Agraphia

DEFINITION

Agraphia is the inability to write due to either a learning disability or damage to or degeneration of specific regions of the brain.

DESCRIPTION

Although it usually refers to a complete inability to write, “agraphia” is sometimes used interchangeably with “dysgraphia,” an impairment in writing ability and/or the inability to spell when writing.

Acquired agraphia or acquired dysgraphia is the loss of writing ability following brain damage or degeneration.

It almost always occurs in conjunction with alexia, the inability to read, dyslexia, an impairment in reading ability. Acquired agraphia without alexia is extremely rare, whereas acquired alexia without agraphia is relatively standard.

Thus, stroke victims may find themselves unable to read even the simplest words or recognize letters, yet their writing ability is unimpaired; however, they cannot read what they have written.

Various aspects of writing ability are controlled by different brain parts and by interactions between these areas. The temporal and also parietal lobes of the cerebral hemispheres are involved in the comprehension of written words.

The parietal lobe is also believed to be involved in converting sounds, phonemes into written symbols or graphemes.

Wernicke’s receptive speech area is located in the left temporal lobe. In the left frontal lobe of the brain, Exner’s writing area and Broca’s expressive speech area are involved in the expression. Therefore, agraphia can result from damage to different brain regions.

Agraphia is usually a symptom of aphasia. Aphasias are acquired communication disorders caused by injury to or degeneration of specific areas in the brain.

Aphasias affect the brain’s ability to process language without affecting intelligence or cognition.

Most people with aphasia have at least some problems with writing and reading, speaking, and/or comprehending spoken language.

Types of aphasia  

Different types of aphasia have different effects on writing and other communication skills:

• Global aphasia, the most severe form, is common immediately after a stroke. Global aphasia patients can neither write nor read, have little recognizable speech, and understand little or no spoken language.
• Wernicke’s aphasia—also called fluent, receptive, or sensory aphasia—primarily affects spoken language comprehension but often includes severely impaired writing and reading. Speech is impaired but fluent.
• Broca’s aphasia—also called nonfluent, expressive, or motor aphasia—primarily affects the ability to speak but often causes agraphia as well.
• Mixed nonfluent aphasia is similar to Broca’s aphasia in its effects on speech and speech comprehension and the ability to read and write.
• Anomic aphasia is characterized by the inability to utilize appropriate words in both spoken and written language.
• Many aphasias are combinations of neurological deficits, including agraphia, that do not fit a specific classification.

Types of Agraphia 

They are classified in various ways:

• Pure agraphia is writing impairment in the absence of any other language disorder.
• Frontal agraphia is a writing impairment caused by a disorder in the frontal lobe.
• Aphasic agraphia is aphasia with the same impairment pattern in both written and spoken language.
• Alexic agraphia (also called alexia with agraphia, central alexia, or angular gyrus syndrome) is an aphasia characterized by loss of the ability to read and write. It usually includes loss of the ability to spell and understand spelled words and often includes paraphasia, or speech utilizing wrong or senseless words or sounds.
• Apraxic agraphia is an impairment of motor coordination involved in writing, in the absence of other motor or language impairments, and intact spelling ability.
• Visuospatial or spatial agraphia is a deficit in visual-spatial analysis in the absence of aphasia.
• Phonological agraphia is an impairment in written language processing that usually occurs in combination with phonological alexia and is characterized by difficulty spelling and reading nonwords. However, the spelling and reading of real words are generally also impaired.

Agraphia is one of the four deficits that define a rare disorder known as Gerstmann syndrome.

The other three deficits of Gerstmann syndrome are the loss of simple arithmetic ability (acalculia or dyscalculia), the inability to distinguish between right and left sides of the body, and finger agnosia or the inability to recognize one’s own or another’s fingers.

Gerstmann syndrome often includes alexia and difficulty in expressing and understanding speech. There are rare reports of developmental Gerstmann syndrome occurring in children.

Writing is often the most significant challenge for children with learning disabilities. However, it is unclear whether agraphia exists as a separate learning disorder in children since it is rare in the absence of learning disorders affecting reading and/or mathematics.

DEMOGRAPHICS

Although the incidence of agraphia is unknown, it primarily affects older individuals of both genders and racial and ethnic groups.

Aphasia usually involves agraphia, and stroke is probably the most common cause of aphasia.

There are more than 700 000 strokes in the United States each year and approximately 170 000 new cases of aphasia related to stroke.

Neurodegenerative disorders, including Alzheimer’s disease, also frequently result in language deficits, including agraphia.

There are approximately five million Alzheimer’s patients in the United States.

CAUSES AND SYMPTOMS

• malformations of the arteries or veins in the brain
• infarction, or tissue death due to an obstruction in local blood circulation
• brain hemorrhage
• infection
• traumatic brain injury (TBI)
• brain tumors
• Alzheimer’s disease
• frontotemporal dementia
• Parkinson’s disease

• Global aphasia usually involves a large lesion in the left hemisphere that includes Wernicke’s and Broca’s areas.
• Wernicke’s aphasia is caused by a large lesion in the left temporoparietal region that includes Wernicke’s area.
• Broca’s aphasia is caused by a large lesion in the dominant left frontal or frontoparietal region, including Broca’s area.
• Alexic agraphia generally results from a lesion in the angular gyrus of the left inferior parietal lobule.
• Phonological agraphia appears to be related to damage to the left perisylvian cortical region involved in phonological processing. It is common following a stroke of the left-middle cerebral artery. Phonological agraphia can also result from injury to or vascular abnormalities in the posterior corpus callosum or the superior temporal gyrus or from epilepsy (called acquired epileptic dysgraphia).
• Gerstmann syndrome is associated with damage to the dominant (left) parietal lobe in the angular gyrus region, either from a stroke or other brain injury or as a developmental disorder.

DIAGNOSIS