Aphasia - An Overview


What Is Aphasia?
Aphasia is a communication disorder that results from damage or injury to language parts of the brain. It's more common in older adults, particularly those who have had a stroke.

Aphasia gets in the way of a person's ability to use or understand words. Aphasia does not impair the person's intelligence. People who have aphasia may have difficulty speaking and finding the "right" words to complete their thoughts. They may also have problems understanding conversation, reading and comprehending written words, writing words, and using numbers.


What Causes Aphasia?
Aphasia is usually caused by a stroke or brain injury with damage to one or more parts of the brain that deal with language. According to the National Aphasia Association, about 25% to 40% of people who survive a stroke get aphasia.

Aphasia may also be caused by a brain tumor, brain infection, ordementia such as Alzheimer's disease. In some cases, aphasia is a symptom of epilepsy or other neurological disorder.

What Are the Types of Aphasia?
There are types of aphasia. Each type can cause impairment that varies from mild to severe. Common types of aphasia include the following:

1.  Expressive aphasia (non-fluent):
With expressive aphasia, the person knows what he or she wants to say, yet has difficulty communicating it to others. It doesn't matter whether the person is trying to say or write what he or she is trying to communicate.  Given below are its sub-types:

-Broca's Aphasia:
A type of nonfluent aphasia, so called because speech production is halting and effortful. Damage is typically in the anterior portion of the left hemisphere. The dominant feature is agrammatism (impaired syntax). Content words (nouns, verbs) may be preserved but sentences are difficult to produce due to the problems with grammar, resulting in "telegraphic speech." In its more severe form, spoken utterances may be reduced to single words. Comprehension is typically only mildly to moderately impaired, and impairments are primarily due to difficulty understanding complex grammar. Repetition of words and sentences is usually poor.

-Global  Aphasia:
A type of nonfluent aphasia with severe impairment of both expressive and receptive skills. Usually associated with a large left hemisphere lesion. People are often alert and may be able to express themselves through facial expressions, intonation, and gestures.

-Transcortical Motor Aphasia:
A type of nonfluent aphasia similar to Broca's aphasia, but again with strong repetition skills. The person may have difficulty spontaneously answering a question but can repeat long utterances without difficulty.

2.  Receptive aphasia (fluent):
With receptive aphasia, the person can hear a voice or read the print, but may not understand the meaning of the message. Oftentimes, someone with receptive aphasia takes language literally. Their own speech may be disturbed because they do not understand their own language.

-Wernicke's  Aphasia:
A type of fluent aphasia. Damage is typically in the posterior portion of the left hemisphere. Comprehension is poor and the person often produces jargon, or nonsensical words and phrases when attempting to speak. These utterances typically retain sentence structure but lack meaning. The person is usually unaware of how they are speaking and may continue to talk even when they should pause to allow others to speak; this is often referred to as "press of speech." Repetition of words and sentences is poor.

-Transcortical Sensory Aphasia:
A type of fluent aphasia similar to Wernicke's with the exception of a strong ability to repeat words and phrases. The person may repeat questions rather than answer them ("echolalia").

-Conduction  Aphasia:
A type of fluent aphasia with a prominent impairment with repetition. Damage typically involves the arcuate fasciculus and the left parietal region. The patient may be able to express him- or herself fairly well, with some word-finding issues, and comprehension can be functional. However, the patient will show significant difficulty repeating phrases, particularly as the phrases increase in length and complexity and as they stumble over words they are attempting to pronounce. This type of aphasia is rare.

3.  Anomic Aphasia:
A mild form of aphasia. The most prominent difficulty is in word-finding, with the person using generic fillers in utterances, such as nonspecific nouns and pronouns (e.g., "thing"), or circumlocution, where the person describes the intended word. Comprehension and repetition of words and sentences is typically good; however, the person may not always recognize that a word they have successfully retrieved is the correct word, indicating some difficulty with word recognition.

4.  Crossed Aphasia:
A type of aphasia that occurs when a person's language centers are not in the expected hemisphere. In most right-handed individuals, language centers are located in the left hemisphere. This is also true for a majority of left-handed people, although there are exceptions for both groups. An example of crossed aphasia would be a right-handed person who has a right hemisphere stroke which results in aphasia.

