Home > Diagnosis, Early recognition, Types of dementia > What is Topographical Disorientation?

What is Topographical Disorientation?

Image courtesy sippakorn @ http://www.freedigitalphotos.net(Author’s note:  I got inspiration for this post while watching the “Today” show this morning.  A woman with the developmental form of this disorder was profiled, and I was motivated to do a little further research on the subject.  I’d like to share the results of that research with you, my readers.)

Topographical disorientation is a term which refers to an inability to find one’s way in the surrounding area, as a result of a brain injury or dysfunction.  It can also be referred to as topographical agnosia or topographagnosia.  The person who has this disability may be unable to interpret spatial information, such as environmental landmarks, or to use cognitive strategies to navigate within his surroundings.  It can also occur in a developmental form, which is present from early childhood.

There have been several dozen case reports, over the last century, of people who have been unable to find their way around large-scale environments.  These reports have been studied extensively, and are still being scrutinized, in an effort to determine what causes this topographical disorientation.  It is found in people who have had a stroke (especially if hemispatial neglect is present), or a progressive illness such as Alzheimer’s disease or other forms of dementia.  One study identified it in 17 out of 41 persons with Mild Cognitive Impairment.

One sub-type of TD is egocentric disorientation.  A person with this disability will have difficulty localizing objects in respect to their own bodies.  They will have trouble reaching for specific objects, or stating how one object is positioned with respect to another.  However, they will be able to name these objects, and describe them in other ways, and will usually have good visual acuity.  Auditory cues may or may not be helpful.  One example of this is when a person is greeted by someone approaching from their left, and they turn to the right to meet them.  This behavior has been found to originate with lesions in the posterior parietal lobe of the brain.

Another form of TD is known as heading disorientation, and is characterized by difficulty using landmarks to find their way to a particular location.  The person who has this disability will be able to determine where they are at the present time, due to physical landmarks in the area, but will not be able to use those landmarks to get to another place.  If you were to ask this person how to get from one place to another, he would not be able to tell you.  There is some evidence that this behavior is due to lesions in the posterior cingulate, and has been known at times to resolve itself after a period of time.

The inability to recognize landmarks is known (perhaps logically) as landmark agnosia.  People who have this disorder are able to draw detailed maps, and to distinguish between types of buildings (such as houses and schools).  However, they are unable to locate specific landmarks, such as their own house or the school their children attend.  Interestingly, the ability to localize places familiar to them before their injury is preserved.  Damage is usually noted in the lingual gyrus.

The last form of TD is known as anterograde disorientation.  This is characterized by trouble getting around in new or unfamiliar places.  Damage in these individuals is usually noted to be in the medial temporal lobe and the parahippocampus.  This is particularly significant when one recalls that the hippocampus and surrounding areas of the brain are important in the formation of long-term memories — especially spatial memories.

A comprehensive battery of neuropsychiatric tests will typically be used to diagnose TD.  Orientation should be evaluated in both real and virtual environments.  The TD is often only a symptom of a larger medical problem, however, and its presence should trigger further tests to determine what this might be.  Brain imaging will be used.  An overall assessment will most likely also consist of tests of memory, visuospatial abilities, object recognition, mental rotation, imagery abilities, and spatial abilities.  The person should be asked to read and draw a map, follow a route dictated to him, and point out landmarks along that route.

The prognosis for someone who has TD is dependent on the physical cause for the condition.  In someone who has had a stroke, the disability may eventually resolve itself — either with or without assistance.  An individual who has dementia will most likely have some difficulty of this type for the rest of his life, however,  In the aforementioned study of persons with MCI, it was speculated that the presence of TD may be suggestive of the early stages of Alzheimer’s.  In another study, it was found that a significant number of patients with Alzheimer’s disease, who were still living in the community, showed signs of TD.  These persons required an escort by others to their homes, reported a history of repeated change of residence, had a restricted spatial range in which they felt comfortable, and reported feeling disoriented when they were outside of their “safety zone.”  Their caregivers also expressed a high degree of concern for their safety when they were traveling alone.

It may be possible to treat the disorder through training in alternate strategies to use while trying to navigate around the individual’s surroundings.  These strategies can be of a temporary nature, or a permanent one, depending on the cause of the individual’s TD and their overall prognosis.  This would most likely be best carried out by a referral to an occupational therapist or a speech-language pathologist.

Personally speaking, I think this information is highly significant when considering the wandering behavior that is so common in persons with dementia.  Perhaps this provides another method for analyzing this problem, and for dealing with it.  I know that I will be following the work in this area, and will be curious to see how it develops.




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