A roadmap for research in post-stroke fatigue: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable.

RATIONALE: Fatigue affects almost half of all people living with stroke. Stroke survivors rank understanding fatigue and how to reduce it as one of the highest research priorities. METHODS: We convened an interdisciplinary, international group of clinical and pre-clinical researchers and lived experience experts. We identified four priority areas: (1) best measurement tools for research, (2) clinical identification of fatigue and potentially modifiable causes, (3) promising interventions and recommendations for future trials, and (4) possible biological mechanisms of fatigue. Cross-cutting themes were aphasia and the voice of people with lived experience. Working parties were formed and structured consensus building processes were followed. RESULTS: We present 20 recommendations covering outcome measures for research, development, and testing of new interventions and priority areas for future research on the biology of post-stroke fatigue. We developed and recommend the use of the Stroke Fatigue Clinical Assessment Tool. CONCLUSIONS: By synthesizing current knowledge in post-stroke fatigue across clinical and pre-clinical fields, our work provides a roadmap for future research into post-stroke fatigue.

A roadmap for research in post-stroke fatigue: Consensus-based core recommendations from the third Stroke Recovery and Rehabilitation Roundtable.

RATIONALE: Fatigue affects almost half of all people living with stroke. Stroke survivors rank understanding fatigue and how to reduce it as one of the highest research priorities. METHODS: We convened an interdisciplinary, international group of clinical and pre-clinical researchers and lived experience experts. We identified four priority areas: (1) best measurement tools for research, (2) clinical identification of fatigue and potentially modifiable causes, (3) promising interventions and recommendations for future trials, and (4) possible biological mechanisms of fatigue. Cross-cutting themes were aphasia and the voice of people with lived experience. Working parties were formed and structured consensus building processes were followed. RESULTS: We present 20 recommendations covering outcome measures for research, development, and testing of new interventions and priority areas for future research on the biology of post-stroke fatigue. We developed and recommend the use of the Stroke Fatigue Clinical Assessment Tool. CONCLUSIONS: By synthesizing current knowledge in post-stroke fatigue across clinical and pre-clinical fields, our work provides a roadmap for future research into post-stroke fatigue.

Effects of CPAP on Language Recovery in Post-Stroke Aphasia: A Review of Recent Literature.

Obstructive sleep apnea is highly prevalent in the post-stroke population, and has been shown to affect cognitive, neurological, and functional status. Continuous positive airway pressure (CPAP) treatment is one of the most effective interventions for obstructive sleep apnea, but compliance is often low due to confounding effects of co-occurring conditions, side effects of treatment titration procedures, and individual patient personality characteristics, perceptions, and social factors. Current research suggests that CPAP treatment for obstructive sleep apnea is not associated with significant risk and can subsequently improve post-stroke motor and neurocognitive function. However, effects of CPAP treatment on post-stroke speech and language recovery remain unclear. Post-stroke communication disorders (e.g., aphasia, dysarthria, and apraxia) are also highly prevalent in this population. Knowledge of the potential positive impact of CPAP on language recovery could contribute to patients' motivation to comply with CPAP treatment and provide incentive for speech-language pathologists to refer patients to sleep medicine specialists. In this review of the literature, we examine the question of what effect CPAP treatment may have on post-stroke speech and language function and recovery, as well as summarize the current knowledge on cognitive, neurological, and functional effects. While this review of the literature found CPAP to have varying effects on different cognitive domains, there was not sufficient evidence to determine effects on language recovery. Further research is necessary to determine the potential effects of CPAP treatment on speech and language recovery among stroke patients.

Pervasiveness of speech-language disorders and fatigue in stroke: A systematic scoping review.

