Questions:
61. What are the clinical characteristics of posterior cortical atrophy?
62. What are the neuroimaging findings in posterior cortical atrophy?
63. What are common etiologies of posterior cortical atrophy?
64. What visual difficulties are commonly seen in Alzheimer disease?
65. What are the neuroimaging findings in Alzheimer disease?
66. What are the OCT findings in Alzheimer disease?
67. What visual difficulties are commonly seen in the Heidenhain variant of sporadic Creutzfeldt-Jakob disease?
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Questions with answers:
61. What are the clinical characteristics of posterior cortical atrophy?
Posterior cortical atrophy is characterized by a progressive illness combining memory, insight, judgment impairment, alexia with or without agraphia, visual agnosia, components of Balint syndrome (simultagnosia, ocular apraxia, and optic ataxia), Gerstmann syndrome (right-left confusion, finger agnosia, acalculia, and agraphia), and transcortical sensory aphasia (fluent aphasia with intact ability to repeat).
62. What are the neuroimaging findings in posterior cortical atrophy?
Neuroimaging reveals cerebral atrophy that is more severe posteriorly.
63. What are common etiologies of posterior cortical atrophy?
Etiologies include Alzheimer disease and other dementias.
64. What visual difficulties are commonly seen in Alzheimer disease?
Alzheimer disease is a slowly progressive degenerative dementia that is often associated with visual disturbances (e.g., difficulty reading), which may predominate early in the course of the disease. Although these patients have numerous visual complaints (e.g., difficulty reading, difficulty seeing, and difficulty processing what they see), they have normal visual acuity and normal ocular examination, and frequently normal visual fields. The correct diagnosis is often delayed.
65. What are the neuroimaging findings in Alzheimer disease?
Brain CT and MRI are often normal or show some posterior cerebral atrophy at the parieto-occipital junction. Functional imaging, such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT), may help make the diagnosis.
66. What are the OCT findings in Alzheimer disease?
Alzheimer’s disease patients showed significant differences in ganglion cell-inner plexiform layer thickness (standardized mean difference [SMD], -0.46; 95% confidence interval [CI], -0.80 to -0.11; I2 = 71%), ganglion cell complex thickness (SMD, -0.84; 95% CI, -1.10 to -0.57; I2 = 0%), macular volume (SMD, -0.58; 95% CI, -1.03 to -0.14; I2 = 80%), and macular thickness of all inner and outer sectors (SMD range, -0.52 to -0.74; all P < 0.001) when compared with controls. Peripapillary retinal nerve fiber layer thickness (SMD, -0.67; 95% CI, -0.95 to -0.38; I2 = 89%) and choroidal thickness (SMD range, -0.88 to -1.03; all P < 0.001) also were thinner in Alzheimer’s disease patients.
67. What visual difficulties are commonly seen in the Heidenhain variant of sporadic Creutzfeldt-Jakob disease?
The Heidenhain variant of sporadic Creutzfeldt-Jakob disease manifests with early, prominent visual complaints (e.g., visual hallucinations, difficulty reading, homonymous hemianopia, and distortion of vision).
The information below is from Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme
10.3 Causes of Disorders of Higher Cortical Functions
Cerebral disturbances of vision can be caused by any condition that affects the visual association cortices or subcortical white matter. They commonly result from bilateral cerebral lesions and are most often found in patients with cerebral hypoxia resulting in bilateral watershed infarctions or with bilateral infarctions in the territory of the posterior cerebral arteries, diffuse encephalopathy and encephalitis, and degenerative disorders producing dementia.
Computed tomography (CT) and magnetic resonance imaging (MRI) of the brain are sometimes normal or show nonspecific cerebral atrophy in most degenerative dementias. The diagnosis is often difficult and is delayed in patients in whom visual complaints predominate.
