Verbal Semantics and the Left Dorsolateral Anterior Temporal Lobe: A Longitudinal Case of Bilateral Temporal Degeneration
Vonk, Jet M J; Borghesani, Valentina; Battistella, Giovanni; Younes, Kyan; DeLeon, Jessica; Welch, Ariane; Hubbard, H Isabel; Miller, Zachary A; Miller, Bruce L; Gorno-Tempini, Maria Luisa
(2020) Aphasiology, volume 34, issue 7, pp. 865 - 885
(Article)
Abstract
Background: Semantic variant primary progressive aphasia (svPPA), a clinical syndrome characterized by loss of semantic knowledge, is associated with neurodegeneration that starts in the anterior temporal lobe (ATL) and gradually spreads towards posterior temporal and medial frontal areas. At the earliest stages, atrophy may be predominantly lateralized to either the
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left or right ATL, leading to different clinical profiles with the greatest impairment of word comprehension or visual/social semantics, respectively. Methods & Procedures: We report the in-depth longitudinal investigation of cognitive and neuroanatomical features of JB, an unusual case of ATL neurodegeneration with relative sparing of left lateral ATL regions. Outcomes & Results: Over the course of 9 years, neurodegeneration progressed to involve bilateral temporo-lateral and frontal regions, resulting in a relatively symmetric and diffuse frontotemporal atrophy pattern. In parallel, JB developed greater behavioral, cognitive, and language impairments, as well as signs of motor neuron disease at her last evaluation. Episodic memory and socio-emotional processing deficits arose, likely secondary to semantic verbal deficits, while visuospatial processing, executive function, and non-semantic language abilities remained largely unaffected throughout the course of the disease. Conclusions: The details of this rare case of early medial more than lateral ATL degeneration are consistent with a bilateral organization of the semantic system and, crucially, with a functional dissociation between medial paralimbic and lateral neocortical temporal regions. Cases of frontotemporal dementia (FTD) such as JB, who initially do not meet current clinical criteria for svPPA and instead present with some features of behavioral variant FTD, highlight the need for specific criteria for the right temporal variant of FTD that we propose could be called semantic variant FTD.
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Keywords: Primary progressive aphasia, semantic dementia, right temporal variant, frontotemporal dementia, motor neuron disease, Clinical Neurology, Neurology, Developmental and Educational Psychology, Language and Linguistics, LPN and LVN, Otorhinolaryngology, Linguistics and Language, Journal Article
ISSN: 0268-7038
Publisher: Taylor and Francis Ltd.
Note: Funding Information: This work was funded by the National Institutes of Health (M.GT., NINDS R01 NS050915), (M.GT., NIDCD K24 DC015544), (B.M., NIA P50 AG023501), and by Alzheimer Nederland (J.V.). We thank JB and her family for their time and effort dedicated to our research. We kindly thank Grace Rice and Matthew Lambon Ralph for providing control data of the Over-regular Object Test. Funding Information: These analyses were performed using the in-house Brainsight system, developed at UCSF by Katherine P. Rankin, Cosmo Mielke, and Paul Sukhanov, and powered by the VLSM script written by Stephen M. Wilson, with funding from the Rainwater Charitable Foundation and the UCSF Chancellor’s Fund for Precision Medicine. Acknowledgments Publisher Copyright: © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.
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