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Alexia
Published in Alexander R. Toftness, Incredible Consequences of Brain Injury, 2023
Alexia without agraphia is relatively uncommon, but it is so intriguing to researchers that it has been called the “most studied” of the various acquired reading disorders (Starrfelt & Shallice, 2014, p. 367). Such cases frequently lead to moments where the person can write something down to help themselves remember it, but then they struggle to decipher it later. It gets even more specific. A person with alexia without agraphia usually struggles to copy writing by looking at it, but they are able to write when dictated to, such as when they are told to write something down, and they can also write spontaneously on their own (Lhermitte & Beauvois, 1973). If they don't overthink it and just let their muscles and brain produce the writing, it can flow like magic, even though technically they have little to no idea what the letters themselves mean.
Non-Organic Vision Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Ashwini Kini, Mangayarkarasi Thandampallayam Ajjeya, Padmaja Sudhakar
Posterior hemisphere strokes/alexia without agraphia: Alexia without agraphia is a relatively uncommon condition, which should always be thought in a patient presenting with difficulty in reading with normal visual acuity and normal writing. This is caused by a left occipital lobe lesion with ipsilateral coinvolvement of the splenium of the corpus callosum or adjacent periventricular white matter leading to a disconnection syndrome. Features include right homonymous hemianopia with sparing of key language areas but an inability to access lexical visual information processed in the intact right occipital lobe.
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
Anterior disconnection syndrome may follow from lesions to the foremost portion of the corpus callosum. Such lesions are associated with infarction of the anterior cerebral artery. Patients demonstrate unilateral APRAXIA of the left hand, and cannot name or otherwise verbalize information about objects held in the left hand. Posterior disconnection syndrome is associated with lesions of the SPLENIUM portion of the corpus callosum. Tumours or infarction of the posterior cerebral artery are common aetiology. Patients may complain of visual disturbances. Functional dissociation between reading impairment (DYSLEXIA) and writing impairment (DYSGRAPHIA) may be associated with some disconnections between the cerebral hemispheres. ALEXIA without AGRAPHIA is attributable to a complex set of lesions that cause dysfunction of the left VISUAL CORTEX in conjunction with a lesion of the posterior corpus callosum which effectively isolates the right visual cortex from the (damaged) left visual cortex. Consequently, both the right and left visual cortices are isolated from the (intact) language area. The intact language areas allow written language production (WRITING) whilst the disconnection of visual stimulus input to the language areas results in failed comprehension of written language (READING). The clinical indication of this complex syndrome is demonstrated by an intact ability to copy or write spontaneously with the striking failure to read what was written.
A case of aneurysmal subarchnoid haemorrhage and superficial siderosis complicated by prospagnosia, simultagnosia and alexia without agraphia
Published in British Journal of Neurosurgery, 2023
Mohammed Fadelalla, Avinash Kanodia, Mustafa Elsheikh, John Ellis, Vivien Smith, Kismet Hossain-Ibrahim
Alexia without agraphia, also known as ‘pure alexia’, ‘word blindness’ and ‘agnostic alexia, is known to be caused by lesions to the visual word form area in the left occipital lobe.5 In our case MRI ruled out any lesions in the fusiform gyri, occipital lobes and temporal lobes. The only prominent abnormality was widespread deposition of hemosiderin over the brain surfaces especially the corpus callosum and adjacent brain surfaces.