Mechanisms of reading and spelling in a case of alexia without agraphia

In the clinical syndrome of alexia without agraphia, reading is greatly disturbed while writing and spelling remain relatively intact. The most commonly accepted explanation of this pattern of findings is that the center for written language interpretation remains intact, but has become inaccessible to visual input. This paper examines the nature of the intact written language center with respect to specific mechanisms of reading and spelling in a patient presenting with the major components of alexia without agraphia. It is concluded that the dissociation between reading and writing performance found in this patient reflects the existence of separate and distinct mechanisms for reading and spelling.     

Orthography influences the perception of speech in alexic patients

Interactive models of reading propose that phonological representations directly activate and/or constrain orthographic representations through feedback. These models also predict that spoken words should activate their orthographic forms. The effect of word orthography on auditory lexical access was investigated in two patients with alexia without agraphia. Several theories of alexia suggest that letter-by-letter reading results from impaired access to orthographic representations. Although alexics can often correctly identify orally spelled words and spell to dictation, it is unknown whether they can access the whole orthographic "word-form" as a unit via auditory presentation. The nonobligatory activation of orthography was examined in an auditory lexical decision task, in which the orthographic and phonological similarity between prime and target was manipulated. In controls, the combined effect of phonological and orthographic relatedness (OP) produced greater facilitation than phonological relatedness alone, indicating that orthography can influence auditory lexical decisions. The alexics displayed patterns of facilitation comparable to controls, suggesting they can quickly access whole-word orthographic information via the auditory modality. An alternate account posits that the OP advantage does not require on-line access of orthography, but instead is a developmental by-product of learning to read an orthographically inconsistent language. The results have implications for cognitive theories of alexia and provide support for interactive models of word recognition.     

Alexia and agraphia in Wernicke''s aphasia.

Three patients with otherwise typical Wernicke's aphasia showed consistently greater impairment of reading than auditory comprehension. While this syndrome resembles alexia with agraphia, the paraphasia of speech, repetition, and naming underline the aphasic nature of the disorder. Together with previous reports of isolated word deafness in Wernicke's aphasia, these cases suggest a relative independence of auditory and visual language processing.     

Alexia without agraphia: a clinico-tomographic study

The authors report the clinical findings and CT-scanning results in two cases of alexia without agraphia and review the literature on this subject. Both patients had extensive infarction in the territory supplied by the left posterior cerebral artery and developed severe alexia without agraphia, right hemianopia without color-anomia and one of them presented with transient verbal memory difficulties. In both cases the evolution was very good, with total regression of the alexia after 17 months in the first patient and almost complete recovery after there months in the second one. The authors comment on the causes and possible mechanisms of the alexias, especially of the alexia without agraphia, and suggest that every patient with right hemianopic disturbances due to occlusion of the left posterior cerebral artery be thoroughly studied from a neurological point of view, so that this syndrome can be detected since, notwithstanding its recognized rarity, it seems highly probable that many cases have been overlooked as a result of incomplete examination of the patients.     

Alexia caused by a fusiform or posterior inferior temporal lesion

We evaluated the alexia and agraphia of three patients with different lesions using Japanese kanji (morphograms) and kana (phonograms) and made a lesion-to-symptom analysis. Patient 1 (pure alexia for both kanji and kana and minor agraphia for kanji after a fusiform lesion) made more paragraphic errors for kanji, whereas patient 2 (alexia with agraphia for kanji after a posterior inferior temporal lesion) showed severe reading and writing disturbances and more agraphic errors for kanji. Brodmann Area 37 was affected in both patients, but in patient 2 the lesion was located lateral to that in patient 1. Patient 3 showed agraphia without alexia after restricted lesion to the angular gyrus. We believe that pure alexia (patient 1) results from a disconnection between the medial fusiform gyrus and posterior inferior temporal area (the lateral fusiform and inferior temporal gyri), whereas alexia with agraphia for kanji (patient 2), corresponding to lexical agraphia in Western countries, results from damage to the posterior inferior temporal area, in which whole-word images of words are thought to be stored. Furthermore, restricted lesion in the angular gyrus (patient 3) does not produce alexia; the alexic symptom of "angular" alexia with agraphia may be the result of damage to the adjacent lateral occipital gyri.     

