within a single, unified, and implemented computational framework, and the literatures on healthy participants and patients are largely separated. These investigations also span different types of data, including behavioral results and functional MRI brain activations, which augment the challenge for any unified theory. Consequently, many key issues, apparent contradictions, and puzzles remain to be solved. We developed a neurocomputational, bilateral pathway model of spoken language production, designed to provide a unified framework to simulate different types of data from healthy participants and aphasic patients. The model encapsulates key computational principles (differential computational capacity, emergent division of labor across pathways, experience-dependent plasticity-related recovery) and provides an explanation for the bilateral yet asymmetric lateralization of language in healthy participants, chronic aphasia after left rather than right hemisphere lesions, and the basis of partial recovery in patients. The model provides a formal basis for understanding the relationship between behavioral performance and brain activation. The unified model is consistent with the degeneracy and variable neurodisplacement theories of language recovery, and adds computational insights to these hypotheses regarding the neural machinery underlying language processing and plasticity-related recovery following damage., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

Objective: To review the research literature pertaining to post-stroke language recovery, and to discuss neurocognitive assessment in patients in the context of aphasia, time course of language recovery, factors associated with language recovery, and therapeutic techniques designed to facilitate language recovery. Method: Articles were identified through PubMed, MEDLINE, PsychINFO, and Google Scholar searches. Examples of utilized keywords include "post-stroke aphasia," "post-stroke language recovery," "post-stroke neurocognitive assessment," and "neuropsychology and aphasia." Results: Most language recovery occurs in the first few weeks following stroke, but residual recovery may occur for many years. Although initial aphasia severity is the single largest determinant of post-stroke language recovery, a number of other variables also contribute. Several techniques have been developed to aid in the recovery process including speech-language therapy and noninvasive brain stimulation, although the effectiveness of acute and subacute treatment remains unclear. Some degree of valid neurocognitive assessment is possible in patients with aphasia, and the information gained from such an evaluation can aid the rehabilitative process Conclusions: Significant recovery of language function is possible following a stroke, but prediction of level of recovery in an individual patient is difficult. Information about initial aphasia severity and the integrity of cognitive domains other than language can help guide the rehabilitation team, as well as manage expectations for recovery.

Background: Bilingual aphasia forms a significant part of speech-language pathologists' (SLP) caseload, globally, and specifically in South Africa. Few tools supporting clinical decision-making are available due to limited understanding of typical and disordered cross-linguistic processing (how the languages interact). Speech errors may provide insight about "hidden" bilingual mechanisms., Objectives: To determine what speech errors can impart about cross-linguistic processing, as well as, associated language and impairment variables in Sepedi-English individuals with aphasia., Method: The case series included six participants, purposively selected from three rehabilitation sites in South Africa. Detailed language and clinical profiles were obtained. Participants performed a confrontation naming task in their most dominant (MDL) and less dominant language (LDL). Responses were audio recorded, transcribed, and analyzed for overall accuracy and error type in MDL and LDL; verified by a Sepedi-speaking linguist and a qualified SLP., Results: (1) No statistically significant differences in MDL-LDL naming accuracy were found, supporting recent literature of simultaneous inter-activation of both languages and shared word retrieval mechanisms. All types of speech errors occurred, and semantic errors were produced most frequently and consistently in each participant's MDL and LDL. (2) Language proficiency, language recovery patterns, and aphasia type (Broca's and Anomic) and severity (mild and/or moderate) appeared to be more strongly linked to cross-linguistic processing than Sepedi-English linguistic differences and age of acquisition of both languages., Conclusions: Participants with bilingual aphasia may use typical cross-linguistic and word retrieval mechanisms, concurring with current theories of bilingualism. Findings are preliminary, warranting investigations of other language tasks, modalities, pairs, and related variables.

