Progressive anterior operculum syndrome due to FTLD-TDP: a clinico-pathological investigation

Atypical TDP-43 proteinopathy clinically presenting with progressive nonfluent aphasia: A case report

Progressive nonfluent aphasia (PNFA) is a form of frontotemporal lobar degeneration (FTLD) caused by tau and transactive response DNA-binding protein of 43 kDa (TDP-43) accumulation. Here we report the autopsy findings of a 64-year-old right-handed man with an atypical TDP-43 proteinopathy who presented with difficulties with speech, verbal paraphasia, and dysphagia that progressed over the 36 months prior to his death. He did not show pyramidal tract signs until his death. At autopsy, macroscopic brain examination revealed atrophy of the left dominant precentral, superior, and middle frontal gyri and discoloration of the putamen. Spongiform change and neuronal loss were severe on the cortical surfaces of the precentral, superior frontal, and middle frontal gyri and the temporal tip. Immunostaining with anti-phosphorylated TDP-43 revealed neuronal cytoplasmic inclusions and long and short dystrophic neurites in the frontal cortex, predominantly in layers II, V, and VI of the temporal tip, amygdala, and transentorhinal cortex. Immunoblot analysis of the sarkosyl-insoluble fractions showed hyperphosphorylated TDP-43 bands at 45 kDa and phosphorylated C-terminal fragments at approximately 25 kDa. The pathological distribution and immunoblot band pattern differ from the major TDP-43 subtype and therefore may represent a new FTLD-TDP phenotype.

Corticobasal syndrome mimicking Foix-Chavany-Marie syndrome with suggested 4-repeat tauopathy by tau PET

BACKGROUND

Corticobasal syndrome (CBS) is a neurodegenerative disease diagnosed based on clinical manifestations such as asymmetrical parkinsonism, limb apraxia, and speech and language impairment. The background pathology of CBS is commonly a variety of proteinopathies, but association with cerebrovascular disease has also been reported. Foix-Chavany-Marie syndrome (FCMS) is a rare neurological disorder characterized by facio-pharyngo-glossal diplegia with automatic-voluntary movement dissociation presenting with bilateral paresis of the facial, lingual, pharyngeal and masticatory muscles. FCMS is commonly attributable to stroke. Transactive response DNA binding protein of 43 kD (TDP-43) proteinopathy is also known as the pathological background of FCMS, while the pathological background of the majority of CBS cases consists of diverse tauopathies instead of TDP-43 proteinopathy. In this report, we describe a case mimicking FCMS that was finally diagnosed as CBS with suggested 4-repeat tauopathy.

CASE PRESENTATION

A 68-year-old female started experiencing difficulty speaking followed by difficulty writing, and especially texting, several years before her visit. Her impairment had been gradually worsening, and she came to our hospital. On neurological examination, she demonstrated the facial apraxia, frontal lobe dysfunction, and upper motor neuron signs. She presented some characteristics suggestive of FCMS. Her symptoms exhibited rapid progression and myoclonus, parkinsonism, and left-side dominant cortical sensory deficit occurred, resulting in the fulfillment of diagnostic criteria for CBS after 9 months. Tau PET imaging displayed notable ligand uptake in the brainstem, subthalamic nuclei, basal ganglia, and bilateral subcortical frontal lobe, suggesting that her pathological background was 4-repeat tauopathy. As a result of her progressive dysphagia, she became unable to eat and passed away after 12 months.

CONCLUSION

We hereby present an atypical case of CBS showing clinical features mimicking FCMS at first presentation. TDP-43 proteinopathy was suspected based on the clinical symptoms in the early stages of the disease; however, the clinical course and imaging findings including tau PET suggested that her pathological background was 4-repeat tauopathy.

Coming to Terms with a Conundrum: A Case of Primary Progressive Apraxia of Speech due to Corticobasal Degeneration?

Primary progressive apraxia of speech (PPAOS) is a progressive disorder impairing the motor speech act leaving linguistic function unattained. Although apraxia of speech frequently co-occurs with other neurodegenerative conditions, PPAOS defines a clinical syndrome where apraxia of speech is the sole or prominent symptom for much of the disease's natural history. Mounting evidence is beginning to fully define this disease as the epiphenomenon of 4-repeat (4R) tau pathology although other pathologic signatures have been reported. Indeed, PPAOS patients generally present a parkinsonian syndrome late into their natural history mostly qualifying for either corticobasal syndrome (CBS) or progressive supranuclear palsy (PSP). This is starting to be reflected in diagnostic criteria for PSP, namely, in the PSP speech and language (SL) subcategory; however, this inclusion is not reflected for CBS. Here, we present a single case of a patient with PPAOS and her clinical follow-up lasting 6 years, from the time she sought our attention to her death which occurred 8 years into the disease. PPAOS was the only and prominent symptom for most of the illness with extrapyramidal signs overtly presenting in the last months of its course. Clinical evaluation, imaging, genetic, and cerebrospinal fluid biomarkers all pointed toward an underlying CBD pathology, albeit the eventual anatomopathological confirmation was not performed. Had her clinical course been more suggestive of PSP, she would have qualified for criteria as PSP-SL. Our case therefore suggests the hypothetic need to discuss the broadening of the existing CBS criteria to encompass isolated PPAOS.