Unilateral right cerebral representation of reading in a familial left-hander

Several recent hypotheses of cerebral functional organization in natural left-handers hold that language, including reading, is localized either unilaterally in the left hemisphere or bilaterally, but not unilaterally in the right hemisphere. A case of alexia without agraphia in a left-hander with an infarct in the right occipital lobe and splenium of the corpus callosum is reported. That a permanent and complete alexia resulted from a single, right hemisphere lesion indicated that reading was completely lateralized to that hemisphere. The case demonstrates that in some natural left-handers language functions can be unilaterally represented in the right hemisphere.     

Alexia without agraphia: a study of a case of verbal alexia without accompanying colour-naming defect

Summary A 47-year-old man developed a persistent form of alexia without agraphia as the result of a haemorrhagic intracerebral lesion in the left inferior temporo-occipital region, due to the rupture of an arteriovenous malformation. Surgical evacuation of the haematoma and excision of the malformation did not produce any modification of the reading deficit, which remained unchanged during a 4-year follow-up. The reading deficit was restricted to words and the patient was able to read only letter-by-letter, so that the whole words were reconstructed from the auditory names of the letters. So far, the disconnection explanation is the standard explanation of alexia without agraphia and the present case of verbal alexia may be regarded as being within this overall category. However, this explanation meets with unanswered questions that suggest more flexible interpretations. Neurolinguistic studies have questioned the unique character of alexia without agraphia as a clinical entity and, in contrast to the disconnection hypothesis, support the notion that the different varieties of alexia that are traditionally described represent distinctive syndromes, each with its own clinical features and pathophysiological basis. In this context, the reading properties in this case seem fully compatible with a deficit of the visual word-form system postulated by Warrington and Shallice, that is, the relatively early stage of the reading process through which a word-form or equivalent unit is attained. This system might be lateralized to the left hemisphere, as suggested by the fact that this case, like other cases of verbal alexia, had sustained damage to the left hemisphere and did not show any differential preservation of the reading of concrete words.

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Zusammenfassung Bei einem 47jährigen Mann trat eine intracerebrale Blutung infolge Ruptur eines arteriovenösen Angioms der linken basalen Temporookzipitalregion auf. Dies führte zu einer persistierenden Alexie ohne Agraphie. Auch die chirurgische Ausräumung des Hämatoms und der Mißbildung bewirkte keine Veränderung der Leseschwierigkeiten, die während vier Jahren konstant blieben. Die Lesestörung beschränkte sich auf Wörter, und der Patient war lediglich fähig, Buchstabe um Buchstabe zu lesen, so daß das Gesamtwort lediglich rekonstruiert wurde. Bisher beruht die Standarderklärung der Alexie ohne Agraphie auf der Diskonektionstheorie und der vorgelegte Fall verbaler Alexie kann innerhalb dieser Kategorie gedeutet werden. Immerhin wirft dieser Fall eine Reihe von offenen Fragen auf, welche eine flexiblere Interpretation nahelegen. Neurolinguistische Studien haben den einmaligen Charakter der Alexie ohne Agraphie als klinische Entität in Frage gestellt und sprechen — im Gegensatz zu der Diskonektionshypothese — zugunsten der Annahme, daß unterchiedliche Arten von Alexie auch eigenständige Syndrome darstellen, jedes davon mit seinen eigenen klinischen Eigenheiten und pathophysiologischen Grundlagen. In diesem Zusammenhang scheinen die Leseeigentümlichkeiten im vorliegenden Fall kompatibel zu sein mit einem Defizit des visuellen Wort-Formsystemes, wie es von Warrington und Shallice postuliert wurde: das ist ein relativ frühes Stadium des Leseprozesses durch welches eine Wortform oder äquivalente Einheit erreicht wird. Dieses System könnte im Bereiche der rechten Hemisphäre lokalisiert sein, wofür ein Argument im vorliegenden Fall, wie auch in anderen Fällen von verbaler Alexie sprechen würde: hier war eine Läsion der linken Hemisphäre erzeugt worden, ohne daß irgend eine selektive Erhaltung der Fähigkeit zum Lesen konkreter Worte nachweisbar gewesen wäre.

     

Alexia without agraphia following biopsy of a left thalamic tumor

Alexia without agraphia is a rare disconnection syndrome characterized by the loss of reading ability with retention of writing and verbal comprehension. We report a patient who developed alexia without agraphia after undergoing a biopsy for a malignant glioma involving the left thalamus. A 15-year-old right-handed male presented with 3 days of severe headache, and vomiting, and 1 month of blurry vision in his right visual field. Magnetic resonance imaging of the brain disclosed a large exophytic mass originating in the left thalamus, with mass effect and hydrocephalus. The patient underwent biopsy of the left thalamic mass via a transcallosal approach. Postoperatively, the patient complained of inability to read or identify letters. Examination revealed alexia without agraphia. The syndrome of alexia without agraphia can be rarely caused after surgery. A transcallosal procedure through the splenium of the corpus callosum may disrupt the visual association fibers traveling from the right occipital cortex to the left angular gyrus. In our case the syndrome occurred because of a preexisting right homonymous hemianopia resulting from a left thalamic tumor.     

