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Aphasia

Aphasia

Definition

Aphasia is a communication disorder that occurs after language has been developed, usually in adulthood. Not simply a speech disorder, aphasia can affect the ability to comprehend the speech of others, as well as the ability to read and write. In most instances, intelligence per se is not affected.

Description

Aphasia has been known since the time of the ancient Greeks. However, it has been the focus of scientific study only since the mid-nineteenth century. Although aphasia can be caused by a head injury and neurologic conditions, its most common cause is stroke , a disruption of blood flow to the brain, which affects brain metabolism in localized areas of the brain. The onset of aphasia is usually abrupt, and occurs in individuals who have had no previous speech or language problems. Aphasia is at its most severe immediately after the event that causes it. Although its severity commonly diminishes over time through both natural, spontaneous recovery from brain damage and from clinical intervention, individuals who remain aphasic for two or three months after its onset are likely to have some residual aphasia for the rest of their lives. However, positive changes often continue to occur, largely with clinical intervention, for many years. The severity of aphasia is related to a number of factors, including the severity of the condition that brought it about, general overall health, age at onset, and numerous personal characteristics that relate to motivation.

Demographics

The National Aphasia Association estimates that approximately 2540% of stroke survivors develop aphasia. There are approximately one million persons in the United States with aphasia, and roughly 100,000 new cases occur each year. There are more people with aphasia than with Parkinson's disease , cerebral palsy , or muscular dystrophy .

Causes and symptoms

Although aphasia occasionally results from damage to subcortical structures such as basal ganglia or the thalamus that has rich interconnections to the cerebral cortex, aphasia is most frequently caused by damage to the cerebral cortex of the brain's left hemisphere. This hemisphere plays a significant role in the processing of language skills. However, in about half of left-handed individuals (and a few right-handed persons), this pattern of dominance for language is reversed, making right-hemisphere damage the cause of aphasia in this small minority. Because the left side of the brain controls movement on the right side of the body (and vice versa), paralysis affecting the side of the body opposite the side of brain damage is a frequent co-existing problem. This condition is called hemiplegia and can affect walking, using one's arm, or both. If the arm used for writing is paralyzed, it poses an additional burden on the diminished writing abilities of some aphasic individuals. If paralysis affects the many muscles involved in speaking, such as the muscles of the tongue, this condition is called dysarthria . Dysarthria often co-occurs with aphasia.

There are a few more problems that can result from the same brain injury that produces aphasia, and complicate its presentation. Most notable among them are the problems collectively called apraxia , which influences one's ability to program movement. Apraxic difficulties make voluntary movements difficult and hard to initiate. Apraxia of speech results in difficulty initiating speech and in making speech sounds consistently. It frequently co-occurs with both dysarthria and aphasia. Finally, sensory problems such as visual field deficits (specifically, hemianopsia ) and changes in (or absence of) sensation in arms, legs, and tongue commonly occur with aphasia.

There are neurological disorders other than aphasia that also manifest difficulty with language. This makes it important to note what aphasia is not. Traumatic brain injury and dementias such as Alzheimer's disease are excellent examples. Although brain injury is a cause of aphasia, most head injuries produce widespread brain damage and result in other neuropsychological and cognitive disorders. These disorders often create language that is disturbed in output and form, but are typically the linguistic consequences of cognitive disturbances. In Alzheimer's disease, the situation is much the same. Language spoken by individuals with Alzheimer's reflect their cognitive problems, and, as such, differ from the language retrieval problems typically designated as aphasia. In

short, if the damage that results in language problems is general and produces additional intellectual problems, then aphasia is a correct diagnosis. In the absence of other significant intellectual problems, then the language disorder is probably localized to the brain's language processing areas and is properly termed aphasia.

Finally, aphasia is not conventionally used to refer to the developmental language learning problems encountered by some atypically developing children. However, when children who have been previously developing language normally have a stroke or some other type of localized brain damage, then the aphasia diagnosis is appropriate.

Aphasia manifests different language symptoms and syndromes as a result of where in the language-dominant hemisphere the damage has occurred. The advent of neuroimaging has improved the ability to localize the area of brain damage. Nevertheless, the different general patterns of language strengths and weaknesses, as well as unexpected dissociations in language function, can explain how normal language is processed in the brain, as well as provide insights into intervention for aphasia.

