Seeing is not believing.

An 84-year-old woman with a history of dry age-related macular degeneration presented with an acute inability to read, but intact writing ability (pure alexia or alexia without agraphia). She denied any difficulty speaking, paresthesias, or hemiparesis. Her visual acuity was 20/20 in each eye. Macular examination, optical coherence tomography, and fluorescein angiography demonstrated the previously diagnosed macular drusen and geographic atrophy of the retinal pigment epithelium consistent with the dry form of age-related macular degeneration both eyes. Automated perimetry revealed a right homonymous hemianopsia. Neuroimaging confirmed a left occipital ischemic infarction with involvement of the splenium of the corpus callosum producing the classic disconnection syndrome of alexia without agraphia.

Pure Alexia: A Combined First-Person Account and Neuropsychological Investigation.

Pure alexia is an acquired reading disorder where patients' ability to read words and text is severely impaired, while their writing is left unaffected. Patients with pure alexia typically recover some reading ability over time, although most never regain their premorbid reading skills. A few studies have reported some behavioral and imaging correlates of such remission; however, little is known about the patients' experience of their reading impairment. This paper contains a first-person account of pure alexia, describing the first author's (K.H.) experience of his remission from severe reading problems immediately following a posterior cerebral artery stroke to the mild pure alexia characterizing his reading ability today. To provide a context for this account, we also present neuropsychological and reading data obtained from K.H. at several time points during his recovery.

Pure alexia with intact perception of complex visual stimuli: a case study.

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.

Posterior cerebral artery stroke presenting as alexia without agraphia.

Alexia without agraphia (pure alexia) was the first of the disconnection syndromes to be described by Dejerine who reported a patient of alexia without agraphia secondary to an embolic occipital lobe infarct. We herein report a 55-year-old man who presented with alexia without agraphia with magnetic resonance imaging suggestive of left posterior cerebral artery infarct involving left occipital lobe and splenium of corpus callosum. Alexia without agraphia is a relatively uncommon clinical condition, which should always be thought in a patient presenting with difficulty in reading with normal visual acuity. Ophthalmologists should also be aware of this disconnection syndrome as many patients initially take their advice due to predominant visual complaints. Early diagnosis and treatment of this condition help in ensuring the patient and attendants about nonprogressive nature of the disease and may prevent further episodes of stroke.

[Alexia without agraphia; not being able to read what you have just written]. / Alexie zonder agrafie: niet kunnen lezen wat je zojuist hebt geschreven.

BACKGROUND: Alexia without agraphia is a neurological syndrome that is caused by a specific lesion in the left (or the dominant) cerebral hemisphere. It is characterised by a severe reading disorder with writing ability intact. CASE DESCRIPTION: We describe a patient who, after a fall from a staircase, could no longer read, even that which he had written shortly before. Initially, he also had problems with orientation and facial recognition. Two months after the accident, alexia without agraphia was still manifest while the other symptoms had disappeared. His ability to read showed a slow improvement; complete recovery occurred after two years. The absence of concomitant disorders was exceptional. CONCLUSION: The disorder alexia without agraphia seems improbable, but deserves serious attention to prevent diagnostic delay.

[When shape-invariant recognition ('A' = 'a') fails. A case study of pure alexia and kinesthetic facilitation]. / Als 'A' niet meer als 'a' wordt herkend. Een analyse van verworven woordblindheid.

A right-handed patient, aged 72, manifested alexia without agraphia, a right homonymous hemianopia and an impaired ability to identify visually presented objects. He was completely unable to read words aloud and severely deficient in naming visually presented letters. He responded to orthographic familiarity in the lexical decision tasks of the Psycholinguistic Assessments of Language Processing in Aphasia (PALPA) rather than to the lexicality of the letter strings. He was impaired at deciding whether two letters of different case (e.g., A, a) are the same, though he could detect real letters from made-up ones or from their mirror image. Consequently, his core deficit in reading was posited at the level of the abstract letter identifiers. When asked to trace a letter with his right index finger, kinesthetic facilitation enabled him to read letters and words aloud. Though he could use intact motor representations of letters in order to facilitate recognition and reading, the slow, sequential and error-prone process of reading letter by letter made him abandon further training.

Alexia without agraphia.

Alexia without agraphia (also called pure alexia or word blindness) was the first of the disconnection syndromes (syndromes caused by disconnection of the right from the left cerebral hemisphere through interruption of the communication pathways between them) to be described. Déjerine in 1892 reported a patient who developed this syndrome after an infarct of the left occipital lobe and splenium of the corpus callosum. We describe a patient who developed alexia without agraphia due to an embolic left occipital lobe infarct extending to the posterior commissure and splenium of the corpus callosum.

"Seeing but not identifying": pure alexia coincident with prosopagnosia in occipital arteriovenous malformation.