Treatment of a case of phonological alexia with agraphia using the Auditory Discrimination in Depth (ADD) program.

Phonological alexia and agraphia are acquired disorders characterized by an impaired ability to convert graphemes to phonemes (alexia) or phonemes to graphemes (agraphia). These disorders result in phonological errors typified by adding, omitting, shifting, or repeating phonemes in words during reading or graphemes when spelling. In developmental dyslexia, similar phonological errors are believed to result from deficient phonological awareness, an oral language skill that manifests itself in the ability to notice, think about, or manipulate the individual sounds in words. The Auditory Discrimination in Depth (ADD) program has been reported to train phonological awareness in developmental dyslexia and dysgraphia. We used a multiple-probe design to evaluate the ADD program's effectiveness with a patient with a mild phonological alexia and mixed agraphia following a left hemisphere infarction. Large gains in phonological awareness, reading and spelling nonwords, and reading and spelling real words were demonstrated. A follow-up reassessment, 2 months posttreatment, found the patient had maintained treatment gains in phonological awareness and reading, and attained additional improvement in real word reading.     

纯失读症与大脑半球枕叶病变的关系

目的 探讨纯失读症与大脑半球枕叶病变的关系。方法 分析3例左枕叶梗死和2例右枕叶梗死患者的语言功能，详细阅读及视空间，忽视功能检查和影像学检查资料。结果 3例在枕叶梗死患者中，2例表现失读不伴失定，1例表现失读伴失写，阅读检查各自有其特点，并与病变的部位和范围密切相关；2例右枕叶梗死患者，语言功能无异常，表现视空间功能障碍。结论 大脑半球的左右枕叶分别对文字阅读和视空间结构功能有明显的侧向分化特点，枕叶皮层对各种视觉的语言符号存在着相对分化的阅读中枢或相对独立的阅读系统。     

Alexia without agraphia in multiple sclerosis: case report with magnetic resonance imaging localization

The syndrome of alexia without agraphia occurs rarely in multiple sclerosis (MS). We report a patient with right homonymous hemianopsia and alexia without agraphia as his initial manifestations of relapsing-remitting MS. Magnetic resonance imaging (MRI) demonstrated a hyperintense lesion in the left occipital subcortical white matter (WM) and an enhancing lesion in the splenium of the corpus callosum. The clinical presentation and MRI findings were consistent with disconnection of the functional right occipital visual cortex from structures responsible for language comprehension in the left hemisphere. The diagnosis of MS was confirmed by subsequent development of additional periventricular WM lesions.     

The nature and treatment of phonological text agraphia

Phonological alexia and agraphia are written language disorders characterised by disproportionate difficulty reading and spelling nonwords in comparison to real words. In phonological alexia, it has been shown that, despite relatively accurate reading of words in isolation, text-level reading deficits are often marked and persistent. Specifically, some individuals demonstrate difficulty reading functors and affixes in sentences, a profile referred to as phonological text alexia. In this paper, we demonstrate an analogous manifestation of the phonological impairment on text-level writing and suggest the term “phonological text agraphia”. We examined four individuals with phonological alexia/agraphia who also showed disproportionate difficulty writing well-formed sentences in comparison to their grammatical competence in spoken utterances. Implementation of a phonological treatment protocol resulted in significantly improved sublexical phonology skills as well as improvements in grammatical accuracy of written narratives. These findings support the notion of a common phonological impairment underlying nonword reading/spelling deficits and sentence-level difficulties.     

