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The evidence from bilingual-crossed aphasia which has been used to support a bilingualism-right hemisphere effect for language representation and/or processing is critically reevaluated. Data gathered by the case survey method are shown to have been misrepresented in the literature. The argument based on a single group study of right-lesioned subjects is shown to rest upon a fundamental misinterpretation of those data. The consequences of such misrepresentation and misinterpretation as reflected in recent research are discussed.

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.

脳血栓発症８か月を経過した時点で重度の左半側空間失語と交叉性失語を介併した61歳の画家にリハビリを行い著明な改善をみたので報告した．初診時神経心理学的には，線分二等分テスト，図形探索テスト，図形模写テストを行い全テストで左半側の無視が認められた．また交叉性失語がみられた．患者は右利きで家族歴にも左利きの素因はなかった．患者は病前より画家として認められていたのでクレヨン別を訓練に取り入れ，絵画活動の自立をプログラムに挙げた．訓練15か月後には再び展覧会に人選を果たした．交叉性失語の回復は，初期の重度のレベルから中等度まで改善したが，喚語困難，文法障害ともに顕著であった．半側空間失認の責任病巣に関しては，古典的な右頭頂—側頭—後頭部と考えられた．また半側空間失認のリハビリに関しては，患者の興味を引く訓練をプログラムに取り入れたことが効果的であったと考えられた．

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.

A 56-year-old right-handed male painter (OJH) was studied for three years post-stroke. The stroke had resulted in a large posterior right hemisphere infarction with initial left hemiparesis and sensory loss. The hemiparesis as well as initial signs of the left-sided neglect recovered, but he remained aphasic and apraxic. The findings show that praxis is not always controlled by the hemisphere contralateral to the dominant hand. The patient was studied with neuropsychological tests and experimental tasks. He showed no deficit in gesture, but generally poor non-verbal performances. He resumed painting very early after the stroke. Despite early signs of neglect his ability to paint recovered completely. His intact ability to paint is contrasted with initially average visuo-constructive test performance, poor abstract reasoning performance with visual designs, and poor sequencing ability in evaluating or constructing a pictorial narrative. The results are interpreted as indicating a complete reversal...

Right-handed patients with aphasia due to a right hemisphere lesion, or sinistral aphasics with a left hemisphere lesion, are referred to as crossed aphasics (Bramwell 1899). Since left damaged sinistrals with aphasia are the rule (Brown and Hecaen 1976), it is the dextral with a right hemisphere lesion that has received most of the attention. When we reviewed the topic of crossed aphasia in dextrals some years ago in relation to a case report (Brown and Wilson 1973). only seven other cases could be found that satisfied the minimal criteria of a clearcut aphasia dextrality and a negative family history ofleft handedness, but since this paper there have been many additional observations (e.g. Assal, Perentes and Dervaz 1981, Donoso, Santander and Pavez 1984, Pillon, Desi and Lhermitte 1979, Wechsler 1976; see Joanette, Puel, Nespoulos, Rascol and Lecours [1982] and Castro-Caldas and Confraria [1984] for review).

A case of crossed aphasia in a right-handed woman resulting from a right-hemisphere stroke is reported. Rapid recovery occurred between an initial evaluation performed at one month poststroke and a follow-up evaluation performed at 2 months post. The cerebral organization and the relationship between language and other cognitive abilities in crossed aphasics are discussed. Additionally, the unitary and transient models of crossed aphasia are examined.

We describe the case of a 61-year-old right-handed male who developed global language deficits and muteness following a right hemisphere middle cerebral artery distribution infarct involving the frontal, inferior parietal and superior temporal lobes. Language was evaluated serially during the early stages of recovery in order to document the evolution of this syndrome with regard to the observed areas of linguistic change. Auditory comprehension and information content were the areas showing the greatest change during the early stages of recovery, while gains influency were limited. By 48 days post-onset, this patient's linguistic profile was behaviourally compatible with the Broca's aphasia seen with left hemisphere lesions.

A case of expressive aphasia resulting from right middle cerebral artery occlusion in a fully right-handed woman without sinistral antecedents is reported. The significance of the findings in relation to cerebral dominance is discussed.

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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.

The recognition of the lateralization of language to the left hemisphere in most adults was one of the great triumphs of nineteenth-century neurology, but because the clinical finding of frequent crossed aphasia in children suggested that language functions were bilateral during childhood, the notion arose that lateralization was a developmental process that occurred over the first decade of life. Recent neuroanatomical, electroencephalographic and neuropsychological investigations have tended to support the contrary view that language is primarily lateralized to the left hemisphere from the first months of post-uterine life. Now the collection of more clinical data on acquired childhood aphasia, and the reanalysis of earlier clinical studies, indicate that the modern incidence of crossed aphasia in children is too low to support the hypothesis of a gradual lateralization of language over time, and is more consistent with a theory of developmental invariance of language lateralization.

