Right Temporal Lobe Atrophy
Research on the variants of frontotemporal lobar degeneration (FTLD) reveals distinct clinical, pathological, and neuroanatomical profiles for three subtypes: frontotemporal dementia, semantic dementia, and progressive nonfluent aphasia. Predominantly left-sided frontotemporal atrophy typically presents as the semantic dementia subtype with progressive loss of word and object knowledge. Clinical data involving more prominent right temporal lobe atrophy exist primarily in the form of individual case reports, typically involving patients presenting with prosopagnosia, difficulty recognizing faces (Tyrrell et al., 1990; Evans et al., 1995; Gainotti, 2007). Patients presenting with right temporal lobe atrophy (RTLA) are further characterized by impulsivity, aggression, behavioral disinhibition and hyper-religiosity; making personality changes, disturbances in social behavior, and abnormalities in emotional processing part of the clinical syndrome (Gorno-tempini, 2003; Chan et al., 2009). The neuropathology of RTLA appears similar to FTLD with tissue atrophy, spongiosis, neuronal loss and gliosis as the most prominent features (Edwards-Lee, 1997) while being clinically distinct from the previously outlined subtypes of FTLD due to the relative preservation of speech and language and differences in personality changes compared to left temporal lobe atrophy. For instance, Edward-Lee and colleagues (1997) reported that RTLA patients were socially inept, agitated and profoundly irritable; in contrast to left temporal lobe atrophy (LTLA) patients who were pleasant and socially appropriate. While depression is typical in both variants, RTLA patients frequently demonstrate bizarre affect, and several develop an atypical depression with lack of insight and denial of illness (Edwards-Lee, 1997). Given the similarity in neuropathology between RTLA and FTLD with a distinct clinical presentation, it has been suggested that RTLA should be considered for admission as a new subtype of FTLD.
Abstract: The clinical profile of right temporal lobe atrophy (2009)
“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.”
[Chan, D., Anderson, V., Pijnenburg, Y., Whitwell, J., Barnes, J., Scahill, R., Stevens, J.M., Barkhof, F., Scheltens, P., Rosser, M.N., & Fox, N.C. (2009). The clinical profile of right temporal lobe atrophy. Brain, 132(5), 1287-1298.] http://brain.oxfordjournals.org/content/early/2009/03/18/brain.awp037.short
(1) Overview of Frontotemporal Lobar Degeneration (2013)
b. Dr. Murray Grossman provides an overview of Frontotemporal Degeneration at the February 2012 FTD Caregiver Conference, University of Pennsylvania, Philadelphia, PA.
(2) Frontotemporal Dementia – Diagnostic Overview (2012)
b. Dr. H. Branch Coslett, MD, Professor of Neurology at the University of Pennsylvania, presents on the topic of Diagnostic Overview at the 2005 Frontotemporal Dementia Caregiver Conference in Philadelphia, PA.
(3) Frontotemporal Dementia – Mayo Clinic (2014)
b. Short film by the Mayo Clinic that highlights the symptoms of FTD.
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Eric Watson, MS - East Carolina University, Clinical Health Psychology PhD Program