| Identifier |
Alexia_without_agraphia |
| Title |
Alexia Without Agraphia |
| Creator |
Andrew G. Lee, MD; Hyewon (Sally) Choi, MD |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (HC) Class of 2020, Baylor College of Medicine, Houston, Texas |
| Subject |
Neuroanatomy; Agnosia; Strokes; Vascular Anatomy |
| Description |
Dr. Lee lectures medical students on alexia without agraphia. |
| Transcript |
So today we're going to be talking about alexia without agraphia. So, Lex is read, alexia, you can't read. Graph is write, you can't write. So, alexia without agraphia means you can't read, but you can write. This is a very particular disconnection syndrome characterized by disruption of the connecting pathway and that is called the splenium of the corpus callosum. The corpus callosum as you know is the large interhemispheric band connecting the right and left hemispheres. So, when we have a stroke from a PCA infarct in the left occipital lobe this will produce a very specific visual field defect. Because it's the left occipital lobe, it will produce a right homonymous hemianopsia. However, because the right occipital lobe is intact, they'll still be able to see 20/20 vision because they still have half a macula. And the patient's complaint will be very strange. They can't read even though they can see. So, when they come to the eye doctor their vision will be 20/20, their pupil will be normal, their intraocular pressure, slit lamp, motility, and fundus exam will all be normal. The only thing that will be abnormal is the visual field. But the patient may not complain about the visual field defect. And they're only complaint is "I can't read". So, the key and differentiating piece of the stem is "I can't read but I can see" and so the key question is "Why can't you read?", "I can't read because I can't understand what I'm reading". They might even say that they can spell out the word or say the word out loud and they know what it is, they just can't read it. And that's because the reading center here is the angular gyrus. And the angular gyrus is where the reading center is in most right-handed and actually most left-handed people that's on the left side of your brain. So, the information from the intact right occipital cortex cannot be transmitted across the splenium of the corpus callosum to the left angular gyrus and that produces a very specific disconnection syndrome called alexia without agraphia. It's key and differentiating feature is the presence of the right homonymous hemianopsia. And the key question to ask "Why can't you read?", "I can see, but I can't read because I can't read the words or understand or what I'm saying". And it needs an imaging study preferably MRI and the most common cause is a left posterior cerebral artery infarction. |
| Date |
2019-02 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s6mw6w3f |
| Setname |
ehsl_novel_lee |
| ID |
1403662 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6mw6w3f |
