Tuesday, October 18, 2011

Balint's Syndrome (Etiology and Anatomy)

Balint’s syndrome is a visual and spatial disorder produced by bilateral lesions of the parieto-occipital junction. The lesions characteristically involve the dorsorostral occipital lobe (Brodmann area 19), and often, but not invariably, the angular gyrus, but may spare the supramarginal gyrus and the superior temporal gyrus. The supramarginal gyrus and the posterior part of the superior temporal gyrus are affected in the right hemisphere, but spared on the left. The superior parietal lobule is only minimally involved in either hemisphere. Thus Balint’s syndrome is associated with diseases in which symmetric lesions of the parietooccipital junction are typical. For example, Luria (1959) and Holmes and Horax (1919) have reported this syndrome after patients received penetrating wounds from projectiles entering laterally and traversing the coronal plane through the parietooccipital regions. Strokes successively injuring both hemispheres in the distribution of posterior parietal branches of the middle cerebral artery are another common cause.

In Balint's syndrome, the depth perception is severely impaired as the patient can not judge the distance of objects from him or tell which of two objects is closer to him. Optic ataxia is pronounced. While visual acuity is preserved and patients are able to recognize objects placed directly in front of them, they are unable to interact with, or make sense of, their visual environment. They are lost in space. Fleeting objects that they can recognize, but that they cannot locate or grasp, appear and disappear, and their features are jumbled together. These patients are helpless in a visually chaotic world.