Anomalous cerebral language organization: acquired crossed aphasia in a dextral child

Following a dramatic change of its reported incidence, it was only recently recognized that acquired crossed aphasia in dextral children represents a highly exceptional phenomenon. We describe in a three epoch time-frame model the aphasic and neurocognitive manifestations of an additional case and focus briefly on its anatomoclinical configurations. In our patient, a right parietal cortico-subcortical hemorrhagic lesion caused an initially severe aphasia. After remission of the global aphasic symptoms in the acute phase, an adynamic output disorder with relatively severe auditory-verbal comprehension disturbances developed. In addition to the adynamia of self-generated speech, formal language investigations performed 3 weeks postonset, revealed agrammatism, hypertonic dysarthria, and dysprosodia. A substantial improvement of the aphasic disorder was objectified 83 days postonset. Neuropsychological investigations disclosed both dominant and nondominant hemisphere dysfunctions. Reassessment of neurocognitive functions after a 10-year period evidenced discrete residual anomia, confined to visual confrontational naming and a discrete visuo-perceptual syndrome. Given the posterior localization of the lesion, the syndrome shift from global to predominantly adynamic aphasia represents a finding beyond the plausible anatomoclinical expectations holding in general for the uncrossed, classic types of childhood and adult aphasia. As the first representative of crossed aphasia in dextral children with an anomalous lesion-aphasia profile, our case provides evidence to enrich the discussion on lateralization and intrahemispherical organization of language functions in both childhood and adult aphasia.     

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.     

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.     

Crossed aphasia in an illiterate dextral

An 83 year old illiterate, right-handed woman developed a persistent nonfluent aphasia following a right cerebral infarction (crossed aphasia). Computerized axial tomography localized the lesion to the right posterior frontal lobe.It is suggested that the neural mechanisms involved in learning to read and write may be critical for the complete establishment and maintenance of language dominance in the left hemisphere, and that, in this case, the patient's failure to acquire reading and writing skills altered the normal evolution of language lateralization and resulted in the right hemisphere assuming the dominant role.     

Acquired aphasia in children and the ontogenesis of hemispheric functional specialization.

We have described a series of 26 cases of cortical lesions in children from $\text{3}\text{1}\text{2}$ to 15 years of age (17 left-sided, six right-sided, three bilateral), in which 19 had varying degrees of language disturbance. We have attempted to establish the nature and evolution of these aphasic disorders, and have compared our observations to those previously published. Our analysis appears to indicate a relative hemispheric equipotentiality which permits the transfer of language representation to the opposite hemisphere in the case of a unilateral lesions in childhood. This conclusion, however, has at least the appearance of being in conflict with other reported findings, viz., those deriving from psychometric testing of subjects with unilateral perinatal lesions; and those concerning studies of fetal and newborn brains which suggest a very early, if not innate, hemispheric specialization.The fact of this discrepancy has lead us to reconsider the concept of a critical period as defined by Lenneberg. In this respect, we have also discussed the possibility of a partial transfer of language representation, of an intrahemispheric reorganization by intact “uncommitted” areas (P. Goldman), and finally, the need for an adequate stimulus during a given period in order for a preformed area to become functional.     

Crossed aphasia in Chinese: a clinical survey.

According to our clinical observations from various aspects of stroke patients, such as the total incidence of aphasia, the incidence of aphasia after left brain damage of the dextrals, the aphasia that occurs in patients without hemiplegia, and the types of aphasia, a much higher incidence of crossed aphasia is seen among the stroke patients of the Han (the largest ethnic group in China) as compared with the Uighur-Kazaks (U-K) in China and the Occidentals documented in the literature. Motor aphasia is most common and pure sensory or posterior aphasia is rarely seen in Han patients. The distinct features of the Chinese language is a possible explanation for this difference. We suspect that language function of the Han is not localized in the left brain but in the right or both hemispheres. There is no definite Wernicke's area in the left brain of the Chinese people and the neural pathway of the language function in the brain of the Chinese people is not similar to people who speak phonetic languages. Consequently the universal applicability of the theories of cerebral laterality of the language function and dominant hemisphere established by Dax and Broca are questioned in this paper.     

