Age and type of crossed aphasia in dextrals due to stroke

Thirty-nine cases (37 from the literature and 2 personal) of crossed aphasia in dextrals due to stroke were reviewed concerning age, sex, and type of aphasia. Results showed that Broca's aphasics are younger than the remaining group, males predominate, and several types of aphasia have been described similarly to the aphasias due to left-hemisphere lesions in dextrals.     

Dichotic listening in a child recovering from acquired aphasia

A right-handed 6-year-old boy with acquired aphasia of left-hemisphere origin was investigated with various dichotic listening tasks 8 and 13 months after onset of the symptoms. Total right ear extinction was found repeatedly using both numbers and words as stimuli. Furthermore, magnitude of right ear extinction was not amenable to modification through verbal training, but disappeared when words were presented to the child's right ear with simultaneous white noise to the left ear. The findings are discussed in terms of the plasticity of cerebral dominance during childhood.     

Functional MRI of Language in Aphasia: A Review of the Literature and the Methodological Challenges

Animal analogue studies show that damaged adult brains reorganize to accommodate compromised functions. In the human arena, functional magnetic resonance imaging (fMRI) and other functional neuroimaging techniques have been used to study reorganization of language substrates in aphasia. The resulting controversy regarding whether the right or the left hemisphere supports language recovery and treatment progress must be reframed. A more appropriate question is when left-hemisphere mechanisms and when right-hemisphere mechanisms support recovery of language functions. Small lesions generally lead to good recoveries supported by left-hemisphere mechanisms. However, when too much language eloquent cortex is damaged, right-hemisphere structures may provide the better substrate for recovery of language. Some studies suggest that recovery is particularly supported by homologues of damaged left-hemisphere structures. Evidence also suggests that under some circumstances, activity in both the left and right hemispheres can interfere with recovery of function. Further research will be needed to address these issues. However, daunting methodological problems must be managed to maximize the yield of future fMRI research in aphasia, especially in the area of language production. In this review, we cover six challenges for imaging language functions in aphasia with fMRI, with an emphasis on language production: (1) selection of a baseline task, (2) structure of language production trials, (3) mitigation of motion-related artifacts, (4) the use of stimulus onset versus response onset in fMRI analyses, (5) use of trials with correct responses and errors in analyses, and (6) reliability and stability of fMRI images across sessions. However, this list of methodological challenges is not exhaustive. Once methodology is advanced, knowledge from conceptually driven fMRI studies can be used to develop theoretically driven, mechanism-based treatments that will result in more effective therapy and to identify the best patient candidates for specific treatments. While the promise of fMRI in the study of aphasia is great, there is much work to be done before this technique will be a useful clinical tool.     

Aphasia in left-handers. Comparison of aphasia profiles and language recovery in non-right-handed and matched right-handed patients.

The present retrospective analysis reports two studies. In Study 1, clinical aspects of aphasia are compared in right-handed (RH) and non-right-handed (NRH) patients; in Study 2, recovery from aphasia is compared in RH and NRH aphasic patients with a minimum of 5 months of daily language rehabilitation. From a continuous series of 1200 brain-damaged subjects, 24 NRH patients with a vascular lesion documented by computerized tomography were selected. In 19 cases the lesion was in the left hemisphere and in 5 cases in the right hemisphere. For 14 NRH patients, a RH subject with similar lesion, matched for age, education, length of illness, etiology (ischemic vs. hemorrhagic), and, when possible, sex was found. Presence and type of aphasia were compared in the two patients of the same pair and were found similar except for Pair 14; the RH subject had global aphasia and the NRH had conduction-like aphasia. Fifteen NRH patients were rehabilitated and reexamined at least 5 months after the first examination. Recovery of the 12 patients with a left-hemisphere lesion was compared with recovery of a group of RH subjects and no significant differences were found. Recovery of the three patients with right-hemisphere lesions is described. It is concluded that differences in type of aphasia and recovery between RHs and NRHs have been overemphasized in the past and must be reconsidered.     

