Aphasia

Aphasia is a loss or impairment of the ability to produce or comprehend language, due to brain damage. It is usually a result of damage to the language centres of the brain (like Broca's area). These areas are always located in the left hemisphere and in most people this is where the ability to produce and comprehend language is found. However in a very small number of people language ability is found in the right hemisphere. Damage to these language areas can be caused by a stroke or physical injury. Depending on the area and extent of the damage, someone may be able to speak but not write, or vice versa, or understand more complex sentences than he can produce. The brains of young children with brain damage sometimes restructure themselves to use different areas for speech processing, and regain lost function; adult brains are less "plastic" and lack this ability.

Aphasia can be assessed in a variety of ways, from quick clinical screening at the bedside to several-hour-long batteries of tasks that examine the key components of language and communication.

Aphasia is a language disorder that results from damage to portions of the brain that are responsible for language. For most people, these are parts of the left side (hemisphere) of the brain. Aphasia usually occurs suddenly, often as the result of a stroke or traumatic brain injury or other head injury, but it may also develop slowly, as in the case of a brain tumor. The disorder impairs both the expression and understanding of language as well as reading and writing. Aphasia may co-occur with speech disorders such as dysarthria or apraxia of speech, which also result from brain damage.

Who has aphasia?

Anyone can acquire aphasia, but most people who have aphasia are in their middle to late years. Men and women are equally affected. It is estimated that approximately 80,000 individuals in the United States acquire aphasia each year. About one million persons in the United States currently have aphasia.

Causes

Aphasia is caused by damage to one or more of the language areas of the brain. Many times, the cause of the brain injury is a stroke. A stroke occurs when, for some reason, blood is unable to reach a part of the brain. Brain cells die when they do not receive their normal supply of blood, which carries oxygen and important nutrients. Other causes of brain injury are severe blows to the head, brain tumors, brain infections, and other conditions of the brain.

Individuals with Broca's aphasia have damage to the frontal lobe of the brain. These individuals frequently speak in short, meaningful phrases that are produced with great effort. Broca's aphasia is thus characterized as a nonfluent aphasia. Affected people often omit small words such as "is," "and," and "the." For example, a person with Broca's aphasia may say, "Walk dog" meaning, "I will take the dog for a walk." The same sentence could also mean "You take the dog for a walk," or "The dog walked out of the yard," depending on the circumstances. Individuals with Broca's aphasia are able to understand the speech of others to varying degrees. Because of this, they are often aware of their difficulties and can become easily frustrated by their speaking problems. Individuals with Broca's aphasia often have right-sided weakness or paralysis of the arm and leg because the frontal lobe is also important for body movement.

In contrast to Broca's aphasia, damage to the temporal lobe may result in a fluent aphasia that is called Wernicke's aphasia. Individuals with Wernicke's aphasia may speak in long sentences that have no meaning, add unnecessary words, and even create new "words." For example, someone with Wernicke's aphasia may say, "You know that smoodle pinkered and that I want to get him round and take care of him like you want before," meaning "The dog needs to go out so I will take him for a walk." Individuals with Wernicke's aphasia usually have great difficulty understanding speech and are therefore often unaware of their mistakes. These individuals usually have no body weakness because their brain injury is not near the parts of the brain that control movement.

A third type of aphasia, global aphasia, results from damage to extensive portions of the language areas of the brain. Individuals with global aphasia have severe communication difficulties and may be extremely limited in their ability to speak or comprehend language.

Diagnosis

Aphasia is usually first recognized by the physician who treats the individual for his or her brain injury. Frequently this is a neurologist. The physician typically performs tests that require the individual to follow commands, answer questions, name objects, and converse. If the physician suspects aphasia, the individual is often referred to a speech-language pathologist, who performs a comprehensive examination of the person's ability to understand, speak, read, and write.

