Destruction of Wernicke's area without language disturbance. A fresh look at crossed aphasia

A 74-year old right-handed man was accidentally found at autopsy to have his left Wernicke's area destroyed by an old infarct. No aphasia was noticed during life, and this seems to represent therefore the first case in which negative evidence can be btought in support of crossed cerebral dominance for speech in a right-handed subject.One way to estimate the frequency of crossed dominance for speech is to investigate the published cases of crossed aphasia. In a recent review of the literature it is noticed that only 16/69 cases (23 per cent) are vascular in etiology. This is in sharp contrast with the frequency of vascular accidents as a cause of aphasia in the general population and leads us to believe that traumatic and tumoral cases must be interpreted with caution in their diagnostic significance in aphasia. Well documented cases of aphasia following cerebrovascular disease in the right hemisphere of right-handed patients are quite rare.     

Word deafness in Wernicke's aphasia.

Three patients with otherwise typical Wernicke's aphasia showed consistent superiority of visual over auditory comprehension. The precedents for and anatomical basis of a selective auditory deficit in Wernicke's aphasia are discussed, including the relationship to pure word deafness. One implication of spared visual language function may be the use of gesture in language therapy for such patients.     

Meynert on Wernicke's aphasia

This paper examines Meynert's contribution to aphasia, in particular the suggestion that Meynert already had described the syndrome of sensory aphasia. I examine Meynert's own writings on this subject, Wernicke's statements on this issue and biographies of Meynert and Wernicke. I argue that Meynert did not describe sensory aphasia, nor is there convincing evidence that he stimulated Wernicke in this direction. Meynert was primarily interested in the global neuroanatomical organization of the brain and in particular the special role of the frontal lobes.     

Wernicke's and global aphasia without alexia.

It has been proposed that the comprehension of written language requires transcoding from the visual (grapheme) to the auditory (phoneme). It has also been proposed that visual word images can be comprehended without grapheme-phoneme transcoding. We describe three aphasic patients with left hemisphere impairment who had poor speech comprehension but could comprehend written language. One of these patients had a subsequent right hemisphere lesion and lost his ability to read. We propose that the right hemisphere in some individuals may be capable of extracting semantic information from iconic images (ideogram) without phonological processing.     

The experience of Wernicke's aphasia

The authors induced a transient Wernicke's aphasia in a patient with left frontal arteriovenous malformation by superselective Wada injection exclusively into the lower division of the left middle cerebral artery. The patient was then asked to recall his experience, which the authors matched against his language during anesthesia. The patient's account showed that there was a more systematic attempt to respond appropriately than the authors could infer from his overt behavior. His narrative suggests that a thought process not measured by aphasia examinations may exist independent of language.     

Preserved oral reading in Wernicke's aphasia

In two patients with Wernicke's aphasia, both oral reading and reading comprehension were relatively preserved despite total destruction of Wernicke's area. The pattern of oral reading suggested an intact ability to derive phonology directly from print; the pattern of reading comprehension implied at least partial ability to interpret syntactic constructions. These features are not readily compatible with current notions of right hemisphere function and may suggest that undamaged left hemisphere structures mediated residual reading in these patients.     

Two cases of crossed aphasia in dextrals.

Two cases of crossed aphasia in dextrals are reported, in one of which right hemisphere dominance was confirmed by an intracarotid amytal test. The possibility of a partial dissociation between oral and graphic expression is considered.     

Paralexic errors in Broca's and Wernicke's aphasia

Paralexic speech errors were examined during the oral reading of sentences for 12 right-handed adults, including four Broca's aphasics, four Wernicke's aphasics and four patients with unilateral right-hemisphere lesions. A category system of error types was developed, and 129 errors were analyzed in terms of identifiable linguistic components, operating in isolation as well as interactively. The two aphasic groups produced a variety of errors, whereas the right-hemisphere group produced very few in number and type. Broca's aphasics committed more morphological errors than did Wernicke's aphasics, whereas Wernicke's aphasics committed more graphophonemic-neologistic errors than did Broca's.     

Tense processing in Broca's and Wernicke's aphasia

Background: Evidence from the picture–word interference literature reveals that picture–word pairs bearing a non-categorical relationship (e.g., RING—expensive) will facilitate naming more than picture–word pairs bearing a categorical relationship (e.g., BRACELET—earrings). It is not known whether these differential effects would be found within a naming treatment paradigm for aphasia; however, if it is the case that one type of semantic relations will yield more robust treatment effects than another, this would provide a more efficient and effective delivery of treatment. Moreover, since semantic errors are commonly produced by individuals with aphasia, an approach which helps strengthen the semantic network will, in turn, strengthen lexical retrieval and access processes.