Crossed Wernicke's aphasia: a case report

Crossed aphasia is a phenomenon in which an individual sustains a lesion in the right hemisphere (typically non-language dominant), but who exhibits an aphasic syndrome. The authors present a case study of an individual with crossed aphasia (CA) in an attempt to provide anecdotal information for four questions posed by : (a). Is CA a reversal of the normal cerebral hemisphere pattern of language function? (b). Does the presence of aphasia following a right cerebral hemisphere lesion indicate that typical right hemisphere functions (e.g., visual perception) are intact? (c). How may the aphasia's presentation differ from typical left hemisphere aphasias? And (d). is the pattern of improvement following CA similar to that of typical left hemisphere aphasias? We longitudinally examined the communicative-cognitive performance of an adult man with crossed aphasia of the Wernicke's type following a cerebrovascular accident. A 21-week follow-up evaluation indicated improvements in his language functioning from our initial evaluation, but he continued to exhibit a classic, moderately severe Wernicke's aphasia.     

Factor-derived categories of chronic aphasia

A large sample of patients with aphasia (N = 118), unselected for etiology, were administered the Porch Index of Communicative Ability more than 6 months after the onset of aphasia. Factor analysis of PICA subtest scores identified five factors which accounted for 83.9% of the total variance. The factors were labeled speaking, writing, comprehension, gesturing, and copying. Cluster analyses of the factor scores yielded five patient categories which differed in the pattern of impairment on the language factors as well as in overall severity of aphasia. A subgroup of the parent sample consisting of 52 patients with localized left-hemisphere CVA had cluster analyses repeated after having first been studied as part of the larger sample. The factor-derived categories for the subgroup were similar to those of the entire group. Discriminant functions of the PICA raw scores of the 52-patient subsample correctly classified all of the patients. When discriminant functions were based upon the factor scores of the 118-patient parent sample, 80.7% of the 52 patients were correctly classified into the five categories.     

Inference revision processing in adults with and without aphasia

Processing abilities in aphasia, and the nature of processing breakdowns, were the focuses of this investigation. Individuals with either fluent or nonfluent aphasia, plus a control group, participated in a cross-modal lexical priming task designed to elicit priming effects when activation of inference interpretations occurred. Comprehension of inferences was measured by responses to four types of questions that related to the inferences. Results indicated that both the control group, as well as the nonfluent aphasia group, activated the intended meaning of the stimuli whereas the fluent aphasics did not. Comprehension of the inferences was best demonstrated by control participants, nonfluent aphasic participants, and fluent aphasic participants, in that order.     

Analyzing aphasia data in a multidimensional symptom space

The utility of single-case vs. group studies has been debated in neuropsychology for many years. The purpose of the present study is to illustrate an alternative approach to group studies of aphasia, in which the same symptom dimensions that are commonly used to assign patients to classical taxonomies (fluency, naming, repetition, and comprehension) are used as independent and continuous predictors in a multivariate design, without assigning patients to syndromes. One hundred twenty-six Italian-speaking patients with aphasia were first classified into seven classic aphasia categories, based on fluency, naming, auditory comprehension, and repetition scales. There were two goals: (1) compare group analyses based on aphasia types with multivariate analyses that sidestep classification and treat aphasic symptoms as continuous variables; (2) present correlation-based outlier analyses that can be used to identify individuals who occupy unusual positions in the multivariate "symptom space." In the service of the first goal, group performance on an external validation measure (the Token Test) was assessed in three steps: analyses of variance based on aphasia type, regressions using the same cut-offs for fluency, naming, comprehension and repetition as independent but dichotomous predictors, and regressions using the same subscales as continuous predictors (with no cut-offs). More variance in Token Test performance was accounted for when symptoms were treated as continuous predictors than with the other two methods, though use of independent but dichotomous predictors accounted for more variance than aphasia taxonomies. Thus, if we by-pass classical taxonomies and treat patients as points in a multidimensional symptom space, better predictions are obtained. Outlier analyses show that group results depend on heterogeneity among patients, which can be used as a search tool to identify potentially interesting dissociations. Hence this multivariate group approach is complementary to and compatible with single-case methods.     

