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PubMed1998

Prosopagnosia and alexia without object agnosia.

Following a trauma causing bilateral posterior brain damage, a patient complained of dyslexia and prosopagnosia, but not object agnosia. On testing she showed intact recognition of object drawings, even when it was assessed with perceptually demanding tasks such as Ghent's overlapping figures and Street completion test. This pattern of deficit is inconsistent with Farah's (1990) prediction that the simultaneous occurrence of alexia and prosopagnosia is invariably associated with object agnosia. The patient's reading performance had the features typically found in letter-by-letter readers. On face tests, she showed a discrepancy between the impairment exhibited in familiarity recognition and famous face naming and the correct (though slow) performance in matching the names of famous persons with their photographs. This apparent contradiction was clarified by showing that the patient had maintained the ability to generate the mental images of famous faces in response to the presentation of their names. We assume that face recognition units were intact, but partially disconnected from the output of perceptual processing.

Adult↗
PubMed1998

Optic aphasia with pure alexia: a mild form of visual associative agnosia? A case study.

A single-case study is reported of a naming disorder selective to the visual modality. The patient showed intact access to structural knowledge of objects and letters, but impaired access to complete semantic knowledge of objects and alphabetical knowledge of letters from visual input. The impairment was most striking when the patient had to discriminate between semantically similar objects or within a given symbolic repertoire, i.e. letters. The co-occurrence of a partial deficit of visual recognition for objects and for letters indicated features of optic aphasia and pure alexia. This symmetric performance between object and letter processing may also constitute a mild form of visual associative agnosia.

Aged↗
PubMed1990

Intermittent alexia.

A case of intermittent alexia, sometimes accompanied by severe dysgraphia and sometimes by mild dysgraphia, which had a probable migrainous origin, is described. On some occasions the patient could write to dictation, although with many errors, while unable to read words or letters. On other occasions the patient's writing to dictation was seriously disordered in terms of content and the letters were produced clumsily. Reading of numbers, colour vision and colour naming were normal although impairments on right-left orientation and visual short term memory were present and a mild finger agnosia was apparent. Blood flow scans (SPECT) taken under normal and alexic conditions support the view that the disturbance had a vascular origin.

Adolescent↗
PubMed1980

Alexia for arithmetical signs. A cause of disturbed calculation.

Asymbolic acalculia is a variety of acalculia characterized by a failure to differentiate the arithmetical symbols. Two patients presenting this disturbance as the only source of their calculating errors are reported. Neither aphasia nor visuo-verbal disconnection could explain the failure to identify the arithmetical signs. This defect is interpreted as an alexia for this particular semiotic system, the arithmetical signs being stripped of their names and of the corresponding computational rules.

Adult↗
PubMed1981

Pure alexia in a Kannada-English bilingual.

The case history of a fifty seven year old Kannada-English bilingual who suddenly lost his ability to read is presented. The relative severity of the reading disorder at various levels, in Kannada and English, as well as its recovery is described. The possible reasons for the findings as well as their implications for the interpretation of alexia as a total inability to read, are discussed.

Dyslexia, Acquired↗
PubMed2003

Phonological alexia with vowel-consonant dissociation in non-word reading.

We present a patient with alexia secondary to cerebral lesion whose errors in the reading of non-words affect vowels more than consonants. The interest of the case resides in: (1) the documentation of a vowel-consonant dissociation selectively affecting the reading of non-words; and (2) the localization of the alteration in a specific stage of the perilexical reading pathway, that is, the blending of phonetic chains. The case contributes to the discussion on the nature of representations and the processing of vowels and consonants.

Adult↗
PubMed1998

Acquired alexia: lessons from successful treatment.

Two individuals with anomic aphasia and acquired alexia were each provided treatment for their reading impairment. Although reading of single words in isolation was fairly accurate, their text reading was slow and effortful, including functor substitutions and semantic errors. Prior to treatment, reading reaction times for single words showed grammatical class and word-length effects. Both patients responded positively to a treatment protocol that included two phases: (1) multiple oral rereading of text, and (2) reading phrase-formatted text that had increased spacing between phrasal clauses. Their reading rates for text improved while maintaining good comprehension. Following treatment, reading reaction times for single words showed the elimination of grammatical class and word-length effects, suggesting improved access to word forms, particularly functors.

