Applied Neuropsychology: Adult ISSN: 2327-9095 (Print) 2327-9109 (Online) Journal homepage: http://www.tandfonline.com/loi/hapn21 Alexia Without Agraphia in a Right-Handed Individual Following Right Occipital Stroke Jordan S. Robinson, Robert L. Collins & Shalini V. Mukhi To cite this article: Jordan S. Robinson, Robert L. Collins & Shalini V. Mukhi (2015): Alexia Without Agraphia in a Right-Handed Individual Following Right Occipital Stroke, Applied Neuropsychology: Adult, DOI: 10.1080/23279095.2014.973495 To link to this article: http://dx.doi.org/10.1080/23279095.2014.973495 Published online: 23 Sep 2015. Submit your article to this journal View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=hapn21 Download by: [University of Nebraska, Lincoln] Date: 26 September 2015, At: 00:02 APPLIED NEUROPSYCHOLOGY: ADULT, 0: 1–5, 2015 ISSN: 2327-9095 print/2327-9109 online DOI: 10.1080/23279095.2014.973495 Alexia Without Agraphia in a Right-Handed Individual Following Right Occipital Stroke Jordan S. Robinson Mental Health Care Line, Michael E. DeBakey Veterans Affairs Medical Center, and Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, Texas Downloaded by [University of Nebraska, Lincoln] at 00:02 26 September 2015 Robert L. Collins Neurology Care Line, Michael E. DeBakey Veterans Affairs Medical Center, and Department of Neurology, Baylor College of Medicine, Houston, Texas Shalini V. Mukhi Diagnostics & Therapeutic Care, Michael E. DeBakey Veterans Affairs Medical Center, and Department of Radiology, Baylor College of Medicine, Houston, Texas Alexia without agraphia is a disconnection syndrome that typically involves damage to the occipital lobe, with splenium involvement, in the dominant left hemisphere. We describe an exceptionally rare case of a right-handed individual displaying this deficit following a right-sided occipital stroke. A report of a single case of a 65-year-old man is presented with data from appointments with the neurology and neuropsychology departments that occurred approximately 10 and 12 months following the patient's stroke. During the evaluation, he exhibited a marked deficit in his ability to read, with vision grossly intact. His ability to write single words and short phrases from dictation was intact, but he was later unable to read them. This case demonstrates the complexity of the organization of language in the human brain. Although a large majority of individuals exhibit language dominance in their left hemispheres, it remains possible that some right-handed individuals may show atypical organization of language. This highlights the need for clinicians to consider atypical cortical organization when observed deficits may not necessarily match expected lesions within the cortex. Key words: alexia, assessment/diagnosis, cerebral stroke, cognition, magnetic resonance imaging, neuropsychology INTRODUCTION Alexia without agraphia, also called “pure alexia” or “word blindness,” is one of the classic disconnection syndromes first described in the literature by Dejerine (1892). This represents one of several disconnection syndromes in which the brain is unable to access information from the orthographic network of the language-dominant hemisphere after receiving textual visual input (Geschwind, 1965). In such cases, although patients are unable to spontaneously read This article is not subject to U.S. copyright law. Address correspondence to Robert L. Collins, Ph.D. Neurology Care Line, Michael E. DeBakey VAMC, 2002 Holcombe Blvd., Houston, TX 77030. E-mail: robert.collins3@va.gov written material, their ability to write remains intact, but they are unable to read what they have written upon later recall. Other aspects of language such as speech comprehension, spelling out loud, confrontation naming, and repetition remain generally intact. The anatomic basis of this disconnection syndrome typically involves damage to the language-dominant hemisphere’s visual cortex, with accompanying damage to the splenium or trunk of the corpus callosum, causing damage to white-matter tracts that are crucial to the interhemispheric transmission of visual information from the external environment (Binder & Mohr, 1992; Damasio & Damasio, 1983). In most right-handed individuals, the language-dominant hemisphere is lateralized to the left hemisphere (Knecht et al., 2000). Within the language-dominant hemisphere Downloaded by [University of Nebraska, Lincoln] at 00:02 26 September 2015 2 ROBINSON, COLLINS, & MUKHI exists regions in which specialized language activities occur (e.g., language comprehension, speech motor output) as well as cortical-to-cortical pathways connecting these regions. For example, it is generally accepted that the visual word form areas, an area thought to be crucial for the neuronal representation of orthographic information, can be found within the left ventral occipitotemporal cortex (Glezer & Riesenhuber, 2013). Due to this lateralization, the most common cause of alexia without agraphia is a cerebrovascular accident involving the left posterior cerebral artery (PCA), which damages the posterior visual cortex in the dominant hemisphere and also has the ability to damage the posterior sections of the corpus callosum