Objective: Report of a case with suspected TDP-43 proteinopathy as the pathological background in the early stage of the disease, and a final diagnosis of corticobasal syndrome (CBS)-four-repeat (4R)-tauopathy by tau PET.

Background: Progressive anterior operculum syndrome is a clinical syndrome characterized by non-fluent/agrammatic variant of primary progressive aphasia with early onset of buccofacial apraxia, dysphagia [1]. Several reports have demonstrated FTLD-TDP as the background pathology [1,2]. However, in total there have been few reports on the background pathology of neurodegenerative diseases presenting with this syndrome.

Method: A case report.

Results: A 68-year-old right-handed woman with difficulty speaking since several years ago. She exhibited kana (syllabograms) dominant agraphia. Mistakes were more common in mobile text messages than in handwriting, suggesting dystextia. On neurological examination, she showed apraxia of speech, eyelid opening, oculomotor, and buccofacial movement. Perseveration, pathological laughing, and increased limb tendon reflexes were prominent. The dissociation between spontaneous and voluntary movements of facial expression suggested anterior operculum syndrome. MRI and SPECT showed bilateral atrophy and decreased blood flow in the frontotemporal lobe including the anterior operculum. Taken together, she was diagnosed with non-fluent/agrammatic variant of primary progressive aphasia, and her pathological background was estimated to be TDP-43 proteinopathy.

Her clinical symptoms continued to gradually worsen, and she presented with bradykinesia, postural instability, left-side neglect, and left dominant cortical sensory deficit 9 months later. Tau PET with ¹⁸F-florzolotau demonstrated remarkable uptake of the ligand around the brainstem, subthalamic nucleus, basal ganglia, and bilateral subcortical frontal lobe, resembling 4R-tauopathy [3]. Based on the neurological findings and tau PET findings, she was finally diagnosed with CBS-4R-tauopathy.

Conclusion: We report a case of CBS presenting with early progressive anterior operculum syndrome. Although TDP-43 proteinopathy was suspected based on the clinical symptoms in the early stages of the disease, tau PET suggested that her pathological background was 4R-tauopathy.

References: 1. Otsuki M, Nakagawa Y, Mori F, et al. Progressive anterior operculum syndrome due to FTLD-TDP: a clinico-pathological investigation. J Neurol. 2010;257(7):1148-53.
2. Clark CN, Quaegebeur A, Nirmalananthan N, et al. Foix-Chavany-Marie syndrome due to type E TDP43 pathology. Neuropathol Appl Neurobiol. 2020;46(3):292-295.
3. Tagai K, Ono M, Kubota M, et al. High-Contrast In Vivo Imaging of Tau Pathologies in Alzheimer’s and Non-Alzheimer’s Disease Tauopathies. Neuron. 2021;109(1):42-58.e8.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cbs-presenting-rapidly-progressive-anterior-operculum-syndrome-with-suggested-background-pathology-of-4-repeat-tauopathy-by-tau-pet-a-case-report/