Voxel-Based Lesion Analysis of Ideomotor Apraxia.

Ideomotor apraxia is a cognitive disorder most often resulting from acquired brain lesions (i.e., strokes or tumors). Neuroimaging and lesion studies have implicated several brain regions in praxis and apraxia, but most studies have described (sub)acute patients. This study aimed to extend previous research by analyzing data from 115 left hemisphere chronic stroke patients using the praxis subtest of the Western Aphasia Battery, which is divided into four action types: facial, upper limb, complex, and instrumental. Lesion-symptom mapping was used to identify brain regions most critically associated with difficulties in each of the four subtests. Complex and instrumental action deficits were associated with left precentral, postcentral, and superior parietal gyri (Brodmann areas 2, 3, 4, 5, and 6), while the facial and upper limb action deficits maps were restricted to left inferior, middle, and medial temporal gyri (Brodmann areas 20, 21, 22, and 48). We discuss ideas about neuroplasticity and cortical reorganization in chronic stroke and how different methodologies can reveal different aspects of lesion and recovery networks in apraxia.

Data-Driven, Visual Framework for the Characterization of Aphasias Across Stroke, Post-resective, and Neurodegenerative Disorders Over Time.

Aphasia classifications and specialized language batteries differ across the fields of neurodegenerative disorders and lesional brain injuries, resulting in difficult comparisons of language deficits across etiologies. In this study, we present a simplified framework, in which a widely-used aphasia battery captures clinical clusters across disease etiologies and provides a quantitative and visual method to characterize and track patients over time. The framework is used to evaluate populations representing three disease etiologies: stroke, primary progressive aphasia (PPA), and post-operative aphasia. A total of 330 patients across three populations with cerebral injury leading to aphasia were investigated, including 76 patients with stroke, 107 patients meeting criteria for PPA, and 147 patients following left hemispheric resective surgery. Western Aphasia Battery (WAB) measures (Information Content, Fluency, answering Yes/No questions, Auditory Word Recognition, Sequential Commands, and Repetition) were collected across the three populations and analyzed to develop a multi-dimensional aphasia model using dimensionality reduction techniques. Two orthogonal dimensions were found to explain 87% of the variance across aphasia phenotypes and three disease etiologies. The first dimension reflects shared weighting across aphasia subscores and correlated with aphasia severity. The second dimension incorporates fluency and comprehension, thereby separating Wernicke's from Broca's aphasia, and the non-fluent/agrammatic from semantic PPA variants. Clusters representing clinical classifications, including late PPA presentations, were preserved within the two-dimensional space. Early PPA presentations were not classifiable, as specialized batteries are needed for phenotyping. Longitudinal data was further used to visualize the trajectory of aphasias during recovery or disease progression, including the rapid recovery of post-operative aphasic patients. This method has implications for the conceptualization of aphasia as a spectrum disorder across different disease etiology and may serve as a framework to track the trajectories of aphasia progression and recovery.

A valid alternative for in-person language assessments in brain tumor patients: feasibility and validity measures of the new TeleLanguage test.

BACKGROUND: Although language deficits after awake brain surgery are usually milder than post-stroke, postoperative language assessments are needed to identify these. Follow-up of brain tumor patients in certain geographical regions can be difficult when most patients are not local and come from afar. We developed a short telephone-based test for pre- and postoperative language assessments. METHODS: The development of the TeleLanguage Test was based on the Dutch Linguistic Intraoperative Protocol and existing standardized English batteries. Two parallel versions were composed and tested in healthy native English speakers. Subsequently, the TeleLanguage Test was administered in a group of 14 tumor patients before surgery and at 1 week, 1 month, and 3 months after surgery. The test includes auditory comprehension, repetition, semantic selection, sentence or story completion, verbal naming, and fluency tests. It takes less than 20 minutes to administer. RESULTS: Healthy participants had no difficulty performing any of the language tests via the phone, attesting to the feasibility of a phone assessment. In the patient group, all TeleLanguage test scores significantly declined shortly after surgery with a recovery to preoperative levels at 3 months postsurgery for naming and fluency tasks and a recovery to normal levels for the other language tasks. Analysis of the in-person language assessments (until 1 month) revealed a similar profile. CONCLUSION: The use of the TeleLanguage battery to conduct language assessments from afar can provide convenience, might optimize patient care, and enables longitudinal clinical research. The TeleLanguage is a valid tool for various clinical and scientific purposes.

Accuracy of pre-surgical fMRI confirmed by subsequent crossed aphasia.

Atypical patterns of language activation in functional MRI (fMRI) are not unusual, particularly in patients with severe epilepsy. Still, the functional significance of these activations is under debate. We describe a case of a right-handed patient affected by drug-refractory right temporal lobe epilepsy in whom pre-surgical fMRI showed bilateral language activations, greater in the right hemisphere (RH). After surgery, a right subdural hematoma caused epileptic status and severe aphasia. This post-surgical complication of a crossed aphasia confirmed the prior fMRI findings of RH language thus stressing the value of pre-surgical fMRI evaluations, even when surgery is planned in the RH of a right-handed patient.

Abeta amyloid and glucose metabolism in three variants of primary progressive aphasia.

OBJECTIVE: Alzheimer's disease (AD) is found at autopsy in up to one third of patients with primary progressive aphasia (PPA), but clinical features that predict AD pathology in PPA are not well defined. We studied the relationships between language presentation, Abeta amyloidosis, and glucose metabolism in three PPA variants using [11C]-Pittsburgh compound B ([11C]PIB) and [18F]-labeled fluorodeoxyglucose positron emission tomography ([18F]FDG-PET). METHODS: Patients meeting PPA criteria (N = 15) were classified as logopenic aphasia (LPA), progressive nonfluent aphasia (PNFA), or semantic dementia (SD) based on language testing. [11C]PIB distribution volume ratios were calculated using Logan graphical analysis (cerebellar reference). [18F]FDG images were normalized to pons. Partial volume correction was applied. RESULTS: Elevated cortical PIB (by visual inspection) was more common in LPA (4/4 patients) than in PNFA (1/6) and SD (1/5) (p < 0.02). In PIB-positive PPA, PIB uptake was diffuse and indistinguishable from the pattern in matched AD patients (n = 10). FDG patterns were focal and varied by PPA subtype, with left temporoparietal hypometabolism in LPA, left frontal hypometabolism in PNFA, and left anterior temporal hypometabolism in SD. FDG uptake was significant asymmetric (favoring left hypometabolism) in PPA (p < 0.005) but not in AD. INTERPRETATION: LPA is associated with Abeta amyloidosis, suggesting that subclassification of PPA based on language features can help predict the likelihood of AD pathology. Language phenotype in PPA is closely related to metabolic changes that are focal and anatomically distinct between subtypes, but not to amyloid deposition patterns that are diffuse and similar to AD.