Lesion site patterns in severe, nonverbal aphasia to predict outcome with a computer-assisted treatment program

Changes in Language Function and Recovery-Related Prognostic Factors in First-Ever Left Hemispheric Ischemic Stroke

Objective

To investigate longitudinal changes in language function in left-hemispheric ischemic stroke patients as well as factors that influence language recovery until 1 year after stroke onset.

Methods

We analyzed data from 235 patients with first-ever left-hemispheric ischemic stroke. All patients completed the Korean version of the Frenchay Aphasia Screening Test (K-FAST) at 7 days (T1), 3 months (T2), 6 months (T3), and 1 year (T4) after stroke onset. Repeated measures analysis of variance (ANOVA) was used to investigate changes in language function between time points. Subgroup analysis was performed according to the K-FAST scores at T1. Stroke lesion volume was assessed using diffusion tensor images, and involvement of language-related brain regions was examined. Multiple regression analysis was used to analyze factors influencing improvement of K-FAST score.

Results

The K-FAST scores at T1, T2, T3, and T4 differed significantly (p<0.05). In the subgroup analysis, only the severe group showed continuous significant improvement by 1 year. Factors that negatively influenced improvement of language function were the age at onset, initial National Institutes of Health Stroke Scale (NIHSS) score, and initial K-FAST score, whereas education level and stroke lesion volume positively affected recovery. Involvement of language-related brain regions did not significantly influence long-term language recovery after ischemic stroke.

Conclusion

Recovery of language function varied according to the severity of the initial language deficit. The age at stroke onset, education level, initial severity of aphasia, initial NIHSS score, and total stroke lesion volume were found to be important factors for recovery of language function.

Brain-Derived Neurotrophic Factor Genotype-Specific Differences in Cortical Activation in Chronic Aphasia

Purpose The brain-derived neurotrophic factor (BDNF) gene has been shown to be important for synaptic plasticity in animal models. Human research has suggested that BDNF genotype may influence stroke recovery. Some studies have suggested a genotype-specific motor-related brain activation in stroke recovery. However, recovery from aphasia in relation to BDNF genotype and language-related brain activation has received limited attention. We aimed to explore functional brain activation by BDNF genotype in individuals with chronic aphasia. Consistent with findings in healthy individuals and individuals with poststroke motor impairment, we hypothesized that, among individuals with aphasia, the presence of the Met allele of the BDNF gene is associated with reduced functional brain activation compared to noncarriers of the Met allele. Method Eighty-seven individuals with chronic stroke-induced aphasia performed a naming task during functional magnetic resonance imaging scanning and submitted blood or saliva samples for BDNF genotyping. The mean number of activated voxels was compared between groups, and group-based activation maps were directly compared. Neuropsychological testing was conducted to compare language impairment between BDNF genotype groups. The Western Aphasia Battery Aphasia Quotient (Kertesz, 2007) was included as a covariate in all analyses. Results While lesion size was comparable between groups, the amount of activation, quantified as the number of activated voxels, was significantly greater in noncarriers of the Met allele (whole brain: 98,500 vs. 28,630, p < .001; left hemisphere only: 37,209 vs. 7,000, p < .001; right hemisphere only: 74,830 vs. 30,630, p < .001). This difference was most strongly expressed in the right hemisphere posterior temporal area, pre- and postcentral gyrus, and frontal lobe, extending into the white matter. Correspondingly, the atypical BDNF genotype group was found to have significantly less severe aphasia (Western Aphasia Battery Aphasia Quotient of 64.2 vs. 54.3, p = .033) and performed better on a naming task (Philadelphia Naming Test [Roach, Schwartz, Martin, Grewal, & Brecher, 1996] score of 74.7 vs. 52.8, p = .047). A region of interest analysis of intensity of activation revealed no group differences, and a direct comparison of average activation maps across groups similarly yielded null results. Conclusion BDNF genotype mediates cortical brain activation in individuals with chronic aphasia. Correspondingly, individuals carrying the Met allele present with more severe aphasia compared to noncarriers. These findings warrant further study into the effects of BDNF genotype in aphasia. Supplemental Material https://doi.org/10.23641/asha.10073147 Presentation Video https://doi.org/10.23641/asha.10257581.

