"Semantic variant primary progressive aphasia" due to comorbidity of Lewy body disease and a previous cerebral venous infarction in the left anterior temporal lobe: A case report

Clinicoradiological and neuropathological evaluation of primary progressive aphasia

BACKGROUND

Primary progressive aphasia (PPA) defines a group of neurodegenerative disorders characterised by language decline. Three PPA variants correlate with distinct underlying pathologies: semantic variant PPA (svPPA) with transactive response DNA-binding protein of 43 kD (TDP-43) proteinopathy, agrammatic variant PPA (agPPA) with tau deposition and logopenic variant PPA (lvPPA) with Alzheimer's disease (AD). Our objectives were to differentiate PPA variants using clinical and neuroimaging features, assess progression and evaluate structural MRI and a novel 18-F fluorodeoxyglucose positron emission tomography (FDG-PET) image decomposition machine learning algorithm for neuropathology prediction.

METHODS

We analysed 82 autopsied patients diagnosed with PPA from 1998 to 2022. Clinical histories, language characteristics, neuropsychological results and brain imaging were reviewed. A machine learning framework using a k-nearest neighbours classifier assessed FDG-PET scans from 45 patients compared with a large reference database.

RESULTS

PPA variant distribution: 35 lvPPA (80% AD), 28 agPPA (89% tauopathy) and 18 svPPA (72% frontotemporal lobar degeneration-TAR DNA-binding protein (FTLD-TDP)). Apraxia of speech was associated with 4R-tauopathy in agPPA, while pure agrammatic PPA without apraxia was linked to 3R-tauopathy. Longitudinal data revealed language dysfunction remained the predominant deficit for patients with lvPPA, agPPA evolved to corticobasal or progressive supranuclear palsy syndrome (64%) and svPPA progressed to behavioural variant frontotemporal dementia (44%). agPPA-4R-tauopathy exhibited limited pre-supplementary motor area atrophy, lvPPA-AD displayed temporal atrophy extending to the superior temporal sulcus and svPPA-FTLD-TDP had severe temporal pole atrophy. The FDG-PET-based machine learning algorithm accurately predicted clinical diagnoses and underlying pathologies.

CONCLUSIONS

Distinguishing 3R-taupathy and 4R-tauopathy in agPPA may rely on apraxia of speech presence. Additional linguistic and clinical features can aid neuropathology prediction. Our data-driven brain metabolism decomposition approach effectively predicts underlying neuropathology.

Dyslexia and dysgraphia of primary progressive aphasia in Chinese: A systematic review

Introduction

Currently, little is known about Chinese-speaking primary progressive aphasia (PPA) patients compared to patients who speak Indo-European languages. We examined the demographics and clinical manifestations, particularly reading and writing characteristics, of Chinese patients with PPA over the last two decades to establish a comprehensive profile and improve diagnosis and care.

Methods

We reviewed the demographic features, clinical manifestations, and radiological features of Chinese-speaking PPA patients from 56 articles published since 1994. We then summarized the specific reading and writing errors of Chinese-speaking patients.

Results

The average age of onset for Chinese-speaking patients was in their early 60's, and there were slightly more male patients than female patients. The core symptoms and images of Chinese-speaking patients were similar to those of patients who speak Indo-European languages. Reading and writing error patterns differed due to Chinese's distinct tone and orthography. The types of reading errors reported in Chinese-speaking patients with PPA included tonal errors, regularization errors, visually related errors, semantic errors, phonological errors, unrelated errors, and non-response. Among these errors, regularization errors were the most common in semantic variant PPA, and tonal errors were specific to Chinese. Writing errors mainly consisted of non-character errors (stroke, radical/component, visual, pictograph, dyskinetic errors, and spatial errors), phonologically plausible errors, orthographically similar errors, semantic errors, compound word errors, sequence errors, unrelated errors, and non-response.

