Recent advances in the treatment of post-stroke aphasia

Oscillatory beta/alpha band modulations: A potential biomarker of functional language and motor recovery in chronic stroke?

Stroke remains one of the leading causes of various disabilities, including debilitating motor and language impairments. Though various treatments exist, post-stroke impairments frequently become chronic, dramatically reducing daily life quality, and requiring specific rehabilitation. A critical goal of chronic stroke rehabilitation is to induce, usually through behavioral training, experience-dependent plasticity processes in order to promote functional recovery. However, the efficiency of such interventions is typically modest, and very little is known regarding the neural dynamics underpinning recovery processes and possible biomarkers of their efficiency. Some studies have emphasized specific alterations of excitatory–inhibitory balance within distributed neural networks as an important recovery correlate. Neural processes sensitive to these alterations, such as task-dependent oscillatory activity in beta as well as alpha bands, may be candidate biomarkers of chronic stroke functional recovery. In this review, we discuss the results of studies on motor and language recovery with a focus on oscillatory processes centered around the beta band and their modulations during functional recovery in chronic stroke. The discussion is based on a framework where task-dependent modulations of beta and alpha oscillatory activity, generated by the deep cortical excitatory–inhibitory microcircuits, serve as a neural mechanism of domain-general top-down control processes. We discuss the findings, their limitations, and possible directions for future research.

Common Neuroanatomical Substrate of Cholinergic Pathways and Language-Related Brain Regions as an Explanatory Framework for Evaluating the Efficacy of Cholinergic Pharmacotherapy in Post-Stroke Aphasia: A Review

Despite the relative scarcity of studies focusing on pharmacotherapy in aphasia, there is evidence in the literature indicating that remediation of language disorders via pharmaceutical agents could be a promising aphasia treatment option. Among the various agents used to treat chronic aphasic deficits, cholinergic drugs have provided meaningful results. In the current review, we focused on published reports investigating the impact of acetylcholine on language and other cognitive disturbances. It has been suggested that acetylcholine plays an important role in neuroplasticity and is related to several aspects of cognition, such as memory and attention. Moreover, cholinergic input is diffused to a wide network of cortical areas, which have been associated with language sub-processes. This could be a possible explanation for the positive reported outcomes of cholinergic drugs in aphasia recovery, and specifically in distinct language processes, such as naming and comprehension, as well as overall communication competence. However, evidence with regard to functional alterations in specific brain areas after pharmacotherapy is rather limited. Finally, despite the positive results derived from the relevant studies, cholinergic pharmacotherapy treatment in post-stroke aphasia has not been widely implemented. The present review aims to provide an overview of the existing literature in the common neuroanatomical substrate of cholinergic pathways and language related brain areas as a framework for interpreting the efficacy of cholinergic pharmacotherapy interventions in post-stroke aphasia, following an integrated approach by converging evidence from neuroanatomy, neurophysiology, and neuropsychology.

Differential Effects of Speech and Language Therapy and rTMS in Chronic Versus Subacute Post-stroke Aphasia: Results of the NORTHSTAR-CA Trial

BACKGROUND & OBJECTIVE

Contralesional 1-Hz repetitive transcranial magnetic stimulation (rTMS) over the right pars triangularis combined with speech-language therapy (SLT) has shown positive results on the recovery of naming in subacute (5-45 days) post-stroke aphasia. NORTHSTAR-CA is an extension of the previously reported NORTHSTAR trial to chronic aphasia (>6 months post-stroke) designed to compare the effectiveness of the same rTMS protocol in both phases.

METHODS

Sixty-seven patients with left middle cerebral artery infarcts (28 chronic, 39 subacute) were recruited (01-2014 to 07-2019) and randomized to receive rTMS (N = 34) or sham stimulation (N = 33) with SLT for 10 days. Primary outcome variables were Z-score changes in naming, semantic fluency and comprehension tests and adverse event frequency. Intention-to-treat analyses tested between-group effects at days 1 and 30 post-treatment. Chronic and subacute results were compared.

RESULTS

Adverse events were rare, mild, and did not differ between groups. Language outcomes improved significantly in all groups irrespective of treatment and recovery phase. At 30-day follow-up, there was a significant interaction of stimulation and recovery phase on naming recovery (P <.001). Naming recovery with rTMS was larger in subacute (Mdn = 1.91/IQR = .77) than chronic patients (Mdn = .15/IQR = 1.68/P = .015). There was no significant rTMS effect in the chronic aphasia group.