Aphasic individuals almost uniformly have some difficulty in using the substantive words of their native language. Most experts in aphasia recognize that aphasia varies along two major dimensions: auditory comprehension ability and fluency of speech output. In reality, aphasic behaviors vary greatly from individual to individual, and fluctuate in a given individual as a result of fatigue and other factors. In addition, largely in relationship to lesion size, aphasias differ in overall severity.

Nonfluent aphasia

Frontal cortex is responsible for shaping, initiating, and producing behaviors. Individuals with nonfluent aphasia characteristically have brain damage affecting Broca's area of the cortex and the frontal brain areas surrounding it. These areas are responsible for formulating sound, word, and sentence patterns. Damage to the anterior speech areas results in slow, labored speech with limited output and prosody and difficulty in producing grammatical sentences. Because the motor cortex is closely adjacent, nonfluent Broca's aphasia, by far the most common nonfluent variant, is quite likely to co-occur with motor problems.

Several additional characteristics of nonfluent aphasia can be noted: in nonfluent aphasia verbs and prepositions are disproportionately affected; speech errors occur mostly at the level of speech sounds, producing sound transpositions and inconsistencies; auditory comprehension is only minimally affected; reading abilities parallel comprehension, writing problems parallel speech output, but are sometimes further complicated by hemiplegia; finally, there is an inability to repeat what someone else says.

Fluent aphasia

Fluent aphasias occur when damage occurs in the posterior language areas of the brain, where sensory stimuli from hearing, sight, and bodily sensation converge. In fluent aphasia, the prosody and flow of speech is maintained; one typically must listen closely to recognize that the speech is not normal. Because this posterior damage is located far from the motor areas in the frontal lobes, individuals with fluent aphasia seldom have co-existing difficulty with the mechanics of speech, arm use, or walking. There are three major variants of fluent aphasia, each thought to occur as a function of disruption to different posterior brain regions.

WERNICKE'S APHASIA Wernicke's aphasia results from temporal lobe damage, where auditory input to the brain is received. The essential characteristic is that individuals with this disorder have disproportionate difficulty in understanding spoken and written language. They also have problems comprehending and monitoring their own speech. They are often verbose, and frequently use inappropriate and even jargon words when they speak. Reading and writing are impaired in similar ways to auditory comprehension and speech output. Their comprehension difficulties preclude their being able to repeat others' words.

ANOMIC APHASIA Most people, particularly as they grow older, have trouble with the names of persons and things; all aphasic persons experience these difficulties. But when brain damage occurs in the area of the posterior brain where information from temporal, parietal, and occipital lobes converge, this problem of naming is much more pervasive than for normal and aphasic speakers alike. Most anomic aphasic individuals have excellent auditory comprehension and read well. But for most of them, writing mirrors speech, and individuals with anomic aphasia can take advantage of words provided by others. Hence, their repetition ability is good. Although anomic aphasia is classified as a fluent syndrome, frequent stops, starts, and word searches typically make speech choppy in between runs of fluency.

CONDUCTION APHASIA Individuals with conduction aphasia are thought to have a discrete brain lesion that disrupts the pathways that underlie the cortex and connect the anterior and posterior speech regions. These individuals have good comprehension, as well as high awareness of the errors that they make. Placement of their brain damage also suggests that there should be little interference with speech production, reading, and writing. However, damage to the neural links between posterior and anterior speech areas makes it quite difficult for these individuals to correct the errors they hear themselves making. Conduction aphasia also affects the ability to repeat the speech of others or to take advantage of the cues others provide. The speech of individuals with this problem includes many inappropriate words, typically involving inappropriate sequences of sounds.

UNUSUAL APHASIA SYNDROMES There are a few other rare aphasic syndromes (called "transcortical aphasias") and unique dissociations in aphasic patterns. The above aphasias represent the most common distinctive syndromes. However, they are estimated to account for only approximately 40% of individuals with aphasia.

MIXED AND GLOBAL APHASIA The remaining majority, about 60% of aphasic individuals, have aphasias that result from brain lesions involving both the anterior and posterior speech areas. Their aphasias, thus, affect both speech production and comprehension. They frequently have reading and writing disorders as well. Individuals with mixed and global aphasia are also very likely to have hemiplegia and dysarthria, as well as a variety of sensation losses. Depending upon the severity of these symptoms, people with mild-to-moderate symptomatology of this type are said to have mixed aphasia; global aphasia describes individuals with extensive difficulties in all language skills.