Background: In this case series, functional magnetic resonance imaging was used to examine brain networks that mediate different aspects of language function in 4 young adults (17-22 years) with a history of left middle cerebral artery (MCA) stroke in childhood (40 years of age). Although it is widely believed that altered lateralization patterns are more likely to occur following early brain injuries compared with later brain injuries, the presumed plasticity of the young brain has been challenged in recent years, particularly in the domain of language., Methods: We explored this issue by contrasting the brain activation patterns of individuals with childhood left MCA stroke and adult left MCA stroke while performing two language tasks: verb generation and picture-word matching. Importantly, both groups showed significant recovery of language function, based on standard clinical indicators., Results: Controls showed left lateralized activation for both tasks, although much more pronounced for verb generation. Adult stroke patients also showed left lateralization for both tasks, though somewhat weaker than controls. Childhood stroke patients exhibited significantly weaker lateralization than the adult group for verb generation, but there was no significant group difference for picture-word matching., Conclusions: These preliminary findings suggest that successful reorganization of language function is more likely to involve bilateral recruitment following left MCA stroke in childhood than in adulthood. Of importance, although childhood stroke patients had primarily subcortical lesions, there were substantial alterations in cortical activation patterns.

Current theories of language recovery after stroke are limited by a reliance on small studies. Here, we aimed to test predictions of current theory and resolve inconsistencies regarding right hemispheric contributions to long-term recovery. We first defined the canonical semantic network in 43 healthy controls. Then, in a group of 43 patients with chronic post-stroke aphasia, we tested whether activity in this network predicted performance on measures of semantic comprehension, naming, and fluency while controlling for lesion volume effects. Canonical network activation accounted for 22%-33% of the variance in language test scores. Whole-brain analyses corroborated these findings, and revealed a core set of regions showing positive relationships to all language measures. We next evaluated the relationship between activation magnitudes in left and right hemispheric portions of the network, and characterized how right hemispheric activation related to the extent of left hemispheric damage. Activation magnitudes in each hemispheric network were strongly correlated, but four right frontal regions showed heightened activity in patients with large lesions. Activity in two of these regions (inferior frontal gyrus pars opercularis and supplementary motor area) was associated with better language abilities in patients with larger lesions, but poorer language abilities in patients with smaller lesions. Our results indicate that bilateral language networks support language processing after stroke, and that right hemispheric activations related to extensive left hemispheric damage occur outside of the canonical semantic network and differentially relate to behavior depending on the extent of left hemispheric damage. Hum Brain Mapp 38:1636-1658, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

The introduction of non-invasive functional neuroimaging techniques such as functional magnetic resonance imaging (fMRI), in the practice of scientific and clinical research can increase our knowledge about the organization of cognitive processes, including language, in normal and reorganization of these cognitive functions in post-stroke aphasia. The article discusses the results of fMRI studies of functional organization of the cortex of a healthy adult's brain in the processing of various voice information as well as the main types of speech reorganization after post-stroke aphasia in different stroke periods. The concepts of 'effective' and 'ineffective' brain plasticity in post-stroke aphasia were considered. It was concluded that there was an urgent need for further comprehensive studies, including neuropsychological testing and several complementary methods of functional neuroimaging, to develop a phased treatment plan and neurorehabilitation of patients with post-stroke aphasia.

