Subangular alexia without agraphia or hemianopsia

A 40 year old right-handed woman underwent resection of an unruptured vascular malformation which was located just deep to the left posterior insula. Postoperatively she demonstrated a transient syndrome of alexia without agraphia or hemianopsia. Analysis of her postoperative findings, in conjunction all available anatomical data, let to the conclusion that the responsible lesion was in the white matter of the left occipitotemporal region, below the angular gyrus and lateral to the lateral ventricle. Hence the lesion in the present case was truly subangular, and is therefore distinctly differentiated from the classical lesion in alexia without agraphia, which may be described as splenio-occipital.     

Iconic reading in a case of alexia without agraphia caused by a brain tumor: a tachistoscopic study

The lack of nonverbal reading comprehension in the clinical disconnection syndrome, alexia without agraphia, has been contradictory to the relative reading comprehension of the right hemisphere in split brains. We report a 39-year-old patient with verbal alexia without agraphia caused by brain tumor. On rapid tachistoscopic presentation of object names, he denied seeing anything but showed nonverbal reading comprehension by pointing to the corresponding objects. He lost this ability when he recovered ability to name individual letters of the object names. Our results suggest that even partial verbal reading such as the naming of single letters makes demonstration of iconic reading impossible and that total functional disconnection from verbalization, as initially noted in this case or in split brain studies, is necessary to show nonverbal reading comprehension.     

Residual reading capability in a patient with alexia without agraphia

A case of pure alexia due to an ischemic lesion of the occipital temporal region is described. Written words could be matched but not read. Immediate memory span for graphemes was defective. The reading defect probably depends on the inability to modify the written word “globally”; the phonological process was intact, but the memory disturbance impeded reading. The dissociation is explained by the preservation of word forms, which are linked to the semantic stage. Nonwritten stimuli trigger a “meaning” which evokes the word form and so the written word is recognized even though it cannot be read.     

Alexia without agraphia: An experimental case study

A 51-year-old right-handed male experienced reading difficulty and an upper right visual field cut after a head injury. The patient's letter naming was impaired and word naming was painstakingly slow. Words were decoded in a letter by letter sequence and performance varied directly with word length. Apart from his reading difficulties the patient was linguistically competent. He was sensitive to manipulations of word frequency and orthographic regularity. He wrote spontaneously and could identify the written counterpart to a spoken word with relative ease. Computerized axial tomography revealed damage to the posterior temporal-parietal region of the left hemisphere.     

Pure agraphia and Gerstmann's syndrome as a visuospatial-language dissociation: an experimental case study

A right-handed man suffered a left parieto-occipital cerebral infarction, causing agraphia with Gerstmann's syndrome but without major aphasia, alexia, or apraxia. Oral spelling was superior to written spelling. Experiments were performed involving (1) analysis of errors in writing, (2) tasks of visual imagery, and (3) identifying letters drawn without leaving a visual trace. The results suggest that the agraphia and Gerstmann's syndrome are due to a dissociation of language skills and visuospatial skills caused by a dominant parieto-occipital lesion.     

Acquired surface alexia in Spanish: a case report

This paper reports a case study of acquired surface alexia in Spanish and discusses the most suitable tests to detect this syndrome in a writing system that is very regular for reading at the segmental and supra-segmental levels. Patient MM has surface alexia characterized by quantitatively good performance in reading words and pseudowords; accurate but slow and syllabic reading of words, nonwords and sentences; good performance in lexical decision tasks including words and nonwords; errors in lexical decision with pseudohomophones; and homophone confusions. This pattern of reading can be interpreted as a disorder in the lexical reading route and overdependence on the non-lexical route. We discuss nonlexical impairments and the interpretation of alexia and suggest tasks to identify surface alexia in a shallow orthography.     