Diagnosis

As an aid to accurate diagosis immediately following stroke, it is important to differentiate aphasia from cognitive disorders such as confusion and disorientation. To this end, brief, but general testing of the language functions (naming, comprehension, reading, writing, and repetition) can be incorporated into broader testing that might determine other cognitive functions. Evaluators must remember that language is the medium though which most of these other functions are observed. Therefore, language should be assessed first; if extensive aphasia is present, then only cautious interpretations of other cognitive functions may be given. At present, there are few available objective and standardized measures for testing during the acute phases of disorders such as stroke.

A number of standardized measures are available that provide an inventory of aphasic symptoms. These tests are useful in providing baseline and follow-up assessments to measure progress in treatment, as well as to guide the treatment itself. A fairly general feature of aphasia tests is that individuals without aphasic symptoms should perform with almost no errors on them. Tests are available to measure the extent and severity of language impairments as well as to provide information about functional skills and outcomes. Finally, there are assessments designed specifically to look at quality of life with aphasia.

Treatment team

Because of the various other problems in addition to language that affect most individuals with aphasia, a multidisciplinary team is used in rehabilitation centers for the management of aphasia. Team members, as well as speech-language pathologists, typically include physical and occupational therapists, clinical neuropsychologists, nurses, and social workers who are guided by physiatrists and neurologists. Once discharged from rehabilitation centers, aphasic individuals often continue their treatment by speech-language pathologists in settings such as speech and hearing clinics. Self-help groups and support via the Internet are available as well.

Treatment

Most individuals with aphasia are hospitalized for some period of time for treatment of the condition that has resulted in aphasia. Assessment of the extent and type of language disorder is made during that time, as assessment of the ability to swallow (dysphagia). Early medical intervention is important for lessening the long-term effects of stroke.

Recovery and rehabilitation

To date, no pharmacological treatments for aphasia have proven effective, although a number of drugs (dopaminergic, cholinergic, and neurotrophic) continue to be investigated, usually in conjunction with behavioral treatments for aphasia. Various behavioral treatment approaches for aphasia exist. They are usually characterized dichotomously as restorative (restitutive) or compensatory. The goal of restorative treatments is to reestablish disordered language skills. Goals for compensatory approaches are to develop and train alternative approaches to circumvent the language skills that have been affected by aphasia. Most clinicians use both approaches (often simultaneously) to aid in language recovery. Some examples of restorative approaches include practice of carefully selected syntactic structures, naming drills, or practice using self-selected communication needs such as using the telephone.

Compensatory approaches include training conversational partners to modify their own language and communication skills in ways that make it easier for the aphasic individual to communicate, or teaching aphasic individuals to use a relatively intact language skill such as writing or drawing to substitute for talking. Computerized approaches to both restitutive and compensatory aphasia treatment are increasing. Many clinics offer both individual treatment and group treatment, with the latter offering increased psychosocial support. Many clinics also incorporate family support groups.

Clinical trials

Randomized control trials (RCTs) are rare for the behavioral realm of treatments. Aphasia is no exception. To date, only four RCTs have been completed, with three of the four addressing to the efficacy of treatment. A far greater number of phases I and II studies exist, and investigate the value of language intervention, particularly post stroke. The largest testimony comes from single-case designs and qualitative case studies that agree that treatment has a positive influence on outcome. Only one meta-analysis of significant scope has been completed (Robey, 1998).

Prognosis

The traditional view is that most of the language gains made by aphasic individuals will occur in the first six months following injury, except in persons with global aphasia, who may begin the recovery process later, but are shown to make gains through one year. Significantly, it must be noted that most traditional treatment techniques have been validated using aphasic patients whose period of spontaneous recovery has passed. Some people with aphasia may be able to return to work, although the communicative demands of many occupations may affect employment.

As of the late 1990s, research has begun to focus on recovery across the remainder of the lifespan, and it has become apparent that aphasic individuals continue to make progress, often for years after the precipitating event. The factors that explain very late recovery are not clear and will require scientific observation and study.

Special concerns

Despite the prevalence of aphasia, the disorder is neither well recognized nor well understood. Aphasia's psychosocial and vocational consequences are over-whelmingly devastating, but community understanding is at best limited. Similarly, despite substantial evidence concerning the effectiveness of intervention, skepticism about the value of treatment remains. As a consequence of both of these factors, many aphasic individuals and their families are not well informed about either the disorder or what might be done to alleviate it.

Additionally, although a significant and growing number of individuals in the United States is bilingual, there is a surprising lack of research concerning the effects of speaking more than one language on recovery from aphasia. Finally, current funding for only very limited treatment for aphasia is available via third-party reimbursement.

