Hemispatial Neglect in a Patient With Callosal Infarction

Abstract

Left hemispatial neglect, confined to right-hand and verbal responses, was exhibited by a 56-yr-old right-handed male patient with callosal lesions due to cerebral infarction. Various disconnection signs were also present. His CT and MRI scans disclosed major lesions situated in the posterior half of the genu and the whole trunk of the corpus callosum, as well as in the left medial frontal and temporo-occipital lobes. Left hemispatial neglect was invariably demonstrated in right-hand performance such as copying drawings, line bisection, matching identical figures and copying multiple digit numbers, and in verbal performance such as confrontation naming and reading aloud multiple digit numbers. In contrast, little or no right hemispatial neglect was demonstrated in tasks performed with the left hand. These findings support the hypothesis that the left hemisphere is only concerned with attending to the contralateral hemispace and that the right hemisphere is specialized for attending to both sides of space although the preponderant tendency is for attending to the contralateral hemispace. The neglect symptoms observed in our patient may be a disconnection sign which was attributable to a combination of lesions in the corpus callosum and in the left medial frontal lobe.

Right unilateral spatial neglect in aphasic patients

“…Mesulam (1981Mesulam ( , 1985Mesulam ( , 2000 added to this hypothesis by proposing that the rightward attention that is subserved by the right hemisphere is less predominant than leftward attention. Kashiwagi, Kashiwagi, Nishikawa, Tanabe, and Okuda (1990) observed the phenomenon of USN in a callosal-damaged patient following a cerebral infarction, which seems to support Mesulam's hypothesis. This patient exhibited remarkable left USN in activities that required left hemisphere functions, such as language tasks and copying or pointing with the right hand, but mild right USN in activities that required right hemisphere functions, such as copying or pointing with the left hand.…”

Right fronto-parietal dysfunction underlying spatial attention in bipolar disorder

“…Given that the left bias still exists when the right hand is used, this suggests interhemispheric spreading activation, probably via the corpus callosum, from the left hemisphere motor areas to the dominant attention network in the right hemisphere (McCourt et al, 2001). The role of the corpus callosum in visual line bisection is supported by studies on patients with callosal infarction (Kashiwagi et al, 1990;Corballis, 1995), patients with partial or complete commissurotomy (Heilman et al, 1984;Hausmann et al, 2003a) and younger children associated with immaturity of the corpus callosum especially in the posterior subareas (i.e., splenium).…”

Line Bisection in the Split Brain.

“…Kashiwagi, Kashiwagi, Nishikawa, Tanabe, and Okuda (1990) reported left hemineglect in a patient with callosal infarction in the trunk and genu of the corpus callosum, with rightward errors in line bisection, but only when the right hand was used. A more symmetrical effect of hand, with the left hand showing a significant left bias and the right hand a significant right bias, was reported by Heilman, Bowers, and Watson (1984) in a 43-year-old right-handed woman with a hemorrhage in the region of the corpus callosum, extending from the genu to the splenium.…”