mTh1 driven expression of hTDP-43 results in typical ALS/FTLD neuropathological symptoms

Transgenic mouse models are indispensable tools to mimic human diseases and analyze the effectiveness of related new drugs. For a long time amyotrophic lateral sclerosis (ALS) research depended on only a few mouse models that exhibit a very strong and early phenotype, e.g. SOD1 mice, resulting in a short treatment time window. By now, several models are available that need to be characterized to highlight characteristics of each model. Here we further characterized the mThy1-hTDP-43 transgenic mouse model TAR6/6 that overexpresses wild type human TARDBP, also called TDP-43, under control of the neuronal Thy-1 promoter presented by Wils and colleagues, 2010, by using biochemical, histological and behavioral readouts. Our results show that TAR6/6 mice exhibit a strong TDP-43 expression in the hippocampus, spinal cord, hypothalamus and medulla oblongata. Apart from prominent protein expression in the nucleus, TDP-43 protein was found at lower levels in the cytosol of transgenic mice. Additionally, we detected insoluble TDP-43 in the cortex, motoneuron loss, and increased neuroinflammation in the central nervous system of TAR6/6 animals. Behavioral analyses revealed early motor deficits in the clasping- and wire suspension test as well as decreased anxiety in the elevated plus maze. Further motor tests showed differences at later time points compared to non-transgenic littermates, thus allowing the observation of onset and severity of such deficits. Together, TAR6/6 mice are a valuable tool to test new ALS/FTLD drugs that target TDP-43 expression and insolubility, neuroinflammation, motoneuron loss or other TDP-43 related downstream signaling pathways since these mice exhibit a later pathology as previously used ALS/FTLD mouse models.

Nonfluent/agrammatic PPA with in-vivo cortical amyloidosis and Pick's disease pathology

The role of biomarkers in predicting pathological findings in the frontotemporal dementia (FTD) clinical spectrum disorders is still being explored. We present comprehensive, prospective longitudinal data for a 66 year old, right-handed female who met current criteria for the nonfluent/agrammatic variant of primary progressive aphasia (nfvPPA). She first presented with a 3-year history of progressive speech and language impairment mainly characterized by severe apraxia of speech. Neuropsychological and general motor functions remained relatively spared throughout the clinical course. Voxel-based morphometry (VBM) showed selective cortical atrophy of the left posterior inferior frontal gyrus (IFG) and underlying insula that worsened over time, extending along the left premotor strip. Five years after her first evaluation, she developed mild memory impairment and underwent PET-FDG and PiB scans that showed left frontal hypometabolism and cortical amyloidosis. Three years later (11 years from first symptom), post-mortem histopathological evaluation revealed Pick's disease, with severe degeneration of left IFG, mid-insula, and precentral gyrus. Alzheimer's disease (AD) (CERAD frequent/Braak Stage V) was also detected. This patient demonstrates that biomarkers indicating brain amyloidosis should not be considered conclusive evidence that AD pathology accounts for a typical FTD clinical/anatomical syndrome.

Progressive nonfluent aphasia: a rare clinical subtype of FTLD-TDP in Japan

Progressive nonfluent aphasia (PNFA) is a clinical subtype of frontotemporal lobar degeneration (FTLD). FTLD with tau accumulation (FTLD-tau) and FTLD with TDP-43 accumulation (FTLD-TDP) both cause PNFA. We reviewed clinical records of 29 FTLD-TDP cases in the brain archive of our institute and found only one case of PNFA. The patient was an 81-year-old male at death. There was no family history of dementia or aphasia. He presented with slow, labored and nonfluent speech at age 75. Behavioral abnormality and movement disorders were absent. MRI at age 76 demonstrated atrophy of the perisylvian regions, including the inferior frontal gyrus, insular gyrus and superior temporal gyrus. The atrophy was more severe in the left hemisphere than the right. On post mortem examinations, neuronal loss was evident in these regions as well as in the substantia nigra. There were abundant TDP-43-immunoreactive neuronal cytoplasmic inclusions and round or irregular-shaped structures in the affected cerebral cortices. A few dystrophic neurites and neuronal intranuclear inclusions were also seen. FTLD-TDP showing PNFA seems to be rare but does exist in Japan, similar to that in other countries.