Conclusion

This paper provides the latest comprehensive demographic information and unique presentations on the reading and writing of Chinese-speaking patients with PPA. More detailed studies are needed to address the frequency of errors in reading and writing and their anatomical substrates.

Comorbid Neurodegeneration in Primary Progressive Aphasia: Clinicopathological Correlations in a Single-Center Study

Introduction. Primary progressive aphasia (PPA) is a clinically variable syndrome manifesting as slow progressive loss of speech and language with multiple underlying neurodegenerative pathologies. Materials and Methods. We included data from nine PPA patients with available autopsies. We then retrospectively reviewed all available medical records, neuropsychology, and MRI results to confirm the corresponding subtypes of PPA and compared them with postmortem neuropathological results. Results. Clinical presentations corresponded to the nonfluent/agrammatic variant in six cases, the semantic variant in one case, the logopenic variant in one case, and the mixed variant (concomitant nonfluent/agrammatic plus semantic variant) in one case. Patients with a broader clinical presentation, i.e., combining manifestations of one PPA subtype and symptoms of another PPA variant, had autopsy comorbidities showing multiple neurodegenerative disorders. Of the nine subjects enrolled in the study, Alzheimer’s disease (AD) was found in eight cases; however, in only one case, AD was detected as an isolated neuropathological substrate of PPA. In eight brain samples, different comorbid neuropathologies were detected: three cases with comorbid AD and dementia with Lewy bodies, two cases with comorbid AD and TDP-43 pathology, one case with comorbid AD and complex tauopathies, and one case with comorbid AD with both tau and TDP-43 deposits. Finally, one case had comorbid tau and TDP-43 pathology but without comorbid AD pathology. Conclusions. Our observation suggests that PPA cases could be more heterogeneous in their etiology than previously thought and underlying neurodegenerative comorbidities should be considered in routine practice, especially if the clinical presentation of PPA is atypical.

Diffuse Lewy body disease presenting as Parkinson's disease with progressive aphasia

Primary progressive aphasia (PPA) is a progressive language disorder often due to an underlying neurodegenerative disease. The most common pathologies associated with PPA include frontotemporal lobar degeneration (FTLD)-tau, FTLD-associated with transactivation response DNA-binding protein of 43 kDa (TDP-43) (FTLD-TDP), and Alzheimer's disease (AD). Accumulating evidence has suggested that Lewy body disease (LBD) can also be associated with PPA. We herein report a 78-year-old Caucasian woman who initially presented with levodopa-responsive parkinsonism at age 67 and later developed cognitive impairment, visual hallucinations, rapid eye movement sleep behavior disorder, and progressive aphasia, characterized by reduced spontaneous speech, word-finding difficulty, and difficulties in writing and reading. ¹⁸ Fluorodeoxyglucoase (FDG)-positron emission tomography (PET) performed at the age of 73 years identified hypometabolism in the frontal (right > left), temporal (left > right), and parietal (left > right) lobes. Neuropathological assessment revealed diffuse LBD (DLBD), AD, and TDP-43 stage 6 with prehippocampal sclerosis. Senile plaques were numerous, but only a few neurofibrillary tangles were present in the neocortex. The Braak neurofibrillary tangle stage was IV, and the Thal amyloid phase was 3. Lewy-related pathology was severe in the neocortex, as well as limbic cortices, basal forebrain, amygdala, and brainstem. Compared to 166 DLBD cases with a clinical diagnosis of dementia with Lewy bodies (DLB), the Lewy body count of the patient in this report was highest in the inferior parietal cortex, followed by midfrontal and superior temporal cortices. The findings suggest that severe cortical LBD pathology has contributed to her progressive aphasia. Autopsy cases of LBD presenting as PPA have been reported, but patients with PD and autopsy-proven DLBD who later developed progressive aphasia have not been reported. Our findings indicate that PD can be associated with progressive aphasia later in the disease course. Although uncommon, LBD should be considered as a differential diagnosis of progressive aphasia.