10.3.1 Posterior Cortical Atrophy
Posterior cortical atrophy is characterized by a progressive illness combining memory impairment, insight, and judgment impairment, alexia with or without agraphia, visual agnosia, and components of Balint syndrome, Gerstmann syndrome, and transcortical sensory aphasia (fluent aphasia with intact ability to repeat). Neuroimaging reveals cerebral atrophy, more severe posteriorly. Etiologies include Alzheimer disease and other dementias.
10.3.2 Alzheimer Disease
Alzheimer disease is a slowly progressive degenerative dementia that is often associated with visual disturbances (e.g., difficulty reading), which may predominate early in the course of the disease. Although these patients have numerous visual complaints (e.g., difficulty reading, difficulty seeing, and difficulty processing what they see), they have normal visual acuity and normal ocular examination, and frequently even normal visual fields, and the correct diagnosis is often delayed. Brain CT and MRI are often normal or show some posterior cerebral atrophy at the parieto-occipital junction. Functional imaging, such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT), may help make the diagnosis.
10.3.3 Creutzfeldt–Jakob Disease
Creutzfeldt–Jakob disease is a rapidly progressive dementia that is usually lethal within a few months. Along with kuru, Gerstmann–Sträussler syndrome, and fatal familial insomnia, it comprises a group of dementing illnesses known as human transmissible spongiform encephalopathies. The Heidenhain variant of sporadic Creutzfeldt–Jakob Disease manifests with early, prominent visual complaints (e.g., visual hallucinations, difficulty reading, homonymous hemianopia, and distortion of vision).
The diagnosis is based on the following:
● Normal conventional brain MRI with abnormal diffusion-weighted images
● Abnormal electroencephalogram (periodic activity)
● Positive testing for mutation 14–3–3 in the prion protein gene in the cerebrospinal fluid
● Abnormal brain biopsy
Spectral-Domain OCT Measurements in Alzheimer’s Disease: A Systematic Review and Meta-analysis. Ophthalmology. 2019;126(4):497-510.
RESULTS: We identified 30 eligible studies, involving 1257 AD patients, 305 MCI patients, and 1460 controls, all of which were cross-sectional studies. In terms of the macular structure, AD patients showed significant differences in GC-IPL thickness (standardized mean difference [SMD], -0.46; 95% confidence interval [CI], -0.80 to -0.11; I2 = 71%), GCC thickness (SMD, -0.84; 95% CI, -1.10 to -0.57; I2 = 0%), macular volume (SMD, -0.58; 95% CI, -1.03 to -0.14; I2 = 80%), and macular thickness of all inner and outer sectors (SMD range, -0.52 to -0.74; all P < 0.001) when compared with controls. Peripapillary RNFL thickness (SMD, -0.67; 95% CI, -0.95 to -0.38; I2 = 89%) and choroidal thickness (SMD range, -0.88 to -1.03; all P < 0.001) also were thinner in AD patients.
CONCLUSIONS: Our results confirmed the associations between retinal measurements of SD OCT and AD, highlighting the potential usefulness of SD OCT measurements as biomarkers of AD.
Abbreviations: spectral-domain (SD) OCT, Alzheimer’s disease (AD), ganglion cell-inner plexiform layer (GC-IPL), ganglion cell complex (GCC), retinal nerve fiber layer (RNFL)
Reference:
1. Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme
2. Spectral-Domain OCT Measurements in Alzheimer’s Disease: A Systematic Review and Meta-analysis. Ophthalmology. 2019 Apr;126(4):497-510. doi: 10.1016/j.ophtha.2018.08.009. Epub 2018 Aug 13. Chan VTT1, Sun Z2, Tang S2, Chen LJ2, Wong A3, Tham CC2, Wong TY4, Chen C5, Ikram MK6, Whitson HE7, Lad EM8, Mok VCT9, Cheung CY10.
Full-Text https://drive.google.com/file/d/11jTTheLoqXyjbude_8hVFwt_LFJvBEG-/view
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