Shirley H. Wray, MD, PhD, FRCP, Professor of Neurology, Harvard Medical School; Director, Unit for Neurovisual Disorders, Massachusetts General Hospital
Right Homonymous Hemianopia;
Alexia without Agraphia;
Infarct of the Left Visual Cortex and Splenium of the Corpus Callosum;
The video clips are offered in Real Media, Quicktime, Windows Media, Flash and MP4 formats. Use the iPod icon for your mobile device. You must have the appropriate player installed on your computer to view the video.
The formats available for this video are the following, ordered as they appear below: Real Media (Download), Quicktime (Download), Windows Media (Non-Download), and Windows Media (Download), Flash Video (Non-Download, H.264 (Download), and MP4 for iPod (Download).
To download the video onto your computer for offline viewing:
1) Click on an icon with the "DL" notation
2) Right-click ( Ctrl-click on Mac ) on the red Download link when the window opens and choose "Save..." or "Download..."
3) Choose location to save in dialog box that appears.
4) Wait for file to download.
5) Now the video is stored on your computer and you can play it any time, with no Internet connection required.
To view the video without downloading to your computer, choose and click on an icon WITHOUT a "DL" notation.
The patient is a 69 year old left handed man with a history of hypertension, insulin dependent diabetes mellitus and atrial fibrillation. Treated with coumadin, adjusted to keep the INR between 2 and 3.
On the morning of admission he awoke at 4 a.m., sat momentarily on the side of the bed and then stood up and walked without difficulty a distance of ten feet before falling to the ground. His wife found him disoriented and mildly confused. He told her that he could only see half of her face.
On examination in the ER, he had rapid atrial fibrillation (127 beats per minute) and an elevated blood pressure 215/128, which quickly fell to a stable level of 150/90.
He was alert and oriented to Mass General Hospital and to the month, but gave the year incorrectly as 1992. His attention fluctuated.
On memory testing he had a diminished five-minute recall for a name, address and flower, and recall for well known events through which he had lived, for example, John F. Kennedy assassination. He could not recall the names of the last five Presidents. He followed one-step commands correctly.
His speech was normal apart from minor errors naming objects. His reading was severely impaired (alexia). He was unable to recognize written words on the page and had difficulty with most single letters when presented visually. In contrast, when words were spelled out to him, he could recognize them without difficulty and his ability to spell was intact.
His writing was fluent when asked to spontaneously write a description of the weather and also correct on dictation with no spelling errors.
He was asked to write his name and address which he did correctly, and three words, house, rose and mountain. He wrote the words correctly and was then distracted for approximately 5 minutes and asked to re-read them. He was unable to read the words out loud. When the patient listened to the spelling of these words out loud, he was able to identify the word correctly. He was unable to read single letters.
He was given the Ishihara pseudo-isochromatic test of color vision and performed it without error, as he could read single and two digit numbers or he traced them out correctly with his finger.
He was unable to name colors correctly (color anomia). When shown different colored bottle caps, he was able to name red and blue correctly but called green purple and yellow orange. He matched two red objects correctly.
He was able to identify famous faces and had no visual disorientation (simultanagnosia).
Visual acuity of 20/60 or better, (making errors reading the Snellen chart)
Automated perimetry: dense right homonymous hemianopia (Figure 1).
Pupils, ocular motility and fundus examination normal
• A slight right facial weakness with blunting of the
• A mild right hemiparesis with right drift
• Mild hyperreflexia on the right with an extensor plantar response
• No sensory extinction, apraxia, astereognosis, or agraphesthesia.
A chest x-ray showed cardiomegaly.
EKG atrial fibrillation with normal axis.
MRI with diffusion weighted imaging (DWI), a bright lesion in the left thalamus and internal capsule consistent with an infarct in the distribution of the posterior choroidal vessels.
The new stroke presentation was characterized by:
• Alexia without agraphia
• A dense right homonymous hemianopia
• Color anomia
Repeat MRI with DWI showed a new left occipital lobe infarct in the distribution of the left P2 division of the posterior cerebral artery (PCA).
The MRI supported the diagnosis of a disconnection syndrome affecting connections involved in naming a seen object and in reading.
With destruction of the left visual cortex and splenium (or intervening white matter), words perceived in the right visual cortex cannot cross over to the language areas and the patient cannot read.
Figure 3 shows diagrammatically how a visual pattern is transferred from the visual cortex and association areas to the angular gyrus, which arouses the auditory pattern in the Wernicke area. The auditory pattern is transmitted to Broca’s area, where the articulatory form is aroused and transferred to the contiguous face area of the motor cortex.
