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Hemispatial neglect is a neuropsychological condition in which, after damage to one hemisphere of the brain (e.g. after a stroke), a deficit in attention and awareness towards the side of space opposite brain damage (contralesional space) is observed.
Consequently, the left side of the forebrain mostly represents the right side of the body, and the right side of the brain primarily represents the left side of the body. The contralateral organization involves both executive and sensory functions (e.g., a left-sided brain lesion may cause a right-sided hemiplegia).
Damage to the Broca's area and the Wernicke's area of the brain (left side) typically causes problems with speech and language. Damage to the right side of the brain may interfere with the ability to express emotions or interpret what one sees. Damage on either side can cause paralysis of the opposite side of the body. [citation needed]
In children, the most common cause is a stroke of the ventral pons. [9]Unlike persistent vegetative state, in which the upper portions of the brain are damaged and the lower portions are spared, locked-in syndrome is essentially the opposite, caused by damage to specific portions of the lower brain and brainstem, with no damage to the upper brain.
Lesions to V4 can cause color-blindness, [13] and bilateral lesions to MT/V5 can cause the loss of the ability to perceive motion. Lesions to the parietal lobes may result in agnosia, an inability to recognize complex objects, smells, or shapes, or amorphosynthesis, a loss of perception on the opposite side of the body. [14]
Another factor in secondary injury is loss of cerebral autoregulation, the ability of the brain's blood vessels to regulate cerebral blood flow. [5] Other factors in secondary damage are breakdown of the blood–brain barrier, edema, ischemia and hypoxia. [15] Ischemia is one of the leading causes of secondary brain damage after head trauma. [9]
The cause for hemispheric disconnection is if the interhemispheric fibers, as mentioned earlier, are cut or reduced. [ citation needed ] An example is commissural disconnect in adults which usually results from surgical intervention, tumor, or interruption of the blood supply to the corpus callosum or the immediately adjacent structures.
[1] [2] It is a secondary condition caused by a primary injury on the opposite hemisphere of the brain. [3] Kernohan's notch is an ipsilateral condition, in that a left-sided primary lesion (in which Kernohan's notch would be on the right side) evokes motor impairment in the left side of the body and a right-sided primary injury evokes motor ...