Crossed aphasia in multilinguals

Reports of crossed aphasia in single case studies of bilinguals have led to incidence studies of crossed aphasia among larger groups of stroke patients. Among a few others, studies carried out in India (K. R. Nair & Virmani, 1973 Indian Journal of Medical Research, 61, 9; P. Chary, 1986, In Language processing in bilinguals: Psycholinguistic and neuropsychological perspectives) have lent support to the notion of a higher incidence of crossed aphasia among bi- and multilinguals and form major citations in support of the hypothesis that bilingualism could lead to a greater bilateral cerebral representation of languages. This paper reports on the incidence of crossed aphasia in a large unselected population of stroke patients in monolingual and multilingual speakers of South India, which is in agreement with the previous reports of a higher incidence of crossed aphasia in multilinguals. However, along with this high incidence of crossed aphasia a low incidence of sinistrality was also seen. In order to confirm these findings and their significance two further studies were carried out-an incidence study of crossed aphasia in a population of mono- and multilingual aphasics and an incidence study of hand dominance in a normal population. The results and their significance to the issue of crossed aphasia in multilinguals are presented.     

Frontal-opercular aphasia.

The standard nomenclature divides nonfluent aphasic syndromes with relatively spared comprehension into Broca's aphasia and transcortical motor aphasia. We report on a patient with a persistent nonfluent aphasia from a discrete, primarily cortical, frontal-opercular lesion who had impaired syntax but intact repetition and, therefore, did not conform to the traditional classification. Based on this patient's behavior and a review of other cases, we have divided the nonfluent aphasias with intact comprehension into five disorders. (1) Verbal akinesia-exhibiting diminished intention or drive to speak and associated with medial frontal lesions (supplementary motor area and cingulate gyrus) or with lesions damaging the efferent projections from these areas. (2) Disorders of syntax-telegraphic and agrammatic utterances that may be associated with dominant pars opercularis lesions. (3) Phonemic disintegration-a failure to correctly produce phonemes, which may be associated with injury to the opercular primary motor cortex or efferent projections from this area. (4) Defects of lexical access-patients who struggle to find words and are impaired at timed word-generation tasks. Defects of lexical access may be associated with lesions of the pars triangularis and adjacent prefrontal cortex. (5) Mixed defects. According to this model, the traditional patient with Broca's aphasia would exhibit disorders of syntax, phonemic disintegration, and defects of lexical access, whereas the traditional patient with transcortical motor aphasia would have verbal akinesia or defects of lexical access or both. Our patient had defects of lexical access and syntax, but only mild symptoms of phonemic disintegration, suggesting that his opercular primary motor cortex was relatively intact. Our patient's ability to repeat normally while his propositional speech remained telegraphic suggests that different neural mechanisms subserve these functions.     

Psychometric and CT scan measurements in a case of crossed aphasia in a dextral

A case of crossed aphasia with lesion deep to the right supramarginal gyrus was studied to determine (1) if this patient behaved similar to patients with the same lesion site in the left hemisphere, (2) if visuospatial deficits were present, and (3) if the CT scan asymmetries were similar to those of other right-handers. Speech and language skills were similar to those patients with similar lesions in the left hemisphere. Visuospatial and arithmetic deficits were similar to those described after right-hemisphere and left-hemisphere damage. CT scan asymmetries were atypical. These results provide behavioral and neuroradiological confirmation of atypical hemispheric dominance.     

Transcortical sensory aphasia in a right-handed patient following watershed infarcts in the right cerebral hemisphere: a 15-month evaluation of another case of crossed aphasia.