Letter imagery deficits in a case of pure apraxic agraphia

Pure apraxic agraphia is a condition in which motor writing is impaired but limb praxis and nonmotor writing (typing, anagram letters) are preserved. This condition is believed to result from disruption of a parietal lobe graphemic area which generates grapheme representations used to program motor-writing patterns. We report a single case of pure apraxic agraphia in which defective letter imagery was evident. Results of writing and imagery evaluations suggest that the graphemic area may be responsible for generating letter images. In this respect, clinical evaluation of letter imagery abilities in cases of apraxic agraphia may be useful in identifying subtypes of the disorder resulting in a better understanding of the neuropsychological process involved in writing.     

Covert reading of letters in a case of global alexia

This study describes the case of a global alexic patient with a severe reading deficit affecting words, letters and Arabic numbers, following a left posterior lesion. The patient (VA) could not match spoken letters to their graphic form. A preserved ability to recognize shape and canonical orientation of letters indicates intact access to the representation of letters and numbers as visual objects. A relatively preserved ability to match lowercase to uppercase letters suggests partially spared access to abstract letter identities independently of their visual forms. The patient was also unable to match spoken letters and numbers to their visual form, indicating that she could not access the graphemic representations of letters from their phonological representations. This pattern of performance suggests that the link between graphemic and phonological representations is disrupted in this patient. We hypothesize that VA’ residual reading abilities are supported by the right hemisphere.     

Selective impairment of phonation: A case study

A 47-year-old right-handed man underwent craniotomy for clipping of an aneurism at the trifurcation of the left middle cerebral artery. Subsequently, he suffered a left hemisphere CVA after which his speech and language resembled that of Broca's aphasia with accompanying apraxia of speech. Medical, behavioral, and acoustical data amassed over a period of several months indicated numerous contraindications to traditional diagnoses of Broca's aphasia, apraxia of speech, and dysarthria. Ultimately, it was determined that the patient had a selective impairement of phonation or laryngeal apraxia. This was illustrated dramatically when he was taught to use an electrolarynx which allowed him to bypass his disrupted phonatory system. Speaking with the electrolarynx, the patient communicated normally. Any semblance of Broca's aphasia disappeared. Supralaryngeal articulation was normal; apraxia of speech behaviors were absent. This case report indicates that dissociation of oral and laryngeal gestures due to brain injury is possible. Mechanisms underlying such a dissociation for this case are reviewed. The possibility of discrete center lesions in the frontal motor association area causing different types of apraxia of speech is discussed.     

A case of literal alexia: evidence for a disconnection syndrome

We describe a patient with literal alexia, agraphia, and only minimal aphasia, resulting from a left occipito-parietal ischemic infarction. Neither impaired visual processing nor impaired oral output could explain the patient's letter reading deficit, since he retained the ability to match letters of mixed case, and remained able to spell aloud and to pronounce and comprehend orally spelled words. His residual word reading was characterized by better performance for nouns and highly imageable words than for functors , poorly imageable words, and nonwords. We propose that this patient's letter reading deficit was due to a partial disconnection of his visual from his linguistic systems, with residual word reading accomplished by a semantically mediated compensatory mechanism. We suggest, further, that the dissociations between word and letter reading observed in some alexic individuals may be attributed, in part, to a difference in the relative contributions of dorsal and ventral occipital structures to the reading process.     

Phonological alexia with optic and tactile anomia: a neuropsychological and anatomical study

We describe a patient with phonological alexia caused by a small hemorrhage in the posterior-inferior portion of the left temporal lobe. The lesion induced a highly selective impairment of phonological reading without concomitant oral language deficits other than anomia for objects presented in the visual and tactile modalities. We propose that an intact dorsal pathway from inferior visual association areas to Wernicke's area via the angular gyrus could mediate reading by the lexical route, while damage to a ventral pathway disrupted the patient's ability to read nonwords. We suggest further that although visually and tactually presented objects could be recognized and both verbally and nonverbally identified, they could not be named because of a disconnection from the area of word representations.     