Summary A case of crossed aphasia in a monolingual dextral with detailed clinical, neuropsychological and language assessment is described. The presence of Gerstmann-syndrome suggested cross-over of even dominant parietal lobe functions. Lateralization and localization of various language functions in relation to crossed aphasia are discussed.

Seven strongly right-handed patients developed aphasia following a right hemisphere vascular lesion documented by computerized tomography. One patient had a severe unilateral neglect, indication of its presence were evident in three and absent in three patients. The Token Test scores were significantly higher than in matched controls. Two patients had Broca aphasia, four had Wernicke aphasia and one had agraphia. The correlation between type of aphasia and locus of lesion was not much different from that normally found in standard left hemisphere brain demaged aphasics.

The correlation between clinical picture, CT scan and regional cerebral blood flow (rCBF) assessed by single photon emission computerized tomography (SPECT) was investigated in two patients with crossed aphasia. The presence and degree or right hemisphere dysfunction, beyond the areas affected by CT, closely paralleled the time course of language disturbances in both patients: transient aphasia in case 1 was associated with temporary reduction of perfusion in the right hemisphere, while in case 2 persistent aphasia and apraxia were found along with severe right hemisphere hypoperf usion three year after the onset of stroke.

Publisher Summary This chapter focuses on the subject of bilingualism and brain lateralization. The notion that the right hemisphere may participate in the relearning of language(s) or certain language functions following left-hemisphere damage has been suggested in several case studies of polyglot aphasia. It has also been proposed that the right hemisphere in bilinguals may, even premorbidly, share language functions with the left hemisphere to a greater extent than is the case in unilinguals. Support for the latter possibility obtains from an extensive survey of the early polyglot aphasia literature, which revealed that the incidence of crossed aphasia in right-handers was 14% among the polyglots, as compared to an estimated 2% among unilinguals. This chapter focuses on theoretical issues bearing on the problem of cerebral hemispheric correlates of language processing in bilinguals. It presents a general summary of clinical and experimental findings, and also discusses a view to addressing whether and why factors intrinsic to bilingualism might influence the extent to which the left and right cerebral hemispheres partake differentially in language processing.

• A right-handed man with a global aphasia and a left hemiparesis was examined after a cerebrovascular accident. Three weeks later, oral language was only mildly impaired but writing disorders were still severe. At autopsy, there was an infarction of the territory supplied by the right middle cerebral artery. There was no lesion in the left hemisphere.

A strictly right-handed man showed aphasia and left hemiplegia following a deep infarct of the right hemisphere. Aphasic semeiology was characterized by an oral and written jargon while comprehension was almost intact. Several hypotheses previously put forward fail to account for the patient's aphasia. Emphasizing the frequency of deep structures involvement in the published cases of crossed dextral aphasias, it is suggested that site of lesion may have a certain part to play in the accurrence of such aphasias.

Three strongly right-handed patients developed fluent aphasia after right hemisphere infarction documented by computerized tomography. For these patients and for other reported cases of crossed aphasia suitable for analysis, the correlation between fluency and infarct localization was similar to that of right-handed aphasies with left-sided lesions. Right hemisphere language representation in most crossed aphasies probably mirrors that normally present in the language-dominant left hemisphere. Two of these patients showed concomitant hemispatial inattention and visuoconstructive impairment. Right hemisphere language dominance therefore does not preclude ipsilateral specialization for visuospatial functions.

Individual cases of crossed aphasia (aphasia after a right hemisphere lesion in a right-hander) have often been reported. A number of theories have been proposed as to the neuropsychological and/or nerobiological mechanisms that might underlie this phenomenon, but there is still disagreement about its language phenomenology and possible significance. We report 2 cases of crossed aphasia after stroke and review 34 cases from the literature with anatomical documentation of lesion site. Analysis of this material suggests that they represent at least two populations. There may be general conclusions concerning mechanisms of cerebral lateralization to be learned from the investigation of anomalous groups such as crossed aphasics.