Resources

BOOKS

Davis, G. A. Aphasology: Disorders and Clinical Practice. Boston: Allyn and Bacon, 2000.

Goodglass, H. Understanding Aphasia. New York: Academic Press, 1993.

Hillis, A. E. The Handbook of Adult Language Disorders. New York: Psychology Press, 2002.

PERIODICALS

Robey, R. R. "A Meta-analysis of Clinical Outcomes in the Treatment of Aphasia." Journal of Speech and Hearing Research 41 (1998): 172187.

ORGANIZATIONS

Aphasia Hope Foundation. 2436 West 137th St., Leawood, KS 66224. (913) 402-8306 or (866) 449-5894; Fax: (913) 402-8315. <http://www.aphasiahope.org>.

National Aphasia Association. 29 John Street, New York, NY 10038. (212) 267-2812 or (800) 922-4622. naa@aphasia.org. <http://www.aphasia.org>.

Audrey L. Holland, PhD

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Aphasia

Aphasia

Definition

Aphasia is condition characterized by either partial or total loss of the ability to communicate verbally or using written words. A person with aphasia may have difficulty speaking, reading, writing, recognizing the names of objects, or understanding what other people have said. Aphasia is caused by a brain injury, as may occur during a traumatic accident or when the brain is deprived of oxygen during a stroke. It may also be caused by a brain tumor, a disease such as Alzheimer's, or an infection, like encephalitis. Aphasia may be temporary or permanent. Aphasia does not include speech impediments caused by loss of muscle control.

Description

To understand and use language effectively, an individual draws upon word memory-stored information on what certain words mean, how to put them together, and how and when to use them properly. For a majority of people, these and other language functions are located in the left side (hemisphere) of the brain. Damage to this side of the brain is most commonly linked to the development of aphasia. Interestingly, however, left-handed people appear to have language areas in both the left and right hemispheres of the brain and, as a result, may develop aphasia from damage to either side of the brain.

Stroke is the most common cause of aphasia in the United States. Approximately 500,000 individuals suffer strokes each year, and 20% of these individuals develop some type of aphasia. Other causes of brain damage include head injuries, brain tumors, and infection. About half of the people who show signs of aphasia have what is called temporary or transient aphasia and recover completely within a few days. An estimated one million Americans suffer from some form of permanent aphasia. As yet, no connection between aphasia and age, gender, or race has been found.

Aphasia is sometimes confused with other conditions that affect speech, such as dysarthria and apraxia. These condition affect the muscles used in speaking rather than language function itself. Dysarthria is a speech disturbance caused by lack of control over the muscles used in speaking, perhaps due to nerve damage. Speech apraxia is a speech disturbance in which language comprehension and muscle control are retained, but the memory of how to use the muscles to form words is not.

Causes and symptoms

Aphasia can develop after an individual sustains a brain injury from a stroke, head trauma, tumor, or infection, such as herpes encephalitis. As a result of this injury, the pathways for language comprehension or production are disrupted or destroyed. For most people, this means damage to the left hemisphere of the brain. (In 95 to 99% of right-handed people, language centers are in the left hemisphere, and up to 70% of left-handed people also have left-hemisphere language dominance.) According to the traditional classification scheme, each form of aphasia is caused by damage to a different part of the left hemisphere of the brain. This damage affects one or more of the basic language functions: speech, naming (the ability to identify an object, color, or other item with an appropriate word or term), repetition (the ability to repeat words, phrases, and sentences), hearing comprehension (the ability to understand spoken language), reading (the ability to understand written words and their meaning), and writing (the ability to communicate and record events with text).

KEY TERMS

Anomic aphasia A condition characterized by either partial or total loss of the ability to recall the names of persons or things as a result of a stroke, head injury, brain tumor, or infection.

Broca's aphasia A condition characterized by either partial or total loss of the ability to express oneself, either through speech or writing. Hearing comprehension is not affected. This condition may result from a stroke, head injury, brain tumor, or infection.

Computed tomography (CT) An imaging technique that uses cross-sectional x rays of the body to create a three-dimensional image of the body's internal structures.

Conduction aphasia A condition characterized by the inability to repeat words, sentences, or phrases as a result of a stroke, head injury, brain tumor, or infection.

Frontal lobe The largest, most forward-facing part of each side or hemisphere of the brain.

