Study of two cases of aphasia by infarction of the left thalamus, without cortical lesion

Two patients suffering from a left thalamus infarct were studied over a long period. The precise location of the lesion has been demonstrated by the C.T. scan. In spite of the absence of any cortical lesion, both presented with aphasia and other neuropsychological disorders (left-right confusion, dyscalculia and possible finger agnosia). Their speech disorders although different, had several features in common. The observations were compared with the other cases reported in the literature.     

Visual object agnosia: current conceptions

Visual agnosia for objects is a difficulty in recognizing objects presented visually. This difficulty can not be explained by a mental deterioration, a disorder of attention or a lack of familiarity with the object. Two criteria are essential but disputed: the absence of visual sensory difficulty necessary for adequate perception; possible recognition of the object by another sensory modality. An object is characterized by a triple representation: formal, semantic, lexical. The clinical, cognitive, pathophysiological analysis lead to distinguish 3 types of visual agnosia. 1) Aperceptive visual agnosia: patients see badly with morphological errors; the disorder concerns visual informations processing that is a necessary condition for identifying the formal representation of the object; the lesions are bilateral and involve the occipito-temporal cortex. 2) Associative visual agnosia: patients can copy, are not aphasic, but give erroneous verbal responses; the disorder concerns the links between formal representations and semantic, lexical representations; the lesions are unilateral and involve the left gyrus angularis connections. 3) Asemantic visual agnosia: patients have lost the meanings of objects and words; the disorder concerns semantic representations; the lesions are bilateral and involve the temporo-limbic cortex.     

Angular gyrus syndrome revisited: Acalculia,finger agnosia,right-left disorientation and semantic aphasia

Angular gyrus (Gerstmann) syndrome is classically described as finger agnosia, right-left disorientation, agraphia and acalculia in association to lesions in the left angular gyrus. Aphasia is not typically described as part of this syndrome. Here we report a 58 year old right-handed male, with an ischemic lesion to the left angular gyrus, who developed sudden loss of speech expression and comprehension, and slowly recovered over the following few weeks. After several months he showed significant improvement on his language skills with understanding logic-grammatical relationships, comparison adverbs (e.g. bigger-smaller, younger-older etc., place adverbs (e.g. over-below, on-beneath etc. and time adverbs (e.g. before-after). These language deficits are compatible with a semantic aphasia. Writing difficulties are minimal. In addition, he has important impairments in finger agnosia, right-left discrimination, and in understanding numbers, using numerical concepts, and performing arithmetical operations. We propose that left angular gyrus syndrome should be restated to include acalculia, finger agnosia, right left disorientation and semantic aphasia. A single underlying deficit can account for the simultaneous presentation of these four clinical signs. only mild word-finding difficulties, but with substantial difficulties in     

Tactile agnosia and tactile aphasia: symptomatological and anatomical differences.

Two patients with tactile naming disorders are reported. Case 1 (right hand tactile agnosia due to bilateral cerebral infarction) differentiated tactile qualities of objects normally, but could neither name nor categorize the objects. Case 2 (bilateral tactile aphasia after operation of an epidural left parietal haematoma) had as severe a tactile naming disturbance as Case 1, but could categorize objects normally, demonstrating that tactile recognition was preserved. Case 1 may be the first case of tactile agnosia clearly differentiated from tactile aphasia. CT scans of Case 1 revealed lesions in the left angular gyrus, and in the right parietal, temporal, and occipital lobes. Case 2 had lesions in the left angular gyrus and of posterior callosal radiations. Our findings suggest that tactile agnosia appears when the somatosensory association cortex is disconnected by a subcortical lesion of the angular gyrus from the semantic memory store located in the inferior temporal lobe, while tactile aphasia represents a tactual-verbal disconnection.     