Using magnetoencephalography, we investigated the potential of perilesional and contralesional activity to support language recovery in patients with poststroke aphasia. In healthy young controls, left-lateralized ventral frontotemporal regions responded to semantic anomalies during sentence comprehension and bilateral dorsal frontoparietal regions responded to syntactic anomalies. Older adults showed more extensive bilateral responses to the syntactic anomalies and less lateralized responses to the semantic anomalies, with decreased activation in the left occipital and parietal regions for both semantic and syntactic anomalies. In aphasic participants, we observed compensatory recruitment in the right hemisphere (RH), which varied depending on the type of linguistic information that was processed. For semantic anomalies, aphasic patients activated some preserved left hemisphere regions adjacent to the lesion, as well as homologous parietal and temporal RH areas. Patients also recruited right inferior and dorsolateral frontal cortex that was not activated in the healthy participants. Responses for syntactic anomalies did not reach significance in patients. Correlation analyses indicated that recruitment of homologous temporoparietal RH areas is associated with better semantic performance, whereas higher accuracy on the syntactic task was related to bilateral superior temporoparietal and right frontal activity. The results suggest that better recovery of semantic processing is associated with a shift to ventral brain regions in the RH. In contrast, preservation of syntactic processing is mediated by dorsal areas, bilaterally, although recovery of syntactic processing tends to be poorer than semantic. Hum Brain Mapp 37:2869-2893, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Purpose: Aphasia-acquired loss of the ability to understand or express language-is a common and debilitating neurological consequence of stroke. Evidence suggests that transcranial magnetic (TMS) or direct current stimulation (tDCS) can significantly improve language outcomes in patients with aphasia (PWA). However, the relative efficacy between TMS and tDCS has not yet been explored. Mechanistic and methodological differences, patient inclusion/exclusion criteria and experimental designs may influence observed treatment benefits., Methods: We conducted a systematic review and meta-analyses of TMS and tDCS treatment studies in PWA. Standard mean difference (SMD) for changes in picture naming accuracy was estimated; pooled SMDs were compared using a random-effects model., Results: Eight TMS (N = 143) and 8 tDCS studies (N = 140) met our inclusion criteria. Pooled SMDs of 0.448 (p < 0.001) in favor of TMS, and 0.395 (p < 0.001) in favor of tDCS were found. Between-subject designs were more common in subacute and within/crossover designs in chronic patients. TMS SMDs were significant in both chronic (SMD = 0.348) and subacute (SMD = 0.667) populations while those for tDCS were significant in chronic (SMD = 0.320) but not in subacute (SMD = 0.283) PWA., Conclusions: The magnitude of treatment effects appears to be consistent between TMS and tDCS in PWA. Larger-scale clinical trials should further substantiate our findings.

Predicting functional outcome in stroke is challenging to most clinicians, partly because of the complexity of the condition and also because of the lack of validated prognostic models. The strongest predictors of functional outcome are age and motor function at stroke onset. There is a growing literature on predicting recovery of upper limb after stroke; however, literature on prediction of language recovery remains sparse. This review covers the current status of predicting functional outcome after stroke focusing on recovery of activities of daily living, ambulation, upper limb use, and aphasia. Use of clinical factors, imaging, and neurophysiological measures are discussed., (Copyright © 2015 Elsevier Inc. All rights reserved.)

In the past few years, noninvasive cerebral stimulations have been used to modulate language task performance in healthy and aphasic patients. In this study, a dual transcranial direct current stimulation (tDCS) on anterior and posterior language areas was applied for 2 weeks to a patient with a possible crossed aphasia following a right hemisphere stroke. Inhibitory cathodal stimulation of the right Brodmann areas (BA) 44/45 and simultaneous anodal stimulation of the left BA 44/45 improved the patient's performance in picture naming. Conversely, the same bilateral montage on BA 39/40 did not produce any significant improvement; finally, electrode polarity inversion over BA 39/40 yielded a further improvement compared with the first anterior stimulation. Our findings suggest that ipsilesional and contralesional areas could be useful in poststroke functional reorganization and provide new evidences for the therapeutic value of tDCS in aphasia.

Post-stroke language recovery remains one of the main unresolved topics in the field of aphasia. In recent years, there have been efforts to identify specific factors that could potentially lead to improved language recovery. However, the exact relationship between the recovery of particular language functions and possible predictors, such as demographic or lesion variables, is yet to be fully understood. In the present study, we attempted to investigate such relationships in 42 patients with aphasia after left hemisphere stroke, focusing on three language domains: auditory comprehension, naming and speech fluency. Structural imaging data were also obtained for the identification of the lesion sites. According to our findings, patients demonstrated an overall improvement in all three language domains, while no demographic factor significantly contributed to aphasia recovery. Interestingly, specific lesion loci seemed to have a differential effect on language performance, depending on the time of testing (i.e., acute/subacute vs. chronic phase). We argue that this variability concerning lesion–deficit associations reflects the dynamic nature of aphasia and further discuss possible explanations in the framework of neuroplastic changes during aphasia recovery. [ABSTRACT FROM AUTHOR]

