2020–2021 BCSC Basic and Clinical Science Course™
Chapter 6: The Patient With Illusions, Hallucinations, and Disorders of Higher Cortical Function
The Patient With Disorders of Higher Cortical Function
Disorders of Visual-Spatial Relationships
Simultanagnosia, which is the failure to integrate multiple elements of a scene to form the total picture, can be assessed by asking patients to describe a picture scene (Fig 6-2). A patient with simultanagnosia will describe only part of the picture and not the other portions unless the examiner identifies them. Testing color vision with the Ishihara pseudoisochromatic color plates may suggest simultanagnosia if the patient can identify colors but not the shapes of numbers (ie, the patient does not see the whole picture as the sum of its parts).
Balint syndrome is a rare phenomenon resulting from bilateral occipitoparietal lesions and consists of the triad of simultanagnosia, optic ataxia (disconnection between visual input and the motor system), and acquired ocular motor apraxia (loss of voluntary movement of the eyes while fixating on a target). Clinically, this triad of findings rarely occurs together.
Patients with visual allesthesia see their environment as rotated, flipped, or inverted. These symptoms localize the lesion to either the lateral medullary region (Wallenberg syndrome) or the occipitoparietal area.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.