Advances in neurocognitive rehabilitation research from 1992 to 2017: The ascension of neural plasticity

OBJECTIVE

The last 25 years have seen profound changes in neurocognitive rehabilitation that continue to motivate its evolution. Although the concept of nervous system plasticity was discussed by William James (1890), the foundation for experience-based plasticity had not reached the critical empirical mass to seriously impact rehabilitation research until after 1992. The objective of this review is to describe how the emergence of neural plasticity has changed neurocognitive rehabilitation research.

METHOD

The important developments included (a) introduction of a widely available tool that could measure brain plasticity (i.e., functional MRI); (b) development of new structural imaging techniques that could define limits of and opportunities for neural plasticity; (c) deployment of noninvasive brain stimulation to leverage neural plasticity for rehabilitation; (d) growth of a literature indicating that exercise has positively impacts neural plasticity, especially for older persons; and (e) enhancement of neural plasticity by creating interventions that generalize beyond the boundaries of treatment activities. Given the massive literature, each of these areas is developed by example.

RESULTS

The expanding influence of neural plasticity has provided new models and tools for neurocognitive rehabilitation in neural injuries and disorders, as well as methods for measuring neural plasticity and predicting its limits and opportunities. Early clinical trials have provided very encouraging results.

CONCLUSION

Now that neural plasticity has gained a firm foothold, it will continue to influence the evolution of neurocognitive rehabilitation research for the next 25 years and advance rehabilitation for neural injuries and disease. (PsycINFO Database Record

Semantic memory retrieval circuit: role of pre-SMA, caudate, and thalamus

We propose that pre-supplementary motor area (pre-SMA)-thalamic interactions govern processes fundamental to semantic retrieval of an integrated object memory. At the onset of semantic retrieval, pre-SMA initiates electrical interactions between multiple cortical regions associated with semantic memory subsystems encodings as indexed by an increase in theta-band EEG power. This starts between 100-150 ms after stimulus presentation and is sustained throughout the task. We posit that this activity represents initiation of the object memory search, which continues in searching for an object memory. When the correct memory is retrieved, there is a high beta-band EEG power increase, which reflects communication between pre-SMA and thalamus, designates the end of the search process and resultant in object retrieval from multiple semantic memory subsystems. This high beta signal is also detected in cortical regions. This circuit is modulated by the caudate nuclei to facilitate correct and suppress incorrect target memories.

IMITATE: An intensive computer-based treatment for aphasia based on action observation and imitation

BACKGROUND: Neurophysiological evidence from primates has demonstrated the presence of mirror neurons, with visual and motor properties, that discharge both when an action is performed and during observation of the same action. A similar system for observation-execution matching may also exist in humans. We postulate that behavioral stimulation of this parietal-frontal system may play an important role in motor learning for speech and thereby aid language recovery after stroke. AIMS: The purpose of this article is to describe the development of IMITATE, a computer-assisted system for aphasia therapy based on action observation and imitation. We also describe briefly the randomized controlled clinical trial that is currently underway to evaluate its efficacy and mechanism of action. METHODS AND PROCEDURES: IMITATE therapy consists of silent observation of audio-visually presented words and phrases spoken aloud by six different speakers, followed by a period during which the participant orally repeats the stimuli. We describe the rationale for the therapeutic features, stimulus selection, and delineation of treatment levels. The clinical trial is a randomized single blind controlled trial in which participants receive two pre-treatment baseline assessments, six weeks apart, followed by either IMITATE or a control therapy. Both treatments are provided intensively (90 minutes per day). Treatment is followed by a post-treatment assessment, and a six-week follow-up assessment. OUTCOMES #ENTITYSTARTX00026; RESULTS: Thus far, five participants have completed IMITATE. We expect the results of the randomized controlled trial to be available by late 2010. CONCLUSIONS: IMITATE is a novel computer-assisted treatment for aphasia that is supported by theoretical rationales and previous human and primate data from neurobiology. The treatment is feasible, and preliminary behavioral data are emerging. However, the results will not be known until the clinical trial data are available to evaluate fully the efficacy of IMITATE and to inform theoretically about the mechanism of action and the role of a human mirror system in aphasia treatment.