CONCLUSIONS

The addition of rTMS to SLT led to significant supplemental gains in naming recovery in the subacute phase only. While this needs confirmation in larger studies, our results clarify neuromodulatory vs training-induced effects and indicate a possible window of opportunity for contralesional inhibitory stimulation interventions in post-stroke aphasia.

NORTHSTAR TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT02020421.

A Pilot Randomized Controlled Trial of Intermittent Theta Burst Stimulation as Stand-Alone Treatment for Post-Stroke Aphasia: Effects on Language and Verbal Functional Magnetic Resonance Imaging (fMRI)

BACKGROUND There is an ongoing need for facilitating language recovery in chronic post-stroke aphasia. The primary aim of this study (NCT01512264) was to examine if noninvasive intermittent theta burst stimulation (iTBS) applied to the injured left-hemispheric cortex promotes language improvements and fMRI changes in post-stroke aphasia. MATERIAL AND METHODS Participants were randomized to 3 weeks of sham (Tx0) or 1-3 weeks of iTBS (Tx123). We assessed participants who completed the first 2 functional MRI (fMRI) sessions (T1, T2) where they performed 2 overt language fMRI tasks, and examined longitudinal response after 3 months (T3). Language performance and fMRI activation changes, and relationships between these changes were assessed. RESULTS From T1 to T2, both groups showed improvements on the Boston Naming Test (BNT). From T1 to T3, Tx123 improved on the Aphasia Quotient, post-scan word recognition on the verbal paired associates task (VPAT), and perceived communicative ability. Each group exhibited significant activation changes between T1 and T2 for both tasks. Only the Tx123 group exhibited fMRI activation changes between T2 to T3 on the verb-generation task and between T1 and T3 on VPAT. Delayed aphasia symptom improvement for Tx123 was associated with increased left ventral visual stream activation from T1 to T3 (rho=0.74, P=0.0058), and with decreased bilateral supplementary motor area activation related to VPAT encoding from T2 to T3 (rho=-0.80, P=0.0016). CONCLUSIONS Observed iTBS-induced language improvements and associations between delayed fMRI changes and aphasia improvements support the therapeutic and neurorehabilitative potential of iTBS in post-stroke aphasia recovery.

Functional Magnetic Resonance Imaging of Language Following Constraint-Induced Aphasia Therapy Primed with Intermittent Theta Burst Stimulation in 13 Patients with Post-Stroke Aphasia

Background

Aphasia is a debilitating consequence of stroke. This study aimed to investigate the role of functional magnetic resonance imaging (fMRI) activation changes during overt language tasks in promoting language improvements following constraint-induced aphasia therapy (CIAT) primed with intermittent theta burst stimulation (iTBS) in 13 patients with aphasia following ischemic stroke.

Material/Methods

Participants with post-stroke aphasia participated in CIAT primed with iTBS on 10 consecutive weekdays. They also underwent language testing and fMRI while performing overt language tasks at baseline (N=13), immediately post-treatment (N=13), and after 3 months (N=12). Outcome measures were compared between time points, and relationships between changes in language ability and fMRI activation were examined.

Results

We observed improvements in naming (p<0.001), aphasia symptoms (p=0.038), apraxia of speech symptoms (p=0.040), perception of everyday communicative ability (p=0.001), and the number of spoken words produced during fMRI (p=0.028). Pre- to post-treatment change in naming was negatively correlated with change in right postcentral gyrus activation related to noun-verb associations (rho=−0.554, p=0.0497). Change in aphasia symptoms from immediately after to 3 months post-treatment was negatively correlated with change in bilateral supplementary motor area activation related to verbal encoding (rho=−0.790, p=0.0022).

Conclusions

Aphasia improvements coupled with fMRI activation changes over time provide support for treatment-induced neuroplasticity with CIAT primed with iTBS. However, a larger randomized sham-controlled study is warranted to confirm our findings and further our understanding of how iTBS can potentiate beneficial effects of language therapy in post-stroke aphasia.

