Verbal semantics and the left dorsolateral anterior temporal lobe: a longitudinal case of bilateral temporal degeneration

Jet M.J. Vonk, Valentina Borghesani, Giovanni Battistella, Kyan Younes, Jessica DeLeon, Ariane Welch, H. Isabel Hubbard, Zachary A. Miller, Bruce L. Miller, Maria Luisa Gorno-Tempini

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

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 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.

Original languageEnglish
Pages (from-to)865-885
Number of pages21
JournalAphasiology
Volume34
Issue number7
DOIs
StatePublished - Jul 2 2020

Bibliographical note

Publisher Copyright:
© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.

Keywords

  • Primary progressive aphasia
  • frontotemporal dementia
  • motor neuron disease
  • right temporal variant
  • semantic dementia

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Language and Linguistics
  • Developmental and Educational Psychology
  • Linguistics and Language
  • Neurology
  • Clinical Neurology
  • LPN and LVN

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