What is Alexia?

Overview

Alexia, sometimes known as ‘word blindness’ is a complete or partial deficit in the ability to read and comprehend written language that might happen due to a stroke, damage or trauma to the brain. It does not refer to deficits acquired in early life or a mechanical one such as poor education or visual impairment.¹ Alexia and dyslexia are often used interchangeably; however, these are different conditions and should be treated as such. There are subtypes of Alexia that are different based onthe degree of deficit, other communication deficits present and the area of the brain affected. These subtypes include posterior (or occipital) alexia, central (or parietal-temporal) alexia and frontal (or anterior) alexia.

Alexia is commonly associated with other language difficulties, most notably agraphia (the loss of the ability to write). People remain capable of spelling and writing words and sentences in pure alexia (also referred to as posterior alexia). In the other two subtypes, however, agraphia is a key feature. 

Causes of alexia

In its simplest form, alexia is caused by infarction to the left hemisphere of the brain, either by stroke or trauma resulting in a lesion. Less common causes of alexia could be multiple sclerosis, migraine, acute encephalopathy or occipital tumours.

The type of alexia you have depends on the specific area of the left hemisphere that is damaged.

• Posterior alexia (pure alexia or occipital alexia) is caused by infarction to the left posterior cerebral artery, and/or a haemorrhage in the occipital region. This can result in an impairment in the visual cortex communicating with the language centres in our brain
• Central alexia (parietal-temporal alexia) is caused by damage to the angular gyrus, and/or infarction to the middle and left posterior cerebral arteries. This causes damage to pathways that connect the language centres of the brain to the visual and auditory word-forming areas
• Anterior alexia (frontal alexia) is caused by a lesion or infarction to the anterior left hemisphere²

Signs and symptoms of alexia

Posterior alexia: Loss of the ability to read and to understand written language. Patients may be able to write out a word correctly but would be unable to read the whole word. Individuals with posterior alexia can recognise letters and symbols separately. The person is able to spell out words verbally and interpret words spelt out to them. This type is also often associated with right-sided visual impairment in some cases.¹

Central alexia: People with central alexia would present with a sudden inability to read words and not recognise letters or symbols. Agraphia is present, which means they have lost the ability to write. They will lose the ability to interpret words spelt out to them, or spell out words themselves. Aphasia (difficulty with language or speech) is often a feature of central alexia. Lastly, some right-sided visual impairment may be observed.¹

Anterior alexia: This type is also associated with difficulty  in writing. People with this type of alexia may recognise some short words but cannot recognise individual letters and symbols. As with central alexia, the person is not able to understand words spelt out to them or to spell words out verbally themselves. Motor apraxia is also a notable feature sometimes occuring alongside anterior alexia. Motor apraxia is the loss of ability to perform simple movements and is associated with frontal lobe injury.¹

Management and treatment for alexia

Treatment of alexia can be difficult because of the varying types of alexia and because it is often accompanied by other language deficits such as difficulties in speaking and understanding speech. Rehabilitation can be a long process with most treatments focusing on relearning to recognise letters and words.

LiPS (Lindamood Phoneme Sequencing Program) works by going through various steps to recognise the sounds in words. Sounding out the words helps patients identify individual words. The theory is that words unfamiliar to the person will be more easily identified. Studies have shown this treatment to improve spelling and reading speed.¹

Read Right Therapy involves a written text sliding across a screen, the topic can be picked based on the person’s interests and passion. It’s a free program and has shown huge improvements, even a full return to normal reading in some cases.¹

Tactile Kinaesthetic involves using touch and movement to recognise words and letters. The thought is that this form of treatment encourages the recognition of words through touch rather than visuals.^1,3

Multiple oral reading involves re-reading a specific text for 30 minutes daily for a week. This results in significant improvements in reading.¹

There are a number of other treatment techniques for rehabilitation. The best treatment would depend entirely on the range and severity of symptoms. The course of rehabilitation would also be discussed fully by a speech and language pathologist.  

Diagnosis of alexia

Diagnosis of alexia is determined through clinical examination, which includes establishing onset, looking at symptoms and then confirmation with an MRI of the brain. The loss of ability to read and comprehend text must be in someone who was previously literate. Follow up scans and examinations by a speech and language pathologist will look to diagnose which type of alexia one may have.

FAQs

Can alexia be prevented?

Alexia can occur as a result of damage to the brain, usually a stroke or traumatic injury. Therefore, there is nothing you can do to specifically prevent alexia from occurring secondary to a damage. You can, however, reduce the risk of a stroke by optimising your physical wellbeing and the risk of head injury by avoiding unnecessary risks that could lead to such injuries, for example, wearing a helmet when cycling. 

How common is alexia?

Studies suggest that alexia is common after a brain injury to the left hemisphere, additionally, they observed that in 60% of cases, alexia occurs in addition to other language impairments, most notably aphasia (trouble speaking or understanding speech).^{3, 4}

Who is at risk of alexia?

Any person who has experienced a stroke or injury to the left hemisphere of the brain may get alexia, either with or without agraphia. There is no documentation suggesting certain risk factors that are unique to alexia. 

When should I see a doctor?

As alexia occurs due to a stroke or traumatic head injury, the likelihood is that you are already in a hospital being cared for by health professionals. Following such an injury to the brain, comprehensive assessment and monitoring of your recovery could detect the potential presence of alexia during the initial recovery phase. If you suddenly lose the ability to read or understand language at home, you might have had a stroke or other injury to your brain and should immediately seek medical attention for scans and examination. 

Summary

Alexia, which may be better known as word blindness, is a condition that results from some form of damage or injury to the left side of the brain. There are numerous types and subtypes of alexia with a range of symptoms that influence communication. The main symptom is loss of ability to read and understand written text which often known as pure alexia. Other types of alexia have other features that might have impacts on reading, writing speech and sometimes movement. As the range of symptoms is so wide, there is no one overarching treatment, but a range of treatments that aim to solve a particular problem. In some cases, rehabilitation has resulted in a complete return of the ability to read and understand written text, as well as resolving some of the other symptoms.