while leaving the opposing hemisphere largely undamaged (Johansson & Fahlgren, 1979). Due to this pattern of damage and cerebral lateralization, most cases seen occur in right-handed individuals following insult to the aforementioned areas of the dominant left hemisphere and adjoining posterior aspect of the corpus callosum. As of this writing, only one case of alexia without agraphia in a right-handed individual who sustained damage to the traditionally nondominant right hemisphere has been published (Hirose, Kin, & Murakami, 1977). It should be noted that this previous case involved a patient whose primary language was logographic (e.g., visual symbol-based) in nature rather than phonographic. Herein, we report a case of alexia without agraphia following right PCA stroke, with resulting damage to the right posterior visual cortex and splenium of the corpus callosum, in a right-handed native English speaker. To our knowledge, this is the first such case with this pattern of damage and subsequent neuropsychological deficits in which the primary language is phonemic in nature, thereby highlighting the importance of considering atypical cerebral organization of language abilities in individuals who show unexpected deficits given circumscribed cerebral lesions. and a normal gait observed. The patient was referred for more extensive neuropsychological evaluation due to noted difficulties with word finding and reading, which were unexpected given the location of his stroke. Magnetic resonance imaging completed approximately 1 month prior to the neuropsychological evaluation revealed encephalomalacia of the right occipital lobe with tissue loss extending into the right aspect of the splenium corpus callosum, posterior lateral right thalamus, pulvinar of thalamus, and posteromedial temporal lobe compatible with a chronic right PCA territory infarct. Also noted were scattered regions or remaining tissue within the right occipital lobe demonstrating varying signal intensity compatible with a combination of gliosis, laminar necrosis, and chronic hemosiderin deposition (Figure 1). Magnetic resonance angiography at this time revealed chronic occlusion of the right PCA and mild diffuse narrowing of the right M2 segment of the middle cerebral artery along with mild-to-moderate narrowing of the right internal carotid artery at the bifurcation. A basic metabolic panel evaluation was normal with the exception of mildly elevated glucose levels. During the neuropsychological evaluation, the patient's primary complaint was persisting memory difficulty, confusion, and vision problems since his stroke. At this time, he displayed a general lack of awareness and concern regarding any changes in his ability to read and believed that his difficulties with reading were primarily a result of his problems with vision. During the interview and testing, his level of frustration observed did not appear consistent CASE REPORT The patient is a 65-year-old right-handed gentleman initially seen for evaluation through the Neurology Department at the Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC) and who was later referred for neuropsychological testing. Approximately 10 months prior to his neuropsychological evaluation, the patient sustained an ischemic stroke of the right PCA and was treated at an outside hospital before beginning rehabilitation though the MEDVAMC. The patient underwent neurological evaluation approximately 2 months prior to neuropsychological testing and was noted to have a left lower homonymous quadrantanopsia. He was also experiencing altered sensation in the V1–3 areas of the face, with light touch impaired in his left arm and leg diffusely. Testing of strength and reflexes was normal with no dysmetria noted FIGURE 1 Axial T2 W/FLAIR. Demonstrates encephalomalacia and gliosis of the right paramedian occipital lobe, posterior temporal lobe, and thalamus. FLAIR hyperintense signal extending into the splenium corpus callosum represents gliosis. Downloaded by [University of Nebraska, Lincoln] at 00:02 26 September 2015 ALEXIA WITHOUT AGRAPHIA IN RIGHT-SIDED STROKE with his observed deficits, suggestive of a lack of awareness as to the severity of his difficulties. His wife reported that he had difficulty with writing since the stroke, at times writing upside down. Significant symptoms of anxiety and depression were denied. The patient reported no difficulties with sleep. The patient's wife reported that she had assumed responsibility for the management of household finances and his medications since the stroke due to his reported problems with memory. The patient reported that he had not driven independently since the stroke due to his vision problems. It was reported that the patient was independent in activities of self-care and grooming. During the neuropsychological evaluation, the patient was noted to have good speech comprehension, was conversant with the examiners, and was able to answer verbal questions in a reasonable manner. The patient reported that he had been experiencing vision problems, to which he attributed his difficulty with reading. He was oriented to person and place but reported the incorrect year (reported 2006, but the actual year was 