Previous findings have demonstrated the importance of discourse analysis in post-stroke aphasia, as it allows for in-depth examination of language impairment and represents key components of functional communication. However, little is known about the recovery of discourse over time. The main aim of this study is to measure the longitudinal changes in descriptive discourse production from the acute to chronic stages of post-stroke aphasia recovery. The secondary aim is to explore the association between discourse measures and overall language impairment severity measures at different testing points. Seventeen French-Canadian speakers with various types and severities of aphasia following a first left middle cerebral artery stroke participated in this study. They underwent three language assessments (acute: 0 to 72 hours; subacute: 7 to 14 days; chronic: 6 to 12 months post-onset). The picture description from the Western Aphasia Battery was analyzed at three time points. Changes in terms of thematic informativeness and microstructural variables were analyzed. Regarding the micro-structural variables, the mean length of utterances (MLU) and the number of words per minute showed significant positive changes between the acute and chronic phases. For the thematic informativeness measures, the number of thematic units (TUs), the number of thematic units per minute (TUs/min) and the number of thematic units per utterance (TUs/utt) increased significantly between the acute and chronic phases. Positive correlations between TUs and MLU in the acute phase and a general language impairment severity measure in the acute and chronic phases suggest a relationship between these measures and global language performance suggesting the potential predictive value of these variables in the acute phase. These findings support the use of thematic units in descriptive discourse analysis during an acute clinical examination of language as they require minimal additional time to score and track changes in post-stroke aphasia recovery. They capture long-term changes in discourse abilities and appear related to overall language measures in both the acute and chronic stages of recovery. The interpretation of the changes in MLU and the number of words per minute is less straightforward, as improvements in these measures carry different interpretations depending on the type of aphasia. Nonetheless, further studies are required to investigate test-retest reliability and the effect of therapy on the changes observed over time when using thematic units to document change in discourse. [ABSTRACT FROM AUTHOR]

Background & Objective: Aphasia—acquired loss of the ability to understand or express language—is a common and debilitating neurological consequence of stroke. Evidence suggests that transcranial magnetic stimulation (TMS) can significantly improve language outcomes in patients with aphasia. Repetitive transcranial magnetic stimulation (rTMS) has been reported to improve naming in chronic stroke patients with nonfluent aphasia since 2005. Methods: We conducted a systematic review and meta-analyses of TMS treatment studies in patients with aphasia. Eight electronic databases (PubMed, Medline, Embase, Scopus, ScienceDirect, Cochrane Central Register of Controlled Trials, Journals@ Ovid, and clinicaltrials.gov) were searched for articles. Relevant studies were further evaluated and studies that met inclusion criteria were reviewed. We included studies if were: randomized controlled blinded clinical trials, meta-analyses or crossover designs of rTMS alone or with speech therapy or any other therapy tested with rTMS. Standard mean difference (SMD) for changes in picture naming accuracy was estimated. Results: The literature search yielded 423 studies. Fifty articles were further evaluated to be included. Eleven met all inclusion criteria and were chosen for review. Eleven eligible studies involving 301 stroke patients were identified in this meta-analysis. Further analyses demonstrated prominent effects for the naming subtest (SMD = 1.26, 95% CI = 0.80 to 1.71, P=0.01), with heterogeneity (I2 = 69.101%). The meta-analysis continued to show that there was a statistically significant effect of rTMS compared with sham rTMS on the severity of aphasia. None of the patients from the 11 included articles reported adverse effects from rTMS. Conclusions: There are some strong studies evaluating the efficacy of rTMS in stroke patients but further research is required to fully establish the usefulness of this treatment. This meta-analysis indicates a clinically positive effect of rTMS with or without speech and language therapy (SLT) for patients with aphasia following stroke in overall language function and expressive language, including naming, repetition, writing, and comprehension. Low-frequency (1 Hz) rTMS over the unaffected hemisphere is effective and compatible with the concept of interhemispheric inhibition. Moreover, the treatment of 1 Hz rTMS for patients with aphasia after stroke was safe. [ABSTRACT FROM AUTHOR]

