The temporal variant of frontotemporal dementia

Abstract

Frontotemporal dementia is a dementia syndrome with diverse clinical characteristics. Based upon clinical parameters and single photon emission computed tomography, we identified 47 frontotemporal dementia subjects. In 10 of these 47 the primary site of brain dysfunction was anterior temporal and orbital-frontal with other frontal regions relatively spared. In this temporal lobe variant (TLV) of frontotemporal dementia, five of the subjects had more severe left-sided, and five had more right-sided, hypoperfusion. The clinical, neuropsychological and neuropsychiatric features of predominantly left-sided (LTLV) and right-sided (RTLV) TLV subjects are discussed and contrasted with more frontal presentations of frontotemporal dementia. In LTLV, aphasia was usually the first and most severe clinical abnormality RTLV patients presented with behavioural disorders characterized by irritability, impulsiveness, bizarre alterations in dress, limited and fixed ideas, decreased facial expression and increased visual alertness. These findings suggest that: (i) frontotemporal dementia is clinically heterogeneous with bitemporal and inferior frontal lobe dysfunction contributing to the clinical presentation; (ii) behavioural disturbance and aphasia are the most prominent features of predominantly temporal subtypes of frontotemporal dementia; (iii) the right and left anterior temporal regions may mediate different behavioural functions. The results of this study suggests that TLV offers a valuable source of information concerning the behavioural disorders seen with combined anterior temporal and inferior frontal lobe dysfunction.

Anatomical and functional alterations in semantic dementia: A voxel-based MRI and PET study

“…It is worth noting that, with the evolution of the disease, SD patients develop executive dysfunction and behavioural symptoms [18], in accordance with the role of the frontal lobes in behaviour regulation.…”

“…SPECT has been used in few studies to investigate the patterns of regional cerebral blood flow in SD. The results of these studies have principally demonstrated temporal bilateral or left involvement [32,71] or temporal and frontal bilateral involvement [18]. PET has a better spatial resolution and quantitative accuracy than SPECT, and appears to be a more promising functional imaging technique for the diagnosis and differential diagnosis of dementia [30].…”

“…The head was positioned on a head-rest according to the cantho-meatal line and gently restrained with straps. 18 FDG uptake was measured in the resting condition, with eyes closed, in a quiet and dark environment. A catheter was introduced in a vein of the arm to inject the radiotracer.…”

“…A catheter was introduced in a vein of the arm to inject the radiotracer. Following 68 Ga transmission scans, three to five mCi of 18 FDG were injected as a bolus at time 0, and a 10 min PET data acquisition started at 50 min post-injection period. Sixty-three planes were acquired with septa out (volume acquisition), using a voxel size of 2.2  2.2  2.43 mm (x y z).…”

“…There is compelling evidence to consider that this syndrome, termed either temporal variant of frontotemporal dementia [18,35] or semantic dementia (SD) [70], is part of the disease spectrum of frontotemporal lobar degeneration (FTLD). Although FTLD is a relatively common cause of dementia, accounting for about 20% of cases of dementia with presenile onset, most of cases suffer from the frontal variant of FTD, while the temporal variant is a relatively rare disorder [61].…”