Predicting language recovery in post-stroke aphasia using behavior and functional MRI

Language outcomes after speech and language therapy in post-stroke aphasia are challenging to predict. This study examines behavioral language measures and resting state fMRI (rsfMRI) as predictors of treatment outcome. Fifty-seven patients with chronic aphasia were recruited and treated for one of three aphasia impairments: anomia, agrammatism, or dysgraphia. Treatment effect was measured by performance on a treatment-specific language measure, assessed before and after three months of language therapy. Each patient also underwent an additional 27 language assessments and a rsfMRI scan at baseline. Patient scans were decomposed into 20 components by group independent component analysis, and the fractional amplitude of low-frequency fluctuations (fALFF) was calculated for each component time series. Post-treatment performance was modelled with elastic net regression, using pre-treatment performance and either behavioral language measures or fALFF imaging predictors. Analysis showed strong performance for behavioral measures in anomia (R² = 0.948, n = 28) and for fALFF predictors in agrammatism (R² = 0.876, n = 11) and dysgraphia (R² = 0.822, n = 18). Models of language outcomes after treatment trained using rsfMRI features may outperform models trained using behavioral language measures in some patient populations. This suggests that rsfMRI may have prognostic value for aphasia therapy outcomes.

Non-invasive brain stimulation as add-on therapy for subacute post-stroke aphasia: a randomized trial (NORTHSTAR)

Introduction

Non-invasive brain stimulation (NIBS) with speech therapy might improve recovery from post-stroke aphasia. This three-armed sham-controlled blinded prospective proof-of-concept study tested 1 Hz subthreshold repetitive transcranial magnetic stimulation (rTMS) and 2-mA cathodal transcranial direct current stimulation (ctDCS) on the right pars triangularis in subacute post-stroke aphasia.

Patients and methods

Sixty-three patients with left middle cerebral artery infarcts were recruited in five hospitals (Canada/United States/Germany, 01-2014/03-2018) and randomized to receive rTMS (N = 20), ctDCS (N = 24) or sham stimulation (N = 19) with ST for 10 days. Primary outcome variables were Z-score changes in naming, semantic fluency and comprehension tests and adverse event frequency. Secondary outcome variable was the percent change in the Unified Aphasia Score. Intention-to-treat analyses tested between-group effects at days 1 and 30 post-treatment with a pre-planned subgroup analysis for lesion location (affecting Broca's area or not).

Results

Naming was significantly improved by rTMS (median = 1.91/interquartile range = 0.77/p = .01) at 30 days versus ctDCS (median = 1.11/interquartile range = 1.51) and sham stimulation (median = 1.02/interquartile range = 1.71). All other primary results were non-significant. The rTMS effect was driven by the patient subgroup with intact Broca's area where NIBS tended to improve UnAS (median = 33.2%/interquartile range = 46.7%/p = .062) versus sham stimulation (median = 12.5%/interquartile range = 7.9%) at day 30. Conversely, in patients with infarcted Broca's area, UnAS tended to improve more with sham stimulation (median = 75.0%/interquartile range = 86.9%/p = .053) versus NIBS (median = 12.7%/interquartile range = 31.7).Conclusion: We found a delayed positive effect of low-frequency rTMS targeting the right pars triangularis on the recovery of naming performance in subacute post-stroke aphasia. This intervention may be beneficial only in patients with morphologically intact Broca's area.

Functional connectivity of language networks after perinatal stroke

Successful language acquisition during development is imperative for lifelong function. Complex language networks develop throughout childhood. Perinatal stroke may cause significant language disabilities but function can also be remarkably normal. Studying such very early brain injury populations may inform developmental plasticity models of language networks. We examined functional connectivity (FC) of language networks in children with arterial and venous perinatal stroke and typically developing controls (TDC) in a population-based, controlled, cohort study. Resting state functional MRI was performed at 3 T (TR/TE = 2000/30 ms, 150 volumes, 3.6mm3 voxels). Seed-based analyses used bilateral inferior frontal and superior temporal gyri. A subset of stroke participants completed clinical language testing. Sixty-six children participated (median age: 12.85±3.8y, range 6-19; arterial N = 17; venous N = 15; TDC N = 34]. Children with left hemisphere strokes had comparable FC in their right hemispheres compared to TDC. Inter- and intra-hemispheric connectivity strengths were similar between TDC and PVI but lower for AIS. Reduced FC was associated with poorer language comprehension. Language networks can be estimated using resting-state fMRI in children with perinatal stroke. Altered connectivity may occur in both hemispheres, is more pronounced with arterial lesions, and is associated with clinical function. Our results have implications for therapeutic language interventions after early stroke.