Well-documented cases of crossed (transcortical sensory) aphasia, especially those with longitudinal evaluation, are rare. We report a case of crossed transcortical sensory aphasia following watershed infarcts in the right hemisphere, from the moment of the accident until 15 months afterward. The aphasia type, and the course of recovery, is a "mirror" representation of that seen in cases of uncrossed aphasia. Unfortunately, the data do not permit strong conclusions regarding the lateralization of language in association with praxis and visuospatial abilities. This underlines the need for more well-documented (case) studies to come to a better understanding of the mechanisms through which lateralization occurs.     

Preserved recognition of familiar personal names in global aphasia.

Recognition of proper and common nouns was compared in four patients diagnosed with global aphasia secondary to ischemic left-hemisphere infarction. For proper noun recognition, subjects matched the spoken or written name of a famous person to a photograph, and for common nouns, subjects were tested on standardized and special word recognition tests. As expected, common noun recognition was severely compromised in the aphasic patients. In contrast, familiar personal names, despite their greater length and complexity, were recognized equally well by aphasic and normal control subjects. The right hemisphere may mediate the ability to recognize personally familiar names, as it may be specialized for establishing personally relevant environmental stimuli.     

Central deafness and subcortical motor aphasia

Clinical and autopsy studies were made on a right-handed man who had central deafness and subcortical motor aphasia, and the literature on central deafness and on subcortical motor aphasia was analyzed. Central deafness is due to bilateral destruction of the primary auditory cortex. It is sometimes difficult to distinguish from word deafness and from auditory agnosia, which are due to pathology in other parts of the temporal lobes. There is almost always some preserved hearing in central deafness, possibly from some auditory pathway other than the classical pathway. In this patient the subcortical motor aphasia was due to bilateral destruction of the motor cortex for the mouth and throat. In some other cases subcortical motor aphasia was due to the same pathology that usually causes Broca's aphasia; in these cases the unexpected preservation of writing was perhaps related to some difference in how language functions were organized in the brain.     

Visuomotor tracking abilities of speakers with apraxia of speech or conduction aphasia

This investigation examined the visuomotor tracking abilities of persons with apraxia of speech (AOS) or conduction aphasia (CA). In addition, tracking performance was correlated with perceptual judgments of speech accuracy. Five individuals with AOS and four with CA served as participants, as well as an equal number of healthy controls matched by age and gender. Participants tracked predictable (sinusoidal) and unpredictable signals using jaw and lip movements transduced with strain gauges. Tracking performance in participants with AOS was poorest for predictable signals, with decreased kinematic measures of cross-correlation and gain ratio and increased target-tracker difference. In contrast, tracking of the unpredictable signal by participants with AOS was performed as well as for other groups (e.g. participants with CA, healthy controls). Performance of the subjects with AOS on the predictable tracking task was found to strongly correlate with perceptual judgments of speech. These findings suggest that motor control capabilities are impaired in AOS, but not in CA. Results suggest that AOS has its basis in motor programming deficits, not impaired motor execution.     

Linguistic and nonlinguistic priming in aphasia

Studies of real-time processing in aphasia suggest that linguistic symptoms may be due to deficits in activation dynamics rather than loss of linguistic knowledge. To investigate the domain specificity of such processing deficits, we compared performance by Italian-speaking fluent aphasics, nonfluent aphasics, and normal controls in a linguistic priming task (grammatical gender) with their performance in a color-priming task that requires no verbal mediation. Normal or larger than normal color-priming effects were demonstrated in both aphasic groups. Gender priming did not reach significance in either group, even though the patients displayed above-chance sensitivity to gender class and gender agreement in their accuracy scores. The demonstration of spared gender knowledge despite impaired gender priming underscores the utility of on-line techniques in the study of aphasia. The demonstration of spared color priming suggests that priming deficits in aphasia are either (1) specific to speech and language or (2) specific only to those sensorimotor and attentional processes that language shares with other nonlinguistic systems.     