Language disorders in Landau-Kleffner syndrome

In the present long-term study, we analyzed language disorders in four patients with Landau-Kleffner syndrome. Their common first symptoms were disability in understanding spoken words, followed by inarticulation and a decreased amount of speech. All patients showed auditory verbal agnosia to some degree at some stage of their illness. However, one patient showed typical sensory aphasia as the first symptom, and another patient showed nonverbal auditory agnosia followed by pure word deafness. Thus, patients with Landau-Kleffner syndrome show sequential and sometimes hierarchical language disorders beginning with sensory aphasia, followed by auditory agnosia, and finally word deafness during their disease process. During long-term follow-up (20 to 30 years), all patients showed marked recovery in language without any intellectual handicap, but with some disability in spoken language, auditory verbal perception, and a discrepancy between Wechsler Verbal and Performance IQ scores.     

The assessment of auditory function in CSWS: Lessons from long-term outcome

In Landau-Kleffner syndrome (LKS), the prominent and often first symptom is auditory verbal agnosia, which may affect nonverbal sounds. It was early suggested that the subsequent decline of speech expression might result from defective auditory analysis of the patient's own speech. Indeed, despite normal hearing levels, the children behave as if they were deaf, and very rapidly speech expression deteriorates and leads to the receptive aphasia typical of LKS. The association of auditory agnosia more or less restricted to speech with severe language decay prompted numerous studies aimed at specifying the defect in auditory processing and its pathophysiology. Long-term follow-up studies have addressed the issue of the outcome of verbal auditory processing and the development of verbal working memory capacities following the deprivation of phonologic input during the critical period of language development. Based on a review of neurophysiologic and neuropsychological studies of auditory and phonologic disorders published these last 20 years, we discuss the association of verbal agnosia and speech production decay, and try to explain the phonologic working memory deficit in the late outcome of LKS within the Hickok and Poeppel dual-stream model of speech processing.     

The impact of linguistic deficits on verbal communication

Background: The verbal communication of persons with aphasia may be disturbed by semantic, phonological, and/or syntactic processing deficits. For those with prominent linguistic-level disorders at least part of aphasia therapy is spent on the main linguistic skills, aimed at improvement of verbal communicative abilities. However, the relationship between these linguistic levels and verbal communication is not straightforward. This is especially true for deficits at the word level: semantic and phonological disorders. Aims: Exploration of the relative impact of semantic and phonological deficits on verbal communicative ability was the aim of the study. The hypothesis was that a lexical semantic deficit has a larger impact on the verbal communicative ability of persons with aphasia than a phonological deficit. Methods & Procedures: A total of 29 persons with aphasia who had both a semantic and phonological deficit were assessed by means of semantic and phonological tasks, and a test of verbal communication (ANELT-A). Semantic measures: Semantic Association Test, Synonym Judgement (receptive tasks), Wordfluency Categories, AAT spontaneous speech: semantics (expressive tasks). Phonological measures: Repetition of words, Repetition of non-words, Wordfluency Letters, AAT spontaneous speech: phonology. Linear regression analyses were performed with the ANELT-A as dependent variable and the semantic and phonological measures as independent variables. Multivariate regression analyses were performed to directly compare the independent contribution of the semantic version of a measure with the phonological version of the same measure. Outcomes & Results: Univariate regression analysis showed that the expressive semantic measures, Wordfluency Categories and AAT semantics, contributed significantly to the prediction of ANELT-A. One phonological measure, Wordfluency Letters, was selected as a significant predictor. However, in the multivariate regression analysis, only the semantic measures appeared to contribute independently to the prediction of the ANELT-A. The contribution of Wordfluency Letters, found in the univariate regression analysis, can be explained by a correlation with its semantic counterpart. Conclusions: These results support the hypothesis that semantic measures contribute more to the prediction of the ANELT-A (Understandability in verbal communication) than phonological measures. The ability to generate semantically correct content words, both in connected speech and in isolation, appears to be decisive for the aphasics' verbal communicative skills. Taking into account the severity of the semantic disorder in relation to other deficits, perhaps the best way to improve verbal communication in persons with both a semantic and a phonological deficit is to address the deficit with the greatest impact: the lexical semantic deficit.     