5.  Subcortical Aphasia:
A form of aphasia that results from damage to subcortical regions such as the thalamus, internal capsule, and the basal ganglia. The symptoms can mirror those arising from cortical lesions, and subcortical damage can also co-occur with cortical lesions. Aphasic symptoms can arise from diaschisis (remote effects), such as subcortical inputs to the frontal lobe being altered, or may directly stem from damage to subcortical areas that support language processing.

6.  Mixed Transcortical Aphasia:
A combination of the two transcortical aphasias where both reception and expression are severely impaired but repetition remains intact.

7.  Primary Progressive Aphasia (PPA):
A focal dementia (or focal cortical atrophy syndrome) characterized by gradual loss of language function in the context of relatively well-preserved memory, visual processing, and personality until the advanced stages. Symptoms usually begin with word-finding problems and progress to impaired grammar (syntax) and comprehension (sentence processing and semantics). Symptoms associated with impaired speech production can also accompany PPA, such as dysarthria and apraxia of speech. Typically, a diagnosis of PPA is made following a 2-year decline in language function not accompanied by any marked decline in other cognitive functions. (However, a 2-year hiatus in making a definitive diagnosis should not delay proactive management of the aphasia and general life planning.) Structural and physiological abnormalities are typically noted only in the left hemisphere language-related cortices (i.e., frontal, parietal and temporal regions). PPA is not due to neoplastic, vascular, or metabolic etiologies nor to infectious disease (Mesulam, 2001; Rogers, 2004).Aphasia may be mild or severe. With mild aphasia, the person may be able to converse, yet have trouble finding the right word or understanding complex conversations. Severe aphasia limits the person's ability to communicate. The person may say little and may not participate in or understand any conversation.

What Are the Symptoms of Aphasia?
The main symptoms of aphasia include:
  • Trouble speaking
  • Struggling with finding the appropriate term or word
  • Using strange or inappropriate words in conversation
Some people with aphasia have problems understanding what others are saying. The problems occur particularly when the person is tired or in a crowded or loud environment. Aphasia does not affect thinking skills. But the person may have problems understanding written material and difficulties with handwriting. Some people have trouble using numbers or even doing simple calculations.

How Is Aphasia Diagnosed?
Usually, a doctor first diagnoses aphasia when treating a patient for a stroke, brain injury, or tumor. Using a series of neurological tests, the doctor may ask the person questions. The doctor may also issue specific commands and ask the person to name different items or objects. The results of these tests help the doctor determine if the person has aphasia. They also help determine the severity of the aphasia.

How Is Aphasia Treated?
Treatment for someone with aphasia depends on factors such as:
  • Age
  • Cause of brain injury
  • Type of aphasia
  • Position and size of the brain lesion
For instance, a person with aphasia may have a brain tumor that's affecting the language center of the brain. Surgery to treat the brain tumor may also improve the aphasia.

A person with aphasia who has had a stroke may benefit from sessions with a speech-language pathologist. The therapist will meet regularly with the person to increase his or her ability to speak and communicate. The therapist will also teach the person ways to communicate that don't involve speech. This will help the person compensate for language difficulties.

How Can We Prevent Aphasia?
Following are some precautions that should be taken to avoid aphasia, by decreasing the risk of stroke, the main cause of aphasia:
  • Exercising regularly
  • Eating a healthy diet
  • Keeping alcohol consumption low and avoiding tobacco use
  • Controlling blood pressure
Here are some tips from the National Stroke Association for someone with aphasia:
  • Use props to help get the message across.
  • Draw words or pictures on paper when trying to communicate.
  • Speak slowly and stay calm when talking.
  • Carry a card to let strangers know you have aphasia and what aphasia means.
References:
http://www.asha.org/Practice-Portal/Clinical-Topics/Aphasia/Common-Classifications-of-Aphasia/
http://www.webmd.com/brain/aphasia-causes-symptoms-types-treatments
http://en.wikipedia.org/wiki/Aphasia
Share on Google Plus