Aphasia rehabilitation based on mirror neuron theory: a randomized-block-design study of neuropsychology and functional magnetic resonance imaging

When watching someone performs an action, mirror neurons are activated in a way that is very similar to the activation that occurs when actually performing that action. Previous single-sample case studies indicate that hand-action observation training may lead to activation and remodeling of mirror neuron systems, which include important language centers, and may improve language function in aphasia patients. In this randomized-block-design experiment, we recruited 24 aphasia patients from, Zhongda Hospital, Southeast University, China. The patients were divided into three groups where they underwent hand-action observation and repetition, dynamic-object observation and repetition, or conventional speech therapy. Training took place 5 days per week, 35 minutes per day, for 2 weeks. We assessed language function via picture naming tests for objects and actions and the Western Aphasia Battery. Among the participants, one patient, his wife and four healthy student volunteers underwent functional magnetic resonance imaging to analyze changes in brain activation during hand-action observation and dynamic-object observation. Results demonstrated that, compared with dynamic-object observation, hand-action observation led to greater performance with respect to the aphasia quotient and affiliated naming sub-tests and a greater Western Aphasia Battery test score. The overall effect was similar to that of conventional aphasia training, yet hand-action observation had advantages compared with conventional training in terms of vocabulary extraction and spontaneous speech. Thus, hand-action observation appears to more strongly activate the mirror neuron system compared with dynamic-object observation. The activated areas included Broca’s area, Wernicke’s area, and the supramarginal gyrus. These results suggest that hand-action observation combined with repetition might better improve language function in aphasia patients compared with dynamic-object observation combined with repetition. The therapeutic mechanism of this intervention may be associated with activation of additional mirror neuron systems, and may have implications for the possible repair and remodeling of damaged nerve networks. The study protocol was approved by the Ethical Committee of Nanjing Medical University, China (approval number: 2011-SRFA-086) on March 11, 2011. This trial has been registered in the ISRCTN Registry (ISRCTN84827527).

[Regression of post-stroke aphasia and associated non-speech syndromes caused by a course of restorative treatment including intensive speech therapy]

AIM

To analyze clinical and fMRI indicators related with the therapeutic effectiveness of complex restorative treatment including intensive speech therapy in various clinical forms and severity of the aphasia syndrome.

MATERIAL AND METHODS

The study included 40 right-handed patients with aphasia syndrome after the first hemispheric ischemic stroke. Patients were studied 3 month after disease onset. Patients were examined before and after rehabilitation treatment (4.7 weeks) including intensive speech therapy (15 hours of exercise per week). Evaluation of the effectiveness of treatment was carried out based on the dynamics of the results of neuropsychological, neurological and neuroimaging examinations of patients before and after treatment. The degree of recovery of speech and non-speech cognitive functions (based on the 10-point cognitive assessment, the dynamics of focal neurological deficit (NIHSS) and functional recovery of patients (Barthel index, modified Rankin scale) were assessed. Neuroimaging methods included structural MRI and two fMRI methods: fMRI resting state and fMRI equivalent of the evoked potentials of mismatch negativity (HP), using a sequence of standard and deviant sounds (Russian phonemes) to obtain the equivalent of HP. For statistical calculations, the program in Python version 3.6.0 was used.

RESULTS

The maximum efficacy of restorative treatment (≥15% improvement in the scores of 10-point quantifying) was detected in 28 (70%) cases: 18 patients with initially severe and 10 patients with moderate aphasia, regardless of the clinical form of aphasia, and 11 patients with isolated sensory aphasia. Regression of speech and non-speech cognitive impairments in sensory aphasia was accompanied by a pronounced activation of intact speech homologues of the right hemisphere and the appearance of a small temporal and parietal region, which was small in volume and weak in intensity, similar in the localization to the norm. Regardless of the clinical form of aphasia, maximum therapeutic efficacy was accompanied by a reorganization of the speech neuronal rest network, which includes enhancement of both intra- and interhemispheric functional connectivity, with the predominance of amplification of the intra-hemispheric interactions of the posterior speech zones to the left while reducing their interhemispheric connectivity. Significant improvement in motor and sensory functions was detected in 9 (22%) patients with moderate contralateral spastic hemiparesis (p≤0.00) and did not correlate with the degree of regression of speech and non-speech focal cognitive impairments. A slight therapeutic effect was observed in 12 (30%) patients with mild to moderate speech and non-speech cognitive impairment. This effect was not correlated with a specific clinical form of aphasia.