Global aphasia A condition characterized by either partial or total loss of the ability to communicate verbally or using written words as a result of widespread injury to the language areas of the brain. This condition may be caused by a stroke, head injury, brain tumor, or infection. The exact language abilities affected vary depending on the location and extent of injury.

Hemisphere One of the two halves or sides-the left and the right-of the brain.

Magnetic resonance imaging (MRI) An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Subcortical aphasia A condition characterized by either partial or total loss of the ability to communicate verbally or using written words as a result of damage to non language-dominated areas of the brain. This condition may be caused by a stroke, head injury, brain tumor, or infection.

Temporal lobe The part of each side or hemisphere of the brain that is on the side of the head, nearest the ears.

Transcortical aphasia A condition characterized by either partial or total loss of the ability to communicate verbally or using written words that does not affect an individual's ability to repeat words, phrases, and sentences.

Wernicke's aphasia A condition characterized by either partial or total loss of the ability to understand what is being said or read. The individual maintains the ability to speak, but speech may contain unnecessary or made-up words.

The traditional classification scheme includes eight types of aphasia:

  • Broca's aphasia, also called motor aphasia, results from damage to the front portion or frontal lobe of the language-dominant area of the brain. Individuals with Broca's aphasia may be completely unable to use speech (mutism ) or may be able to use single-word statements or even full sentences, though these sentences may require a great deal of effort to construct. Small words, such as conjunctions (and, or, but) and articles (the, an, a), may be omitted, leading to a "telegraph" quality in their speech. Hearing comprehension is usually not affected, so they are able to understand other people's speech and conversation and can follow commands. Often, they may experience weakness on the right side of their bodies, which can make it difficult to write. Reading ability is impaired, and they may have difficulty finding the right word when speaking. Individuals with Broca's aphasia may become frustrated and depressed because they are aware of their language difficulties.
  • Wernicke's aphasia is caused by damage to the side portion or temporal lobe of the language-dominant area of the brain. Individuals with Wernicke's aphasia speak in long, uninterrupted sentences; however, the words used are frequently unnecessary or even made-up. They have a great deal of difficulty understanding other people's speech, sometimes to the point of being unable to understand spoken language at all. Reading ability is diminished, and although writing ability is retained, what is written may be abnormal. No physical symptoms, such as the right-sided weakness seen with Broca's aphasia, are typically observed. Also, in contrast to Broca's aphasia, individuals with Wernicke's aphasia are not aware of their language errors.
  • Global aphasia is caused by widespread damage to the language areas of the left hemisphere. As a result, all basic language functions are affected, but some areas may be more affected than others. For example, an individual may have difficulty speaking but may be able to write well. The individual may experience weakness and loss of feeling on the right side of their body.
  • Conduction aphasia, also called associative aphasia, is rather uncommon. Individuals with conduction aphasia are unable to repeat words, sentences, and phrases. Speech is fairly unbroken, although individuals may frequently correct themselves and words may be skipped or repeated. Although able to understand spoken language, it may also be difficult for the individual with conduction aphasia to find the right word to describe a person or object. The impact of this condition on reading and writing ability varies. As with other types of aphasia, right-sided weakness or sensory loss may be present.
  • Anomic or nominal aphasia primarily influences an individual's ability to find the right name for a person or object. As a result, an object may be described rather than named. Hearing comprehension, repetition, reading, and writing are not affected, other than by this inability to find the right name. Speech is fluent, except for pauses as the individual tries to recall the right name. Physical symptoms are variable, and some individuals have no symptoms of one-sided weakness or sensory loss.
  • Transcortical aphasia is caused by damage to the language areas of the left hemisphere outside the primary language areas. There are three types of aphasia: transcortical motor aphasia, transcortical sensory aphasia, and mixed transcortical aphasia. All of the transcortical aphasias are distinguished from other types by the individual's ability to repeat words, phrases, or sentences. Other language functions may also be impaired to varying degrees, depending on the extent and particular location of brain damage.

As researchers continue to learn more about the brain's structure and function, new types of aphasia are being recognized. One newly recognized type of aphasia, subcortical aphasia, mimics the symptoms of other traditional types of aphasia but involves language disorders that are not typical. This type of aphasia is associated with injuries to areas of the brain typically not identified with language and language processing.