Crossed Aphasia in a Dextral: A Test of the Alexander–Annett Theory of Anomalous Organization of Brain Function

A case of crossed aphasia is presented in a strongly right-handed 77-year-old white female without history of familial sinistrality or prior neurological illness. She developed a right middle cerebral artery infarction documented by CT and accompanied by obvious clinical signs of a conduction aphasia with some resolution but continuing obvious language defect after 9 weeks in rehabilitation. Comprehensive neuropsychological and aphasia testing suggested anomalous lateralization of phonologic-output aspects of language, emotional prosody, motor planning and body schema modules with usual lateralization of lexical–semantic aspects of language and visuo-spatial functions. Experimental validation of the uncrossed lexical–semantic aspects of language using tachistoscope methods found support for the Alexander–Annett theory that different aspects of language can be dissociated in their lateralization. The subject had difficulty identifying a semantic associate of a picture presented to the left visual field (7 errors out of 10) relative to right visual field presentation (2 errors out of 10). Bilateral free naming errors (6 and 5 errors in the left and right visual fields, respectively) occurred consistent with the aphasic presentation, suggesting phonologic-output dysfunction from the right cerebral vascular accident. Implications of the results for aphasia classification are discussed.     

The italian determiner system in normal acquisition, specific language impairment, and childhood aphasia

The paper presents a comparison of the development of the Italian determiner system in three different populations: normally developing children, a child recovering from childhood aphasia from the age of 3 years, 9 months, and 11 specific language impairment (SLI) children. Data from Italian normal children provide evidence for the hypothesis (1) that no prefunctional stage exists as far as the determiner system is concerned and (2) that the syntactic properties of determiners play an essential triggering role early on. The analysis of the determiner system in the aphasic child has a double interest. On the one hand, it may help to shed light on some of the intriguing questions concerning this type of disorder; on the other, it may be relevant for the discussion of the notion of agrammatism. Results of the morphosyntactic analysis reveal that, apart from timing differences, recovery from childhood aphasia shares important features with normal development. Differently from mean length of utterance (MLU)-matched normal controls and the aphasic child, SLI children omit determiners significantly more often than almost any other functional category or free morpheme. We will argue that the reasons for the SLI children's atypical behavior have to be sought in the nonaccessibility to or in the misappreciation of one fundamental syntactic property of determiners: their role as elements that assign argumenthood to nominal expressions (Szabolcsi, 1987; Longobardi, 1994).     

The ontogeny of hemispheric specialization: some old hypotheses revisited

This paper re-examines two hypotheses on the ontogeny of hemispheric specialization that long ago fell into disfavor in neuropsychology. It is argued that these hypotheses, equipotentiality and progressive lateralization, may have suffered from misinterpretation that fostered premature acceptance of the developmental invariance view of hemispheric specialization. An alternative view is presented that incorporates both hypotheses within a neurodevelopmental context using anatomical (postmortem) and childhood aphasia data.     

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.     

Synaesthesia: learned or lost?

The question why synaesthesia, an atypical binding within or between modalities, occurs is both enduring and important. Two explanations have been provided: (1) a congenital explanation: we are all born as synaesthetes but most of us subsequently lose the experience due to brain development; (2) a learning explanation: synaesthesia is related to some learning process during childhood. Three recent studies provide conflicting support for these explanations. Two studies supported the idea that synaesthesia is learned by showing that the frequency of everyday language implicitly modulates the synaesthetic experience. Another study argued that synaesthesia reflects basic, innate magnitude representations. In this paper we reassess these points of view, and show that it is possible for both to be valid. These findings are integrated into an interactive specialization account of development in order to explain the neuronal mechanism underlying synaesthesia.     

Right hemisphere involvement in non-fluent primary progressive aphasia

We described a 56-years-old man with a diagnosis of "non-fluent primary progressive aphasia" (NfPPA). An accurate neuropsychological, neurological and neuroimaging evaluation was performed in order to assess clinical and behavioural features of the patient. From a neuropsychological point of view, the patient showed a typical cognitive profile of subjects affected by NfPPA: a prominent language deficit, associated with impairments in several cognitive domains after three years from the onset of the symptomatology. The most intriguing feature is that SPECT revealed hypoperfusion in the right frontal cortex, albeit the patient is right-handed. This unexpected finding shows that NfPPA may arise not only from cortical abnormalities in the language-dominant left hemisphere, but also from right hemisphere involvement in a right hander (crossed aphasia).     