Embolic infarct of the left visual cortex and spenium of the corpus callosum with a dense right homonymous hemianopia
Alexia without agraphia
The video of this 67 year old patient with alexia without agraphia and a right homonymous hemianopia shows:
Impairment of his vision in the right half field with difficulty seeing a moving hand on the right.
He readily identifies a moving hand in the left half field. He was unaware of any visual impairment looking at the examiner’s face.
When asked to read he was
• Unable to read words
• Able to read single letters randomly
• Unable to read the word ‘CART’ but was able to read the word ‘car’.
• Able to read random numbers correctly but was unable to read ‘95’ on the visual acuity card
• Naming pictures was correct for ‘house’, ‘donkey’, ‘birthday cake’ and ‘phone’
• Identified famous faces correctly –
George Burns and Robert Dole yet unable to name Clinton
When asked to write he
• Writes with his left hand.
• Writes the days of the week correctly and after being distracted and asked to read the words again he read Monday and Wednesday correctly
• Able to read a written word ‘hospital’ correctly
He showed no frustration as a result of his difficulties.
The criteria for the diagnosis of pure alexia is:
1. Severe disturbance of reading comprehension,
2. Linguistically correct writing (spontaneously and to
3. Normal oral spelling
4. Absence of aphasia and dementia
The associated findings with pure alexia are:
A right homonymous hemianopia
Verbal amnesia may or may not be present
Psychologists have noticed that pure alexics often read slowly, pronouncing or naming each letter aloud, resulting in an increase in reading time for words as a function of their length. This has been termed “letter-by-letter reading” and the question it raises is: How is letter and word information transmitted across different parts of the callosum from right to left. (Figure 4)
The basic idea has been that letter identities are transmitted in parallel through the splenium and in less efficient, possibly serial ways elsewhere.
For discussion of these mechanisms (See Bub, D. and Arguin, M. Visual word activation in pure alexia. Brain and Language, 1995, 49:77-103. and Cognitive Neuropsychology, Vol 15, Issues 1/2: Special issue: Pure Alexia (Letter-by-letter Reading)).
Color anomia is not a necessary accompaniment of pure alexia. Dejerine’s original patient could name colors without difficulty in his left, nonachromatopsic field, as could Greenblatt’s. (Figures 5 and 6)
Geschwind and Fusillo’s patient could not name colors. (Figure 7)
In Damasio’s cases of pure alexia color anomia was seen only when there were lesions in the mesial occipitotemporal cortex in addition to the paraventricular region.
Damasio concluded that color anomia probably occurs only when these conditions are present:
1. Damage to the left lingual gyrus
2. Damage to the left hippocampal region
(hippocampus plus parahippocampal region), and
3. Presence of right hemianopia.
Furthermore, Damasio points out that since all patients with color anomia have right hemianopia, visual information arriving in the right hemisphere fails to evoke color names in that hemisphere and, after transfer to the left hemisphere, that information still fails to evoke color naming when lingual gyrus and hippocampus are damaged.
The visuoverbal disconnection mechanism for color operates there – a different site from where disconnection affects reading. Connections from the right hemisphere, crucial for color naming but not for reading, may cross in the most medial aspect of the left occipitotemporal junction (in the border zone between rostral lingual gyrus and caudal parahippocampal gyrus) and would be damaged by lesions that involve both lingual and parahippocampal cortices. In patients with right hemianopia, this would cause color anomia.
A CT brain scan in the ER was negative for brain hemorrhage.
MRI with diffusion weighted imaging (DWI) and axial FLAIR images demonstrated T2 hyperintensity in the mesial occipital and mesial temporal lobe.
A repeat MRI revealed a change in the distribution of the bright pattern on DWI, indicative of a new area of cerebral infarction. The area previously seen in the left thalamus and lateral internal capsule had largely resolved on DWI. There was new bright signal in the left occipital lobe, in the distribution of the left P2 division of the posterior cerebral artery (PCA).
Magnetic resonance angiogram at the same time revealed normal flow in the Circle of Willis.
The Anatomic Basis of Pure Alexia has been reviewed by Damasio AR, Damasio H. Neurology 1983,33:1573-83.
The authors analyzed the comparable behavioral and anatomic data of the cases of Dejerine, Geschwind and Fusillo, Greenblatt, and Mohr et al.
The first 3 cases had pure alexia.