Background: Discourse analysis allows the examination of functional and ecological language impairment in post-stroke aphasia. Given its complexity, various methods of analysis have been developed to measure the multiple components of discourse. Clinical assessment usually includes discourse analysis, but how clinicians should assess recovery of discourse, particularly in acute care settings, is still a matter of debate. Aims: This study aimed to measure improvements in discourse production in early post-stroke aphasia recovery. Methods & Procedure: Twenty-three persons with aphasia following a first left middle cerebral artery stroke were recruited in the stroke unit of Hôpital du Sacré-Coeur de Montréal (May 2015-July 2018). Patients treated with thrombolysis (n = 10) and untreated patients underwent two aphasia assessments (0 to 72 hours, 7 to 14 days post-onset). Discourse assessment consisted of the picture description task from the Western Aphasia Battery. Changes in microlinguistic and thematic informativeness measures between the two assessment periods were analyzed. Outcomes & Results: In-depth microlinguistic analyses showed no significant difference between the initial and follow-up assessments. Conversely, some thematic informativeness variables improved significantly during the same time period. Patients treated with thrombolysis produced more thematic units than untreated patients at both assessments, but the change between the two groups was not significant. Conclusions & Implications: This study suggests that thematic informativeness variables are sensitive to language improvement in early post-stroke aphasia recovery whereas no microlinguistic variables improved significantly in the same period. In contrast to previous evidence, the difference between patients treated with thrombolysis and untreated patients was not evident over time. The results suggest that thematic informativeness constitutes an interesting path to explore as a routine clinical assessment in acute-care settings because it is time-efficient, simple to conduct and reliable in assessing early changes in the discourse production of individuals with aphasia in the acute post-stroke phase. [ABSTRACT FROM AUTHOR]

Stroke in the language dominant hemisphere is the most frequent cause of aphasia. In the course of post-stroke aphasia different mechanisms can contribute to the recovery of language: recovery from ischemia, compensatory rerouting of language modalities and neuroplasticity occur at different time scales after the initial injury. These mechanisms may occur spontaneously or may be induced or influenced by various therapeutic interventions. This report contains a systematic review of the literature concerning the debated role of the right hemisphere in the recovery from stroke-related aphasia. The existing literature was approached using the PICOS principle and well-established inclusion and exclusion criteria. Although many gaps remain in the knowledge on the role of the right hemisphere, there is some evidence of a facilitation of spontaneous language recovery in the acute and subacute phase. In the subacute and chronic phase, the right hemisphere homologous language areas, along with memory and attention-related areas, facilitate treatment related improvement. In contrast, in therapy-free periods in the chronic stage, the right hemisphere no longer contributes to language recovery or may even be inhibitory. Injury-, language- and therapy-related variables impact on the role of the right hemisphere in aphasia recovery. [ABSTRACT FROM AUTHOR]

Background: Post-stroke loss and recovery of language functions evolves in time and space. A high functional dynamic can be observed in the first days and weeks after stroke, which has been associated with reorganisation processes in the left-lateralised language network, its right-hemisphere homologues and in the vicinity of the lesion site. With the advances in in vivo neuroimaging techniques, mapping changes in the language network over time (e.g., lesion extent, structural integrity of grey or white matter, task-based activity, functional or structural connectivity) is currently the focus of ongoing investigations. Main Contribution: This review highlights the recent findings on the neurobiology of language recovery from the hyperacute to the subacute phase after stroke. It relates pathophysiological processes of stroke evolution and the spatio-temporal characteristics of recovery patterns within the anatomically distributed language network to the behavioural dynamics of early language recovery. Conclusions: Understanding distinct, yet characteristic, recovery patterns within the language network promoting an improvement of language functions has lately provided new targets for non-invasive brain stimulation to enhance language rehabilitation mainly in the chronic phase after stroke. We argue that a more profound understanding of the natural history of behaviour–physiology relationships during aphasia evolution could open up new opportunities for an early system-level, neurobiologically motivated therapeutic use of neuromodulation techniques during language rehabilitation. [ABSTRACT FROM PUBLISHER]