BACKGROUND: After a stroke, it is highly likely that an individual will experience substantial fatigue that can significantly affect recovery and function; stroke survivors also have more than a 50% chance of having at least one speech-language disorder. Current reviews of post-stroke fatigue have not provided evidence focused on speech-language disorders or the potential influence they may have on post-stroke fatigue and related recovery. OBJECTIVES: The aim of this review was to determine how speech-language disorders are represented in post-stroke fatigue research and to catalogue methods used to identify speech-language disorders and measure fatigue. METHODS: A systematic scoping review was conducted to identify studies measuring post-stroke fatigue. To identify these studies, a comprehensive literature search was conducted using relevant databases and grey literature sources, followed by several stages of review that adhered to PRISMA guidelines. We evaluated these studies using pre-established eligibility criteria and extracted data regarding the inclusion/exclusion of persons with speech-language disorders and the assessment methods used. RESULTS: The scoping review analysis was conducted on 161 studies. Of these, 41 (26%) excluded all speech-language disorders, 71 (44%) excluded severe speech-language disorders, and 49 (30%) included participants with speech-language disorders. Of the 120 studies that did not explicitly exclude all speech-language disorders, only 34 were confirmed to report data from at least one person with a speech-language disorder. Further, only 5 studies reported data that could be used to determine a relationship between speech-language disorders and fatigue. CONCLUSIONS: Persons with speech-language disorders are underrepresented in post-stroke fatigue research and very few studies have examined the relationship between post-stroke fatigue and speech-language disorders, limiting conclusions that can be drawn. This is problematic because medical professionals relying on this evidence to guide clinical practice are likely to be treating individuals with co-occurring fatigue and speech-language disorders and the current research does not provide enough information about the potential impact of fatigue on speech-language disorders or vice versa. To bridge this gap, we suggest methods of assessment that could provide ways to more accurately 1) reflect the real population in post-stroke fatigue studies, and 2) measure and document fatigue in post-stroke speech-language disorder studies. We also propose the Filter-Funnel Model of Post-Stroke Fatigue, which considers the role of speech-language disorders and communicative demands in the context of post-stroke fatigue.

Relationship Between Physiologically Measured Attention and Behavioral Task Engagement in Persons With Chronic Aphasia.

Purpose Persons with aphasia (PWAs) have been shown to have impaired attention skills that may interfere with their ability to successfully participate in speech and language therapy. Fluctuations in attention can be detected using physiological measures such as electroencephalography (EEG), but these measures can be impractical for clinical use. The primary purpose of this study was to investigate observable behavioral signs of attention as a means of measuring within-session fluctuations in attention by comparing behavioral ratings to physiological changes. Other aims were to understand the relationship between observable behaviors and task performance and to determine whether syntactic complexity influences behavioral attention. Method Ten PWAs and 10 neurologically healthy adults underwent a sentence-reading task with 45 active and 45 passive sentences while video/audio and EEG data were recorded continuously. EEG data for each trial were classified into one of four levels of attention using a classification algorithm (Berka et al., 2004), and video/audio data were scored for accuracy and behavioral engagement by two trained speech-language pathologist students using a behavioral rating scale of inattention (Whyte et al., 1996). Results Results showed that behavioral engagement was significantly correlated with task performance, with higher engagement scores associated with fewer errors. Behavioral engagement did not differ based on syntactic complexity for either group, but PWAs had significantly lower behavioral engagement scores when they were in lower/distracted states of physiologically measured vigilant attention. Conclusion Behavioral observation may provide an alternative means of detecting clinically significant lapses in attention during aphasia therapy.

Sleepiness, Exertion Fatigue, Arousal, and Vigilant Attention in Persons With Chronic Aphasia.

Purpose Individuals in the acute and chronic stages of stroke recovery often report more daytime sleepiness (Sterr, Herron, Dijk, & Ellis, 2008) and fatigue that qualitatively differs from "normal" feelings of fatigue they experienced prestroke (De Doncker, Dantzer, Ormstad, & Kuppuswamy, 2018). Speech-language pathologists frequently observe signs of fatigue in their clients with aphasia and perceive that client fatigue impedes therapeutic interventions (Riley, 2017). The current study aimed to quantify daytime sleepiness, exertion fatigue, and physiologically measured arousal and vigilant attention in persons with aphasia. Method We measured sleepiness, exertion fatigue, arousal, and vigilant attention in 10 participants with aphasia and 10 neurologically healthy adults. Daytime sleepiness was measured using the Epworth Sleepiness Scale (Johns, 1991). Exertion fatigue was measured using the Visual Analog Fatigue Scale (B. Y. Tseng, Gajewski, & Kluding, 2010) before and after a 72-min computer-administered language task. Arousal was measured using heart rate and variability (Shaffer & Ginsberg, 2017). Vigilant attention was measured using electroencephalography and subsequently classified into 1 of 4 levels of vigilant attention using a classification algorithm (Berka et al., 2004). Results Persons with aphasia did not show significant differences from controls in reported amount of daytime sleepiness, exertion fatigue, or overall physiological arousal but demonstrated different patterns of electroencephalography-measured vigilant attention and error production as compared to controls. Conclusions Although overall sleepiness, exertion fatigue, and overall arousal did not differ between groups, physiological measures of vigilant attention may be more sensitive to differences and may explain feelings of fatigue that persons with chronic aphasia experience.

