Hemispatial neglect

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Hemispatial neglect, also called unilateral neglect, spatial neglect or neglect syndrome is a neurological condition in which, after damage to one hemisphere of the brain, a deficit in attention to the opposite side of space is observed. It most commonly results from brain injury to the right cerebral hemisphere, causing visual neglect of the left-hand side of space. Although most strikingly affecting visual perception ('visual neglect'), neglect in other forms of perception can also be found, either alone, or in combination with visual neglect.

For example, a stroke affecting the right parietal lobe of the brain can lead to neglect for the left side of the visual field, causing a patient with neglect to behave as if the left side of sensory space is nonexistent. In an extreme case, a patient with neglect might fail to eat the food on the left half of their plate, even though they complain of being hungry. If someone with neglect is asked to draw a clock, their drawing might show only the numbers 12 and 1 to 6, the other side being distorted or left blank. Neglect patients may also ignore the contralesional side of their body, shaving or adding make-up only to the non-neglected side.

Neglect may also present as a delusional form, where the patient denies ownership of a limb or an entire side of the body. Since this delusion often occurs alone without other signs of mental illness, it is often labeled as a monothematic delusion.

1 Causes
2 Treatment
3 See also
4 External links
- 4.1 References

[edit] Causes

Brain areas in the parietal and frontal lobes are associated with the deployment of attention (internally, or through eye movements, head turns or limb reaches) into contralateral space. Neglect is most closely related to damage to the temporo-parietal junction and posterior parietal cortex. The lack of attention to the left side of space can manifest in the visual, auditory, proprioceptive, and olfactory domains. Although hemispatial neglect often manifests as a sensory deficit (and is frequently co-morbid with sensory deficit), it is essentially a failure to pay sufficient attention to sensory input. This is particularly evident in a related, but separate, condition known as extinction. A patient with extinction following right-hemisphere damage will successfully report the presence of an object in left space when it is the only object present. However, if the same object is presented simultaneously with an object in right space, the patient will only report the object on the right.

Neglect patients can also have problems with "interior" left information, since cases have been reported in which the patient when asked to describe something he knew before his brain damage describes only its right part.

Although hemispatial neglect has been identified following left hemisphere damage (resulting in the neglect of the right side of space), it is most common after damage to the right hemisphere. This disparity is thought to reflect the fact that the right hemisphere of the brain is specialized for spatial perception and memory, whereas the left hemisphere is specialized for language. Hence the right hemisphere is able to compensate for the loss of left hemisphere function, but not vice versa.

[edit] Treatment

Treatment consists of finding ways to bring the patient's attention toward the left, usually done incrementally, by going just a few degrees past midline, and progressing from there. Throwing a soft ball from the left, playing a game that involves attending to the left, replying to speakers on the left, or manipulating objects on the left may help. Rehabilitation of neglect is often carried out by neuropsychologists and occupational therapists.