In this study, we examined regions in the left and right hemisphere language network that were altered in terms of the underlying neural activation and effective connectivity subsequent to language rehabilitation. Eight persons with chronic post-stroke aphasia and eight normal controls participated in the current study. Patients received a 10 week semantic feature-based rehabilitation program to improve their skills. Therapy was provided on atypical examples of one trained category while two control categories were monitored; the categories were counterbalanced across patients. In each fMRI session, two experimental tasks were conducted: (a) picture naming and (b) semantic feature verification of trained and untrained categories. Analysis of treatment effect sizes revealed that all patients showed greater improvements on the trained category relative to untrained categories. Results from this study show remarkable patterns of consistency despite the inherent variability in lesion size and activation patterns across patients. Across patients, activation that emerged as a function of rehabilitation on the trained category included bilateral IFG, bilateral SFG, LMFG, and LPCG for picture naming; and bilateral IFG, bilateral MFG, LSFG, and bilateral MTG for semantic feature verification. Analysis of effective connectivity using Dynamic Causal Modeling (DCM) indicated that LIFG was the consistently significantly modulated region after rehabilitation across participants. These results indicate that language networks in patients with aphasia resemble normal language control networks and that this similarity is accentuated by rehabilitation. [ABSTRACT FROM AUTHOR]

Little is known about anatomical predictors of recovery from post-stroke aphasia. Forkel et al. use DTI of the perisylvian language networks to examine six-month recovery in patients with left-hemisphere stroke. Results reveal a role for the right-hemisphere language network in recovery, and may provide clinically useful predictive biomarkers.Stroke-induced aphasia is associated with adverse effects on quality of life and the ability to return to work. For patients and clinicians the possibility of relying on valid predictors of recovery is an important asset in the clinical management of stroke-related impairment. Age, level of education, type and severity of initial symptoms are established predictors of recovery. However, anatomical predictors are still poorly understood. In this prospective longitudinal study, we intended to assess anatomical predictors of recovery derived from diffusion tractography of the perisylvian language networks. Our study focused on the arcuate fasciculus, a language pathway composed of three segments connecting Wernicke’s to Broca’s region (i.e. long segment), Wernicke’s to Geschwind’s region (i.e. posterior segment) and Broca’s to Geschwind’s region (i.e. anterior segment). In our study we were particularly interested in understanding how lateralization of the arcuate fasciculus impacts on severity of symptoms and their recovery. Sixteen patients (10 males; mean age 60 ± 17 years, range 28–87 years) underwent post stroke language assessment with the Revised Western Aphasia Battery and neuroimaging scanning within a fortnight from symptoms onset. Language assessment was repeated at 6 months. Backward elimination analysis identified a subset of predictor variables (age, sex, lesion size) to be introduced to further regression analyses. A hierarchical regression was conducted with the longitudinal aphasia severity as the dependent variable. The first model included the subset of variables as previously defined. The second model additionally introduced the left and right arcuate fasciculus (separate analysis for each segment). Lesion size was identified as the only independent predictor of longitudinal aphasia severity in the left hemisphere [beta = −0.630, t(−3.129), P = 0.011]. For the right hemisphere, age [beta = −0.678, t(–3.087), P = 0.010] and volume of the long segment of the arcuate fasciculus [beta = 0.730, t(2.732), P = 0.020] were predictors of longitudinal aphasia severity. Adding the volume of the right long segment to the first-level model increased the overall predictive power of the model from 28% to 57% [F(1,11) = 7.46, P = 0.02]. These findings suggest that different predictors of recovery are at play in the left and right hemisphere. The right hemisphere language network seems to be important in aphasia recovery after left hemispheric stroke. [ABSTRACT FROM AUTHOR]

