The association of aphasia and right-sided motor impairment in corticobasal syndrome

Neuroplasticity Following Stroke from a Functional Laterality Perspective: A fNIRS Study

To explore alterations of resting-state functional connectivity (rsFC) in sensorimotor cortex following strokes with left or right hemiplegia considering the lateralization and neuroplasticity. Seventy-three resting-state functional near-infrared spectroscopy (fNIRS) files were selected, including 26 from left hemiplegia (LH), 21 from right hemiplegia (RH) and 26 from normal controls (NC) group. Whole-brain analyses matching the Pearson correlation were used for rsFC calculations. For right-handed normal controls, rsFC of motor components (M1 and M2) in the left hemisphere displayed a prominent intensity in comparison with the right hemisphere (p < 0.05), while for stroke groups, this asymmetry has disappeared. Additionally, RH rather than LH showed stronger rsFC between left S1 and left M1 in contrast to normal controls (p < 0.05), which correlated inversely with motor function (r = - 0.53, p < 0.05). Regarding M1, rsFC within ipsi-lesioned M1 has a negative correlation with motor function of the affected limb (r = - 0.60 for the RH group and - 0.43 for the LH group, p < 0.05). The rsFC within contra-lesioned M1 that innervates the normal side was weakened compared with that of normal controls (p < 0.05). Stronger rsFC of motor components in left hemisphere was confirmed by rs-fNIRS as the "secret of dominance" for the first time, while post-stroke hemiplegia broke this cortical asymmetry. Meanwhile, a statistically strengthened rsFC between left S1 and M1 only in right-hemiplegia group may act as a compensation for the impairment of the dominant side. This research has implications for brain-computer interfaces synchronizing sensory feedback with motor performance and transcranial magnetic regulation for cortical excitability to induce cortical plasticity.

When it is not primary progressive aphasia: A scoping review of spoken language impairment in other neurodegenerative dementias

BACKGROUND

Progressive difficulties with spoken language occur across the spectrum of degenerative dementia. When not a primary presenting and dominant symptom, language difficulties may be overlooked in favor of more prominent cognitive, behavior, or motor deficits. The aim of this scoping review is to examine the extent and nature of the research evidence describing (1) the spoken language impairments found in non-language led dementias, (2) their impact on everyday living, and (3) the reported language interventions.

METHODS

We searched PubMed, MEDLINE, OVID-EMBASE, PsycINFO, and SpeechBITE using terms related to spoken language for the following dementia types: Parkinson's disease dementia (PDD), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), cortico-basal syndrome (CBS), behavior variant frontotemporal dementia (bvFTD), early-onset Alzheimer's disease (EOAD), posterior cortical atrophy (PCA), and motor neuron disease associated with FTD (MND+FTD). Risk of bias was assessed with the QualSyst tool.

RESULTS

Seventy-three eligible studies were included. A wide range of spoken language impairments were reported, involving both linguistic (e.g., syntactic processing) and other cognitive (e.g., sustained attention) underlying mechanisms. Although the severity of these deficits was scarcely reported, in some cases they manifested as non-fluent, dynamic, and global aphasias. No papers in the review described either the impact of these language impairments on everyday living or language therapies to treat them.

DISCUSSION

There is a need to understand better the level of disability produced by language impairment in people living with non-language-led dementias. Our findings suggest three calls for action: (1) research studies should assess the clinical relevance of any spoken language deficits examined, (2) both linguistic and cognitive underlying mechanisms should be fully described (to inform the design of effective language and behavioral interventions), and (3) trials of language therapy should be conducted in those groups of individuals where significant language impairment is proved.

Reduced capacity for empathy in corticobasal syndrome and its impact on carer burden

Corticobasal syndrome (CBS) is clinically characterised by a wide range of motor, cognitive, and behavioural features but remains challenging to diagnose accurately. Despite recent evidence supporting the presence of social cognition and emotion processing disturbances, few studies have explored the nature of empathic ability in CBS. This study aimed to (a) investigate the extent to which cognitive and affective dimensions of empathy are affected in CBS and (b) to determine the impact of such changes on carer burden. Empathic capacity was assessed in 29 CBS patients and 28 matched healthy controls. We employed the Interpersonal Reactivity Index (IRI), an instrument measuring: (a) perspective taking, (b) fantasy, (c) empathic concern, and (d) personal distress. A significant change in both perspective taking and empathic concern was observed in CBS following disease onset. Furthermore, affective empathy deficits in CBS patients predicted higher levels of carer burden. Disturbances in both cognitive and affective empathy are present in CBS and lead to increased levels of carer burden.

Primary progressive aphasia and the FTD-MND spectrum disorders: clinical, pathological, and neuroimaging correlates

Objective: Behavioral variant frontotemporal dementia (bvFTD), is commonly considered the cognitive presentation of the frontotemporal dementia-motor neuron disease (FTD-MND) spectrum disorder. We evaluated the prevalence of primary progressive aphasia in a series of pathologically confirmed cases of FTD-MND spectrum. Methods: Pathologically confirmed cases of frontotemporal lobar degeneration-motor neuron disease (FTLD-MND) were obtained from the UCSF brain bank. Cases were analyzed for presence of language impairment via retrospective chart review of research visits that include neurologic exam, in-depth cognitive testing and magnetic resonance imaging (MRI) imaging. Forty one cases were included. Thirty two were diagnosed with FTD-MND, while nine cases were diagnosed as MND-only from clinical evaluation. Results: Ten FTLD-MND cases (31%) presented with prominent or isolated language involvement consistent with a diagnosis of primary progressive aphasia (PPA), which we called progressive aphasia with motor neuron disease (PA-MND). Of these, three cases that mirrored the non-fluent variant of PPA (nfvPPA) were named nfvPA-MND. The imaging pattern of these nfvPA-MND showed atrophy strictly confined to the frontal and anterior temporal language cortical areas. Another group of seven cases that resembled patients with the semantic variant PPA (svPPA) were named svPA-MND. The group of svPPA-MND on imaging analysis showed selective atrophy of the temporal lobe and orbitofrontal cortex. Conclusions: Language impairment was a frequent phenotype of FTD-MND associated with focal atrophy patterns within the language networks. This data suggest patients with FTD-MND can present quite often with language phenotype of nfvPPA and svPPA, as opposed to exclusive bvFTD symptoms.

