Hemispatial Neglect: The Neuropsychological Condition

Hemispatial neglect, in particular of the right hemisphere, is a common disabling condition after unilateral neurological damage. It is most often seen after cerebral infarction or internal bleeding in the skull, although it can be caused by various pathological conditions and has an acute effect on up to two-thirds of right-hemisphere patients of stroke.

The neglected patient is often unaware of and/or fails to recognize articles on the contralesional side (left for patients with right brain damage), instead of taking care of articles on the same side as their brain damage, the ipsilesional side. Their neglect could be so profound that in extrapersonal space they might disregard and be unaware of large objects, and even people.

Hemispatial neglect is most often caused by strokes and brain unilateral damage to the right cerebral hemisphere, with rates as high as 80% causing visual neglect on the left side of space in the critical stage. Massive strokes in the middle brain artery often result in neglect and are diversified, so that most of the sufferers do not have all of the features of the syndrome.

The right-wing spatial neglect is rare because both the left and the right brain hemispheres redundantly process the right space, while the left space is only handled in the right brain hemisphere in most left-wing brains.

They can only eat from one side of a plate, write on one side of a page, and shave or make-up their face on the non-neglected or ipsilesional side (same side as brain damage). When putting the numbers in a clock drawing, for example, their drawings can overlook things on the overlooked side. Many patients are often unaware that they have a problem (anosognosia).

The neglect syndrome has traditionally been linked to damage to the right posterior parietal cortex. More recent research has begun to cast doubt on this theory, implying that a broader network of areas, including those implicated in neuroimaging studies, could be involved.

Individuals who have been neglected may or may not have a primary sensory or motor disability. Their visual fields, for example, may be totally intact. As a result, if a prominent, bright object on their ignored side is flashed on a dark backdrop, they can be able to identify it. Patients can fail to report the same stimulus if it is presented in a cluttered context, even if they are not blind. People who have been neglected may have no weakness in their eye or limb muscles, but they are unable to focus their gaze or use their hands to explore contralesional space. Instead, their visual quest can be limited to objects on their ipsilesional hand.

Neglect can take many forms, including visual, auditory, and somatosensory systems. It may also affect scene memories, which is known as representational neglect. Bisiach and Luzzatti (1978) conducted a popular experiment in which they asked patients with left-sided visual neglect in Milan to imagine seeing the central square, the Piazza del Duomo, from the cathedral in the square’s middle. They discovered that these patients often failed to mention locations or streets off to the left of the square from that vantage point.

When asked to imagine looking directly at the cathedral, i.e., changing their point of view by 180 degrees, the same people forgot to notice places on the side of the square they had just reported – places that now fall to their left from the new imagined point of view. They instead remembered locations to the right of the latest imagined vantage point.

Diagnosis of Hemispatial Neglect

Neglect can be assessed in a variety of ways. Since various types of tests can reveal different deficits in different patients, there is no single test that can be used to diagnose the disorder. Many patients will engage in neglectful behavior when engaging with others in their daily lives, so patient assessment is critical. Furthermore, a battery of neuropsychological tests has been developed to capture and measure the level of neglect.

The majority of batteries have the following features:

• The task of cancellation. There are visual search exercises in which the patient is asked to surround or cancel out any of the targets that they may locate on a sheet of paper in front of them.
• Bisection of a line. On a sheet of paper, the patient must mark the midpoint of a horizontal line.
• A copying task. The patient is asked to copy one or more line drawings by the examiner.

Line of Treatment and Mitigation

It is now widely accepted that strategies aimed solely at improving contralesional space exploration, such as guiding gaze in that direction on quest tasks, are successful in reducing neglect on those tasks, but that these gains do not generalize or ‘move’ to an amelioration of neglect in daily life.

Patients do not search the ignored side of space substantially better after such training when put back into daily circumstances. There has been evidence of substantial progress in neglect and functional outcome indicators for up to 2 months when combined with the vibration of the contralesional neck muscles.

Neck muscle vibration is thought to trigger an illusory alteration of the afferent knowledge about the head’s position in space, resulting in a recentering of the egocentric frame of reference.

There has also been a lot of interest in prism adaptation as a way to improve neglect in recent years. Adapting to rightward-deviating prisms seems to result in long-term gains in left-sided neglect. However, the factors underlying this behavior change are still being debated, and it has become clear that not all patients respond to this type of treatment.

Teaching patients to self-alert or use an alerting system that serves to arouse them, as well as limb activation therapy, which includes directing attention to the contralesional side, has shown to be beneficial in some cases.

Some studies have shown that repeated transcranial magnetic stimulation applied to the contralesional hemisphere improves neglect. The underlying mechanism is thought to be short-term suppression of the intact side of the brain, which corrects any attentional orienting mismatch.

FAQs

Ques. Is hemispatial neglect a psychiatric condition?
Ans. It is primarily a neurocognitive condition. At best, it can be described as neuropsychological and it falls within the ambit of neuroscience and neurosurgery.

Ques. What are the treatment methodologies available?
Ans. Hemispatial neglect is a new and frontal area of research in neuroscience with numerous studies and academic papers being actively carried out. Physical therapy, behavioral approaches, and common exercises have been observed to have substantive effects.

Ques. Who can have this condition?
Ans. It is extremely rare. People who have had a stroke, concussion, internal hemorrhage, blunt trauma, head injury, and nerve damage are high-risk groups for developing neglect.

Ques. What exactly is the primary symptom of hemispatial neglect?
Ans. The individual displays the mechanical inability to distinguish objects visually at a certain angle. For instance, they may have a reduced field of vision and this could interfere with their capacity to discern things in their field of view. They might not even be aware of this condition.