Dejerine’s case had right hemiachromatopsia
Geschwind’s and Fusillo’s case had right hemianopia
Greenblatt’s case had no hemianopia.
These cases had autopsy studies.
My patient, reported here, is a replica of Geschwind and Fusillo’s case of alexia with hemianopia and color anomia due to extensive infarction of the left posterior cerebral artery territory.
At autopsy, Geschwind’s and Fusillo’s case showed that the calcarine, splenial and mesial temporal branches were involved. Accordingly, damage encompassed the white matter of the occipitotemporal junction (including the paraventricular area, mesial occipital cortex (inferiorly and superiorly) and the left half of the splenium and forceps major.
Thus, the patient showed the classic lesion of pure alexia without agraphia with infarction of the left calcarine cortex and the splenium of the corpus callosum. The splenium of the corpus callosum was destroyed dorsally as well as ventrally and so was the left hippocampus.
In contrast, in Dejerine’s case, which is the prototype of alexia without hemianopia or color anomia, only the posterior temporal and calcarine branches of the PCA were involved. The splenial branch was spared although a small lesion in the callosum was present.
In Greenblatt’s patient with pure alexia and no hemianopia the visual cortex was spared but there existed a block in the processing of information beyond its arrival in the left occipital cortex, that is, beyond the point at which the experience of “seeing” in the right visual field took place and before the stage at which the experience of “recognizing” was organized.
(This careful analysis is taken from Demasio’s paper (4)).
No autopsy in this case.
Left occipital infarction due to embolic occlusion of the left posterior cerebral artery.
Alexia without agraphia; Infarct of the left occipital cortex and splenium of the corpus colosum;
Intravenous Heparin followed by long term Coumadin.
1. Bub, D. and Arguin, M. Visual word activation in pure alexia. Brain and Language, 1995, 49:77-103. http://www.ncbi.nlm.nih.gov/pubmed/7788347
2. Pure Alexia (Letter-by-letter Reading) Cognitive Neuropsychology, 1998, Vol 15, Issues 1/2: Special issue.
3. Cohen L, Martinaud O, Lemer C. Lehericy S, Samson Y, Obadia M. Slachevsky A, Dehaene S. Visual word recognition in the left and right hemispheres: anatomical and functional correlates of peripheral alexias. Cereb Cortex. 2003,13(12):1313-1333. http://www.ncbi.nlm.nih.gov/pubmed/14615297
4. Damasio AR, Damasio H. The anatomic basis of pure alexia. Neurology 1983, 33:1573-1583 http://www.ncbi.nlm.nih.gov/pubmed/6685830
5. Dejerine J. Sur un cas de cecité verbale avec agraphie, suivi d’autopsie. Memoires Societé Biologique 1891;3:197-201.
6. Dejerine, J. Contribution of l’étude anatomo-pathologique et clinique des differentes varietiés de cecité verbale. Memoires Societé Biologique 1892;4:61-90.
7. Geschwind N. Disconnexion syndromes in animals and man. I. Brain. 1965;88:237-294. http://www.ncbi.nlm.nih.gov/pubmed/5318481
8. Geschwind N, Fusillo M. Color-naming detects in association with alexia. Arch Neurol 1966;15:137-146. http://www.ncbi.nlm.nih.gov/pubmed/5945970
9. Greenblatt S. Alexia without agraphia or hemianopsia; anatomical analysis of an autopsied case. Brain 1973;96:307-316. http://www.ncbi.nlm.nih.gov/pubmed/4351762
10. Leff, AP, Scott SK, Crewes H, Hodgson TL, Cowey A, Howard D, and Wise RJS. Impaired reading in patients with right hemianopia. Ann Neurol 2000;47:171-178. http://www.ncbi.nlm.nih.gov/pubmed/10665487
11. Marsh EB, Hillis AE. Cognitive and neural mechanisms underlying reading and naming: evidence from letter-by-letter reading and optic aphasia. Neurocase. 2005;11:325-337. http://www.ncbi.nlm.nih.gov/pubmed/16251134
12. Mohr JP, Leiceister J, Stoddard LT, Sidman M. Right hemianopia with memory and color deficits in circumscribed left posterior cerebral artery territory infarction. Neurology (Minneap) 1971;21:1104-1113. http://www.ncbi.nlm.nih.gov/pubmed/5315885
Steve Smith, Videographer; Ray Balhorn, Digital Video Compressionist;
David Caplan, M.D., Ph.D, Massachusetts General Hospital, 2006
Spencer S. Eccles Health Sciences Library, University of Utah