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Abstract
Alexia refers to a reading disorder caused by some form of acquired brain pathology, most commonly a stroke or tumor, in a previously literate subject. In neuropsychology, a distinction is made between central alexia (commonly seen in aphasia) and peripheral alexia (a perceptual or attentional deficit). The prototypical peripheral alexia is alexia without agraphia (pure alexia), where patients can write but are impaired in reading words and letters. Pure alexia is associated with damage to the left ventral occipitotemporal cortex (vOT) or its connections. Hemianopic alexia is associated with less extensive occipital damage and is caused by a visual field defect, which creates problems reading longer words and passages of text. Reading impairment can also arise due to attentional deficits, most commonly following right hemisphere or bilateral lesions. Studying patients with alexia, along with functional imaging studies of normal readers, has improved our understanding of the neurobiological processes involved in reading. A key question is whether an area in the left ventral occipitotemporal cortex is specialized for or selectively involved in word processing, or whether reading relies on tuning of more general purpose perceptual areas. Reading deficits may also be observed in dementia and traumatic brain injury, but often with less consistent deficit patterns than in patients with focal lesions.
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Affiliation(s)
- Randi Starrfelt
- Department of Psychology, University of Copenhagen, Copenhagen, Denmark.
| | - Zoe Woodhead
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
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Vaddiparti A, Huang R, Blihar D, Du Plessis M, Montalbano MJ, Tubbs RS, Loukas M. The Evolution of Corpus Callosotomy for Epilepsy Management. World Neurosurg 2020; 145:455-461. [PMID: 32889189 DOI: 10.1016/j.wneu.2020.08.178] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/25/2020] [Indexed: 01/11/2023]
Abstract
Corpus callosotomy, first used in the management of epilepsy by William P. van Wagenen in 1940, was for years a contentious procedure. Two decades later, Nobel Laureate Roger W. Sperry's split-brain studies inspired surgeons to reexamine the role of corpus callosotomy in the control of epileptic seizures. In 1962, Joseph Bogen and Philip Vogel performed complete corpus callosotomies in patients with a history of generalized seizures. The identification of a set of postsurgical disconnection symptoms and other neurologic deficits begged the improvement of the surgical technique. Modifications to the operation, including anterior callosotomy, posterior callosotomy, partial callosotomy, staged callosotomy, microsurgical techniques, and radiosurgical techniques, continue to refine the procedure.
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Affiliation(s)
- Aparna Vaddiparti
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Richard Huang
- Department of Pathology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts, USA
| | - David Blihar
- Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada, West Indies
| | - Maira Du Plessis
- Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada, West Indies
| | - Michael J Montalbano
- Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada, West Indies
| | - R Shane Tubbs
- Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada, West Indies; Department of Neurosurgery, Tulane University School of Medicine, New Orleans, Louisiana, USA; Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana, USA
| | - Marios Loukas
- Department of Anatomical Sciences, School of Medicine, St. George's University, Grenada, West Indies; Department of Anatomy University of Warmia and Mazury, Olsztyn, Poland.
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Spang KM, Grimsen C, Brunner F, Fahle MW. Pure alexia with intact perception of complex visual stimuli: a case study. Neurocase 2019; 25:159-168. [PMID: 31282280 DOI: 10.1080/13554794.2019.1634739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
After a stroke involving the left occipitotemporal cortex our patient shows a word-length effect and has problems to identify letters or numbers in strings of symbols. But he is normal in identifying isolated letters and in non-verbally categorizing even complex images such as faces or natural scenes. His cortical lesion is stretching from the visual word form area (VWFA) anteriorly causing additional problems to name visual stimuli and to match acoustic stimuli with images. We conclude that our patient suffers from pure alexia without deficits to identify even complex visual stimuli. Our results directly contradict several explanations for letter-by-letter reading.
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Affiliation(s)
- Karoline M Spang
- Department of Human-Neurobiology, University of Bremen , Bremen , Germany
| | - Cathleen Grimsen
- Department of Human-Neurobiology, University of Bremen , Bremen , Germany
| | - Freimuth Brunner
- Department of Neurology, Klinikum Bremen-Mitte , Bremen , Germany
| | - Manfred W Fahle
- Department of Human-Neurobiology, University of Bremen , Bremen , Germany
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