Abstract: Functional magnetic resonance imaging is the most widely used imaging technique to study treatment-induced recovery in post-stroke aphasia. The longitudinal design of such studies adds to the challenges researchers face when studying patient populations with brain damage in cross-sectional settings. The present review focuses on issues specifically relevant to neuroimaging data analysis in aphasia treatment research identified in discussions among international researchers at the Neuroimaging in Aphasia Treatment Research Workshop held at Northwestern University (Evanston, Illinois, USA). In particular, we aim to provide the reader with a critical review of unique problems related to the pre-processing, statistical modeling and interpretation of such data sets. Despite the fact that data analysis procedures critically depend on specific design features of a given study, we aim to discuss and communicate a basic set of practical guidelines that should be applicable to a wide range of studies and useful as a reference for researchers pursuing this line of research. [Copyright &y& Elsevier]

Abstract: New structural and functional neuroimaging methods continue to rapidly develop, offering promising tools for cognitive neuroscientists. In the last 20years, advanced magnetic resonance imaging (MRI) techniques have provided invaluable insights into how language is represented and processed in the brain and how it can be disrupted by damage to, or dysfunction of, various parts of the brain. Current functional MRI (fMRI) approaches have also allowed researchers to purposefully investigate how individuals recover language after stroke. This paper presents recommendations for quantification of brain lesions derived from discussions among international researchers at the Neuroimaging in Aphasia Treatment Research Workshop held at Northwestern University (Evanston, Illinois, USA). Methods for detailing and characterizing the brain damage that can influence results of fMRI studies in chronic aphasic stroke patients are discussed. Moreover, we aimed to provide the reader with a set of general practical guidelines and references to facilitate choosing adequate structural imaging strategies that facilitate fMRI studies in aphasia treatment research. [Copyright &y& Elsevier]

Abstract: Quantifying change in brain activation patterns associated with post-stroke recovery and reorganization of language function over time requires accurate understanding of inter-scan and inter-subject variability. Here we report inter-scan variability measures for fMRI activation patterns associated with verb generation (VG) and semantic decision/tone decision (SDTD) tasks in 4 healthy controls and 4 aphasic left middle cerebral artery (LMCA) stroke subjects. A series of 10 fMRI scans was completed on a 4T Varian scanner for each task for each subject, except for one stroke subject who completed 5 and 6 scans for SDTD and VG, thus yielding 35 and 36 total stroke subject scans for SDTD and VG, respectively. Group composite and intraclass correlation coefficient (ICC) maps were computed across all subjects and trials for each task. The patterns of reliable activation for the VG and SDTD tasks correspond well to those regions typically activated by these tasks in healthy and aphasic subjects. ICCs for activation were consistently high (R 0.05 ≈0.8) for individual tasks among both control and aphasic subjects. These voxel-wise measures of reliability highlight regions of low inter-scan variability within language circuitry for control and post-recovery stroke subjects. ICCs computed from the combination of the SDTD/VG data were markedly reduced for both control and aphasic subjects as compared with the ICCs for the individual tasks. These quantitative measures of inter-scan variability support the proposed use of these fMRI paradigms for longitudinal mapping of neural reorganization of language processing following left hemispheric insult. [Copyright &y& Elsevier]

Changes in brain connectivity during language therapy were examined among participants with aphasia (PWA), aiming to shed light on neural reorganization in the language network. Four PWA with anomia following left hemisphere stroke and eight healthy controls (HC) participated in the study. Two fMRI scans were administered to all participants with a 3.5-month interval. The fMRI scans included phonological and semantic tasks, each consisting of linguistic and perceptual matching conditions. Between the two fMRI scans, PWA underwent Phonological Components Analysis treatment. Changes in effective connectivity during the treatment were examined within right hemisphere (RH) architecture. The results illustrate that following the treatment, the averaged connectivity of PWA across all perceptual and linguistic conditions in both tasks increased resemblance to HC, reflecting the normalization of neural processes associated with silent object name retrieval. In contrast, connections that were specifically enhanced by the phonological condition in PWA decreased in their resemblance to HC, reflecting emerging compensatory reorganization in RH connectivity to support phonological processing. These findings suggest that both normalization and compensation play a role in neural language reorganization at the chronic stage, occurring simultaneously in the same brain. [ABSTRACT FROM AUTHOR]