The Neuroscience on the Web Series:
CMSD 636 Neuropathologies of Language and Cognition

CSU, Chico, Patrick McCaffrey, Ph.D.


Chapter 13. Right Hemisphere Involvement: Symptoms and Diagnosis


For most people, the right hemisphere is the non dominant hemisphere for speech and language. Individuals who are right hemisphere dominant are usually left handed or ambidextrous. (Only about 15% of left handed persons are right hemisphere dominant for speech and language). Because the right hemisphere usually plays only a secondary role in language processing, patients were not routinely treated by speech-language pathologists until recently. It is currently recognized that, while RHD patients do not typically have the types of language problems seen in aphasia, they frequently have both communicative and cognitive deficits which can be addressed in speech/language therapy. There are some similarities between closed head injury and right hemisphere lesions.

It should be noted that fewer statements about site of lesion can be made concerning the impairments associated with right hemisphere damage (RHD) than in regard to the aphasic syndromes caused by left hemisphere damage. This is the case because relatively little is known about localization of function in the right hemisphere. According to Brownwell et al. (1995), some believe that the right hemisphere is "less focally organized" than the left.

Deficits Associated with Right Hemisphere Damage

According to Myers (1994), impairments of perception and attention are the underlying causes of the extra-linguistic, linguistic and nonlinguistic deficits manifested by patients with RHD. According to Love and Webb (2001), neglect, inattention and denial are three major characteristics of right hemisphere syndrome. They are also characteristics of executive function difficulty. Marshall et al., 1998.

Linguistic Deficits

As stated above, right hemisphere patients typically do not have the kinds of language problems seen in aphasia. However, as some do have specific linguistic problems, RHD patients should be given an aphasia battery like the Boston. RHD patients might display deficits on the following Boston subtests: Responsive naming-patients give one word answers to spoken questions. Difficulty with auditory comprehension may effect results. It is important that naming is tested using several modalities. The following sub-tests may be useful also:

Visual confrontation naming is used on the Boston naming test. e.g. patients are asked to name pictures.
Body Part Naming
Auditory Comprehension of Complex Material
Word Fluency
Writing (RHD patients may substitute or omit graphemes)
Auditory comprehension of difficult material
Oral sentence reading
(Myers and Mackisack, 1990, in LaPointe, 1990)

Extralinguistic Deficits

Again, RHD patients are unlikely to display the kinds of phonological, syntactic or semantic problems associated with aphasia. However, although they do not typically have many specific language problems, they definitely have difficulty communicating. This impairment seems to follow from an inability to integrate information; RHD patients apparently do not make adequate use of context in their interpretations of linguistic or nonlinguistic messages. They have difficulty distinguishing significant from unimportant information. For example a patient of mine when asked to describe the "Cookie Theft" picture card from the Boston focused on irrelevant features without describing the overall picture. Some aphasics with typical left hemisphere lesions present with executive function disturbance similar to right hemisphere syndrome.

Literal Interpretations

RHD patients may be able to comprehend only the literal meaning of language. Thus, they will often fail to understand many jokes, metaphors, irony, sarcasm, and common sayings that include figurative language. For example, if an RHD patient hears someone say that they are about to "hit the ceiling," he might assume that the person is really about to begin striking the ceiling. Such a patient may also have trouble understanding indirect requests. For example, if he is asked if he "could open the window," he may fail to identify this as a polite request and simply answer "yes" rather than opening the window.

These problems with figurative language may be viewed as one manifestation of the inability to base interpretations on context.

Difficulty identifying relevant information

When listening to a conversation or reading, an RHD patient may fail to abstract the main point contained in the information being shared. This happens in spite of the fact that, unlike an aphasic, the patient can understand all the individual words and grammatical structures used. For RHD patients, it appears that their comprehension of everyday language is impaired by a failure to distinguish important information from irrelevant detail and also by an inability to integrate According to Blake 2007, RH patients have difficulty comprehending non-literal language, humor, and multiple interpretations Furthermore, Blake says that their difficulty with language production includes: impulsivity, inefficiency, and egocentricity. She also says that the same problems are seen in traumatic brain injury.

Inability to interpret body language and facial expressions

In a conversation, RHD may miss out on important cues that should tell them about the emotional state and true intention of the person with whom they are interacting. This inability to interpret body language and facial expression may be related to an overall failure to use context in the interpretation of individual pieces of information. Problems with the interpretation of facial expression may also be due to the fact that RHD patients often fail to maintain eye contact with their conversation partners.

Flat affect

RHD patients may fail to display a wide range of facial expressions themselves. Also their speech is frequently aprosodic, or lacking variations in pitch and stress. Some patients will sound "robot-like," and thus be unable to express emotion or changes in meaning via changes in intonation. These patients will no longer be able to vary pitch to signal the difference between a question and a statement or use word stress changes within a sentence to signal a difference in meaning.

Problems with Conversational Rules

RHD patients may fail to follow conversational rules, including those governing turn-taking, the initiation and closure of a conversation. RHD patients may tend to dominate conversations, as they are frequently verbose. They may also fail to properly estimate levels of shared knowledge, failing to give the listener enough background information to understand their statements. According to Myers and Mackisack (1990), RHD patients appear to not care about the needs of the listener. They, like children in an early developmental phase, may assume too much knowledge on the part of the listener; or not enough. They appear to answer without adequate search for the right answer. They also may fail to pick up on non verbal cues that signal listener's reactions.