Semantic Typicality Effects in Primary Progressive Aphasia.

Prototypical items within a semantic category are processed faster than atypical items within the same category. This typicality effect reflects normal representation and processing of semantic categories and when absent may be reflective of lexical-semantic deficits. We examined typicality effects in individuals with semantic and nonsemantic variants of primary progressive aphasia (PPA; semantic-PPA-S, agrammatic-PPA-G), a neurodegenerative disorder characterized by specific decline in language function, and age-matched controls. Using a semantic category verification task, where participants were asked to decide whether visual or auditory words (category typical, atypical, or nonmembers) belonged within a specified superordinate category, we found a typicality effect (ie, faster response times for typical vs atypical items) for all participant groups. However, participants with more severe PPA-S did not show a typicality effect in either modality. Findings may reflect increased intracategory semantic blurring as the disease progresses and semantic impairment becomes more severe.

EEG Error Prediction as a Solution for Combining the Advantages of Retrieval Practice and Errorless Learning.

Given the frequency of naming errors in aphasia, a common aim of speech and language rehabilitation is the improvement of naming. Based on evidence of significant word recall improvements in patients with memory impairments, errorless learning methods have been successfully applied to naming therapy in aphasia; however, other evidence suggests that although errorless learning can lead to better performance during treatment sessions, retrieval practice may be the key to lasting improvements. Task performance may vary with brain state (e.g., level of arousal, degree of task focus), and changes in brain state can be detected using EEG. With the ultimate goal of designing a system that monitors patient brain state in real time during therapy, we sought to determine whether errors could be predicted using spectral features obtained from an analysis of EEG. Thus, this study aimed to investigate the use of individual EEG responses to predict error production in aphasia. Eight participants with aphasia each completed 900 object-naming trials across three sessions while EEG was recorded and response accuracy scored for each trial. Analysis of the EEG response for seven of the eight participants showed significant correlations between EEG features and response accuracy (correct vs. incorrect) and error correction (correct, self-corrected, incorrect). Furthermore, upon combining the training data for the first two sessions, the model generalized to predict accuracy for performance in the third session for seven participants when accuracy was used as a predictor, and for five participants when error correction category was used as a predictor. With such ability to predict errors during therapy, it may be possible to use this information to intervene with errorless learning strategies only when necessary, thereby allowing patients to benefit from both the high within-session success of errorless learning as well as the longer-term improvements associated with retrieval practice.

Training Pseudoword Reading in Acquired Dyslexia: A Phonological Complexity Approach.

BACKGROUND: Individuals with acquired phonological dyslexia experience difficulty associating written letters with corresponding sounds, especially in pseudowords. Previous studies have shown that reading can be improved in these individuals by training letter-sound correspondence, practicing phonological skills, or using combined approaches. However, generalization to untrained items is typically limited. AIMS: We investigated whether principles of phonological complexity can be applied to training letter-sound correspondence reading in acquired phonological dyslexia to improve generalization to untrained words. Based on previous work in other linguistic domains, we hypothesized that training phonologically "more complex" material (i.e., consonant clusters with small sonority differences) would result in generalization to phonologically "less complex" material (i.e., consonant clusters with larger sonority differences), but this generalization pattern would not be demonstrated when training the "less complex" material. METHODS & PROCEDURES: We used a single-participant, multiple baseline design across participants and behaviors to examine phonological complexity as a training variable in five individuals. Based on participants' error data from a previous experiment, a "more complex" onset and a "less complex" onset were selected for training for each participant. Training order assignment was pseudo-randomized and counterbalanced across participants. Three participants were trained in the "more complex" condition and two in the "less complex" condition while tracking oral reading accuracy of both onsets. OUTCOMES & RESULTS: As predicted, participants trained in the "more complex" condition demonstrated improved pseudoword reading of the trained cluster and generalization to pseudowords with the untrained, "simple" onset, but not vice versa. CONCLUSIONS: These findings suggest phonological complexity can be used to improve generalization to untrained phonologically related words in acquired phonological dyslexia. These findings also provide preliminary support for using phonological complexity theory as a tool for designing more effective and efficient reading treatments for acquired dyslexia.

