Alexia

Alexia

Alexia, also known as acquired dyslexia, is a neurological disorder characterized by the loss of the ability to read. This condition occurs due to damage to the brain, particularly in the left hemisphere, which is responsible for language processing. Alexia is distinct from developmental dyslexia, which is a learning disability present from childhood.

Classification

Alexia can be classified into several types based on the nature and location of the brain damage:

• Pure Alexia: Also known as "letter-by-letter reading," this form occurs when there is damage to the visual word form area (VWFA) in the left occipito-temporal region. Patients can write and understand spoken language but have difficulty reading.

• Surface Alexia: This type is characterized by difficulty reading irregularly spelled words. It is often associated with damage to the left temporal lobe.

• Phonological Alexia: Patients with this form have trouble reading unfamiliar words or non-words, often due to damage in the left perisylvian area.

• Deep Alexia: This severe form involves both phonological and semantic reading errors, often resulting from extensive damage to the left hemisphere.

Causes

Alexia is typically caused by stroke, traumatic brain injury, or other forms of brain damage. Lesions in specific areas of the brain, such as the left angular gyrus or the left occipito-temporal region, are commonly associated with different types of alexia.

Diagnosis

Diagnosis of alexia involves a comprehensive assessment by a neurologist or neuropsychologist. This includes:

• Neuroimaging techniques such as MRI or CT scan to identify brain lesions.
• Reading tests to evaluate the patient's ability to recognize words, letters, and sentences.
• Cognitive assessments to rule out other language disorders such as aphasia.

Treatment

Treatment for alexia focuses on rehabilitation and may include:

• Speech and language therapy to improve reading skills.
• Use of assistive technology, such as text-to-speech software.
• Cognitive exercises to enhance visual and verbal processing.

Prognosis

The prognosis for individuals with alexia varies depending on the severity of the brain damage and the type of alexia. Some patients may experience significant improvement with therapy, while others may have persistent difficulties.

See also

• Aphasia
• Dyslexia
• Neurology

References

• Leff, A. P., & Starrfelt, R. (2013). Alexia: Diagnosis, Treatment and Theory. Springer.
• Dehaene, S. (2009). Reading in the Brain: The Science and Evolution of a Human Invention. Viking Adult.