Aim: The aim of the study was to compare a features condition, or a condition in which attributes were used, to a categorical condition, or a condition in which categorical members were used to see which would yield greater naming improvements in aphasia.

Methods &; Procedures: Eight individuals with aphasia were recruited for the study. A multiple-baseline design across behaviours with a crossover component was used. A categorical–features sequence was used in four participants, and a features–categorical sequence was used in four other participants. Accuracy of correct naming was calculated to determine improvements in treatment. The types of naming errors produced by individuals with positive treatment effects in the trained condition were compared to the types of naming errors produced in the control condition.

Outcome &; Results: A range of small to large treatment effect sizes was obtained in six of the eight participants when considering both treated conditions. However, no overwhelming advantage was found for either condition. Analyses of naming error patterns indicated increased lexical access and retrieval of the targeted picture name.

Conclusions: Approaches that use cues focusing either on categorical membership or attributes will facilitate naming abilities in individuals with aphasia whether naming per cent accuracy is calculated or naming error types are tallied. However, the current results did not indicate an overwhelming advantage in using one or the other condition. Future studies should specify the type of features used (e.g., associative cues, thematic cues or perceptual cues) to determine whether such a differentiation will yield clearer differential treatment effects.     

Non-verbal disturbances in crossed aphasia

Abstract

Aphasia is generally accompanied by signs of non-verbal dysfunction. The study of crossed aphasia can help to clarify the relationship between the two orders of phenomena. Four personal cases are reported and the relevant literature is reviewed concerning disorders of non-verbal function which accompany crossed aphasia. Left-sided neglect and constructional apraxia are common findings. Limb apraxia is a rarity among the cases reported, but bucco-facial apraxia is as frequent as in left hemisphere lesioned aphasics. In the light of these observations, the role of each hemisphere for verbal and non-verbal behaviour is reconsidered.     

A Japanese case of crossed aphasia in a right-handed patient. Apropos of kana and kanji

The Japanese orthography has some unique characteristics. Two types of Japanese characters, kana (phonetic symbols) and kanji (semantic and phonetic symbols), are used in combination. Although kana has simple forms and a limited number of characters, and kanji has complex forms and an infinite number of characters, Japanese aphasic patients often have trouble using kana characters properly. In the present case of crossed aphasia of a right-handed Japanese man due to a large hypertensive intracerebral hematoma in the right side, we also observed the impairment in kana processing. He could neither speak nor read aloud, but on multiple choice examinations, he could point to pronounced kanji letters. Although he could point to pronounced kana words, he could not point to kana letters. We will review some tachistoscopic studies of recognition and comprehension of the lateralized visual informations of kana and kanji for normal Japanese and for Japanese patients with disconnection syndrome. And we will discuss the right (minor) hemispheric ability to recognize kanji letters and kana words, and we will also talk about the restricted capacity for transcallosal transference of the visual language informations.     

Inhibition and auditory comprehension in Wernicke's aphasia

Background: While research findings support the presence of inefficiencies in allocation of attention in individuals with aphasia, the cognitive mechanisms behind these inefficiencies remain unclear. One mechanism that would affect resource allocation for selective processing is an impaired inhibitory mechanism which, when normally functioning, would actively suppress distracting information. Aims: The purpose of this study was to investigate the cognitive process of inhibition, at the lexical‐semantic level of language processing, and its relation to auditory comprehension in Wernicke's aphasia. Methods & Procedures: The classic Stroop Colour‐Word Test was adapted to be applicable for use with an aphasic population. We administered this computerised manual‐response, numerical version of the Stroop test to five individuals with Wernicke's aphasia and twelve age‐ and education‐matched non‐brain‐injured controls. Correlations with Stroop interference examined associations with auditory comprehension as measured by the Token Test and the Complex Ideational Material subtest of the Boston Diagnostic Aphasia Examination. Outcomes & Results: Analysis of the Stroop reaction time and error percentage data indicated that the interference effect was significantly larger for the participants with Wernicke's aphasia than for the controls, without an accompanying increase in facilitation, reflecting an impairment of inhibition in Wernicke's aphasia. In addition, the magnitude of Stroop interference was significantly positively correlated with the clinical‐behavioural symptom of severity of auditory comprehension deficits as measured by the Token Test. Conclusions: Findings support an impairment in inhibition at the lexical‐semantic level of language processing in Wernicke's aphasia, reflecting the inability to effectively ignore the automatically evoked, distracting stimulus. The significant correlation between the Stroop interference effect and the severity of auditory comprehension deficits suggests that at least part of the attentional difficulties contributing to the striking reductions in auditory comprehension in this population can be attributed to impaired inhibition. Our findings expand upon our understanding of resource allocation in aphasia and reinforce our need to clinically assess and treat reductions in attention for maximised rehabilitation outcome.     