2013) and date upon inquiry. Despite the error on reported year, he was able to accurately report on several recent news stories. During testing, he was generally pleasant and cooperative but at times became mildly frustrated during tasks in which reading ability was assessed. Upon formal testing, his ability to match pictures to spoken words/short phrases was intact (Multilingual Aphasia Examination [MAE] Aural Comprehension), with him correctly identifying 17/18 stimuli. When tasked with matching written words to the same pictures (MAE Reading Comprehension), he was unable to read the written words and unable to accurately match to the words outside of randomly guessing. When asked to read the individual letters of the words from this task, such as “steeple,” he answered “c, ec, c . . . e, cee” before discontinuing the task. On a task of one- and two-step commands (MAE Token Test) he performed in the impaired range (25/44). He was accurate with one-step commands but had marked difficulty with two-step commands that included a conjunctive command such as touching all tokens of a certain color except…, or commands requiring him to use a token as an action upon another token. He displayed impaired performance on a task of sentence repetition (MAE Sentence Repetition, 7/14) in which sentences of increasing length are presented orally. When his cognition was further assessed, the patient was able to write words and short phrases (e.g., “the brown dog”) but was unable to read these at a later time. He was also able to copy short words and phrases presented to him visually but was noted to do so in a slow and labored manner. He also demonstrated difficulty in identifying block letters presented to him. For example, when asked to identify an “L,” he picked out the letter “T.” When asked to orally spell out words such as “rice” and “steel,” he did so without difficulty. When asked to spell words with block letters, he showed significant impairment. For example, 3 when asked to spell “clear” he spelled it “clesa” and placed the letter “A” upside down. The patient's ability to name line-drawn pictures of common objects (Repeatable Battery for the Assessment of Neuropsychological Status [RBANS] Picture Naming) was within normal limits, with him accurately identifying 9/10 pictures. His performance on a line bisection task displayed evidence of left visual neglect, consistent with the left hemispatial neglect. On a visual-spatial task requiring him to identify line drawings of objects that have been cut into two or more parts (Hooper Visual Organization Test), he performed in the severely impaired range (9.5/30). It should be noted that he was able to identify some easier items (e.g., airplane, hammer), and for some complex items, though not able to identify the picture, he was able to identify the semantic superordinate (e.g., animal for cat). His copy of a complex figure (RBANS Figure Copy) was impaired. He appeared to accurately draw much of the figure, but his visual neglect likely caused problems copying elements from the left side of the figure. He was also noted to have drawn the copy to the extreme left of the sheet of paper that he was given for the copy trial. His clock drawing was generally intact, with only a number placement error noted (i.e., placing the number 1 at the top instead of 12, but the numbers were in correct order around the clock face) and the correct time designated by the minute and hour hands. His overall cognition (RBANS Total Scale) was severely impaired. All indexes within the RBANS (Immediate Memory, Visuospatial/Constructional, Attention, and Delayed Memory) were in the severely impaired range, with the exception of RBANS Language falling in the low-average range. Of note, his memory functioning was amnestic in nature, with no help from repetition of material or recognition cueing. Also, although the Language Index was low average, this is not surprising in this context as the language measures included on the RBANS (confrontation naming and semantic fluency) are not sensitive to the types of impairments seen in the patient's presentation. DISCUSSION We describe a patient with right-sided occipital stroke with splenium involvement who displays cognitive deficits consistent with alexia without agraphia. These deficits include alexia, hemispatial neglect with intact verbal comprehension, confrontation naming, and ability to write to dictation. Although patients with alexia without agraphia are usually able to engage in intact repetition, the patient described earlier showed marked impairment. This may be more likely due to severely impaired verbal attention as he was able to repeat shorter sentences without error and instead had difficulty with increasing sentence length. This disconnection syndrome, in which intact visual information is no Downloaded by [University of Nebraska, Lincoln] at 00:02 26 September 2015 4 ROBINSON, COLLINS, & MUKHI longer able to cross hemispheres to access the semantic networks necessary for identification of the written word, usually occurs in lesions to the dominant left hemisphere. This syndrome in a right-handed individual, with no reported family history of sinistrality, following insult to the right