Visuoverbal disconnection (optical aphasia) for objects, pictures, colors and faces with abstractive alexia

The case is reported of a patient who, after a left occipital infarction, presented a deficit in naming visually presented objects with neither aphasia, nor perturbation in the perceptive and associative processing of visual informations. This visuo-verbal disconnection was accompanied by disturbance of the semantic function when this was explored via the visual channel. In addition the patient showed an alexia which could be described as an abstraction defect. Finally, the patient showed a deficit in naming colors and faces, without evidence for agnosia. This observation argues in favor of maintaining a distinction between visual associative agnosia and optic aphasia. It also demonstrates that the naming deficit implies a deficit in extracting semantic values from visual informations such as objects or graphic symbols.     

Is there a schizophasia? A study applying the single case approach to formal thought disorder in schizophrenia

It has been suggested that formal thought disorder, the incoherent speech of schizophrenia, may involve a language disturbance among other abnormalities, or even be a form of dysphasia. Six patients with and seven without formal thought disorder were evaluated on an aphasia test battery. Spontaneous speech was also analysed using Brief Syntactic Analysis. Poor performance on the aphasia test battery was found to be associated with general intellectual impairment but not with formal thought disorder. Naming was preserved in both groups. Patients with formal thought disorder, but not those without, produced semantic errors in their spontaneous speech, and these were unrelated to general intellectual status. The disorder of language in formal thought disorder thus appears to be one of expressive semantic abnormality, which, however, spares naming. Further analysis of two intellectually preserved patients suggested that formal thought disorder may be associated with an additional difficulty in constructing an appropriate model for generating one's own speech.     

Neurolinguistic analysis of the language abilities of a patient with a "double disconnection syndrome": a case of subangular alexia in the presence of mixed transcortical aphasia.

In contrast to the classic form of alexia without agraphia, subangular alexia results from a single lesion located deep in the white matter of the left parietal lobe. In the present report, a patient with subangular alexia and features of mixed transcortical aphasia is described. Neurolinguistic findings include: alexia without agraphia, paucity of spontaneous speech, moderate auditory comprehension difficulty, excellent repetition, echopraxia, colour agnosia, and naming disorder. Neurolinguistic tests revealed intact phonological organisation and grammatical filter." Our studies revealed a "double disconnection syndrome," the co-existence of two relatively rare neurobehavioural disorders. Furthermore, the studies reported here clearly show dissociations of language functions in both the visual and auditory modality, which demonstrates that the stages of language processing are separable.     

Auditory sound agnosia without aphasia following a right temporal lobe lesion

A 55-year-old right-handed man showed inability to recognize the meaning of non-verbal sounds without impairment of language comprehension after a cerebrovascular accident. His auditory acuity was intact and no other sign of agnosia, apraxia or aphasia was detectable. His errors on a test of sound recognition were acoustic rather than semantic. Brain CT scan showed a small lesion in the posterior part of the right temporal lobe. This case suggests that auditory sound agnosia without language disorder can ensure a lesion confined to the right hemisphere, and that the deficit is discriminative rather than associative in nature.     

Lexical-semantic representation in bilingual aphasia: Findings from semantic priming and cognate repetition priming

Background: While many studies have investigated the nature of language organisation in monolingual speakers with aphasia, our understanding of bilingual aphasia lags far behind. Only a handful of studies have employed on-line psycholinguistic experimental methods to explore the nature of language representation and processing in bilingual speakers with aphasia. Improving our understanding of how language is organised and processed in bilingual speakers with aphasia is central to the development of effective impairment-level language treatments. Cognate/noncognate representation and semantic representation are two key aspects of bilingual language organisation that are yet to be explored in depth in bilingual speakers with aphasia.

Aims: The present study aimed to investigate (1) whether semantic representation was shared across the two languages of a bilingual speaker with aphasia and (2) whether cognate words would produce a processing advantage relative to noncognate words (as has been found in neurologically-normal younger bilingual adults).

Methods & Procedures: A 70-year-old bilingual Italian/English speaker, who presented with nonfluent aphasia and apraxia of speech, completed two priming experiments: a semantic priming experiment and a cognate repetition priming experiment.

