A proposed regional hierarchy in recovery of post-stroke aphasia

Brain and Language, v.98, 118-123 (2006)
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    • "These studies have shown that neuroplasticity occurs, so that focal injury may even result in interhemispheric changes. Some studies suggest that the restoration of perilesional networks, which have escaped irreversible damage, is the principal contribution to recovery, and that the role of the contralesional hemisphere is subsidiary, because it is recruited only when the left hemisphere is severely damaged [Heiss and Thiel, 2006]. However, fMRI studies with language tasks performed very early after the stroke event suggest that activation in the intact right hemisphere is related to the long-term outcome [Crinion and Leff, 2007]. "
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    ABSTRACT: Resting-state studies conducted with stroke patients are scarce. First objective was to explore whether patients with good cognitive recovery showed differences in resting-state functional patterns of brain activity when compared to patients with poor cognitive recovery. Second objective was to determine whether such patterns were correlated with cognitive performance. Third objective was to assess the existence of prognostic factors for cognitive recovery. Eighteen right-handed stroke patients and eighteen healthy controls were included in the study. Stroke patients were divided into two groups according to their cognitive improvement observed at three months after stroke. Probabilistic independent component analysis was used to identify resting-state brain activity patterns. The analysis identified six networks: frontal, fronto-temporal, default mode network, secondary visual, parietal, and basal ganglia. Stroke patients showed significant decrease in brain activity in parietal and basal ganglia networks and a widespread increase in brain activity in the remaining ones when compared with healthy controls. When analyzed separately, patients with poor cognitive recovery (n = 10) showed the same pattern as the whole stroke patient group, while patients with good cognitive recovery (n = 8) showed increased activity only in the default mode network and fronto-temporal network, and decreased activity in the basal ganglia. We observe negative correlations between basal ganglia network activity and performance in Semantic Fluency test and Part A of the Trail Making Test for patients with poor cognitive recovery. A reverse pattern was observed between frontal network activity and the abovementioned tests for the same group. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
    Full-text · Article · Aug 2014 · Human Brain Mapping
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    • "Aphasia rehabilitation works, but in some patients with moderate to severe PSA gains may be insufficient (e.g., limited improvement of non-fluency, incomplete recovery of comprehension deficits) or the achieved benefits vanish after interrupting practice. Furthermore, individual recovery from aphasia is a multifactorial process that is contingent on the localization and extension of the lesion (Heiss and Thiel 2006; Lazar et al. 2008) (Fig. 1) as well as on biographical factors of the host (gender, age, educational level, handedness, and so forth) and environment circumstances (family support, occupational and leisure status) (Code 2001; McClung et al. 2010). Of these factors, one "
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    ABSTRACT: This review considers the role of drug therapy in the treatment of post-stroke aphasia, the evidence for efficacy of different agents, and the theory-based explanations of drug-related benefits for aphasia rehabilitation. Pharmacological interventions modulating stroke-induced disruption of diverse neurotransmitters may improve language and communication deficits in aphasic patients through facilitation of brain plasticity and long-term potentiation. However, benefits are not evident for all compounds and refinement in clinical trial designs is required. Some pharmacological trials have failed because drug treatment was not combined with speech-language therapy, while other trials combining drugs with intensive model-driven therapies also failed probably because of short-trial duration, inadequate sample selection, or lack of drug action. Preliminary data reveals that combining neuroscience-based intensive aphasia techniques (constraint-induced aphasia therapy) and drugs acting on cholinergic and glutamatergic neurotransmitter systems are associated with better outcomes than other strategies and long-term maintenance of benefits. Although further studies are needed, current state of the evidence suggests that drug therapy may play a key role in the treatment of post-stroke aphasia.
    Full-text · Article · Sep 2011 · Neuropsychology Review
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    • "Patients with more severe aphasia usually show more extensive lesions and recruit undamaged righthemispheric areas of the language processing network. The latter strategy is associated with less-efficient compensation but nevertheless leads to favourable recovery in some patients (Heiss and Thiel, 2006). Within this context, a big challenge is imposed by the question which brain processes are associated with therapeutically induced improvement of language functions in aphasic patients. "
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    ABSTRACT: The role of the right hemisphere for language processing and successful therapeutic interventions in aphasic patients is a matter of debate. This study explored brain activation in right-hemispheric areas and left-hemispheric perilesional areas in response to language tasks in chronic non-fluent aphasic patients before and after constraint-induced aphasia therapy (CIAT). In particular, we analysed the relation between brain responses and therapy outcome. Using functional magnetic resonance imaging (fMRI), brain activation was measured during word-reading (REA) and word-stem completion (COM) in 16 chronic non-fluent aphasic and 8 healthy subjects. Before therapy, activation in right inferior frontal gyrus/insula (IFG/IC) was stronger in aphasics compared to controls during REA and in precentral gyrus (PCG) during COM. Therapeutic intervention per se did not change brain activation for either task across all aphasic subjects. However, therapeutic success correlated with a relative decrease of activation in right-hemispheric areas, including the IFG/IC. Most importantly, initial activation in right IFG/IC and other right-hemispheric areas correlated positively with subsequent therapy success. Thus, right-hemispheric activation prior to aphasia therapy strongly predicts therapeutic success, suggesting that brain activation in chronic aphasia indicates the patients' potential for further language improvement.
    Full-text · Article · Jun 2008 · Brain
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