Adult↗
PubMed1998

Rehabilitation of a case of pure alexia: exploiting residual abilities.

We present a case study of a 43-year-old woman with chronic and stable pure alexia. Using a multiple baseline design we report the results of two different interventions to improve reading. First, a restitutive treatment approach using an implicit semantic access strategy was attempted. This approach was designed to exploit privileged access to lexical-semantic representations and met with little success. Treatment was then switched to a substitutive treatment strategy, which involved using the patient's finger to pretend to copy the letters in words and sentences. Reading using this motor cross-cuing strategy was 100% accurate and doubled in speed after 4 weeks of intervention. We propose that this patient's inability to benefit from the implicit semantic access treatment approach may be in part related to her inability to suppress the segmental letter identification process of word recognition.

Adult↗
PubMed2003

Braille alexia during visual hallucination in a blind man with selective calcarine atrophy.

The case of a 56-year-old man who has been blind for 25 years due to retinal degeneration is herein described. The patient complained of elementary visual hallucination, during which it was difficult for him to read Braille. Brain magnetic resonance imaging showed marked atrophy of the bilateral striate cortex. Visual hallucination as a release phenomenon of the primary visual cortex has never been reported to cause alexia for Braille. The present case supports the results of recent functional imaging studies of the recruitment of striate and prestriate cortex for Braille reading.

Atrophy↗
PubMed1995

Contrasting effects of letter-spacing in alexia: further evidence that different strategies generate word length effects in reading.

The reading behaviour of two alexic patients (SA and WH) is reported. Both patients are severely impaired at reading single words, and both show abnormally strong effects of word length when reading. These two symptoms are characteristic of letter-by-letter reading. Experiment 1 examined the pattern of errors when the patients read large and small words. Further experiments examined the effects of inter-letter spacing on word naming (Experiments 2a and 2b) and the identification of letters in letter strings (Experiment 3). For both patients, letter identification was better for widely spaced letters in letter strings, and this effect was most pronounced for the central letters in the strings. This is consistent with abnormally strong flanker interference in letter identification. However, inter-letter spacing affected word reading behaviour in the two patients in different ways. SA's word reading improved with widely spaced letters; WH's word reading was disrupted. This suggests that these patients adopted different strategies when reading words. We conclude that several reading behaviours can elicit word length effects, and that these different behaviours can reflect strategic adaptation to a common functional deficit in patients. We discuss the implications both for understanding alexia and for models of normal word identification.

Adult↗
PubMed1983

Alexia without agraphia in a composer.

A 77-year-old composer had a left occipital lobe haemorrhagic infarct giving a severe reading disturbance with well-preserved writing and without appreciable aphasia. He continued to read music and to compose. His text- and music-reading performance under different conditions suggests that this unusual dissociation was primarily due to four factors. (1) He was unusually talented musically and inferred a great deal about the music he was reading. (2) The symbols of staff music notation are more visually distinctive than the symbols of phonetic language writing systems. (3) In staff music notation, pitch is represented ordinally, and other symbols are also distinguishable by their relative positions and sizes. (4) Music notation can be usefully read by interpreting it acoustically, kinaesthetically or in terms of formal musical concepts; in contrast to written language, it need not be interpreted referentially or in terms of auditory-verbal images. His disorder fits the classic visual-verbal disconnection account of alexia without agraphia and the contemporary view that music involves a family of related but distinct skills probably involving many brain areas in both hemispheres, although different cortical areas make characteristic contributions to different musical behaviours.

Aged↗
PubMed1994

Agnosia, alexia and a remarkable form of amnesia in an adolescent boy.

Childhood cases of global anterograde amnesia, visual agnosia or alexia without agraphia, either alone or in any combination, are extremely rare. Here we report the case of a male adolescent, Neil (a pseudonym), who consequent to a pineal tumour began to exhibit all three disorders in the presence of normal verbal intelligence. The most surprising aspect of Neil's case, however, is his ability to retrieve postmorbid memories through the act of writing without being able to provide any oral account of the content of his written reports. His memory retrieval thus has some of the character of 'automatic writing'. This evidence pointing to Neil's possession of a dissociated form of episodic memory presents a new challenge to our understanding of the organization of memory and of the cerebral systems underlying it.