CONCLUSION

The maximum effectiveness of the 4.7 week restorative inpatient treatment, including intensive speech therapy (15 sessions per week), was obtained mainly with severe aphasia, and also with a specific clinical form - isolated sensory aphasia. According to the fMRI data, various compensatory reorganization of the neural speech network was detected, which probably reflects post stroke neuroplasticity associated with both the severity of aphasia and its specific clinical form.

Further Evidence of the Positive Influence of Repetitive Transcranial Magnetic Stimulation on Speech and Language in Patients with Aphasia after Stroke: Results from a Double-Blind Intervention with Sham Condition

BACKGROUND

After a stroke, up to 20% of patients suffer from aphasia. The preferred treatment for stroke-related aphasia (SRA) is regular speech and language training (SLT). In the present study, we investigated to what extent adjuvant repetitive transcranial magnetic stimulation (rTMS) might enhance recovery. While there is growing evidence of the positive effect of adjuvant rTMS on aphasia, no study has yet been based on an Iranian sample.

METHOD

A total of 12 patients (mean age: 55 years; right-handed; 7 women) underwent treatment for SRA 1 month after stroke. The standard treatment consisted of regular 45-min SLT sessions 5 times a week for 2 consecutive weeks. Additionally, patients were randomly assigned either to adjuvant rTMS (5 times a week for 30 min) or to a sham condition (5 times a week for 30 min). At baseline and after 2 weeks of intervention, the degree of aphasia was assessed with the Farsi version of the Western Aphasia Battery. rTMS was applied to the inferior posterior frontal gyrus of the right hemisphere.

RESULTS

Speech and language improved over time, but more so in the rTMS than in the sham condition. Large effect sizes were observed for content, fluency, and the aphasia quotient; medium effect sizes were observed for command comprehension and repetition, while effect sizes were small for auditory comprehension and naming.

CONCLUSIONS

Among patients with SRA, compared to a sham condition, adjuvant rTMS improved speech and language skills. The present results add to the accumulating evidence that rTMS as a neuromodulation technique has the capacity to enhance the effect of conventional SLT.

Treatment of dysphasia with rTMS and language therapy after childhood stroke: Multimodal imaging of plastic change

Expressive dysphasia accompanies left inferior frontal gyrus (IFG/Broca) injury. Recovery may relate to interhemispheric balance with homologous, contralesional IFG but is unexplored in children. We evaluated effects of inhibitory rTMS to contralesional IFG combined with intensive speech therapy (SLT). A 15year-old, right-handed male incurred a left middle cerebral artery stroke. After 30months, severe non-fluent dysphasia impacted quality of life. Language networks, neuronal metabolism and white matter pathways were explored using MRI. Language function was measured longitudinally. An intensive SLT program was combined with contralesional inhibitory rTMS of right pars triangularis. Procedures were well tolerated. Language function improved persisting to four months. Post-treatment fMRI demonstrated increased left perilesional IFG activations and connectivity at rest. Bilateral changes in inositol and glutamate metabolism were observed. Contralesional, inhibitory rTMS appears safe in childhood stroke-induced dysphasia. We observed clinically significant improvements after SLT coupled with rTMS. Advanced neuroimaging can evaluate intervention-induced plasticity.

Piracetam for Aphasia in Post-stroke Patients: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Aphasia is a common symptom in post-stroke patients. Piracetam is a commonly used nootropic agent that promises various benefits to brain function, including language improvement.

OBJECTIVE

We performed a systematic review and meta-analysis to assess whether piracetam facilitates the rehabilitation of language performance in post-stroke patients.