Linguistic and neuropsychological deficits in crossed conduction aphasia. Report of three cases

This study describes the linguistic and neuropsychological findings in three right-handed patients with crossed conduction aphasia. Despite the location of the lesion in the right hemisphere, all patients displayed a combination of linguistic deficits typically found in conduction aphasia following analogous damage to the left hemisphere. Associated cognitive deficits varied across the three patients. In addition, all cases showed deficits classically attributed to non-dominant hemisphere damage (visuoperceptual deficits and reduced figural memory). As a result, lesion-behaviour relationships in our study sample indicate both dominant and non-dominant qualities of the right hemisphere.     

The occurrence of paraphasias in the spontaneous speech of children with an acquired aphasia

Two children with an acquired aphasia were observed during the recovery process. In the spontaneous speech, paraphasias belonging to different categories, such as neologisms, verbal paraphasias, and literal paraphasias, were found. Especially with regard to neologisms the time of investigation was very important. In addition, one child with a phonemic jargon aphasia and one child with a fluent aphasia and empty speech were observed. These observations implicate a modification of the current clinical picture of childhood aphasia. Some aspects are discussed in relation to adult aphasia.     

A long-term follow-up case study of crossed aphasia assessed by single-photon emission tomography (SPECT), language, and neuropsychological testing

A 65-year-old man with well-defined crossed aphasia secondary to right cerebral infarction 10 years previously was studied for current language and cognitive abilities and regional cerebral blood flow (rCBF) during cognitive activation measured by single-photon emission tomography (SPECT). Reversed hemispheric lateralization was demonstrated by qualitative aspects of the patient's constructional deficits, dominant parietal lobe signs, and absence of the neglect syndrome. Language activation procedures during SPECT produced focal increases in rCBF to both frontal lobes with a phoneme detection task and to right temporal and parietal lobes with a math task. The authors stress the complexities of assessing brain/language mechanisms in vivo and demonstrate variabilities in rCBF during language activation dependent on task selection.     

Increases in language lateralization in normal children as observed using magnetoencephalography

Previous functional magnetic resonance imaging (fMRI) studies investigating hemispheric dominance for language have shown that hemispheric specialization increases with age. We employed magnetoencephalography (MEG) to investigate these effects as a function of normal development. In sum, 22 healthy children aged 7-16 years were investigated using two language tasks: a verb-generation (VG) task and a vowel-identification (VI) task. Significant hemispheric differences were found for both tasks in cerebral language areas using oscillatory MEG spectral analyses, confirming the MEG's ability to detect hemispheric specialization for language in children. Additionally, a significant increase of this lateralization as a function of age was observed for both tasks. As performance in the VI task showed no correlation with age, this increase seems to be unrelated to performance. These results confirm an increase in hemispheric specialization as a function of normal brain maturation.     

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.     

Synesthesia in children with difficulties in written language learning

We tested whether the acquisition of grapheme-color synesthesia during childhood is related to difficulties in written language learning by measuring whether it is more frequent in 79 children receiving speech and language therapy for such difficulties than in the general population of children (1.3%). By using criteria as similar as possible to those used in the reference study (Simner et al., 2009), we did not identify any synesthete (Bayesian 95% credible interval [0, 4.5]% for a flat prior). The odds of the null model (no difference between 0/79 and 1.3%) over alternative models is 28 (Bayes Factor). A higher prevalence of grapheme-color synesthetes among children with learning difficulties is therefore very unlikely, questioning the hypothesis of a link between synesthesia and difficulties in language acquisition. We also describe the difficulty of diagnosing synesthesia in children and discuss the need for new approaches to do so.     

Lateralization effects during semantic and rhyme judgement tasks in deaf and hearing subjects

A visual hemifield experiment investigated hemispheric specialization among hearing children and adults and prelingually, profoundly deaf youngsters who were exposed intensively to Cued Speech (CS). Of interest was whether deaf CS users, who undergo a development of phonology and grammar of the spoken language similar to that of hearing youngsters, would display similar laterality patterns in the processing of written language. Semantic, rhyme, and visual judgement tasks were used. In the visual task no VF advantage was observed. A RVF (left hemisphere) advantage was obtained for both the deaf and the hearing subjects for the semantic task, supporting Neville's claim that the acquisition of competence in the grammar of language is critical in establishing the specialization of the left hemisphere for language. For the rhyme task, however, a RVF advantage was obtained for the hearing subjects, but not for the deaf ones, suggesting that different neural resources are recruited by deaf and hearing subjects. Hearing the sounds of language may be necessary to develop left lateralised processing of rhymes.