Lesion characteristics related to treatment improvement in object and action naming for patients with chronic aphasia

Few studies have examined the relationship between degree of lesion in various locations and improvement during treatment in stroke patients with chronic aphasia. The main purpose of this study was to determine whether the degree of lesion in specific brain regions was related to magnitude of improvement over the course of object and action naming treatments.

PARTICIPANTS AND METHODS

Fifteen left hemisphere stroke patients with aphasia participated in treatments for object and/or action naming. Two raters assessed extent of lesion in 18 left hemisphere cortical and subcortical regions of interest (ROIs) on CT or MRI scans. Correlations were calculated between composite basal ganglia, anterior cortical, and posterior cortical lesion ratings, on the one hand, and both pretreatment scores and treatment change for both object and action naming, on the other hand.

RESULTS

Unexpectedly, greater anterior cortical lesion extent was highly correlated with better object and action naming scores prior to treatment and with greater improvement during treatment when partial correlations controlled for total basal ganglia lesion extent (r ranging from .730 to .858). Greater total basal ganglia lesion extent was highly correlated with worse object and action naming scores prior to treatment and with less improvement during treatment when partial correlations controlled for total anterior lesion extent (r ranging from -.623 to -.785). Correlations between degree of posterior cortical lesion and naming indices generally were not significant. No consistent differences were found between the correlations of ROI lesion ratings with object naming versus action naming scores.

CONCLUSION

Large anterior cortical lesions and intactness of the basal ganglia may both contribute to more efficient reorganization of language functions.

An intention manipulation to change lateralization of word production in nonfluent aphasia: current status

A review of recent aphasia literature indicates that both the left and right hemispheres participate, under various circumstances, in recovery of language and in treatment response. In chronic aphasias with large lesions and poor recovery of function, the right hemisphere is more likely to demonstrate prominent activity than in cases with small lesions and good recoveries. Extraneous activity during language tasks for aphasia patients may occur in both the left and right hemispheres. Right hemisphere activity during language in aphasia patients is likely to occur in structures homologous to damaged left hemisphere structures. When the left hemisphere is so damaged as to preclude a good recovery, recruitment of right-hemisphere mechanisms in the service of rehabilitation may be desirable. Hence a treatment with an intention manipulation (complex left-hand movement) was developed for nonfluent aphasia to assist in relateralization of language production. A review of existing evidence indicates that the intention manipulation adds value to naming treatments and helps shift lateralization of language production to right frontal structures. However, wholesale transfer of language function to the right hemisphere does not occur, and residual language knowledge in the left hemisphere also seems vital for relearning of word production. Further research is needed to understand fully the contribution of the intention manipulation to treatment response.

Functional MRI of language in aphasia: a review of the literature and the methodological challenges

