Questions:
7. What is hemiachromatopsia?
8. Where is the lesion in hemiachromatopsia?
9. How does one test hemiachromatopsia?
10. What clinical signs are associated with hemiachromatopsia?
11. What is prosopagnosia?
12. How does one test for prosopagnosia?
13. What clinical signs are associated with prosopagnosia?
14. Where is the lesion in acquired prosopagnosia?
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Questions with answers:
7. What is hemiachromatopsia?
It is the Higher Cortical Disorder in which the patient does not recognize colors in one hemifield.
8. Where is the lesion in hemiachromatopsia?
Contralateral inferior occipitotemporal lobe
9. How does one test hemiachromatopsia?
Have the patient identify the Ishihara color plates or perform the Farnsworth-Lanthony test while controlling fixation.
10. What clinical signs are associated with hemiachromatopsia?
Ipsilateral homonymous superior quadrantanopia
11. What is prosopagnosia?
It is the Higher Cortical Disorder in which the patient cannot recognize famous people or identify the faces of people they know.
12. How does one test for prosopagnosia?
Have the patient identify famous people in a magazine.
13. What clinical signs are associated with prosopagnosia?
Alexia without agraphia, visual agnosia, and bilateral superior altitudinal visual field defects
The information below is from Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme
10 Disorders of Higher Cortical Function
Unlike the anterior visual and geniculocalcarine pathways that deliver basic visual information from the eyes to the occipital cortex, association cortical visual areas (higher cortical areas) perform the more complex interpretation of visual information. Many of the syndromes of higher cortical dysfunction are secondary to a disconnection of the flow of visual information between the striate cortex and other cortical regions. When these areas are damaged, visual processing is abnormal despite often normal visual acuity and visual fields.
This chapter focuses on some of the main visual disorders of higher cortical function, particularly their clinical and radiologic findings and causes, commonly encountered in neuro-ophthalmology.
10.1 Classification
Disorders of higher cortical function are often grouped into two processing streams. The first stream, the inferior (ventral) or occipitotemporal pathway for object recognition, extends from below the calcarine fissure into the adjacent temporal lobe. It facilitates object recognition and color perception. Disorders here include achromatopsia, prosopagnosia, alexia, and topographagnosia.
The second stream, the superior (dorsal) or occipitoparietal pathway for object localization extends from the upper bank of the calcarine fissure into the adjacent parietal lobe. It processes visuospatial attributes, including location and motion. Disorders here include akinetopsia, Balint syndrome (simultagnosia, ocular apraxia, and optic ataxia), and hemineglect.
▶Table 10.1 lists the clinical findings, recommended tests, associated clinical signs, and lesions associated with these higher cortical disorders.
Reference: 1. Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme
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