Introduction

Traumatic Brain Injury (TBI) is brain damage caused by an external force, such as hard falls, blows to the head, forceful jolts, or object penetration into the brain. Notably, not all impacts result in TBI; it is classified as such only when it leads to an altered mental state.¹ TBI is of high public concern, labelled globally as one of the leading causes of disability and mortality. Vehicle accidents and falls among the elderly are the two most commonly observed causes of TBI.² TBI has a detrimental effect on cognitive functions and has been seen to impair memory and language, reduce processing speed, cause behavioural changes, and more.³ 

In some cases, the cognitive impact of TBI has been seen to cause alexia, a condition characterised by the inability to read and comprehend written words. The symptoms of alexia are very similar to the more commonly known dyslexia. However, the two differ in that people are born with dyslexia, making it an innate disorder, whereas alexia is acquired through brain injury.⁴ Another difference is that dyslexia often affects a child’s ability to spell, whereas alexia only impacts reading ability. Although alexia is considered a rare disorder, it is commonly seen as a result of traumatic brain injury, especially when the injury damages the posterior left hemisphere of the brain, which is typically responsible for language recognition and speech development. 

Types of alexia

Pure alexia

Pure alexia is the most common and well-known type of alexia. In this type of alexia, the individual’s ability to write and spell is unaffected, but they experience great difficulty with reading written words. If spelt aloud, they are able to decipher the word, but putting the word together on paper becomes an impossible task. Patients with this form usually adopt a ‘letter by letter’ reading strategy in order to read each word correctly.⁵ Pure alexia is commonly seen following damage to the left posterior occipitotemporal region of the brain.⁶

Surface alexia

Patients with surface Alexia most commonly struggle to read irregular words that are of low frequency.⁶ They tend to rely on hearing the pronunciation of words to ascertain their meaning but this results in the inability to distinguish between homophones such as ‘pear’ and ‘pair’.⁵ It has been proposed that patients with this disability have damage in the ortho-lexicon region of their brain, causing the reliance on verbal pronunciation for word comprehension. 

Phonological alexia

Phonological Alexia is similar to surface alexia, as individuals can recognise familiar words more easily than unfamiliar ones. However, in phonological alexia, patients can identify individual written words but struggle to read sentences or longer pieces of text. This inability to comprehend words together is not aided by hearing the pronunciation of the words, as it is in surface alexia.⁷ There are several proposed areas of the brain associated with this type of alexia, but the most common is the left middle cerebral artery. 

Deep alexia

Individuals who develop deep alexia also commonly have aphasia, which affects the ability to speak, read and write.⁴ This type of alexia is characterised by semantic paralexia when reading aloud. For example, individuals might say a word that is related but different in meaning to the word written. For example, using synonyms to substitute ‘sore’ for ‘painful’ or antonyms such as ‘hard’ for ‘soft’.⁵

Diagnosis of alexia 

While traumatic brain injuries do not always result in alexia, alexia always stems from an injury to the brain. Since damage to multiple brain regions can cause various forms of alexia, evaluating an individual for signs of alexia after a TBI is crucial. To effectively test for alexia, knowledge of the individual’s reading ability prior to the TBI is beneficial. Patients are typically presented with short pieces of text, and speed and comprehension is evaluated by a professional. Neuroimaging techniques, such as computed tomography (CT) or magnetic resonance imaging (MRI) scans are performed to assess the severity and location of damage in the brain, since the severity of the TBI correlates to the severity of alexia, and helps to confirm the diagnosis.⁸ 

The affect of alexia on quality of life

Alexia can have a significantly negative impact on a person’s quality of life. Unlike innate dyslexia, alexia patients may experience extreme frustration with the sudden onset of their reading disability. This disability can negatively impact an individual’s ability to maintain their occupation or education and affect social relationships and independence. Alexia may lead to depression and anxiety. Fortunately, numerous treatment options are available to help manage the negative effects of alexia.¹

Treatment and rehabilitation strategies

In some cases, alexia can be fully reversed by treating the brain regions affected by the TBI, through surgical intervention to repair lesions or areas of brain damage.⁸ However, in most cases, alexia cannot be cured through surgical intervention and requires rehabilitation strategies. Broadly, these strategies can be divided into three categories depending on the aspect of reading that requires support: letter reading, word reading, or text reading. Each of these strategies will be appropriate for a different form of alexia.⁹ 

These techniques take on two approaches to managing Alexia: the top-down and the bottom-up approach. The bottom-up treatments focus on improving reading by starting with the basics, and progressing from letters to words. In contrast, top-down treatments focus on aiding word recognition by providing the context of the word. The effectiveness of these strategies varies with the form of alexia, making individualised treatment plans essential for optimal recovery.¹⁰

Tactile/kinesthetic treatments

For patients with pure alexia, letter-reading tactile treatments can help with reading words letter-by-letter. This approach utilises touch, often by tracing the shape of letters on the patient's skin and testing recognition to help the individual learn to visualise letters in their mind. Kinesthetic treatment involves physically tracing the letters. This is often used in conjunction with tactile treatment. A study has shown that this combined treatment/approach can cause a 51% improvement in word-reading ability.¹¹

Word-level treatments

Various treatments target the parallel processing of letters; the theory that different areas of the brain work together to produce ‘best guesses’ of language and meaning, rather than producing it letter by letter. This kind of treatment can benefit different kinds of alexia as a training tool.¹⁰

• Semantic and lexical decision tasks: In this treatment, words are presented to the patient for a brief duration in isolation. Patients are then asked to decipher the meaning of the word by choosing between presented options such as ‘edible’ or not
• Reading briefly presented words aloud: This method involves exposing patients to words briefly and having them pronounce the words aloud. Following this, words are pronounced by the practitioner and the patient tries to recognise them as words written on a page. Whilst this method of treatment has been shown to improve text-level reading and word recognition across many forms of alexia, studies have shown that it does not improve the reading ability of those with pure alexia¹²
• Repeated presentation of words with feedback: Also known as “errorless learning”, this treatment works on the principle that errors can result in the formation of incorrect links in the patient’s brain. Patients are required to repeat a presented word, and if they make a mistake, they are immediately corrected and asked to restart the exercise. One study using this treatment showed it improved the patients’ reading speed of untrained words significantly.¹³

Text-reading treatments

The most commonly used text-reading treatment is Multiple oral re-reading (MOR) which involves patients reading aloud texts over and over.¹⁰ This is one of the aforementioned top-down processing treatments. Multiple studies have demonstrated that MOR significantly improves the text-reading abilities of patients.^14,15

Prognosis of alexia

Although many treatments for alexia show promising results and dramatic improvements, full recovery from alexia is rare.⁸ However, the likelihood of improving quality of life is hopeful, and alexia is rarely associated with an increased morbidity rate. Considering the negative mental health consequences of Alexia, one of the most important factors to keep in mind is patient support. This type of support involves educating friends and family, therapy, and support groups. and can be instrumental in preventing the development of mental health disorders, such as anxiety and depression. 

Summary

Alexia is an acquired learning disorder that affects an individual’s ability to read and comprehend written words. Traumatic brain injuries (TBI) which involve dramatic damage to the brain often from impact or a fall, are a common cause of alexia. There are many different types of alexia, depending on the area of the brain affected. Some types affect the comprehension of individual words while others affect the reading of entire texts. Reassuringly, numerous treatment options are available for all forms of alexia, many of which show promising results in improving the condition.