Non-convulsive status epilepticus presenting with Wernicke's aphasia

Ictal aphasia in adults is a rare phenomenon. Most reported cases manifest with non-fluent (Broca) aphasia. Ictal fluent (Wernicke) aphasia is less common. We report a 47-year-old, right-handed woman that presented with recurrent episodes of non-convulsive seizures in the form of Wernicke's aphasia for 2 weeks. An MRI of the brain showed an old cerebral infarction in the left parieto-occipital area. Scalp EEG revealed continuous periodic sharp waves at the left temporal regions with diffusion to the whole left hemisphere and at occasions to the right. This is followed by variable periods of post ictal slowing. Recurrence of the described ictal pattern was noted. Management of status epilepticus was started in the form of intravenous diazepam and a loading dose of phenytoin and phenobarbitone. After treatment, she improved clinically and the EEG improved with disappearance of the left temporal ictal rhythm and normalization of the EEG background. Thus, establishing the diagnosis of non-convulsive partial status epilepticus manifesting as ictal aphasia.     

Wernicke's aphasia reflects a combination of acoustic-phonological and semantic control deficits: a case-series comparison of Wernicke's aphasia, semantic dementia and semantic aphasia

Wernicke's aphasia (WA) is the classical neurological model of comprehension impairment and, as a result, the posterior temporal lobe is assumed to be critical to semantic cognition. This conclusion is potentially confused by (a) the existence of patient groups with semantic impairment following damage to other brain regions (semantic dementia and semantic aphasia) and (b) an ongoing debate about the underlying causes of comprehension impairment in WA. By directly comparing these three patient groups for the first time, we demonstrate that the comprehension impairment in Wernicke's aphasia is best accounted for by dual deficits in acoustic-phonological analysis (associated with pSTG) and semantic cognition (associated with pMTG and angular gyrus). The WA group were impaired on both nonverbal and verbal comprehension assessments consistent with a generalised semantic impairment. This semantic deficit was most similar in nature to that of the semantic aphasia group suggestive of a disruption to semantic control processes. In addition, only the WA group showed a strong effect of input modality on comprehension, with accuracy decreasing considerably as acoustic-phonological requirements increased. These results deviate from traditional accounts which emphasise a single impairment and, instead, implicate two deficits underlying the comprehension disorder in WA.     

Adult crossed aphasia in dextrals revisited

The clinical study of crossed aphasia in dextrals (CAD) may shed light on the discreteness and modularity of several cognitive functions, such as language, gestures and visual spatial abilities, with respect to hemispheric lateralisation. Since 1975 over 180 cases have been described, employing, however, different criteria of assessment and classification. The purpose of this paper is to review them and to propose a set of diagnostic criteria that may be useful to single out a series of reliable CAD cases on which research can be safely carried out. A detailed analysis of such series is dealt with in terms of a number of characteristics concerning both the language disorder and the associated nonverbal cognitive impairments.     

Etiology of stroke in patients with Wernicke's aphasia

We reviewed 49 patients with Wernicke's aphasia resulting from a stroke. Their aphasia was classified on the basis of comprehensive neuropsychological testing. Wernicke's aphasia was more common in older patients and in men. Cerebral infarction occurred in 38 patients (78%) and intracerebral hemorrhage in seven (14%); the remaining four patients (8%) developed aphasia after surgery for aneurysmal subarachnoid hemorrhage. Embolic events were the most common etiology of Wernicke's aphasia in the 38 patients with cerebral infarction, with cardiac emboli in 40% and large-vessel atheroemboli from a carotid source in 16%. In patients with Wernicke's aphasia secondary to infarction, an embolic source should be sought. Patients with Wernicke's aphasia should have computed tomography to exclude intracerebral hemorrhage before institution of anticoagulant therapy.     

De-novo simple partial status epilepticus presenting as Wernicke's aphasia

Language disturbances manifesting as brief periods of speech arrest occur with seizures originating in the frontal or temporal lobes. These language disturbances are usually present with other features of seizures or may occur in an episodic fashion suggesting their likely epileptic origin. Sustained but reversible aphasia as the sole manifestation of partial status epilepticus is rare, particularly without a history of prior seizures. A few cases have been described in the literature where Broca's or mixed aphasia seems to be more common than Wernicke's aphasia. Here we describe a patient who presented with Wernicke's aphasia secondary to simple partial status epilepticus but without any other features of seizures. The diagnosis was confirmed on EEG and the aphasia reversed after antiepileptic treatment.