Animal analogue studies show that damaged adult brains reorganize to accommodate compromised functions. In the human arena, functional magnetic resonance imaging (fMRI) and other functional neuroimaging techniques have been used to study reorganization of language substrates in aphasia. The resulting controversy regarding whether the right or the left hemisphere supports language recovery and treatment progress must be reframed. A more appropriate question is when left-hemisphere mechanisms and when right-hemisphere mechanisms support recovery of language functions. Small lesions generally lead to good recoveries supported by left-hemisphere mechanisms. However, when too much language eloquent cortex is damaged, right-hemisphere structures may provide the better substrate for recovery of language. Some studies suggest that recovery is particularly supported by homologues of damaged left-hemisphere structures. Evidence also suggests that under some circumstances, activity in both the left and right hemispheres can interfere with recovery of function. Further research will be needed to address these issues. However, daunting methodological problems must be managed to maximize the yield of future fMRI research in aphasia, especially in the area of language production. In this review, we cover six challenges for imaging language functions in aphasia with fMRI, with an emphasis on language production: (1) selection of a baseline task, (2) structure of language production trials, (3) mitigation of motion-related artifacts, (4) the use of stimulus onset versus response onset in fMRI analyses, (5) use of trials with correct responses and errors in analyses, and (6) reliability and stability of fMRI images across sessions. However, this list of methodological challenges is not exhaustive. Once methodology is advanced, knowledge from conceptually driven fMRI studies can be used to develop theoretically driven, mechanism-based treatments that will result in more effective therapy and to identify the best patient candidates for specific treatments. While the promise of fMRI in the study of aphasia is great, there is much work to be done before this technique will be a useful clinical tool.

Neural substrates of syntactic mapping treatment: an fMRI study of two cases

Two patients (G01, J02) with chronic nonfluent aphasia and sentence production deficits received syntactic mapping treatment to improve sentence production. The patients had dramatically different outcomes in that improved syntax production generalized to nontreatment tasks for G01, but not for JO2. To learn how treatment influenced the neural substrates for syntax production, both patients underwent pre- and posttreatment functional magnetic resonance imaging (fMRI) of sentence generation. G01 showed more robust activity posttreatment than pretreatment in Broca's area; ventral temporal activity decreased slightly from pre- to posttreatment. Comparison of J02's pretreatment and posttreatment images revealed little change, although activity was more diffuse pre- than posttreatment. Findings suggest that for G01, rehabilitation led to engagement of an area (Broca's area) used minimally during the pretreatment scan, whereas for J02, rehabilitation may have led to more efficient use of areas already involved in sentence generation during the pretreatment scan. fMRI findings are discussed in the context of sentence-production outcome and generalization.

Improved naming after TMS treatments in a chronic, global aphasia patient--case report

We report improved ability to name pictures at 2 and 8 months after repetitive transcranial magnetic stimulation (rTMS) treatments to the pars triangularis portion of right Broca's homologue in a 57 year-old woman with severe nonfluent/global aphasia (6.5 years post left basal ganglia bleed, subcortical lesion). TMS was applied at 1 Hz, 20 minutes a day, 10 days, over a two-week period. She received no speech therapy during the study. One year after her TMS treatments, she entered speech therapy with continued improvement. TMS may have modulated activity in the remaining left and right hemisphere neural network for naming.

Test-retest reliability of fMRI during nonverbal semantic decisions in moderate-severe nonfluent aphasia patients

Cortical reorganization in poststroke aphasia is not well understood. Few studies have investigated neural mechanisms underlying language recovery in severe aphasia patients, who are typically viewed as having a poor prognosis for language recovery. Although test-retest reliability is routinely demonstrated during collection of language data in single-subject aphasia research, this is rarely examined in fMRI studies investigating the underlying neural mechanisms in aphasia recovery.

The purpose of this study was to acquire fMRI test-retest data examining semantic decisions both within and between two aphasia patients. Functional MRI was utilized to image individuals with chronic, moderate-severe nonfluent aphasia during nonverbal, yes/no button-box semantic judgments of iconic sentences presented in the Computer-assisted Visual Communication (C-ViC) program. We investigated the critical issue of intra-subject reliability by exploring similarities and differences in regions of activation during participants' performance of identical tasks twice on the same day. Each participant demonstrated high intra-subject reliability, with response decrements typical of task familiarity. Differences between participants included greater left hemisphere perilesional activation in the individual with better response to C-ViC training. This study provides fMRI reliability in chronic nonfluent aphasia, and adds to evidence supporting differences in individual cortical reorganization in aphasia recovery.

