Alexia, Pure
Dyslexia, Acquired
Agraphia
Hemianopsia
Dyslexia
Reading
Anomia
Writing
Occipital Lobe
Psycholinguistics
Ocular Motility Disorders
Phonetics
Cerebral Infarction
Magnetic Resonance Imaging
Functional Laterality
The functional anatomy of single-word reading in patients with hemianopic and pure alexia. (1/15)
We investigated single-word reading in normal subjects and patients with alexia following a left occipital infarct, using PET. The most posterior brain region to show a lateralized response was at the left occipitotemporal junction, in the inferior temporal gyrus. This region was activated when normal subjects, patients with hemianopic alexia and patients with an incomplete right homonymous hemianopia, but no reading deficit, viewed single words presented at increasing rates. This same area was damaged in a patient with pure alexia ("alexia without agraphia") and no hemianopia, who read words slowly using a letter-by-letter strategy. Although the exact level of the functional deficit is controversial, pure alexia is the result of an inability to map a percept of all the letters in a familiar letter string on to the mental representation of the whole word form. However, the commonest deficit associated with "pure" alexia is a right homonymous field defect; an impairment that may, by itself, interfere with single-word reading because of inability to see the letters towards the end of a word. The relative contributions of pure and hemianopic alexia in individual patients needs to be assessed, as the latter has been shown to respond well to specific rehabilitation programmes. (+info)Visual command hallucinations in a patient with pure alexia. (2/15)
Around 25% of patients with visual hallucinations secondary to eye disease report hallucinations of text. The hallucinated text conveys little if any meaning, typically consisting of individual letters, words, or nonsense letter strings (orthographic hallucinations). A patient is described with textual visual hallucinations of a very different linguistic content following bilateral occipito-temporal infarcts. The hallucinations consisted of grammatically correct, meaningful written sentences or phrases, often in the second person and with a threatening and command-like nature (syntacto-semantic visual hallucinations). A detailed phenomenological interview and visual psychophysical testing were undertaken. The patient showed a classical ventral occipito-temporal syndrome with achromatopsia, prosopagnosia, and associative visual agnosia. Of particular significance was the presence of pure alexia. Illusions of colour induced by monochromatic gratings and a novel motion-direction illusion were also observed, both consistent with the residual capacities of the patient's spared visual cortex. The content of orthographic visual hallucinations matches the known specialisations of an area in the left posterior fusiform gyrus--the visual word form area (VWFA)--suggesting the two are related. The VWFA is unlikely to be responsible for the syntacto-semantic hallucinations described here as the patient had a pure alexic syndrome, a known consequence of VWFA lesions. Syntacto-semantic visual hallucinations may represent a separate category of textual hallucinations related to the cortical network implicated in the auditory hallucinations of schizophrenia. (+info)Alexia without agraphia in a postpartum eclamptic patient with factor V Leiden deficiency. (3/15)
We present a case of eclampsia complicated by alexia without agraphia. To our knowledge, this syndrome has never before been described in the literature. (+info)Transitory alexia without agraphia: a disconnection syndrome due to neurocysticercosis. (4/15)
We describe a 65-year-old male who presented with acute onset inability to read, without any difficulty in writing. A clinical diagnosis of alexia without agraphia was made and the patient was subjected to routine investigations including contrast MRI. MRI showed a ring-enhancing lesion in left occipital area, suggestive of neurocysticercosis supported by quantitative enzyme-linked immunosorbant assay from purified cell fraction of taenia solium cysticerci (PCF-ELISA). Patient was treated with albendazole and prednisolone for one week. The clinical manifestation as well as the radiological finding resolved after treatment. (+info)The rises and falls of disconnection syndromes. (5/15)