Alexia with agraphia produced by localized infarction in the inferior posterior region of the left temporal lobe

There have been several reports on alexia with agraphia due to hemorrhage or trauma in the inferior posterior region of the left temporal lobe since Yamadori (1982) first reported a case of cerebral hemorrhage. We presented the first case of alexia with agraphia due to a circumscribed infarct in the inferior posterior region of the left temporal lobe. A 65-year-old right-handed man had an acute onset of inability to read Japanese "kana" letters and to write any letters. He had no difficulty in speaking or understanding. Neurological examination on admission was normal except for homonymous quadrantanopia in the right upper field. Neuropsychological findings: Spontaneous speech was fluent without dysprosody. There were no disturbances in auditory understanding or in repetition. He could read Japanese "kanji" characters correctly, however, he could not read any "kana" letters. Writing was also disturbed severely even as to his address, name or telephone number. Calculation was also difficult. There were no disturbances in naming colors, no ideomotor or constructional apraxia nor visual agnosia. X-ray computed tomography (CT) scan showed a faint low density area with ring enhancement suggesting a cerebral infarct in the inferior posterior region of the left temporal lobe. Patient's hospital course was characterized by a marked improvement of alexia, especially of "kana" letters as compared with that of "kanji" characters. Dissociative improvement of alexia compared with agraphia in this case could be explained by the fact that the lesion was in close contact with the occipital lobe and that he also had pure alexia in the early stage.     

Focal brain lesions and language dysfunction

To be a neurologist, training in cognitive/behavioral neuroscience is essential. In this review article, the author tries to emphasize the localization relationship between focal brain lesions and language dysfunction, by discussing from split-brain syndromes, hemispheric asymmetry, to pure word dumbness, pure word deafness (verbal auditory agnosia), pure agraphia, and pure word blindness (pure alexia; visual word agnosia), and finally to aphasia and aprosodia in general. Hopefully, after getting familiar with all the terms, the readers will feel free exploring language disturbances and behavioral neurology for their own interests.     

Dorsal type letter-by-letter reading accompanying alexia with agraphia due to a lesion of the lateral occipital gyri

ABSTRACT

We report a patient with alexia with agraphia accompanied by letter-by-letter reading after hemorrhage in the left middle and inferior occipital gyri that spared the angular gyrus and the fusiform gyrus. Kanji (Japanese morphograms) and kana (Japanese phonetic writing) reading and writing tests revealed that alexia with agraphia was characterized by kana-predominant alexia and kanji-predominant agraphia. This type of “dorsal” letter-by-letter reading is discernable from conventional ventral type letter-by-letter reading that is observed in pure alexia in that (1) kinesthetic reading is less effective, (2) kana or literal agraphia coexists, and (3) fundamental visual discrimination is nearly normal.     

Alexia without agraphia associated with right occipital lesion.

A 78 year old, right handed man developed the syndrome of alexia without agraphia due to a right occipital thrombotic stroke. The cerebral dominance test strongly suggests that his right hemisphere is dominant. This is believed to be the first case of alexia without agraphia secondary to a right occipital lesion in a right handed person.     

Pure agraphia. Apropos of 2 cases

Pure agraphia is a disorder of written language without aphasia, alexia or apraxia. Its existence has long been disputed. We report 2 cases due to a left parietal hematoma. In the first patient, with a deep precuneate lesion, agraphia included disorders in handwriting and orthographic problems in copying or writing from dictation with the two hands. The second patient, with a lesion of the postero-inferior part of the left angular gyrus, made errors in choice and combination of letters during dictation, whereas these same letters were well-written and copying was normal. The first cases of pure agraphia were ascribed to frontal lesions and then confusional states. Current opinion tends to implicate parietal lesions of various types: superior or inferior, internal or external. Findings in the present 2 cases and those reported indicate that pure parietal agraphia is heterogeneous.     

A case of alexia with agraphia caused by the re-infarct in left lateral occipital gyrus]

The angular gyrus has been proposed as the key area of reading and writing function. In recent PET (positron emission topography) activation studies, role of angular gyrus in the reading and writing has been reestimated. Whether the angular gyrus is necessary for reading and writing or not is now under discussion and should be clinically revised. We experienced a case that presented classical alexia with agraphia of kana (Japanese syllabogram) caused by the re-infarct in left lateral occipital gyrus. This case showed the alexia with agraphia more apparent in Japanese kana than in kanji characters. Interestingly, no higher cortical dysfunction was revealed at the first cerebral infarction in left angular gyrus which was assumed as the key area for alexia with agraphia. This case supported the opinion which pointed out the importance of left occipital gyrus on Japanese kana reading.     

Alexia without agraphia. Anatomical basis and physiopathological mechanisms

Clinical, neuropsychological and radiological signs were studied in a patient suffering from pure alexia associated with right superior quadrantanopia. The lesion responsible for the defects was located in the periventricular white substance at the level of the left inferior occipitotemporal convolutions. These structures seem to constitute the pathway of the visual information channelled from the two hemispheres towards the language centres. The lesion therefore disconnects the angular gyrus from its visual information and gives rise to alexia without agraphia.