Treatment

In some instances an individual will completely recover from aphasia without treatment. This type of "spontaneous recovery" usually occurs following a transient ischemic attack (TIA), a kind of stroke in which the blood flow to the brain is temporarily interrupted but quickly restored. In these circumstances, language abilities may return in a few hours or a few days. For most cases of aphasia, however, language recovery is not as quick or as complete. While many individuals with aphasia also experience a period of partial spontaneous recovery (in which some language abilities return over a period of a few days to a month after the brain injury), some amount of aphasia typically remains. In these instances, speech-language therapy is often helpful. Recovery usually continues over a 2-year period. Most people believe that the most effective treatment begins early in the recovery process. Some of the factors that influence the amount of improvement include the cause of the brain damage, the area of the brain that was damaged, the extent of the brain injury, and the age and health of the individual. Additional factors include motivation, handedness, and educational level.

Aphasia therapy strives to improve an individual's ability to communicate by helping the person to use remaining abilities, to restore language abilities as much as possible, to compensate for language problems, and to learn other methods of communicating. Treatment may be offered in individual or group settings. Individual therapy focuses on the specific needs of the person. Group therapy offers the opportunity to use new communication skills in a comfortable setting. Stroke clubs, which are regional support groups formed by individuals who have had a stroke, are available in most major cities. These clubs also offer the opportunity for individuals with aphasia to try new communication skills. In addition, stroke clubs can help the individual and his or her family adjust to the life changes that accompany stroke and aphasia. Family involvement is often a crucial component of aphasia treatment so that family members can learn the best way to communicate with their loved one.

What research is being done for aphasia?

Aphasia research is exploring new ways to evaluate and treat aphasia as well as to further understanding of the function of the brain. Brain imaging techniques are helping to define brain function, determine the severity of brain damage, and predict the severity of the aphasia. These procedures include PET (positron emission tomography), CT (computed tomography), and MRI (magnetic resonance imaging) as well as the new functional magnetic resonance imaging (fMRI), which identifies areas of the brain that are used during activities such as speaking or listening. In-depth testing of the language ability of individuals with the various aphasic syndromes is helping to design effective treatment strategies. The use of computers in aphasia treatment is being studied. Promising new drugs administered shortly after some types of stroke are being investigated as ways to reduce the severity of aphasia.

Types of aphasia

Any of the following can be considered aphasia:

• inability to comprehend speech
• inability to read (alexia)
• inability to write (agraphia)
• inability to speak, without muscle paralysis
• inability to form words
• inability to name objects (anomia)
• poor enunciation
• excessive creation and use of personal neologisms (jargon aphasia)
• inability to repeat a phrase
• persistent repetition of phrases
• other language impairment

The common types of aphasia are

• Broca's aphasia (expressive aphasia)
• Wernicke's aphasia (receptive aphasia)
• Nominal aphasia (anomic aphasia)
• Global aphasia
• Conduction aphasia

A few less common varieties include

• Transcortical motor aphasia
• Subcortical motor aphasia
• Transcortical sensory aphasia
• Subcortical sensory aphasia
• Mixed transcortical aphasia
• Acquired eleptiform aphasia (Landau Kleffner Syndrome)

External links

• NIDCD health information: Aphasia (public domain source)
• National Institute of Health: MEDLINEplus Medical Encyclopdia entry on Speech Impairment (adult) (note: not public domain, even though it is on a .gov website)
• "In So Many Words" Radio documentary broadcast on the Canadian Broadcasting Corporation's "The Sunday Edition" program on Sunday, December 15, 2002. Co-produced by Teresa Goff and telling the story of her father Steve Goff, who suffers from aphasia as a result of a stroke.
• Aphasia and Dysphasia - Ideas and Considerations
• "Picturing Aphasia" Documentary film about aphasia that uses drawings to help bridge the gap between hearing, seeing, and comprehending. The video is designed to function as a part of therapy for people with aphasia and to educate people of all language abilities about the condition. Directed by Mores McWreath.
• Description of four types of aphasia: auditory, afferent, efferent, and semantic.