In a brain composed of localized but connected specialized areas, disconnection leads to dysfunction. This simple formulation underlay a range of 19th century neurological disorders, referred to collectively as disconnection syndromes. Although disconnectionism fell out of favour with the move against localized brain theories in the early 20th century, in 1965, an American neurologist brought disconnection to the fore once more in a paper entitled, 'Disconnexion syndromes in animals and man'. In what was to become the manifesto of behavioural neurology, Norman Geschwind outlined a pure disconnectionist framework which revolutionized both clinical neurology and the neurosciences in general. For him, disconnection syndromes were higher function deficits that resulted from white matter lesions or lesions of the association cortices, the latter acting as relay stations between primary motor, sensory and limbic areas. From a clinical perspective, the work reawakened interest in single case studies by providing a useful framework for correlating lesion locations with clinical deficits. In the neurosciences, it helped develop contemporary distributed network and connectionist theories of brain function. Geschwind's general disconnectionist paradigm ruled clinical neurology for 20 years but in the late 1980s, with the re-emergence of specialized functional roles for association cortex, the orbit of its remit began to diminish and it became incorporated into more general models of higher dysfunction. By the 1990s, textbooks of neurology were devoting only a few pages to classical disconnection theory. Today, new techniques to study connections in the living human brain allow us, for the first time, to test the classical formulation directly and broaden it beyond disconnections to include disorders of hyperconnectivity. In this review, on the 40th anniversary of Geschwind's publication, we describe the changing fortunes of disconnection theory and adapt the general framework that evolved from it to encompass the entire spectrum of higher function disorders in neurology and psychiatry. (+info)Shades of Dejerine--forging a causal link between the visual word form area and reading. (6/15)
In 1892, the French neurologist Jules Dejerine suggested that pure alexia resulted from an occipital lesion that selectively disconnected visual input from a region of the brain that housed "optical images of words." In this issue of Neuron, Gaillard and colleagues offer evidence consistent with Dejerine's proposal and provide new insights to the functional role of the "visual word form area." (+info)Structural anatomy of pure and hemianopic alexia. (7/15)
BACKGROUND: The two most common types of acquired reading disorder resulting from damage to the territory of the dominant posterior cerebral artery are hemianopic and pure alexia. Patients with pronounced hemianopic alexia have a right homonymous hemianopia that encroaches into central or parafoveal vision; they read individual words well, but generate inefficient reading saccades when reading along a line of text. Patients with pure alexia also often have a hemianopia but are more disabled, making frequent errors on individual words; they have sustained damage to a brain region that supports efficient word identification. OBJECTIVE: To investigate the differences in lesion site between hemianopic alexia and pure alexia groups, as rehabilitative techniques differ between the two conditions. METHODS: High-resolution magnetic resonance images were obtained from seven patients with hemianopic alexia and from six patients with pure alexia caused by a left occipital stroke. The boundary of each lesion was defined and lesion volumes were then transformed into a standard stereotactic space so that regional comparisons could be made. RESULTS: The two patient groups did not differ in terms of damage to the medial left occipital lobe, but those with pure alexia had additional lateral damage to the posterior fusiform gyrus and adjacent tissue. CONCLUSIONS: Clinicians will be able to predict the type of reading disorder patients with left occipital lesions have from simple tests of reading speed and the distribution of damage to the left occipital lobe on brain imaging. This information will aid management decisions, including recommendations for reading rehabilitation. (+info)Too little, too late: reduced visual span and speed characterize pure alexia. (8/15)
(+info)Alexia, also known as word blindness or pure alexia, is a type of acquired reading disorder that affects the ability to recognize and understand written words, despite having intact intelligence, speech, and language comprehension. It is typically caused by damage to specific areas in the left occipitotemporal cortex of the brain, often as a result of stroke or head injury.
People with pure alexia may have difficulty reading individual words, even those they know well, but can still write and speak normally. They may use strategies such as guessing words based on their first letter or shape, or by using context clues to help them understand written text. Treatment for pure alexia typically involves various forms of rehabilitation and compensatory strategies to help individuals regain or improve their reading abilities.
