What is agraphia?

Agraphia is a neurological condition, that affects people’s ability to write caused by brain defects.¹ It can affect the neurological processes involved, called central agraphia, involving language processing. When this condition affects the motor functions in the body such as writing, it is referred to as peripheral agraphia. Writing involves many processes like motor, sensory and cognitive functions, a disruption in any of these functions can lead to agraphia. It is important to differentiate the differences between central and peripheral agraphia so that patients can get the necessary treatments. 

Central agraphia

What is central agraphia?

The loss of motor and visual abilities through language communication and comprehension is known as central agraphia. This condition usually occurs after a stroke or brain injury. There are three main types of central agraphia:

• Phonological agraphia

Phonological agraphia⁵ is the ability to write familiar words but unable to sound them out. People with phonological agraphia tend to perform well in writing legitimate words of/with unusual spelling patterns but cannot write pseudowords under dictation. They will likely to make spelling errors, eg, ‘concern’ for ‘corner’.

• Lexical agraphia

Lexical agraphia, or surface agraphia, is the inability to write common words that can be sounded out, caused by angular gyrus lesions^1,6 in the hemisphere. Signs of this type of agraphia can include; 

1. Preserved ability to spell regular words
2. Difficulty spelling irregular words 
3. A decline in the ability to write words

• Deep agraphia 

Deep agraphia is a writing disorder caused by lesions in the supramarginal gyrus and the insula.⁷ This can be characterised by;

• Inability to spell nonwords and function words
• A better spelling of high imageability than low imageability nouns
• Semantic paraphasia is closely related to phonological agraphia 

Peripheral agraphia

What is peripheral agraphia?

Peripheral agraphia is focused on the decline or loss of writing ability or spelling modality. Good oral spelling is usually associated with difficulties in writing (or the opposite). Like central agraphia, there are subtypes of peripheral agraphia:

• Apraxic agraphia

Apraxic agraphia is a type of agraphia that defects the peripheral motor process “graphic motor patterns”. This means that writing will contain the correct spelling, though the letters may be deformed, this is conducted by a sequence of motor activity.³

• Spatial agraphia

Spatial agraphia, most commonly known as afferent agraphia, is associated with lesions in the right hemisphere causing duplications or deletions of letters when writing followed by a repeat of strokes.⁴

Differences in origin

Central agraphia is caused by disruptions within the brain’s cognitive and language processing areas. The affected regions are mainly in charge of the cognitive processes such as; sentence formation, word choice and language comprehension. When these areas are damaged, it interferes with the methods that translate concepts and ideas into written language.¹ 

On the other hand, damage to the motor and sensory regions causes peripheral agraphia. These processes involve writing and motor coordination. The linguistic and cognitive parts of writing are unaffected, however, problems in the peripheral regions can cause issues with writing. 

Diagnosis of agraphia

People who experience having strokes or are at high risk of developing Alzheimer's disease are frequently tested for agraphia. They will be asked to submit their responses to a series of open-ended questions such as “What is your daily routine like?” or “Tell me about yourself”. After this, they will be assessed on their writing speed, reading ability and spelling.^1,8

Treatments for agraphia

Speech and language therapy (SLT) is the recommended form of treatment for people who have either central or peripheral agraphia. This can be done by going to therapy, and taking medication regularly and can sometimes require you to have surgery for it to be treated successfully.¹

Summary 

In summary, agraphia is a neurological disorder affecting someone’s ability to speak or write. There are different types of agraphia. Speech and language therapy is a recommended form of treatment for people who are diagnosed with either central or peripheral agraphia.

FAQs

• Can agraphia be prevented?

Agraphia cannot be prevented because it occurs after a brain injury. 

• What is the difference between central agraphia and peripheral agraphia? 

Central agraphia affects one’s ability to spell, whereas peripheral agraphia causes writing difficulties.²