Diagnosis

Following brain injury, an initial bedside assessment is made to determine whether language function has been affected. If the individual experiences difficulty communicating, attempts are made to determine whether this difficulty arises from impaired language comprehension or an impaired ability to speak. A typical examination involves listening to spontaneous speech and evaluating the individual's ability to recognize and name objects, comprehend what is heard, and repeat sample words and phrases. The individual may also be asked to read text aloud and explain what the passage means. In addition, writing ability is evaluated by having the individual copy text, transcribe dictated text, and write something without prompting.

A speech pathologist or neuropsychologist may be asked to conduct more extensive examinations using in-depth, standardized tests. Commonly used tests include the Boston Diagnostic Aphasia Examination, the Western Aphasia Battery, and possibly, the Porch Index of Speech Ability.

The results of these tests indicate the severity of the aphasia and may also provide information regarding the exact location of the brain damage. This more extensive testing is also designed to provide the information necessary to design an individualized speech therapy program. Further information about the location of the damage is gained through the use of imaging technology, such as magnetic resonance imaging (MRI) and computed tomography scans (CT).

Treatment

Initially, the underlying cause of aphasia must be treated or stabilized. To regain language function, therapy must begin as soon as possible following the injury. Although there are no medical or surgical procedures currently available to treat this condition, aphasia resulting from stroke or head injury may improve through the use of speech therapy. For most individuals, however, the primary emphasis is placed on making the most of retained language abilities and learning to use other means of communication to compensate for lost language abilities.

Speech therapy is tailored to meet individual needs, but activities and tools that are frequently used include the following:

  • Exercise and practice. Weakened muscles are exercised by repetitively speaking certain words or making facial expressions, such as smiling.
  • Picture cards. Pictures of everyday objects are used to improve word recall and increase vocabulary. The names of the objects may also be repetitively spoken aloud as part of an exercise and practice routine.
  • Picture boards. Pictures of everyday objects and activities are placed together, and the individual points to certain pictures to convey ideas and communicate with others.
  • Workbooks. Reading and writing exercises are used to sharpen word recall and regain reading and writing abilities. Hearing comprehension is also redeveloped using these exercises.
  • Computers. Computer software can be used to improve speech, reading, recall, and hearing comprehension by, for example, displaying pictures and having the individual find the right word.

Prognosis

The degree to which an individual can recover language abilities is highly dependent on how much brain damage occurred and the location and cause of the original brain injury. Other factors include the individual's age, general health, motivation and willingness to participate in speech therapy, and whether the individual is left or right handed. Language areas may be located in both the left and right hemispheres in left-handed individuals. Left-handed individuals are, therefore, more likely to develop aphasia following brain injury, but because they have two language centers, may recover more fully because language abilities can be recovered from either side of the brain. The intensity of therapy and the time between diagnosis and the start of therapy may also affect the eventual outcome.

Prevention

Because there is no way of knowing when a stroke, traumatic head injury, or disease will occur, very little can be done to prevent aphasia. The extent of recovery, however, in some cases, can be affected by an individual's willingness to cooperate and participate in speech therapy directly following the injury.

Resources

BOOKS

Lyon, Jon G., and Marianne B. Simpson. Coping with Aphasia. San Diego: Singular Publishing Group, 1998.

ORGANIZATIONS

National Aphasia Association. 156 5th Ave., Suite 707, New York, NY 10010. (800) 922-4622. http://www.aphasia.org.

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Aphasia

Aphasia

A condition, caused by neurological damage or disease, in which a person's previous capacity to understand or express language is impaired. The ability to speak, listen, read, or write may be affected depending on the type of aphasia involved.

In contrast to neurological problems that affect the physical ability to speak or perform other linguistic functions, aphasia involves the mental ability to manipulate speech sounds, vocabulary, grammar, and meaning. There are several different types of aphasia. Each has different symptoms and is caused by damage to a different part of the brain .

The great majority of aphasias are caused by damage to the left hemisphere of the brain, which is the dominant

language hemisphere for approximately 95 percent of right-handed people and 60 to 70 percent of left-handed people. Two areas in the left hemisphereBroca's area and Wernicke's areaand the pathways connecting them are especially important to linguistic ability, and damage to these areas is the most common cause of aphasia. Broca's area, located in the frontal lobe of the left hemisphere, is named for the 19th-century French physician Paul Broca (1824-1880), an early pioneer in the study of lateralization (the specialized functioning of the right and left sides of the brain). Aphasia resulting from damage to this area, called Broca's aphasia, is characterized by slow, labored, "telegraphic" speech, from which common grammatical function words, such as prepositions and articles, are missing ("I went doctor"). In general, however, comprehension of spoken and written language is relatively unaffected.