Outcomes & Results: In the semantic priming experiment, the participant demonstrated large priming effects in both within-language conditions and one cross-language condition. The finding of priming in at least one of the cross-language conditions provides some corroboration for shared semantic representation in this bilingual individual with aphasia. In the cognate repetition priming experiment, the participant produced a language-specific cognate advantage in English, for words repeated in the same language. For words repeated in a different language condition (i.e., as their translation equivalent), the participant produced a processing advantage for noncognate words.

Conclusions: The findings of this study provided support for shared semantic representation in bilingual speakers following aphasia; however, the results also suggested that aphasia can disrupt normal lexical access processes. Results in relation to cognate versus noncognate processing suggested that bilingual speakers with aphasia may not, necessarily, always display a cognate advantage. Overall, the present study showed that language processing in bilingual speakers with aphasia is highly complex and is dependent upon the intricate interplay between the speaker’s premorbid language proficiency, inhibitory processing deficits that occur with normal aging and postmorbid language impairment and recovery patterns.     

Differentiating psychosis versus fluent aphasia

Following a stroke, a patient may present with varying degrees of neurological impairment, depending on the area of the brain which is damaged. Specifically, damage to the left cortical hemisphere may result in aphasia. The characteristic speech in a patient with an aphasia caused by a stroke can be similar to the speech in some patients with schizophrenia or other psychotic disorders. In a new patient without a reliable history who presents with suspected aphasia, it is important to include psychotic disorders as part of the differential diagnosis. Failure to differentiate psychotic disorders from aphasia could result in either a lack of treatment that would improve the patient's thought process, thought content, or language, or in a delayed treatment for a stroke, respectively. While a number of psychotic disorders exist and must be differentiated from one another in accordance with DSM-IV guidelines, speech abnormalities in patients with schizophrenia are well described in the literature. For this reason, schizophrenia is the psychotic disorder of focus in this paper. This case report illustrates a clinical situation where a patient required both a psychiatric and neurological consultation in order to determine the etiology of his language disorder. The purpose of this paper is to emphasize the need to consider both psychiatric disorders and aphasia in patients with unknown histories who present with language abnormalities, and to help the clinician critically examine the patient's speech so that, in conjunction with other clinical data, the correct diagnosis can be made and appropriate treatment initiated.     

Acoustic and semantic disturbances of comprehension in aphasia]

The authors carried out a verbal auditory comprehension test on 115 aphasic patients, 44 patients suffering from a left hemispheric lesion without aphasia and 120 normal subjects used as acontrol group. The test also revealed either disorders in acoustico-phonemic discrimination or difficulities in semantic differentiation. The main aim of the research was to check experimentally the theory propounded by Alajouanine and colleagues (1964) according to which, in Wernicke's aphasia, it is possible to demonstrate a twofold correlation between disorders of comprehension and speech disorders both phonemic and semantic. Only one part of the theory of Alajouanine and colleagues has been confirmed by our experiments for our results have shown that there is a very close correlation between semantic paraphasias and disorders of semantic differentiation whilst no correlation can be found between phonemic paraphasias and disturbances in auditory phonemic discrimination.     

Acute auditory agnosia as the presenting hearing disorder in MELAS

MELAS is commonly associated with peripheral hearing loss. Auditory agnosia is a rare cortical auditory impairment, usually due to bilateral temporal damage. We document, for the first time, auditory agnosia as the presenting hearing disorder in MELAS. A young woman with MELAS (A3243G mtDNA mutation) suffered from acute cortical hearing damage following a single stroke-like episode, in the absence of previous hearing deficits. Audiometric testing showed marked central hearing impairment and very mild sensorineural hearing loss. MRI documented bilateral, acute lesions to superior temporal regions. Neuropsychological tests demonstrated auditory agnosia without aphasia. Our data and a review of published reports show that cortical auditory disorders are relatively frequent in MELAS, probably due to the strikingly high incidence of bilateral and symmetric damage following stroke-like episodes. Acute auditory agnosia can be the presenting hearing deficit in MELAS and, conversely, MELAS should be suspected in young adults with sudden hearing loss.     

