Hemineglect: Half of a whole
Hemineglect: Half of a whole
There exists a common condition that many people are unaware of, even those that undergo it, in which people fail to recognize one side of space including their own body. Hemineglect also known as spatial neglect, unilateral neglect, or hemispatial neglect is a neuropsychological disorder that follows after damage to one hemisphere of the brain, in which patients have the inability to pay attention to the side of the space or body affected by the brain damage [3]. This condition is varied in terms of the location and extent of brain damage. Due to this, an imbalance occurs, resulting in the part of the brain that remains intact to pick up the slack.
Patients with destruct to the right side of their brain fail to be aware of items in the left region. For example, the patient may not even touch their food on the left side of the plate or draw only half the numbers on the face of the clock. The hemisphere that is undamaged becomes more active, resulting in greater eye movements on that side of the brain. Clearly, this can reduce the ability of individuals to live independently without harming themselves or others [3].
Backdrop of Hemineglect
The causes underlying hemineglect symptoms are stroke, traumatic brain injury, brain tumors, and aneurysms. People who endure an injury on either side of the brain experience this phenomenon, but this condition often impacts the right hemisphere of the brain [3].
One may wonder, “why don’t patients simply turn their heads to view an object placed on side of neglect?”. The nature of the condition is that of a tangled web. The issue has nothing to do with eye functioning or movement as the visual fields are unimpaired. The problem lies within brain processing – when the eye transmits information to the brain, it is incapable of deciphering that information the way it used to. Interestingly, memory may also be affected as when patients observe images on the side of space they can perceive, they forget that they saw it in the first place, when placed on the side of space that is damaged [4].
Using the Detective Lens
Hemineglect is complex, and so detecting its symptoms can be of great difficulty. Some of the signs to be aware of are the following [2]:
- Anosognosia: the obliviousness of the deficit.
- Self-neglect: the patient will completely ignore the side that has been damaged due to being inattentive towards that side e.g., shaving only half their face.
- Allochiria: patients have the inability to pay attention to stimuli on the neglected side.
- Somatoparaphrenia: patients have the mistaken illusion that the neglected side of their body belongs to someone else. They may experience an illusion by claiming that someone is sitting on their left arm. Undeniably, this has adverse consequences because they cannot even detect pain in the neglected side (commonly the left side).
Identifying Pieces
Since patients differ in their deficits, there are several tests used to detect the condition. Usually when a patient is observed with scrutiny, one can be able to tell. Some of the most common tests are as follows [2]:
- Cancellation task: A visual task in which patients observe a piece of paper that has scattered lines all over it, and they are asked to cross or circle all the lines. By the end, the patient only crosses lines on the non-neglected side, leaving behind the impacted side.
- Line bisection: A paper with a horizontal line is placed in front of them and they are asked to mark the center of the line. Instead of marking the midpoint, they are more inclined to mark the right side of the line, ignoring the left side.
- Reading task: The patients are asked to read a text and it is observed that they typically omit reading the left side and only read the right side i.e., the non-neglected side.
- Copying task: Patients are asked to draw something from memory or asked to copy a drawing given to them.
The Bizarre Case of Alan Burgess
After a stroke, all Alan Burgess had left was inattention to objects, people, and sounds on his left [1]. He reported, “It is not blindness in one eye, and it’s not damage to the primary sensory cortex, it’s a process of ignoring, for want of a better word, one side of space.”
Burgess was assessed by Dr. Malhotra to discover the seriousness of his condition by asking him to mark the center of a 25 cm line on paper. During the initial stages, Burgess marked the center approximately 2 cm from the right edge. As a matter of fact, he showed complete disregard of the left side of the line [1]. His doctor pointed out that patients with neglect do realize that something is off as they are repeatedly told about their mistake. They are aware that there is a problem and try their best to overcome it, yet they are simply incapable of doing so because of the inability to grasp the full picture.
Prior to his condition, Burgess worked as a driver, and after suffering from hemineglect he was dragged into retirement. Intriguigly, he never showed an interest in painting but after his stroke and undergoing hemispatial neglect, it became an outlet for him to cope. Through his newfound hobby, it could be observed that his sketch of a pig had half of its head missing. When solely one side of the world can be processed and vision becomes scathed, everything else including hearing, touch, the sense of self, and identity falls apart [1].
A compelling observation established by Dr. Malhotra was that people having normal vision are rewarded with a praise or compliment when they perform well in any given task. Applying the same to hemineglect patients fosters the same improved performance.
Our eyes are an amazing lens through which we perceive the world without consciously being aware, that they simply send signals to the brain and it is actually the brain that is computing these messages to make sense of what is presented to us.
Hemineglect is quite common after stroke and has a high mortality and morbidity rate. Because of its intricacy, it can be hard to treat, especially because there are several underlying mechanisms. Since patients’ routine and independent living are impacted, there needs to be added care for the individual. Over time recovery is possible, however approximately one-third do not recover, and suffer neglect as a lasting disabling condition.
References
[1] Hoffman, T. (2012, November 23). The man whose brain ignores one half of his world. The Guardian. Retrieved June 19, 2022, from https://www.theguardian.com/science/blog/2012/nov/23/man-brain-ignores-half-world
[2] Husain, M. (2017, January). Hemineglect. Scholarpedia. Retrieved June 16, 2022, from http://www.scholarpedia.org/article/Hemineglect
[3] Sarwar, A., & Emmady, P. D. (2022, May). Spatial neglect NCBI bookshelf. Spatial Neglect. Retrieved June 15, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK562184/
[4] Team, H. J. (2020, March). Hemispatial neglect syndrome causes, symptoms, diagnosis, treatment & prognosis. Hemispatial neglect. Retrieved June 15, 2022, from https://healthjade.net/hemispatial-neglect/
[5] YouTube. (2020). Hemispatial Neglect: When Half Your World Disappears. Retrieved July 19, 2022, from https://www.youtube.com/watch?v=q52ZCoehGrs.
[6] Sutton, M. (2021, March 15). Left neglect after stroke – definition & treatment exercises. Tactus Therapy. Retrieved July 19, 2022, from https://tactustherapy.com/what-is-left-neglect/
Inara is a fourth-year student studying Psychology at the University of Calgary. At present, she is undertaking an independent thesis in forensic psychology with a distinguished faculty member in the Department of Psychology. In her free time, she likes to read fiction novels, volunteer, and swim. She hopes that Science, Translated will help simplify the lives of people who struggle to dismantle scientific literature.