Intraoperative mapping of the subcortical language pathways using direct stimulations. An anatomo-functional study

Functional neuroimaging has improved pre-planning of surgery in eloquent cortical areas, but remains unable to map white matter. Thus, tumour resection in functional subcortical regions still presents a high risk of sequelae. The authors successfully used intraoperative electrical stimulations to perform subcortical language pathway mapping in order to avoid postoperative definitive deficit, and correlated these functional findings with the anatomical location of the eloquent bundles detected using postoperative MRI. At the same time, this also improved knowledge of fibre connectivity. Thirty patients harbouring a cortico-subcortical low-grade glioma in the left dominant hemisphere were operated on whilst awake using intraoperative electrical functional mapping during surgical resection. Language cortical sites and subcortical pathways were clearly identified and preserved in the 30 cases. The anatomo-functional correlations between data obtained using intraoperative subcortical mapping and postoperative MRI revealed the existence in all patients of common pathways which seem essential to language. This was shown by inducing reproducible speech disturbances during stimulations as follows: the subcallosal fasciculus (initiation disorders), the periventricular white matter (dysarthria), the arcuate fasciculus and the insular connections (anomia). Clinically, all patients except three presented a transient postoperative dysphasia, which resolved within 3 months. On control MRI, 14 resections were total and 16 subtotal due to infiltration of functional bundles described above. It is recommended that the combination of the techniques as described could prove ideal for future non-invasive reliable subcortical mapping both in healthy volunteers and in patients harbouring a (cortico)subcortical lesion in order to optimize surgical pre-planning.

Neuroimaging of recovery of function after stroke: implications for rehabilitation

Stroke is a leading cause of morbidity and mortality in individuals. Many patients have good functional recovery after stroke. The mechanisms of recovery remain largely unknown. Neuroimaging of patients recovering from stroke may provide important insight into the mechanisms of recovery as well as assist in the development of new rehabilitation techniques. The first part of this article reviews previous neuroimaging studies that have monitored the reorganization within the motor and language areas after stroke. In the second section, a unifying theory based on John Hughlings Jackson's "Principles of Compensation" is presented as a possible theory for recovery of function. In the final portion of the article, possible implications and future applications of neuroimaging studies for rehabilitation are presented.

Improving outcomes for persons with aphasia in advanced community-based treatment programs

BACKGROUND AND PURPOSE

Studies have yet to document that community-based aphasia treatment programs routinely produce results comparable or superior to published research protocols. We explore this issue here in an outcome study of individuals with aphasia enrolled in 2 community-based, comparably managed and equipped therapy programs, which use a specially designed computer-based tool that is employed therapeutically in adherence to an extensive, detailed, and formally trained patient care algorithm.

METHODS

Patients (n=60) were assessed before and after treatment with standardized instruments at both the impairment and the disability levels. Pretreatment and posttreatment means were calculated and compared, with statistical significance of differences established with the use of 1-tailed matched t tests. One-way ANOVAs were used to analyze the comparability of patient performance changes among various subgroups, eg, patients in acute versus chronic stages of aphasia, patients by aphasia diagnostic type at start of care, patients by severity level at start of care, and patients by treatment location.

RESULTS

Analysis shows that patients spanned a wide range of aphasia diagnostic types, impairment severity levels at start of care, and times after onset. Patients' mean performance scores improved significantly in response to treatment in all measures assessed at both the impairment level and the functional communication level. Mean overall improvements ranged from 6.6% to 19.8%, with statistical significance ranging from P=0.0006 to P<0.0001. ANOVAs revealed no significant differences between improvements in patients in the acute versus chronic stages of aphasia, between those at different impairment severity levels at start of care, between those treated at different locations, or, at the functional level, between those with different diagnostic types of aphasia at start of care.

CONCLUSIONS

Measures of both language impairment and functional communication can be broadly, positively, and significantly influenced by therapy services that are delivered to persons with aphasia in these community-based programs. The significant improvements are shown to be available to individuals with chronic as well as acute aphasia and independent of diagnostic type of aphasia, impairment severity at start of care, or geographic program location.