The clinical profile of right temporal lobe atrophy

Abstract

Frontotemporal lobar degeneration is currently associated with three syndromic variants. Disorders of speech and language figure prominently in two of the three variants, and are associated with left-sided frontotemporal atrophy. The detailed characterization of these syndromes contrasts with the relative paucity of information relating to frontotemporal lobar degeneration primarily affecting the right cerebral hemisphere. The objective of this study was to identify the clinical profile associated with asymmetrical, predominantly right-sided, temporal lobe atrophy. Twenty patients with predominant right temporal lobe atrophy were identified on the basis of blinded visual assessment of the MRI scans. The severity of right temporal lobe atrophy was quantified using volumetric analysis of the whole temporal lobes, the amygdala and the hippocampus. Profiles of cognitive function, behavioural and personality changes were obtained on each patient. The pattern of atrophy and the clinical features were compared with those observed in a group of patients with semantic dementia and predominant left-sided temporal lobe atrophy. The mean right temporal lobe volume in the right temporal lobe atrophy group was reduced by 37%, with the mean left temporal lobe volume reduced by 19%. There was marked atrophy of the right hippocampus and right amygdala, with mean volumes reduced by 41 and 51%, respectively (left hippocampus and amygdala volumes were reduced by 18 and 33%, respectively). The most prominent cognitive deficits were impairment of episodic memory and getting lost. Prosopagnosia was a symptom in right temporal lobe atrophy patients. These patients also exhibited a variety of behavioural symptoms including social disinhibition, depression and aggressive behaviour. Nearly all behavioural disorders were more prevalent in the right temporal lobe atrophy patient group than the semantic dementia group. Symptoms particular to the right temporal lobe atrophy patient group included hyper-religiosity, visual hallucinations and cross-modal sensory experiences. The combination of clinical features associated with predominant right temporal lobe atrophy differs significantly from those associated with the other syndromes associated with focal degeneration of the frontal and temporal lobes and it is, therefore, proposed that this right temporal variant should be considered a separate syndromic variant of frontotemporal lobar degeneration.

Cardiac responses to viewing facial emotion differentiate frontotemporal dementias

“…The findings are consistent with previous work showing reduced autonomic reactivity in bvFTD and nfvPPA18, 26 and preserved autonomic reactivity in svPPA 31. The present work goes further in demonstrating a physiological basis for differentiating subsyndromes within the canonical diagnostic grouping of bvFTD: although a distinct syndrome of rtvFTD has been proposed on neuroanatomical and clinical grounds,2, 3 these are to a degree arbitrary given the extensive clinico‐anatomical overlap between patients and without mechanistic grounding. Autonomic profiling might establish a principled neurobiological rationale for subclassifying bvFTD, which has long presented nosological difficulties on account of its marked phenotypic and pathological heterogeneity.…”

Structural connectivity in a single case of progressive prosopagnosia: The role of the right inferior longitudinal fasciculus

“…The association of modality-specific PP, mild object visual agnosia, and early behavioural changes with insidious onset and gradual progression, in presence of normal phosphorylated tau and beta-amyloid in CSF, might be consistent with a diagnosis of prosopagnosic variant of FTD (Neary et al, 1998), more recently defined as right-temporal variant of FTD (rtFTD; Chan et al, 2009;Josephs et al, 2009;Miller et al, 1993).…”

“…Actually, current clinical diagnostic criteria (Neary et al, 1998) consider PP with insidious onset and gradual progression, often associated to associative agnosia, as the hallmark of the prosopagnosic variant of frontotemporal dementia (FTD) (Neary et al, 1998), more recently defined right-temporal variant (rtFTD; Chan et al, 2009;Josephs et al, 2009;Miller et al, 1993).…”

P2‐241: Focal Temporal Pole Atrophy and Network Degeneration in Semantic Variant Primary Progressive Aphasia

“…Additionally, some patients with semantic dementia ($30%) present initially with greater atrophy in the right anterior temporal lobe, and these patients often have greater social-emotional deficits along with prosopagnosia (Chan et al, 2009;Hodges et al, 2010;Irish et al, 2013). Patient-specific neurodevelopmental factors likely contribute to the selective vulnerability of neural regions and networks to progressive degeneration (Rogalski et al, 2008;Spreng et al, 2010;Miller et al, 2013), and may account for some of the variability observed in the atrophy patterns of patients with svPPA.…”