Abstract
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by impaired higher visual processing skills; however, motor features more commonly associated with corticobasal syndrome may also occur. We investigated the frequency and clinical characteristics of motor features in 44 PCA patients and, with 30 controls, conducted voxel-based morphometry, cortical thickness, and subcortical volumetric analyses of their magnetic resonance imaging. Prominent limb rigidity was used to define a PCA-motor subgroup. A total of 30% (13) had PCA-motor; all demonstrating asymmetrical left upper limb rigidity. Limb apraxia was more frequent and asymmetrical in PCA-motor, as was myoclonus. Tremor and alien limb phenomena only occurred in this subgroup. The subgroups did not differ in neuropsychological test performance or apolipoprotein E4 allele frequency. Greater asymmetry of atrophy occurred in PCA-motor, particularly involving right frontoparietal and peri-rolandic cortices, putamen, and thalamus. The 9 patients (including 4 PCA-motor) with pathology or cerebrospinal fluid all showed evidence of Alzheimer's disease. Our data suggest that PCA patients with motor features have greater atrophy of contralateral sensorimotor areas but are still likely to have underlying Alzheimer's disease.
Highlights
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by progressive decline in visual processing, literacy, numeracy, and other functions that depend on parietal, occipital, and occipitotemporal brain regions (Benson et al, 1988; Kas et al, 2011)
Most individuals with PCA have Alzheimer’s disease (AD) as the underlying pathology, but PCA may be caused by corticobasal degeneration (CBD), dementia with Lewy bodies (DLB), and Creutzfeldt-Jakob disease (CJD) (Renner et al, 2004; Tang-Wai et al, 2003a, 2003b)
There was no significant difference in APOE4 allele frequency between the 2 PCA subgroups and 2 patients in each group were E4 homozygous
Summary
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by progressive decline in visual processing, literacy, numeracy, and other functions that depend on parietal, occipital, and occipitotemporal brain regions (Benson et al, 1988; Kas et al, 2011). Commonly considered a selective visual syndrome, a number of patients with PCA develop sensorimotor signs, often asymmetric, which are more typically seen in CBS (Giorelli et al, 2014; McMonagle et al, 2006; Seguin et al, 2011; Tang-Wai et al, 2003a; Whitwell et al, 2010). In the original proposed criteria for PCA, a normal physical examination is considered supportive of a diagnosis but not mandatory (Mendez et al, 2002). Another proposed criteria excludes early Parkinsonism but recognizes that it may subsequently develop and does not state how early on its presence is acceptable (Tang-Wai et al, 2004). The prevalence of motor features in PCA is currently unclear, as are other potential differences between PCA patients with and without such signs
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