Clinical, FDG and amyloid PET imaging in posterior cortical atrophy.

Tarun D. Singh,Keith A. Josephs,Jennifer L. Whitwell,Val J. Lowe,Liana G. Apostolova,Daniel A. Drubach,Mary M. Machulda

doi:10.1007/s00415-015-7732-5

Abstract

The purpose of this study was to identify the clinical, [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) and amyloid-PET findings in a large cohort of posterior cortical atrophy (PCA) patients, to examine the neural correlates of the classic features of PCA, and to better understand the features associated with early PCA. We prospectively recruited 25 patients who presented to the Mayo Clinic between March 2013 and August 2014 and met diagnostic criteria for PCA. All patients underwent a standardized set of tests and amyloid imaging with [11C] Pittsburg compound B (PiB). Seventeen (68 %) underwent FDG-PET scanning. We divided the cohort at the median disease duration of 4 years in order to assess clinical and FDG-PET correlates of early PCA (n = 13). The most common clinical features were simultanagnosia (92 %), dysgraphia (68 %), poly-mini-myoclonus (64 %) and oculomotor apraxia (56.5 %). On FDG-PET, hypometabolism was observed bilaterally in the lateral and medial parietal and occipital lobes. Simultanagnosia was associated with hypometabolism in the right occipital lobe and posterior cingulum, optic ataxia with hypometabolism in left occipital lobe, and oculomotor apraxia with hypometabolism in the left parietal lobe and posterior cingulate gyrus. All 25 PCA patients were amyloid positive. Simultanagnosia was the only feature present in 85 % of early PCA patients. The syndrome of PCA is associated with posterior hemisphere hypometabolism and with amyloid deposition. Many of the classic features of PCA show associated focal, but not widespread, areas of involvement of these posterior hemispheric regions. Simultanagnosia appears to be the most common and hence sensitive feature of early PCA.

Highlights

Posterior cortical atrophy (PCA) is a neurodegenerative disorder in which the onset of dementia is characterized by the development of higher order visual deficits [1]
Poly-mini-myoclonus is not a feature that is considered, or typically assessed, in patients with posterior cortical atrophy (PCA) yet it was more common than some of the features typically associated with PCA, such as oculomotor apraxia and optic ataxia
We previously reported an association between poly-mini-myoclonus and PCA [35], our previous study was retrospective in nature and clearly underestimated the frequency of this clinical feature compared to the current prospectively recruited cohort, which shows that poly-mini-myoclonus is a common feature of PCA

Summary

Introduction

Posterior cortical atrophy (PCA) is a neurodegenerative disorder in which the onset of dementia is characterized by the development of higher order visual deficits [1] This disease is often accompanied by visuospatial and visuoperceptual impairments, alexia, features of Balint’s syndrome, Gerstmann’s syndrome and transcortical sensory aphasia, whereas episodic memory is relatively preserved or only mildly impaired [2]. These clinical features differ from those of typical dementia of the Alzheimer’s type (DAT) as they show preservation of memory, insight, and judgment until late in the clinical course, when the clinical features of PCA and DAT overlap [3]. Understanding early PCA could have an impact on prognosis and treatment

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