Adolescent↗
PubMed1988

"Pure alexia" without hemianopia or colour anomia.

We report a case of "pure alexia" without hemianopia or colour anomia, caused by a small subcortical haematoma in the dorso-lateral part of the occipital lobe, not affecting the splenium of the corpus callosum. It is argued that the reading disorder was due to a visual-verbal disconnection in spite of the fact that this typically is caused by a lesion in the medial part of the left occipital lobe including the splenium.

Aged↗
PubMed1982

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.

Aged↗
PubMed1991

Posterior cortical dementia with alexia: neurobehavioural, MRI, and PET findings.

A progressive disorder of relatively focal but asymmetric biposterior dysfunction is described in a 54 year old right handed male. Initial clinical features included letter-by-letter alexia, visual anomia, acalculia, mild agraphia, constructional apraxia, and visuospatial compromise. Serial testing demonstrated relentless deterioration with additional development of transcortical sensory aphasia, Gerstmann's tetrad, and severe visuoperceptual impairment. Amnesia was not an early clinical feature. Judgment, personality, insight, and awareness remained preserved throughout most of the clinical course. Extinction in the right visual field to bilateral stimulation was the sole neurological abnormality. Early CT was normal and late MRI showed asymmetrical bioccipitoparietal atrophy with greater involvement of the left hemisphere. Results from positron emission tomography (PET) showed bilaterally asymmetric (left greater than right) occipitotemporoparietal hypometabolism. The metabolic decrement was strikingly asymmetric with a 50% reduction in glucose consumption confined to the left occipital cortex. The picture of occipitotemporoparietal compromise verified by MRI, PET, and neurobehavioural testing would be unusual for such degenerative dementias as Alzheimer's (AD) and Pick's disease, although atypical AD with predominant occipital lobe involvement cannot be excluded. This case supports the concepts of posterior cortical dementia (PCD) as a clinically distinct entity and for the first time documents its corresponding metabolic deficit using PET.

Atrophy↗
PubMed1992

Pure alexia and right hemiachromatopsia in posterior dementia.

A 66 year old, right handed woman presented with pure alexia and right hemiachromatopsia (PARH) in the context of a posterior dementia. PARH was accompanied by prosopagnosia, 2-D object agnosia, and environmental agnosia. Visual fields were normal to confrontation testing. The pathological anatomy of PARH involves circumscribed damage to the lingual and fusiform gyri and paraventricular white matter of the left occipital cortex, two contiguous cortical regions functionally specialised for processing colour and word form information, respectively.

Aged↗
PubMedDate not supplied

Acquired alexia in multilingual aphasia and computer-assisted treatment in both languages: issues of generalisation and transfer.

This single-subject study addresses the issue of investigation and remediation of an acquired reading impairment observed in a Spanish-English bilingual speaker. Detailed bilingual reading testing showed parallel disturbances in the two languages, both from a qualitative and a quantitative point of view, with characteristics of letter-by-letter and aphasic alexia. On the basis of this mixed pattern, common to both languages, a two-step computer-assisted remediation programme was designed for English, then for Spanish, using a crossover AB-AB design. Therapy A consisted of tasks aimed at the inhibition of letter-by-letter reading. This was alternated with therapy B, which was designed to address phonological assembly. Results on therapy reveal transfer of gains when common reading processing are involved and language-specific gains with a greater benefit on the mother tongue when phonological representations are required in therapy and assessment. Consequences for language choice in bilingual aphasia therapy are discussed on the basis of these results.

Aphasia↗
PubMed1985

Palinoptic phenomena as an error mechanism in resolving alexia without agraphia. A case report.

Palinoptic, visual perseverative, or prolonged positive after-image phenomena have most often been met in right-sided occipital pathology. Less frequent with left-sided lesions they can be associated with the alexia without agraphia syndrome (with or without color naming deficit or hemifield loss). This is illustrated by our case in which rapidly fading visual reduplicative sensations--rather than linguistic incompetence--were apparently responsible for most of his paralexic errors.

Afterimage↗