Acquired dyslexia, also known as "alexia" or "word blindness," is a medical condition that affects an individual's ability to understand written language despite having normal intelligence and education. It is characterized by a sudden loss of the ability to read, following damage to specific areas of the brain responsible for visual processing and language comprehension, such as the left occipitotemporal cortex.
Unlike developmental dyslexia, which is present from birth or early childhood, acquired dyslexia occurs later in life due to brain injury, stroke, infection, tumor, or other neurological conditions that damage the language and visual processing areas of the brain. Individuals with acquired dyslexia may have difficulty recognizing words, letters, or symbols, despite having intact hearing and speaking abilities.
Treatment for acquired dyslexia typically involves rehabilitation and compensation strategies to help the individual regain their reading skills or develop alternative ways to process written language. Speech-language therapy, occupational therapy, and assistive technology may be used as part of a comprehensive treatment plan.
Agraphia is a neurological disorder that affects the ability to write, either by hand or through mechanical means like typing. It is often caused by damage to specific areas of the brain involved in language and writing skills, such as the left parietal lobe. Agraphia can manifest as difficulty with spelling, forming letters or words, organizing thoughts on paper, or expressing ideas in writing. Depending on the severity and location of the brain injury, agraphia may occur in isolation or alongside other language or cognitive impairments.
Hemianopsia is a medical term that refers to a loss of vision in half of the visual field in one or both eyes. It can be either homonymous (the same side in both eyes) or heteronymous (different sides in each eye). Hemianopsia usually results from damage to the optic radiations or occipital cortex in the brain, often due to stroke, trauma, tumor, or other neurological conditions. It can significantly impact a person's daily functioning and may require visual rehabilitation to help compensate for the vision loss.
Dyslexia is a neurodevelopmental disorder that impairs an individual's ability to read, write, and spell, despite having normal intelligence and adequate education. It is characterized by difficulties with accurate and fluent word recognition, poor decoding and spelling abilities, and often accompanied by problems with reading comprehension and reduced reading experience. Dyslexia is not a result of low intelligence, lack of motivation, or poor instruction, but rather a specific learning disability that affects the way the brain processes written language. It is typically diagnosed in children, although it can go unnoticed until adulthood, and there are effective interventions and accommodations to help individuals with dyslexia overcome their challenges and achieve academic and professional success.
I'm sorry for any confusion, but "reading" is not a term that has a specific medical definition. Reading is the activity or process of deciphering and understanding written words or text. It is a fundamental skill in language acquisition and communication, and is not typically used in a medical context unless there is a concern related to reading difficulties or disorders, such as dyslexia. If you have any questions related to medical terminology or health concerns, I'd be happy to try to help answer those for you!
Anomia is a language disorder that affects a person's ability to name objects, places, or people. It is often caused by damage to the brain, such as from a stroke, brain injury, or neurological condition. In anomia, a person has difficulty retrieving words from their memory, and may substitute similar-sounding words, describe the object instead of naming it, or be unable to come up with a name at all. Anomia can range from mild to severe and can significantly impact a person's ability to communicate effectively.
I believe there may be some confusion in your question. "Writing" is a common term used to describe the act or process of creating written content, whether it's for literary, professional, or personal purposes. However, if you're asking for a medical term related to writing, perhaps you meant "graphomotor," which refers to the fine motor skills required to produce handwriting or signing one's name. If this is not what you were looking for, please clarify your question so I can provide a more accurate answer.
The occipital lobe is the portion of the cerebral cortex that lies at the back of the brain (posteriorly) and is primarily involved in visual processing. It contains areas that are responsible for the interpretation and integration of visual stimuli, including color, form, movement, and recognition of objects. The occipital lobe is divided into several regions, such as the primary visual cortex (V1), secondary visual cortex (V2 to V5), and the visual association cortex, which work together to process different aspects of visual information. Damage to the occipital lobe can lead to various visual deficits, including blindness or partial loss of vision, known as a visual field cut.