Supra- and infrasylvian conduction aphasia

Fifteen cases of conduction aphasia which were tested with the Aachen Aphasia Test (AAT), are presented. The CT lesion data were transformed to a standard 3D-reference brain referring to the ACPC line. According to the lesion profiles a group of 6 patients had pure suprasylvian lesions, a group of 4 patients had pure infrasylvian lesions, and a group of 5 patients had lesions in both supra- and infrasylvian regions. Suprasylvian conduction aphasics are superior to infrasylvian conduction aphasics in the token test and in repetition tasks. Infrasylvian conduction aphasics use more stereotypes in spontaneous speech than suprasylvian conduction aphasics. Conduction aphasics with both lesion sites perform less well in tests of naming, writing, and comprehension than the pure types. Thus conduction aphasia is a heterogeneous syndrome anatomically and linguistically.     

Anatomoclinical correlations of the aphasias as defined through computerized tomography: Exceptions

We have studied the frequency of exceptions to classical aphasia localizations in right-handed, literate, adult, native speakers of Italian with focal vascular left-hemisphere lesions, correlating clinical and computerized tomography data. Two hundred sixty-seven subjects were given computerized tomography (CT) examinations; lesions were mapped onto lateral diagrams and the sites of the lesions were defined. Patients were then classified as nonfluent aphasics, fluent aphasics, and nonaphasics. Patients with negative CT scans (n = 10) or only "deep" lesions (n = 50) were not studied for anatomoclinical correlations. Of the remaining 207 patients, 36 presented unexpected findings. There were seven cases of fluent aphasia and "anterior" CT lesions and six cases with nonfluent aphasia and "posterior" CT lesions among them. The significance of these findings is discussed.     

Incomplete Kluver-Bucy syndrome and fluent aphasia

A case of probable herpetic viral encephalitis is presented. The clinical picture following the acute phase of disease was dominated by severe fluent aphasia, prominent oral tendencies, visual agnosia, and a decrease in fear reactions. Most of these symptoms, with the obvious exception of aphasia, are similar to those observed by Kluver and Bucy in rhesus monkeys that underwent bitemporal lobectomy. These manifestations may be explained by the tendency of the herpes simplex virus to invade the temporal lobes. "Agnosia" in the auditory field and changes in vocal behavior were observed by H. Kluver and P. C. Bucy (1939, Archives of Neurology and Psychiatry, 42, 949-1000) in some of their bitemporal monkeys. The association of sensory aphasia, as observed in this case, with the auditory "agnosia" observed in some bitemporal monkeys, is discussed.     

Agrammatic Broca's aphasia is not associated with a single pattern of comprehension performance

One influential hypothesis posits that the brain regions implicated in Broca's aphasia are responsible for specific syntactic operations that are necessary for the comprehension and production of sentences (Grodzinsky, 1986, 1990, in press). The empirical basis of this hypothesis is the claim that Broca's aphasics have no difficulty understanding sentences in the active voice (and other "canonical" sentence types, such as subject relatives and clefts with negative predicates), but perform at chance level with passive voice constructions (and other "noncanonical" sentences such as object-gap relatives and object clefts). In the face of well-established results indicating that Broca's aphasics can exhibit several different performance patterns on these sentence types, Grodzinsky, Pi?ango, Zurif, and Drai (1999) argued that these conflicting results do not challenge the theory when the data are analyzed appropriately. They carried out a creative statistical analysis of the comprehension performance of published cases of Broca's aphasia and concluded that all of these cases are in agreement with the predicted pattern: chance on passives and 100% correct on actives. Here we show that the statistical reasoning adopted by Grodzinsky et al. (1999) is flawed. We also show that the comprehension performance of a substantial number of the Broca's aphasics in their own sample does not conform to the pattern required. Rather, contrary to these authors' claim, Broca's aphasia is not associated with a consistent pattern of sentence comprehension performance, but allows for a number of distinct patterns in different patients.