METHODS

Randomized controlled trials (RCTs) of piracetam treatment in post-stroke patients published in any language were included, excluding those involving pre-existing cognitive disorders such as dementia and mood disturbances. We searched several databases including PubMed, EMBASE, Cochrane Central, CINAHL, Web of Science, and PsycINFO for RCTs published up to 31 December 2015. We conducted a meta-analysis using RevMan (version 5.3), with standardized mean differences (SMDs) and fixed-effect models, and used StataSE (version 13) for the detection of publication bias. This study has been submitted to PROSPERO, and its registration number is CRD42016034088.

RESULTS

We identified 1180 titles and abstracts, and finally included seven RCTs in this meta-analysis. The number of participants in each study ranged from 19 to 66, summing up to 261 patients overall. The dose of piracetam was consistent while the frequency and time of therapy varied. The assessment of the language at the end of trials showed no significant improvement in overall severity of aphasia [SMD 0.23, 95 % confidence interval (CI) -0.03 to 0.49, P = 0.08], but written language (SMD 0.35, 95 % CI 0.04 to 0.66, P = 0.03) showed pronounced improvement. Subgroup analyses indicated a dissociation of effectiveness between short- and long-term assessment in overall severity (P = 0.008, I (2) = 85.6 %) in terms of tests for subgroup differences, and a mild trend toward dissociation in written subtests (P = 0.30, I (2) = 5.1 %). Funnel plots and Egger's test identified no obvious publication bias in the primary variable.

CONCLUSIONS

Piracetam plays a limited role in the rehabilitation of overall language impairment and only benefits written language ability at the end of trials. Its effect on overall linguistic level and written language tends to emerge within a short period and declines thereafter.

The role of the supplementary motor area for speech and language processing

Apart from its function in speech motor control, the supplementary motor area (SMA) has largely been neglected in models of speech and language processing in the brain. The aim of this review paper is to summarize more recent work, suggesting that the SMA has various superordinate control functions during speech communication and language reception, which is particularly relevant in case of increased task demands. The SMA is subdivided into a posterior region serving predominantly motor-related functions (SMA proper) whereas the anterior part (pre-SMA) is involved in higher-order cognitive control mechanisms. In analogy to motor triggering functions of the SMA proper, the pre-SMA seems to manage procedural aspects of cognitive processing. These latter functions, among others, comprise attentional switching, ambiguity resolution, context integration, and coordination between procedural and declarative memory structures. Regarding language processing, this refers, for example, to the use of inner speech mechanisms during language encoding, but also to lexical disambiguation, syntax and prosody integration, and context-tracking.

Establishing equivalence of a Chinese version of the stroke specific quality of life measure for stroke survivors

INTRODUCTION

The Stroke Specific Quality of Life Scale is a stroke-specific measure of health-related quality of life. However, there has been no Chinese (Hong Kong) version of the scale.

METHODS

A descriptive study was conducted to examine the reliability, validity and factor structure of the translated version (SSQOL-C) among stroke survivors. Participants completed SSQOL-C, and the Chinese versions of the Medical Outcomes Study Short-Form Health Survey (SF-36), Stroke Self-Efficacy Questionnaire (SSEQ-C) and Frenchay Activities Index (FAI). Thirty of these participants completed the same questionnaires after 4 weeks.

RESULTS

A total of 135 stroke survivors (mean age 58.90 ± 9.75) were recruited. SSQOL-C had good internal consistency with Cronbach's alphas for each domain ranging from 0.63 to 0.90. Most domains had moderate to high correlations with similar dimensions of SF-36, SSEQ-C, FAI and Barthel ADL Index total scores (Spearman's rho: 0.40-0.77, p < 0.01), suggesting acceptable convergent validity. Principal component analyses suggested an 11-factor model in contrast to the 12-factor model for the original scale with six new factors emerging and five original factors retained.

DISCUSSION

The results suggest SSQOL-C is a reliable and valid tool for measuring Chinese stroke survivors' health-related quality of life. More studies are needed to confirm the 11-factor model of the scale. Implications for rehabilitation The translated Chinese version of the Stroke Specific Quality of Life Scale is a reliable and valid tool for measuring Chinese stroke survivors' health-related quality of life. An 11-factor model in contrast to the 12-factor model for the original scale with six new factors emerging and five original factors retained.