Impulsivity

RHD patients may exhibit poor judgment and problem solving abilities. They may require constant supervision due to a tendency to attempt tasks of which they are no longer physically capable. This may be related to anosognosia. They may also exhibit impulsivity in the sense of failing to censor the statements they make to other people.

Confabulation

RHD patients may make untrue statements. These do not usually seem to be deliberate lies. According to Brownwell et al. (1995), this may be the patient's way of responding to his own confusion rather than attempts to mislead the listener

RHD patients may occasionally have hallucinations.

Nonlinguistic Deficits

Disorientation to Time and Direction

RHD patients may exhibit disorientation to time and and direction. They are usually oriented to person and to place, however. Many hospital patients are somewhat disoriented to time. They may be unable to give the date, time of day, or day of the week accurately. Note that it is important to be reasonable when assessing orientation. It is perfectly normal to miss the day of the week or date by one day and such errors should not be taken as an indication that the patient is disoriented. Sometimes when I am on vacation I may not know the day or the date. We shouldn't expect more of our patients.

RHD patients may also have difficulty following directions or finding their way around a building. They will know where they are in a general sense (e.g., in the hospital), but have trouble finding their way to specific locations (e.g., the dining room).

This deficit, known as topological disorientation, is a product of their general inability to process spatial information. Some patients with left hemisphere parietal lobe lesions have similar problems

Left side neglect

Neglect is a syndrome in which the patient fails to recognize one side of the body and the environmental space surrounding this side of the body in the absence of paralysis and visual problems. Neglect is considered a deficit in directed attention. This means that patients demonstrate an inability to be aware of stimuli, attend to stimuli or recognize the significance of stimuli. Neglect may also be described as the inability to orient to stimuli with the purpose of acting upon them. According to Myers (1994, in Chapey,1994), although neglect may occur with left hemisphere damage (LHD) it is more severe, longer lasting and common with RHD. It can occur with frontal, temporal, and parietal lobe lesions as well as with some sub-cortical lesions ( Myers, 1994).

Patients with neglect may fail to eat food on the left side of their plates, begin reading in the middle of sentences and in other ways seem to completely ignore the neglected side. Some may even cease to identify their left side as part of their own bodies. RHD patients have been known to give their paralyzed left arms names like "the baby" or "the dead one." They might also request that someone remove the other person from their bed, referring to their left side. RHD patients with left neglect may also have difficulty with left side detail in visuo-constructional tasks. For example, if drawing a picture or building a model, they might leave out details on the left side. The severity of neglect is usually an indication of the size of lesion and the overall severity of the patient's condition.

Note that RHD patients may have visual deficits including left hemianopsia. This may occur along with neglect or might exist alone and be mistaken for neglect. Scanning behavior may be used to differentiate between left neglect and left hemianopsia. A patient who has hemianopsia without neglect will have difficulty seeing things in his left visual field, but will not ignore his left side. For this reason, such a patient may be observed turning his head to scan the left visual field. On the other hand, a patient who does have neglect will generally make few or no spontaneous efforts to look at things in the left area of his visual field. According to Myers (1994), most theories of neglect consider it a deficit in attention.

At this time, the site of lesion that causes neglect is not known. However, the syndrome is frequently associated with parietal lobe lesions.

As mentioned above,
right side neglect does sometimes occur in patients with left hemisphere damage. However, it is fairly uncommon. (Right side neglect occurs in approximately twenty percent of patients with left hemisphere damage.) It is also less severe and usually of shorter duration than left side neglect.

Anosognosia

This term first used by Babinski is the failure to recognize the symptoms of one's own illness. RHD patients may deny that they have had a stroke. They may appear to be unaware of their hemiplegia or their cognitive deficits (Love and Webb, 2001). It is not uncommon for right hemisphere patients to state that they are perfectly capable of walking, driving and returning to work immediately despite all evidence to the contrary. Anosognosia may be described as severe denial. The source of this denial appears to be cognitive rather than emotional; it seems as though patients are unable rather than unwilling to recognize their deficits.

Because RHD patients do not fully comprehend the extent of their impairment, they are frequently less depressed than those with left hemisphere damage. This type of executive function difficulty can also appear in aphasic patients with left hemisphere lesions.

Visuospatial Deficits

RHD patients have difficulty processing many types of visual stimuli. These problems are apparently due to an inability to integrate information. RHD patients have trouble with figure-ground problems, recall of visual forms and mental rotation, or the ability to imagine how a figure would look if its orientation in space were changed. Constructional apraxia can also be present in patients with RHD. Their drawings tend to be scattered, fragmented, and spatially disorganized (Myers, 1994, in Chapey, 1994). According to Swindell (1988, in Myers, 1994), the drawings of RHD patients may not benefit from a model or from cueing and are not likely to improve over time.

Prosopagnosia, or the inability to recognize familiar faces, is one of the most striking visuospatial processing deficits manifested by RHD patients. This does not represent a difficulty with vision itself. A patient with prosopagnosia is able to describe the features of familiar faces, including eye and hair color, type of nose, etc. An artistic patient will even be able to draw the faces of family members and friends accurately yet be unable to recognize them. Rather, the problem seems to be related to the integration of visual perceptions and their association with information stored in memory. According to Love and Webb (2001), patients with this disorder usually have lesions in the right occipital-temporal lobe region. Color agnosia is often seen with prosopagnosia.

 


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