Welcome back! Wow, this has been a real whirlwind of knowledge. You’ve learned so much about the brain, and the four “A” conditions: amnesia, apraxia, aphasia, agnosia. For the next three days, we’ll learn about three other types of common disorders; these are neglect, dementia, and epilepsy.
Let’s start with neglect.
Definition of Neglect
Neglect describes a condition where the patient ignores or fails to respond to stimuli on one side of their environment, typically opposite to the side of the brain where the lesion is located (this is called the contralateral side).
For example, patients with lesions in the right hemisphere might ignore everything on the left-hand side of their environment. The neglect is not a result of sensory impairment (for example, they are not blind or deaf) or motor impairment; instead, it appears to be more of an “inattention” to that side.
So, for example, if I asked you to close your left eye, and then look for something that is in your left visual field—like a door—what did you do? You probably turned your head to the left so that you could see with your right eye. Patients with neglect do not do this; they are unaware of their neglect and do not accommodate for this deficit. This lack of accommodation is a defining feature between neglect and, for example, hemianopia (where the patient is partially blind and cannot see one side of their environment), because patients with hemianopia will turn their head so that the stimuli appear in their visual field.
How does Neglect Present?
Sensory versus motor neglect. Neglect can present in different ways.
First, patients might suffer from sensory neglect, where they are unable to perceive or detect stimuli on one side. This failure to detect stimuli is not due to the sensory system (e.g., ears, eyes, sense of touch) not working, instead, this is due to inattention to a particular side. Sometimes patients are able to detect stimuli on both sides, but only when presented individually. When the stimuli is presented simultaneously, then the patient might neglect to detect the contralateral side, this is called extinction. Extinction is most noticeable with visual and auditory stimuli.
In contrast, patients might suffer from motor neglect, where the patient doesn’t display sensory neglect, but they fail to respond to the stimuli. This failure is not due to paralysis—their limbs and muscles do work, and they are able to see the objects, but fail to move towards it. For example, if asked to reach a pencil, which is placed in front of their left hand, the patient might reach with the right hand instead. In fact, they may not “be able” to move the left hand at all, despite the muscle tone and nerve responses behaving normally! In this example, the patient has akinesia and from previous lessons, you should be able to guess what this means (“a” = “without”, “kinesis” = “movement”, and “ia” = “syndrome” or “condition”). Like sensory neglect, patients with motor neglect might display motor extinction. That is, they can move each limb individually, but when asked to move them simultaneously, then they only move one.
Spatial vs. personal neglect. Neglect syndromes are also described in terms of where—that is, in which space—they occur. In spatial neglect, patients are unable to perform tasks within the space around them, then they neglect one side. For example, when asked to copy or draw a picture, patients might neglect one half of the image.
Sometimes patients might not be able to read or write information that appears on the left side of the page. For example, if the patient was shown the following sentence:
“This is an example of a sentence.”
Then the patient only read “example of a sentence”. In extreme forms, if patients are shown compound nouns, for example, “fridge magnet” or “cupboard”, then they may only read the right-hand side. In this case, they would read “magnet” or “board”.
Up to now, we’ve discussed neglect that occurs in spaces external to the patient; however, sometimes neglect can occur in the patient’s personal space. Patients with personal neglect fail to realize that their limbs are their own but instead might believe (or feel) that they belong to someone else. For example, the patient doesn’t acknowledge that their left arm is their own, and instead says that it is the clinician’s arm.
Patients with neglect struggle to perform everyday tasks, because they do not perceive, acknowledge, or respond to stimuli present in specific spaces. This condition impacts the patients’ rehabilitation and results in confusion and awkward situations. I’ve included a few example videos of neglect for you below, and in one video you can see how an occupational therapist reminds the patient to check their left-hand side so that they can complete the task.
Tomorrow, we will learn about dementia.
See you tomorrow!
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