The evolution of pure alexia: a longitudinal study of recovery

This case report documents the partial recovery, over a 12-month period, of pure alexia in an adult female following a left occipital infarction. Measures of speed and accuracy were obtained on an oral reading and a lexical decision task immediately postonset and then on 10 subsequent occasions. Explicit letter-by-letter reading was observed only during the first week poststroke but a significant effect of word length was seen in all testing sessions. Reading accuracy was relatively good at all stages and reading latency showed a remarkable decrease over time but did not reach normal reading rates. The inability to use higher-order orthographic knowledge, as manifest in the absence of a word superiority effect, was still noted at one year postonset. We therefore concluded that the change in behavior was attributable to increased proficiency in the use of the adaptive letter-by-letter procedure rather than to the resolution of the underlying deficit. It is suggested that longitudinal neurobehavioral studies add to our understanding of the alexic deficit and provide insight into the recovery process.     

Selective sparing of memory functioning in a patient with amnesia following herpes encephalitis

A patient with amnesia subsequent to herpes encephalitis was assessed on a series of tasks which have been shown to result in normal or near normal performance by amnesic subjects. On a pursuit rotor learning task, our patient performed normally, and continued to show evidence of memory for the skill after a period of 30 days. On a perceptual learning task, which involved the identification of line drawings, he also displayed evidence of learning and long-term retention, but his performance remained below that of control subjects. In two priming experiments, which employed a "case-control" paradigm, performance on homonym-spelling and category item-generation tasks was preceded by exposure to a selected list of words. There was no evidence of differential facilitation in respect of those words used in the initial priming task. The findings point to some degree of selectivity of preserved learning capabilities in amnesia. It is hypothesized that this selectivity may be determined by several variables, including the type of task, the etiology and site of pathology, and the severity of amnesia.     

Selective nontreatment and spina bifida: A case study in ethical theory and application

Defective newborn children are to be considered human persons. Thus, primary duty in proxy consent is to act with the infant's best interest in mind. This duty may at times override the otherwise prima facie right to life, but only under restricted circumstances. Refinements of McCormick's “relational potential” criteria and of ordinary-extraordinary means analysis prove useful in such decisions. Utilitarian considerations of social consequences have impact but can be kept subsidiary. The importance for decision making of available child support services is considered. Spina bifida is used throughout as an example of issues discussed.     

Developmental phonological and lexical agraphia in adults

Many cases of agraphia from acquired cerebral lesions may be divided into two groups, phonological and lexical, suggesting two dissociable spelling systems. Studies of developmental agraphia have described some children who have spelling patterns similar to acquired phonological or lexical agraphia. This study analyzed spelling results from 22 adolescent and adult subjects with developmental agraphia (DA) and compared them to those from control subjects and subjects with acquired agraphia (AA). On the basis of spelling ability, subjects with DA could be divided into two groups. Analysis of the profile of spelling abilities indicated that the two groups of subjects with DA were almost indistinguishable from the two groups of subjects with AA, phonological and lexical. This supports the contention that DA in adults may be divided into phonological and lexical groups and further supports the two-system hypothesis for linguistic agraphia.     

Selective impairment of the graphemic buffer in acquired dysgraphia: a case study

The case of an Italian dysgraphic patient (S.E.), who showed a deficit of both written and oral spelling capacities, without significant differences between words and nonwords, is reported. The pattern of the patient's performance was identical on writing to dictation, delayed copying, and written naming. The most common category of errors was single-letter deletions, and errors were predominantly made in medial positions. Stimulus length appeared to be the single factor that most affected performance. This pattern is consistent with the hypothesis that S.E.'s spelling disorder results from selective damage of the Graphemic Buffer. The case is discussed in relation to current functional models of writing and is compared with similar cases reported previously.     

Alexia and agraphia with spared spelling and letter recognition abilities

A patient with alexia and agraphia had intact spelling and comprehension of spelled words and used a letter-naming strategy to read and write. We propose that there is a graphemic area important for distinguishing graphemic features and for programming movements used in writing. In this patient this area was not functioning or did not have access to the area of visual word imagés. Therefore, he used an ideographic letter-naming strategy to verbally circumvent his disability and gain access to the area of visual word images.