BACKGROUND: Pure alexia and prosopagnosia are two separate and uncommon disorders of visual recognition in neuro-ophthalmology. We report an extremely rare case of pure alexia coincident with prosopagnosia secondary to occipital arteriovenous malformation. The manifestations of these two visual recognition disorders are also described. METHODS: A 35-year-old, left-handed women had suffered from severe blurred vision when recognizing her family's faces and was unable to read or associate separate parts of a word into a whole word. Her visual field revealed slight right homonymous hemianopia. Computed tomography scans and magnetic resonance images were arranged and vertebral angiography confirmed the diagnosis of left occipital arteriovenous malformation. RESULTS: Gamma-knife stereoscopic radiotherapy was performed. Two months after the treatment, the ability to recognize faces and read improved and the visual field recovered. CONCLUSIONS: Ophthalmologists should keep in mind that usual complaints of "blurred vision" might correlate with unusual visual recognition disorders. Pure alexia and prosopagnosia have not been reported to occur together and the left-handed- dominance in our case leads to this scarce concurrence.

Compensational strategies for a merchant after stroke with anosognosia for alexia without agraphia.

We report the first case, to our knowledge, of successful return to work of a patient with alexia without agraphia. This case is also interesting as it is the first report of which we are aware of anosognosia for alexia without agraphia: the patient confabulated when asked to read English text, but immediately stated that he could not read Chinese text because he did not know that language. The selective nature of this confabulation would not be inconsistent with anosognosia being one of the brain's responses to absence of afferent information.

Temporal processing deficits in letter-by-letter reading.

Theories of the cognitive impairment underlying letter-by-letter reading vary widely, including prelexical and lexical level deficits. One prominent prelexical account proposes that the disorder results from difficulty in processing multiple letters simultaneously. We investigated whether this deficit extends to letters presented in rapid temporal succession. A letter-by-letter reader, G.M., was administered a rapid serial visual presentation task that has been used widely to study the temporal processing characteristics of the normal visual system. Comparisons were made to a control group of 6 brain-damaged individuals without reading deficits. Two target letters were embedded at varying temporal positions in a stream of rapidly presented single digits. After each stream, the identities of the two letters were reported. G.M. required an extended period of time after he had processed one letter before he was able to reliably identify a second letter, relative to the controls. In addition, G.M.'s report of the second letter was most impaired when it immediately followed the first letter, a pattern not seen in the controls, indicating that G.M. had difficulty processing the two items together. These data suggest that a letter-by-letter reading strategy may be adopted to help compensate for a deficit in the temporal processing of letters.

Examination of the split fovea theory in a case of pure left hemialexia.

To address the extent to which the visual foveal representation is split, we examine the case of a patient, M.B., suffering from a left mesial occipital lesion and presenting a pure left hemialexia and a right hemianopia with a spared area of the macula. Reading performance on tachistoscopically presented four-letter words and pseudowords in the spared area of the right visual field was significantly better than reading performance in the intact left visual field. Reading performance in the spared area of the right visual field was also significantly better than reading performance of stimuli centred on the fovea. Moreover, a length effect was found only in the left half of pseudowords centred on the fovea, but not in the right half (up to five letters). These differences in reading efficiency between the left and right halves of the foveal region militates in favour of the split fovea theory and cannot be explained by the bilateral projection theory.

Qualitatively different forms of pure alexia.

In this study we investigated two patients with pure alexia, F.C. and L.D.S., in order to make inferences about how processes and levels involved in the early stage of visual word recognition are organized and how they can be selectively damaged. Moreover, we investigated whether pure alexia can be caused by different functional deficits. F.C. and L.D.S. were presented with tasks of letter processing and tasks of orthographic integration. There was a clear double dissociation between the pattern of performance of F.C. and L.D.S. F.C. was able to process single letters rapidly and accurately, but was unable to group together the letters that he had correctly identified. By contrast, L.D.S. was slower and more impaired at letter identification, but she could use letter groups to assist reading. Thus, two different forms of pure alexia emerged: F.C. has a higher level deficit in integrating letters, whereas L.D.S. has a lower level deficit in letter processing. The results support the assumption of a functional organization of the reading process that involves a series of orthographic units (i.e., single letters, sublexical letter groups, and the lexical unit), which can be selectively damaged. Finally, our data present difficulties for models of pure alexia that assume all patients to have a low-level processing deficit.

Patterns of peripheral paralexia: pure alexia and the forgotten visual dyslexia?

The concept of visual dyslexia put forward by Marshall and Newcombe (1973) is assessed. After a long period of neglect it was resurrected in the late 1990s in a narrow form. In the current paper it is proposed that a wider form of the functional syndrome is useful to include amongst other conditions attentional dyslexia and neglect dyslexia. The variety of sub-forms would correspond to the behavioural effects of the different ways in which the orthographic processing systems can be impaired. What distinguishes the broader form from pure alexia is that the patient lacks the capacity to use a serial letter processing strategy, and so interpretation of visual dyslexia in terms of the impairment to the orthographic processing systems is not contaminated by the use of a compensatory strategy that results in processing operations which are qualitatively very different from the normal and highly opaque. The lack of a serial letter processing strategy makes visual dyslexia a much more transparent functional syndrome.