Wernicke's area, in the upper rear part of the left temporal lobe, is named for Carl Wernicke (1848-1905), who first described it in 1874. Aphasia associated with this areacalled Wernicke's aphasiadiffers dramatically from Broca's aphasia. While speech in Broca's aphasia is overly concise, in Wernicke's aphasia it is filled with an abundance of words (logorrhea), but they are words which fail to convey the speaker's meaning. Even though their pitch and rhythm sound normal, many of the words are used incorrectly or are made-up words with no meaning (aphasic jargon). Besides their speech difficulties, persons with Wernicke's aphasia also have trouble comprehending language, repeating speech, naming objects, reading, and writing. An interesting exception to their comprehension impairment is their ability to respond readily to direct commands that involve bodily movement, such as "Close your eyes."

Certain types of aphasiacalled disconnection aphasiasare caused by damage to the connections of Broca's or Wernicke's areas to each other or to other parts of the brain. Conduction aphasia results from damage to the fiber bundles connecting the two language areas and is characterized by fluent but somewhat meaningless speech and an inability to repeat phrases correctly. In transcortical sensory aphasia, the connections between Wernicke's area and the rest of the brain are severed, but the area itself is left intact. Persons with this condition have trouble understanding language and expressing their thoughts but can repeat speech without any trouble. Another type of aphasia, word deafness, occurs when auditory information is prevented from reaching Wernicke's area. Persons affected by word deafness can hear sounds of all kinds and understand written language, but spoken language is incomprehensible to them, since the auditory signals cannot reach the part of the brain that decodes them.

Most types of aphasia are accompanied by some difficulty in naming objects. However, when this problem is the only symptom, the condition is called anomic aphasia. Persons with anomic aphasia can comprehend and repeat the speech of others and express themselves fairly well, although they are unable to find some of the words they need. However, they do poorly when asked to name specific objects. Anomic aphasia is caused by left hemisphere damage that does not affect either Broca's or Wernicke's area. It commonly occurs after a head injury and also in Alzheimer's disease . Global aphasia is caused by widespread damage to the dominant cerebral hemisphere, either left or right. This condition is characterized by an almost total loss of all types of verbal abilityspeech, comprehension, reading, and writing.

It is possible for people suffering from aphasia following a stroke or head injury to recover some of their language abilities with the aid of a speech therapist. However, there is little chance of recovery from severe cases of aphasia.

See also Left-brain hemisphere; Right-brain hemisphere

Further Reading

Browning, Elizabeth. I Can't See What You're Saying. New York: Coward, McCann & Geoghegan, 1973.

Hughes, Kathy. God Isn't Finished With Me Yet. Nashville: Winston-Derek, 1990.

Howard, David. Aphasia Therapy: Historical and Contemporary Issues. Hillsdale, NJ: Erlbaum, 1987.

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Aphasia

APHASIA

Aphasia, a word proposed by Armand Trousseau to replace the term "aphemia," created by Paul Broca, refers to language disturbances that arise from specific cerebral lesions, most often in the cortex. Between 1861 and 1865, when the dispute ended concerning the question of determining whether the cerebral cortex operated as a unit or as a collection of separate elements, Paul Broca showed, through a series of anatomical and clinical observations, that the destruction of the left side of the base of the third circumvolution of the frontal lobe in a right-handed subject who until then was able to speak normally led to the loss of articulate language. The subject was unable to express himself using a sequence of words or phrases.

In 1874 Carl Wernicke extended the field of research by describing two other types of aphasia, all caused by a lesion in the left hemisphere: sensory aphasia from damage to the posterior areas of the second and third circumvolution of the cortex, and conduction aphasia, arising from the disconnection of the bundles connecting this region to the base of the third circumvolution of the frontal lobe. Afterwards, the disturbance identified by Broca would be known as "motor aphasia." Later Wernicke identified two other types of aphasia: "motor transcortical aphasia" and "sensory transcortical aphasia."

By the end of the nineteenth century, three separate approaches to the problem had been developed. Some researchers, such as Jean Martin Charcot and Joseph Grasset, increased the number of types of aphasia; others, like Alfred Vulpian, and later Pierre Marie, renewed the "unitarian" position; the third group, following the important work by Jules Déjerine, demonstrated through the use of clinical and anatomical arguments that the nature of the aphasia would change with the nature and location of the lesion. For example, frontal lesions seemed to primarily affect speech production, posterior lesions seemed to affect speech recognition, and the destruction of the cortex resulted in disturbances of internal language, which affected the subject's autonomy.