Psycholinguistics is not a medical term per se, but it is a subfield of both psychology and linguistics that explores how we understand, produce, and process language. It investigates the cognitive processes and mental representations involved in language use, such as word recognition, sentence comprehension, language production, language acquisition, and language disorders.
In medical contexts, psycholinguistic assessments may be used to evaluate individuals with communication difficulties due to neurological or developmental disorders, such as aphasia, dyslexia, or autism spectrum disorder. These assessments can help identify specific areas of impairment and inform treatment planning.
Ocular motility disorders refer to a group of conditions that affect the movement of the eyes. These disorders can result from nerve damage, muscle dysfunction, or brain injuries. They can cause abnormal eye alignment, limited range of motion, and difficulty coordinating eye movements. Common symptoms include double vision, blurry vision, strabismus (crossed eyes), nystagmus (involuntary eye movement), and difficulty tracking moving objects. Ocular motility disorders can be congenital or acquired and may require medical intervention to correct or manage the condition.
Phonetics is not typically considered a medical term, but rather a branch of linguistics that deals with the sounds of human speech. It involves the study of how these sounds are produced, transmitted, and received, as well as how they are used to convey meaning in different languages. However, there can be some overlap between phonetics and certain areas of medical research, such as speech-language pathology or audiology, which may study the production, perception, and disorders of speech sounds for diagnostic or therapeutic purposes.
Cerebral infarction, also known as a "stroke" or "brain attack," is the sudden death of brain cells caused by the interruption of their blood supply. It is most commonly caused by a blockage in one of the blood vessels supplying the brain (an ischemic stroke), but can also result from a hemorrhage in or around the brain (a hemorrhagic stroke).
Ischemic strokes occur when a blood clot or other particle blocks a cerebral artery, cutting off blood flow to a part of the brain. The lack of oxygen and nutrients causes nearby brain cells to die. Hemorrhagic strokes occur when a weakened blood vessel ruptures, causing bleeding within or around the brain. This bleeding can put pressure on surrounding brain tissues, leading to cell death.
Symptoms of cerebral infarction depend on the location and extent of the affected brain tissue but may include sudden weakness or numbness in the face, arm, or leg; difficulty speaking or understanding speech; vision problems; loss of balance or coordination; and severe headache with no known cause. Immediate medical attention is crucial for proper diagnosis and treatment to minimize potential long-term damage or disability.
Medical Definition:
Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic imaging technique that uses a strong magnetic field and radio waves to create detailed cross-sectional or three-dimensional images of the internal structures of the body. The patient lies within a large, cylindrical magnet, and the scanner detects changes in the direction of the magnetic field caused by protons in the body. These changes are then converted into detailed images that help medical professionals to diagnose and monitor various medical conditions, such as tumors, injuries, or diseases affecting the brain, spinal cord, heart, blood vessels, joints, and other internal organs. MRI does not use radiation like computed tomography (CT) scans.
Functional laterality, in a medical context, refers to the preferential use or performance of one side of the body over the other for specific functions. This is often demonstrated in hand dominance, where an individual may be right-handed or left-handed, meaning they primarily use their right or left hand for tasks such as writing, eating, or throwing.
However, functional laterality can also apply to other bodily functions and structures, including the eyes (ocular dominance), ears (auditory dominance), or legs. It's important to note that functional laterality is not a strict binary concept; some individuals may exhibit mixed dominance or no strong preference for one side over the other.
In clinical settings, assessing functional laterality can be useful in diagnosing and treating various neurological conditions, such as stroke or traumatic brain injury, where understanding any resulting lateralized impairments can inform rehabilitation strategies.
The temporal lobe is one of the four main lobes of the cerebral cortex in the brain, located on each side of the head roughly level with the ears. It plays a major role in auditory processing, memory, and emotion. The temporal lobe contains several key structures including the primary auditory cortex, which is responsible for analyzing sounds, and the hippocampus, which is crucial for forming new memories. Damage to the temporal lobe can result in various neurological symptoms such as hearing loss, memory impairment, and changes in emotional behavior.
Pure alexia