[Pure alexia secondary to progressive multifocal leukoencephalopathy as first manifestation of HIV infection]. / Alexia pura secundaria a leucoencefalopatía multifocal progresiva como presentación de la infección por VIH.

INTRODUCTION: Pure alexia, or alexia without agraphia, is usually caused by disconnection between the gyrus angularis and visual areas of both hemispheres. Cerebrovascular disease is the most frequent cause of this syndrome. CLINICAL CASE: We report the first case of a patient with pure alexia secondary to progressive multifocal leukoencephalopathy (PML) as the first manifestation of Human Immunodeficiency Virus (HIV) infection. Polymerase chain reaction in cerebrospinal fluid was positive for JC virus. Despite favorable immunological and virological response to highly active antiretroviral therapy, neurological symptoms and demyelinating lesions progressed during the first months, and right homonyous hemianopsia, acalculia, and color anomia were noted. In magnetic resonance imaging (MRI) demyelinating lesions involved white matter of both occipital lobes, with left predominance, forceps major and splenium of the corpus callosum, together with white matter of the left temporal lobe and both hippocampal regions. During the following months, coinciding cidofovir treatment, the patient had partial clinical improvement, but neurological deficits persisted. The size of MRI lesions significantly improved. CONCLUSIONS: PML is frequently the first manifestation of AIDS (acquired immunodeficiency syndrome). It should be considered as a possible diagnosis of pure alexia.

Alexia pura secundaria a leucoencefalopatía multifocal progresiva como presentación de la infección por VIH / Pure alexia secondary to progressive multifocal leukoencephalopathy as first manifestation of HIV infection

Introducción. La alexia pura, o alexia sin agrafia, es debida generalmente a la lesión de las fibras que conectan las áreas visuales de ambos hemisferios con el giro angular del hemisferio dominante. La causa más frecuente de este síndrome es la patología cerebrovascular. Caso clínico. Presentamos el primer caso de alexia pura secundaria a leucoencefalopatía multifocal progresiva (LMP) que constituyó la primera manifestación de la infección por el virus de la inmunodeficiencia humana (VIH). La reacción en cadena de la polimerasa para virus JC en líquido cefalorraquídeo fue positiva. A pesar de una buena respuesta virológica e inmunológica con terapia antirretrovírica de gran actividad, los síntomas y las lesiones progresaron durante los primeros meses, asociando hemianopsia homónima derecha, anomia para los colores y acalculia. En la resonancia magnética (RM) las lesiones desmielinizantes afectaron a sustancia blanca de ambos lóbulos occipitales, predominando en el lado izquierdo, fórceps mayor y esplenio del cuerpo calloso, así como a sustancia blanca de lóbulo temporal izquierdo y ambas regiones de hipocampo. En los meses siguientes, coincidiendo con tratamiento con cidofovir, el paciente mejoró clínica mente de forma parcial, aunque persistieron los mismos déficit neurológicos. El tamaño de las lesiones en RM disminuyó de forma significativa. Conclusiones. La LMP con relativa frecuencia constituye la primera manifestación de sida (síndrome de la inmunodeficiencia adquirida) y debe incluirse en el diagnóstico diferencial de la alexia sin agrafia

Introduction: Pure alexia, or alexia without agraphia, is usually caused by disconnection between the gyrus angularis and visual areas of both hemispheres. Cerebrovascular disease is the most frequent cause of this syndrome. Clinical case: We report the first case of a patient with pure alexia secondary to progressive multifocal leukoencephalopathy (PML) as the first manifestation of Human Immunodeficiency Virus (HIV) infection. Polymerase chain reaction in cerebrospinal fluid was positive for JC virus. Despite favorable immunological and virological response to highly active antiretroviral therapy, neurological symptoms and demyelinating lesions progressed during the first months, and right homonyous hemianopsia, acalculia, and color anomia were noted. In magnetic resonance imaging (MRI) demyelinating lesions involved white matter of both occipital lobes, with left predominance, forceps major and splenium of the corpus callosum, together with white matter of the left temporal lobe and both hippocampal regions. During the following months, coinciding cidofovir treatment, the patient had partial clinical improvement, but neurological deficits persisted. The size of MRI lesions significantly improved. Conclusions: PML is frequently the first manifestation of AIDS (acquired immunodeficiency syndrome). It should be considered as a possible diagnosis of pure alexia

Alexia without agraphia in a postpartum eclamptic patient with factor V Leiden deficiency.

We present a case of eclampsia complicated by alexia without agraphia. To our knowledge, this syndrome has never before been described in the literature.