Sigmund Freud's work on aphasia, published in 1891, accepts the work of Paul Broca but questions Wernicke's research, which Freud criticizes for being excessively schematic and lacking in clinical observations. Freud did not question the relationship of language function with the brain but was cautious about hastily assigning specific locations to specific functions. Although he accepts that certain clinically based forms of aphasia"verbal aphasia," "asymbolic aphasia," "agnosic aphasia"can be used to localize the cortical lesion with certainty (which was later confirmed by neurosurgery during the First World War), he refused to extrapolate from pathology to physiology and deduced a cerebral concept of the normal operation of language, with a critical position that was far removed from the scientism that is often attributed to him in this field. In the descriptive sections of his work, Freud distinguished between the representation of words and the representation of things, and their links with auditory images, visual images, and the motor images at work in these phenomena.

Georges LantÉri-Laura

See also: Brain and psychoanalysis, the; Language and disturbances of language; memory; Thing-presentation; Word-presentation.

Bibliography

Freud, Sigmund. (1891b [1953]), On aphasia (A critical study) (E. Stengel, Trans.). New York: International Universities Press.

Hécaen, H. and Lantéri-Laura, Georges. (1977).Évolution des connaissances et des doctrines sur les localisations cérébrales. Paris: Desclée de Brouwer.

. (1989). Les fonctions du cerveau. Paris: Masson.

Lantéri-Laura, Geoerges. (1993). Histoire de la phrénologie. Paris: Presses Universitaires de France.

Further Reading

Miller, Laurence (1991). On aphasia at 100: the neuropsychodynamic legacy of Freud. Psychoanalytic Review, 78, 365-378.

Rizzuto, Anna-Marie. (1990). Origin of Freud's concept of object representation: "On Aphasia." International Journal of Psychoanalysis, 71, 241-248.

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aphasia

aphasia (əfā´zhə), language disturbance caused by a lesion of the brain, making an individual partially or totally impaired in his ability to speak, write, or comprehend the meaning of spoken or written words. It is distinguished from functional disorders such as stammering or stuttering, and from impaired speech due to physical defects in the organs used for speaking. Treatment consists of reeducation; the oral and lip-reading methods employed in the education of deaf and mute children have been found to be of assistance in therapy.

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aphasia

aphasia (dysphasia) (ă-fay-ziă) n. a disorder of language affecting the generation and content of speech and its understanding. It is caused by damage to the language-dominant half of the brain, usually the left hemisphere in a right-handed person. expressive a. difficulty in producing language. receptive a. difficulty with comprehension of the spoken word.
aphasic adj.

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aphasia

a·pha·sia / əˈfāzhə/ • n. Med. loss of ability to understand or express speech, caused by brain damage.Compare with aphonia. DERIVATIVES: a·pha·sic / -zik/ adj. & n.

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aphasia

aphasia Group of disorders of language arising from disease of or damage to the brain. In aphasia, a person has problems formulating or comprehending speech and difficulty in reading and writing. See also brain disorders

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aphasia

aphasia (med.) loss of speech. XIX. — modL. — Gr. aphasíā, f. A-4 + phánai speak; see -IA1.

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aphasia

aphasia •astrantia • Bastia •Dei gratia, hamartia •poinsettia •in absentia, Parmentier •Izvestia •meteor, wheatear •Whittier • cottier • Ostia •consortia, courtier •protea • Yakutia • frontier • Althea •Anthea • Parthia •Pythia, stichomythia •Carinthia, Cynthia •forsythia • Scythia • clothier • salvia •Latvia • Yugoslavia • envier •Flavia, Moldavia, Moravia, Octavia, paviour (US pavior), Scandinavia, Xavier •Bolivia, Livia, Olivia, trivia •Sylvia • Guinevere • Elzevir •Monrovia, Segovia •Retrovir • effluvia • colloquia •Goodyear • yesteryear • brassiere •Abkhazia •Anastasia, aphasia, brazier, dysphasia, dysplasia, euthanasia, fantasia, Frazier, glazier, grazier, gymnasia, Malaysiaamnesia, anaesthesia (US anesthesia), analgesia, freesia, Indonesia, Silesia, synaesthesia •artemisia, Kirghizia, Tunisiaambrosia, crozier, hosier, osier, symposia

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