hemisphere is exceptionally rare. Although other published cases of alexia without agraphia have been reported following a similar pattern of right-hemisphere vascular damage, these have almost exclusively occurred in left-handed patients. The previous case of alexia without agraphia occurring in a right-handed patient was notable in that the patient's native language (Kanji) is logographic in nature. Our reported case occurs in an English-speaking (phonographic/orthographic) patient. The basic structure of a specific language may influence how it is encoded and retrieved in the human brain. The English language, which is phonographic in nature, generally requires access to a semantic language network, usually housed within the dominant left hemisphere in the vast majority of right-handed individuals. The reading pathway involves perceived stimuli first processed in the primary and associative visual cortex in the occipital lobe with subsequent processing into language areas that include the superior temporal and angular gyri (which include Wernicke’s area). Damage to structures along this pathway can cause problems with alexia and agraphia, or problems with written and spoken language. This information circuit can also be disrupted with damage to the corpus callosum, specifically the splenium, through which visual information concerning written material cannot access the phonographic storage in the dominant hemisphere. Kanji, a logographic-based language, involves a different pathway that is largely dependent on the posterior portions of the middle and inferior temporal gyri (Mochizuki & Ohtomo, 1988). These differences in information processing between phonographic and logographic languages are supported by findings in different rates of recovery in patients’ abilities to read and write Kanji (logographic) versus Kana (phonographic). Language functions are strongly lateralizing to the left hemisphere in up to 96% of strongly right-handed individuals (Knecht et al., 2000) and may be more pronounced in men (Shaywitz et al., 1995). Although the majority of individuals, especially those with right-hand dominance, will generally show lateralizing findings for language in their dominant left hemisphere, there is evidence that language can lateralize in the “nondominant” right hemisphere for a variety of reasons. The more salient examples of such atypical development concern situations where neuroplasticity plays a role. Neuroplasticity refers to the concept that when an insult to the brain occurs, other areas of the brain, often the contralateral hemisphere, can subserve those functions to maintain that cognitive function. One example of this insult and atypical development occurs in children with epilepsy. Studies have shown that following left anterior temporal-lobe resection surgery to relive seizures, children show positive relationships with reading ability and right-hemisphere activation, a pattern not seen in control children who are not suffering from epilepsy (Noppeney, Price, Duncan, & Koepp, 2005). In a related study, individuals with seizure foci within the left hemisphere were significantly more likely to show right-sided neural activation on a silent reading task than were controls or individuals with right-sided seizure foci (Berl et al., 2005). Similar findings have been shown with individuals showing atypical language development following pediatric stroke (e.g., Everts et al., 2010). Atypical functional organization in the brain also occurs in the population without evidence of brain injuries or epilepsy. In the case of dyslexia, some research has shown that individuals with this disorder show greater activation more medially in the occipitotemporal region when reading rather than the anterior lateral region of the occipitotemporal region in nonimpaired readers (Shaywitz, et al., 2007). This type of atypical organization is also seen on the lateralizing level with studies suggesting that 19% to 27% of strongly lefthanded individuals show language lateralization to the right hemisphere, while 4% of strongly right-handed individuals show this pattern on word generation tasks (BadzakovaTrajkov, Haberling, Roberts, & Corballis, 2010; Knecht et al., 2000). The uncommon nature of right-hemisphere language lateralization in right-handed individuals, more rare in men, makes the presented case more exceptional given that the incidence of ischemic stroke to the PCA is relatively rare, occurring in approximately 7% of all ischemic strokes (Ng, Stein, Ning, & Black-Schaffer, 2007). This case demonstrates the complexity of the cortical organization of language in the human brain. Although a large majority of individuals exhibit language dominance in their left hemispheres, it remains possible that some right-handed individuals may show atypical organization with language access housed within their right hemispheres. This highlights the need for clinicians to consider atypical cortical organization when observed deficits may not necessarily match expected lesions within the cortex. ACKNOWLEDGMENTS This material is the result of work supported with resources and the use of facilities at the Michael E. 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