Training verb argument structure production in agrammatic aphasia: behavioral and neural recovery patterns.

INTRODUCTION: Neuroimaging and lesion studies indicate a left hemisphere network for verb and verb argument structure processing, involving both frontal and temporoparietal brain regions. Although their verb comprehension is generally unimpaired, it is well known that individuals with agrammatic aphasia often present with verb production deficits, characterized by an argument structure complexity hierarchy, indicating faulty access to argument structure representations for production and integration into syntactic contexts. Recovery of verb processing in agrammatism, however, has received little attention and no studies have examined the neural mechanisms associated with improved verb and argument structure processing. In the present study we trained agrammatic individuals on verbs with complex argument structure in sentence contexts and examined generalization to verbs with less complex argument structure. The neural substrates of improved verb production were examined using functional magnetic resonance imaging (fMRI). METHODS: Eight individuals with chronic agrammatic aphasia participated in the study (four experimental and four control participants). Production of three-argument verbs in active sentences was trained using a sentence generation task emphasizing the verb's argument structure and the thematic roles of sentential noun phrases. Before and after training, production of trained and untrained verbs was tested in naming and sentence production and fMRI scans were obtained, using an action naming task. RESULTS: Significant pre- to post-training improvement in trained and untrained (one- and two-argument) verbs was found for treated, but not control, participants, with between-group differences found for verb naming, production of verbs in sentences, and production of argument structure. fMRI activation derived from post-treatment compared to pre-treatment scans revealed upregulation in cortical regions implicated for verb and argument structure processing in healthy controls. CONCLUSIONS: Training verb deficits emphasizing argument structure and thematic role mapping is effective for improving verb and sentence production and results in recruitment of neural networks engaged for verb and argument structure processing in healthy individuals.

Semantic Typicality Effects in Acquired Dyslexia: Evidence for Semantic Impairment in Deep Dyslexia.

BACKGROUND: Acquired deep dyslexia is characterized by impairment in grapheme-phoneme conversion and production of semantic errors in oral reading. Several theories have attempted to explain the production of semantic errors in deep dyslexia, some proposing that they arise from impairments in both grapheme-phoneme and lexical-semantic processing, and others proposing that such errors stem from a deficit in phonological production. Whereas both views have gained some acceptance, the limited evidence available does not clearly eliminate the possibility that semantic errors arise from a lexical-semantic input processing deficit. AIMS: To investigate semantic processing in deep dyslexia, this study examined the typicality effect in deep dyslexic individuals, phonological dyslexic individuals, and controls using an online category verification paradigm. This task requires explicit semantic access without speech production, focusing observation on semantic processing from written or spoken input. METHODS #ENTITYSTARTX00026; PROCEDURES: To examine the locus of semantic impairment, the task was administered in visual and auditory modalities with reaction time as the primary dependent measure. Nine controls, six phonological dyslexic participants, and five deep dyslexic participants completed the study. OUTCOMES #ENTITYSTARTX00026; RESULTS: Controls and phonological dyslexic participants demonstrated a typicality effect in both modalities, while deep dyslexic participants did not demonstrate a typicality effect in either modality. CONCLUSIONS: These findings suggest that deep dyslexia is associated with a semantic processing deficit. Although this does not rule out the possibility of concomitant deficits in other modules of lexical-semantic processing, this finding suggests a direction for treatment of deep dyslexia focused on semantic processing.