A Rare Clinical Antity; Pure Gerstmann Syndrome

Gerstmann syndrome is defined as a tetrad including agraphia, acalculia, finger agnosia, and right-left disorientation. In the case studies presented in the literature, it has been reported that Gerstmann syndrome usually appears as an incomplete tetrad of symptoms or accompanied by cognitive deficits including aphasia, alexia, apraxia and some perceptual disorders. Here, we present of the patient with left angular and supramarginal gyrus infarction affecting the parietal lobe. In addition to the symptoms mentioned above, the patient had alexia and anomic aphasia as well. We discussed the clinic appearance and reviewed the current literature.     

Visual associative agnosia and optic aphasia. A single case study and a review of the syndromes.

The case is presented of a patient who showed visual naming disturbances caused by a left occipital infarction. His performance on tests of visual naming, of recognition not requiring a verbal response, and of verbal-visual matching demonstrated a wide range of qualitatively different errors, including complete inability to recognize the object, access to partial semantic knowledge, and mere name finding difficulty. On the basis of the present case and of a review of the recent literature, the clinical distinction between visual associative agnosia and optic aphasia and the relation of these disorders with the anatomical site of lesion are discussed.     

Progressive focal cortical atrophies

Progressive focal cortical atrophies are degenerative conditions characterised by the insidious onset and gradual exacerbation of an impairment in a single cognitive domain related to circumscribed cerebral atrophy. Several focal cortical syndromes with deficits in the realm of cognition are reviewed: progressive impairment of language (primary progressive aphasia), speech (progressive anarthria), semantic memory (semantic dementia), episodic memory (pure progressive amnesia), vision (progressive perceptual or visuo-spatial deficits) and gesture (progressive apraxia). These conditions are histologically heterogeneous and can be associated with focal non-specific neuronal loss and gliosis with some spongiform changes (non-specific lesions), pathological features of Pick's disease (inclusion bodies and swollen neurones) or Alzheimer's disease (AD) (senile plaques and neurofibrillary tangles). A relationship between neuropsychological profiles and lesional types emerges from this review of the literature. Non-fluent primary progressive aphasia, semantic dementia and progressive anarthria are usually associated with non-specific lesions and Pick-type pathology. Progressive disorders of episodic memory and progressive visuo-spatial deficits are more often related to AD. If adequate clinical characterisation can determine the underlying disorder, it appears even more important to establish the neuropsychological profile in patients with cortical degenerative disease. Progressive deficits of only one domain of cognition may well be due to preferential involvement of anatomically and functionally defined neural systems and could therefore be considered as "system atrophies". There remains no doubt that these syndromes are particularly well suited models for studies on the relationship between cerebral functions and their neural substrate.     

Primary progressive aphasia: a comparative study of progressive nonfluent aphasia and semantic dementia

Primary progressive aphasia (PPA), a degenerative disorder, is often misdiagnosed as Alzheimer's disease. Its subtypes, semantic dementia (SD), and progressive nonfluent aphasia (PNFA), are often difficult to differentiate from each other. Our objective was to highlight the differences in the language profiles of patients with SD and PNFA. To bring out these differences, we report two patients with PPA, one with SD and the other with PNFA. They were administered the Western aphasia battery (WAB) and a semantic battery, which assesses semantic memory. The profiles of language impairment on the WAB indicated that the patient with PNFA had syntactic errors in expressive speech but relatively preserved semantics and comprehension, whereas the patient with SD had preserved syntax but made semantic errors in expressive speech, and had impaired comprehension. There were differences in their performance on the semantic battery too. The patient with SD made relatively less errors on confrontation naming, although on the pointing task he failed to point to those line drawings, which he was unable to name on confrontation. In contrast, the finding of the PNFA patient was the reverse of this. Supplementing conventional neuropsychological tests with formal tests for assessment of language functions is useful in the early diagnosis of PPA. The performance of PPA patients on a detailed assessment of language that includes use of formal tests such as the semantic battery helps to differentiate PNFA from SD.