Aphasia

Aphasia is a language disorder that results from damage to portions of the brain that are responsible for language. also known as aphemia, is a loss of the ability to produce and/or comprehend 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 head injury, but it may also develop slowly, as in the case of a brain tumor. due to injury to brain areas specialized for these functions, Broca's area, which governs language production, or Wernicke's area, which governs the interpretation of language.The disorder impairs both the expression and understanding of language as well as reading and writing..

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 acquire aphasia each year. About one million persons in the United States currently have aphasia.

What causes aphasia?

Usually, aphasias are a result of damage (lesions) to the language centres of the brain (like Broca's area). It could be 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. These areas are almost 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. In either case, damage to these language areas can be caused by a stroke, traumatic brain injury, or other head injury. Aphasia is 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. Aphasia may also develop slowly, as in the case of a brain tumor or progressive neurological disease, e.g., Alzheimer's or Parkinson's disease. It may also be caused by a sudden hemorrhagic event within the brain.



How is aphasia diagnosed?

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.

How is aphasia treated?

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.

Symptoms

Any of the following may be considered symptoms of aphasia:
inability to comprehend language
inability to pronounce, not due to muscle paralysis or weakness
inability to speak spontaneously
inability to form words
inability to name objects
poor enunciation
excessive creation and use of personal neologisms
inability to repeat a phrase
persistent repetition of phrases
paraphasia (substituting letters, syllables or words)
agrammatism (inability to speak in a grammatically correct fashion)
dysprosody (alterations in inflexion, stress, and rhythm)
incompleted sentences
inability to read
inability to write





Family members are encouraged to:

Simplify language by using short, uncomplicated sentences.
Repeat the content words or write down key words to clarify meaning as needed.
Maintain a natural conversational manner appropriate for an adult.
Minimize distractions, such as a blaring radio, whenever possible.
Include the person with aphasia in conversations.
Ask for and value the opinion of the person with aphasia, especially regarding family matters.
Encourage any type of communication, whether it is speech, gesture, pointing, or drawing.
Avoid correcting the individual's speech.
Allow the individual plenty of time to talk.
Help the individual become involved outside the home. Seek out support groups such as stroke clubs.

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 (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.

Prognosis

The prognosis of those with aphasia varies widely, and is dependent upon age of the patient, site and size of lesion, and type of aphasia.

Classification

Classifying the different subtypes of aphasia is difficult and has led to disagreements among experts. The localizationist model is the original model, but modern anatomical techniques and analyses have shown that precise connections between brain regions and symptom classification don't exist. The neural organization of language is complicated; language is a comprehensive and complex behavior and it makes sense that it isn't the product of some small, circumscribed region of the brain.No classification of patients in subtypes and groups of subtypes is adequate. Only about 60% of patients will fit in a classification scheme such as fluent/nonfluent/pure aphasias. There is a huge variation among patients with the same diagnosis, and aphasias can be highly selective. For instance, patients with naming deficits (anomic aphasia) might show an inability only for naming buildings, or people, or colors.

Localizationist model
Cortex

The localizationist model attempts to classify the aphasia by major characteristics and then link these to areas of the brain in which the damage has been caused. The initial two categories here were devised by early neurologists working in the field, namely Paul Broca and Carl Wernicke. Other researchers have added to the model, resulting in it often being referred to as the "Boston-Neoclassical Model". The most prominent writers on this topic have been Harold Goodglass and Edith Kaplan.
Individuals with Broca's aphasia (also termed expressive aphasia) were once thought to have ventral temporal damage though more recent work by Nina Dronkers using imaging and 'lesion analysis' has revealed that patients with Broca's aphasia have lesions to the medial insular cortex. Broca missed these lesions because his studies did not dissect the brains of diseased patients so only the more temporal damage was visible. 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 (also termed sensory aphasia). These individuals usually have no body weakness because their brain injury is not near the parts of the brain that control movement.
Working from Wernicke's model of aphasia, Ludwig Lichtheim proposed five other types of aphasia but these were not tested against real patients until modern imaging made more indepth studies available. The other five types of aphasia in the localizationist model are:
Pure word deafness
Conduction aphasia
Apraxia of speech, which is now considered a separate disorder in itself.
Transcortical motor aphasia
Transcortical sensory aphasia
Anomia is another type of aphasia proposed under what is commonly known as the Boston-Neoclassical model, which is essentially a difficulty with naming. A final type of aphasia, global aphasia, results from damage to extensive portions of the language areas of the brain.
Fluent, non-fluent and "pure" aphasias
The different types of aphasia can be divided into three categories: fluent, non-fluent and "pure" aphasias.
Fluent aphasias, also called receptive aphasias, are impairments related mostly to the input or reception of language, with difficulties either in auditory verbal comprehension or in the repetition of words, phrases, or sentences spoken by others. Speech is easy and fluent, but there are difficulties related to the output of language as well, such as paraphasia. Examples of fluent aphasias are: Wernicke's aphasia, Transcortical sensory aphasia, Conduction aphasia, Anomic aphasia
Nonfluent aphasias, also called expressive aphasias are difficulties in articulating, but in most cases there is relatively good auditory verbal comprehension. Examples of nonfluent aphasias are: Broca's aphasia, Transcortical motor aphasia, Global aphasia
"Pure" aphasias are selective impairments in reading, writing, or the recognition of words. These disorders may be quite selective. For example, a person is able to read but not write, or is able to write but not read. Examples of pure aphasias are: Alexia, Agraphia, Pure word deafness
Cognitive neuropsychological model
The cognitive neuropsychological model builds on cognitive neuropsychology. It assumes that language processing can be broken down into a number of modules, each of which has a specific function. Hence there is a module which recognises phonemes as they are spoken and a module which stores formulated phonemes before they are spoken. Use of this model clinically involves conducting a battery of assessments (usually from the PALPA), each of which tests one or a number of these modules. Once a diagnosis is reached as to where the impairment lies, therapy can proceed to treat the individual module.
A few less common subtypes include:
Subcortical motor aphasia
Subcortical sensory aphasia
Mixed transcortical aphasia
Acquired epileptiform aphasia (Landau Kleffner Syndrome)
A combination of subtypes is possible.

Primary and secondary aphasia

Aphasia can be divided into primary and secondary aphasia.

Primary aphasia is due to problems with language-processing mechanisms.
Secondary aphasia is the result of other problems, like memory impairments, attention disorders, or perceptual problems.