Elsevier

Survey of Ophthalmology

Volume 51, Issue 6, November–December 2006, Pages 592-595
Survey of Ophthalmology

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The Woman Who Needed a Pet

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Abstract

A 72-year-old woman developed difficulty reading, driving, and playing dominoes. Ophthalmologic examination revealed a homonymous hemianopia, but brain MRI showed no abnormality to explain the visual field defect. Neuropsychiatric testing demonstrated severely impaired visual processing (simultagnosia, visual agnosia, visuospatial difficulty). Positron emission tomography revealed hypometabolism of both parietal and occipital lobes consistent with posterior cortical atrophy or the visual variant of Alzheimer disease. Functional neuroimaging should be considered in the setting of a normal MRI among patients with signs and symptoms of the visual variant Alzheimer disease.

Introduction

Posterior cortical atrophy, a form of Alzheimer disease, presents with visual symptoms that develop years before dementia. In recent years, it has also been described as the visual variant of AD (VVAD).7 It develops in late middle age, with a mean age of onset of 60.8 years,12 whereas AD typically develops much later in life, with a mean onset of 82.3 years.4, 15 Although VVAD develops earlier than Alzheimer disease, the course progresses more slowly, with global dementia symptoms developing after approximately 5.0 years.15

The visual symptoms commonly consist of difficulty reading and writing despite a structurally normal eye examination with normal visual acuity. Other features include an inability to name a visualized object (visual agnosia), an inability to recognize a complex scene (simultanagnosia), difficulty dressing, and visuospatial environmental disorientation. Although patients with Alzheimer disease may also demonstrate the above visual symptoms,2 patients with VVAD do not develop more typical findings of Alzheimer disease such as memory dysfunction or disruption of language fluency until much later in the disease course.2, 3, 6, 8, 15, 16 Visual field testing in VVAD may reveal a homonymous hemianopia or constriction of the visual fields in the setting of a normal magnetic resonance imaging (MRI) of the brain.6

We report a woman with prominent visual symptoms and normal neuroimaging. Positron emission testing (PET) and neuropsychiatric testing revealed the typical findings of VVAD.

Section snippets

Case Report

A 72-year-old white woman presented with difficulty reading, trouble finding objects, and loss of visual contrast beginning 1 year prior. She described her difficulty with reading as “the words run together or overlap.” This visual disturbance caused her to give up reading, driving, and playing bridge and dominoes. The patient denied any difficulty with her memory.

Her past medical history included osteoarthritis, mild sensory neuropathy, restless leg syndrome, and hypothyroidism for which she

Discussion

The visual symptoms of VVAD presumably occur from interference of visual projections of the dorsal stream of visual processing found in the parietal and occipital lobes.11 Histopathologic examination of cerebral tissue from patients with VVAD has revealed the same changes seen in Alzheimer disease: senile plaques and neurofibrillary tangles. Giannakopoulos et al reported that the visual loss of Alzheimer disease resulted from the density of neurofibrillary tangles in the visual association

Conclusion

In this report, we have summarized the presenting symptoms and diagnostic course of a patient with the visual variant of Alzheimer disease. This disorder warrants consideration in older patients complaining of difficulty reading or vague visuospatial dysfunction unexplainable by routine ophthalmologic examination. Although MRI imaging may demonstrate posterior cortical atrophy, some patients with VVAD may have normal MRI results. In these patients, PET scanning may aid in the diagnosis of VVAD

References (17)

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The authors reported no financial or commercial interest in any product mentioned or concept discussed in this article. Support: Unrestricted Grant from Research to Prevent Blindness, New York, NY, and the Lions and Lionesses of Minnesota (MSL, ARH).

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