The role of the motor system in action naming in patients with neurodegenerative extrapyramidal syndromes

Previous studies of patients with brain damage have suggested a close relationship between aphasia and movement disorders. Neurodegenerative extrapyramidal syndromes associated with cognitive impairment provide an interesting model for studying the neural substrates of cognitive and motor symptoms. In this review, we focused on studies investigating language production abilities in patients with Parkinson's disease (PD), Corticobasal Syndrome (CBS) and Progressive Supranuclear Palsy (PSP). According to some reports, these patients exhibit a reduction in performance in both action and object naming or verb production compared to healthy individuals. Furthermore, a disproportional impairment of action naming compared to object naming was systematically observed in patients with these disorders. The study of these clinical conditions offers the unique opportunity to examine the close link between linguistic features and motor characteristics of action. This particular pattern of language impairment may contribute to the debate on embodiment theory and on the involvement of the basal ganglia in language and in integrating language and movement. From a translational perspective, we suggest that language ability assessments are useful in the clinical work-up, along with neuropsychological and motor evaluations. Specific protocols should be developed in the near future to better characterize language deficits and to permit an early cognitive diagnosis. Moreover, the link between language deficits and motor impairment opens a new issue for treatment approaches. Treatment of one of these two symptoms may ameliorate the other, and treating both may produce a greater improvement in patients' global clinical conditions.

[Pathomechanisms and clinical aspects of frontotemporal lobar degeneration]

BACKGROUND

Frontotemporal lobar degeneration (FTLD) includes a spectrum of heterogeneous clinical and neuropathological diseases. In a strict sense this includes the behavioral variant of frontotemporal dementia (bvFTD) and primary progressive aphasia (PPA) and both variants can be associated with amyotrophic lateral sclerosis (FTD-ALS). In a broader sense FTLD also includes progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). In recent years the strong genetic component of FTLD has become increasingly clear.

OBJECTIVE

The association between clinical presentation, neuropathology, genetics and pathophysiological mechanisms of FTLD are presented.

RESULTS

The diagnostic criteria and tools for the clinical differential diagnosis of FTLD are presented. At autopsy patients show neuronal and glial inclusions of Tau, TDP-43 or FUS. While Tau pathology is often associated with extrapyramidal symptoms, patients with TDP-43 and FUS inclusions often also show signs of ALS. Pathogenic mutations directly increase the aggregation propensity of these proteins or impair protein degradation through autophagy or the proteasome. Pathogenic mutations in most FTLD genes trigger cytoplasmic missorting and aggregation of the RNA-binding protein TDP-43 and thus lead to a nuclear loss of TDP-43 function. Microgliosis and mutations in GRN and TREM2 suggest an important role of neuroinflammation in FTLD.

CONCLUSION

There is still no causal therapy for FTLD but preclinical studies focusing on pathogenic mutations in C9orf72, GRN and Tau may lead to clinical trials soon; therefore, establishing large well characterized patient cohorts is crucial for trial readiness.

Cerebral Glucose Metabolism and Dopaminergic Function in Patients with Corticobasal Syndrome

BACKGROUND AND PURPOSE

The corticobasal syndrome (CBS) is a clinical diagnosis that comprises a group of rare neurodegenerative diseases manifesting in movement disorder and cognitive impairment. While diagnosis is based upon clinical criteria, there have been a number of molecular imaging studies, albeit in rather small cohorts. Therefore, we investigated the pattern of cerebral glucose metabolism, as well as dopamine transporter (DAT) availability in a large and clinically well-defined cohort.

METHODS

Thirty-four patients fulfilling either the Armstrong or the Boeve criteria were assessed with [¹⁸ F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and/or [¹²³ I]-Ioflupane single-photon-emission-computed tomography (SPECT) for DAT availability. A small subset of patients had also undergone D_2/3 receptor imaging. Imaging data were analyzed using both statistical parametric mapping and a volume-of-interest-based approach relative to data from healthy controls.

RESULTS

Significant reductions of the cortical glucose metabolism were observed in the central region and the adjacent frontal and parietal association areas contralateral to the side with predominant motor symptoms. Reductions were also evident in the basal ganglia, notably in the putamen contralateral to the clinically affected side, and in the bilateral thalamus. DAT availability was reduced bilaterally, most distinctly on the side contralateral to the main motor symptoms.

CONCLUSIONS

We replicated and refined earlier findings of impaired glucose metabolism and nigrostriatal degeneration in CBS, highlighting asymmetric cortical and subcortical hypometabolism, symmetrically reduced metabolism in the thalamus, and only a slightly asymmetric reduction in DAT, while D_2/3 receptors seem to be mainly preserved. These results provide systematic evidence for the usefulness of FDG PET and dopaminergic SPECT imaging to characterize CBS.