Severe Wernicke's aphasia occurred suddenly in a right-handed man and persisted with little improvement until he died 54 days later. Postmortem examination showed an infarct in the posterior temporoparietal region of the right hemisphere. This case demonstrates two new features of crossed dextral aphasia. First, language skills may be fully lateralized to the right hemisphere in right-handed patients. Second, when crossed lateralization occurs, the usual localization of aphasic syndromes is common, suggesting that the intrahemispheric organization mediating language activities is the same in the right hemisphere of the crossed dextral and the left hemisphere of the typical right-handed individual.

SUMMARY A case is reported of acquired aphasia in a 15-year-old right-handed boy, secondary to a right occipitotemporal tumour. He had aphasia, alexia, agraphia and visuospatial disturbances, which persisted after partial removal of the neoplasm. 15 days after surgery he had an episode of left focal seizures, after which the aphasia worsened. One month later he developed severe (global) aphasia associated with rostral extension of the tumour. Although crossed aphasia was previously considered common in children, there are few reports with anatomical confirmation. In the authors' own series of 31 children with acquired aphasia this is the only case of crossed aphasia, an incidence similar to that found in adult cases.

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.

In 1899, Byrom Bramwell introduced the concept of crossed aphasia (CA) as a deviation from the prevailing insight of an inherent association between cerebral dominance for language and hand preference. He defined as such the phenomenon of aphasia caused by brain damage ipsilateral to the dominant hand (i.e. aphasia resulting from a lesion to the left hemisphere in sinistrals and aphasia following a lesion to the right hemisphere in dextrals). Notable in the development of the concept of CA is the absence of any reference to the understanding of acquired childhood aphasia (ACA) in which aphasia following a right hemisphere lesion was considered a frequent phenomenon. Following an erosion of Bramwell's positions on CA and the decay of the feasibility of so-called Broca's doctrine, a confluence of concepts was established between CA and ACA seven decades later. This paper reviews the history of the collusion of concepts of acquired aphasia in these atypical populations.

A single case study of a 33-year-old right-handed man who suddenly developed left hemiplegia and nonfluent aphasia is reported. Extensive testing of the patient's reading ability revealed the symptom complex of deep dyslexia. The relevance of crossed deep dyslexia in a reader of Italian is discussed.

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.

In aphasia as in so many other fields of study it is the exception to the rule that points the way to new theory. Just when we think we have a handle on the problem of language and brain organization, some unusual disorder comes along and forces us to re-examine the simple explanations we have forced on the data.

The hypothesis is advanced that cerebral dominance includes two elements, interhemispheric specification for language (lateralization) and intrahemispheric language, specification (localization). Consequently, each type of aphasia is determined by the degree of dominance establishment (i.e., lateralization and localization) existing at the moment of brain damage. Evidence for this concept is presented through a comparison of aphasia in left-handers and "anomalous" dextrals with aphasia in childhood.

In Reply.— We have read Dr Winterling's comments with appreciation. The speculation we offered relating original Chinese language experience to crossed aphasia must be viewed with caution as only one possible factor among others. We stated that this linguistic factor could not be the unique one for the same reason offered by Dr Winterling—namely, the paucity of cases of crossed aphasia in Chinese patients or any other patient group. His reference to the article in Science 1 is relevant in showing that the incidence of righthandedness in Chinese is not significantly different from that in Caucasians. In any individual, multiple factors—genetic, pathologic, and others—are probably responsible for determining specific cerebral organization of speech-language functions and handedness. Even though differences in cognitive experience have been correlated with structural and functional properties of developing cortical neurons in the cat visual system, 2 one can only speculate about possible relationships between early language experience

• In a 35-year-old right-handed man who had no personal or family history of left-handedness, left hemiparesis and predominantly motor aphasia suddenly developed following cerebrovascular accident. Clinical and laboratory data, including computerized tomographic scan, showed a clearly defined right hemisphere lesion. On dichotic listening test, a clear-cut right ear extinction was present.

To the Editor.— I found the article about crossed aphasia appearing in a man with a right cerebral infarction most interesting ( Arch Neurol 34:766, 1977). I believe it was well studied and clearly demonstrates crossed aphasia with significant impairment in this man's native Chinese, more so than in his secondary language, English. I disagree most strongly with the statement that this could be related to his early learning of Chinese, an ideographic language based on visual spatial percepts. Although written Chinese utilizes a complex set of nonalphabetized ideographic symbols, in sharp contrast to other languages with alphabets that utilize an abstract set of symbols of more or less phonetic value, the spoken Chinese is basically no different than any other language in that its symbols are purely auditory. No visual spatial concepts are required. Blind Chinese children learn Chinese as blind children of any linguistic group learn their mother tongue.

• A persistent nonfluent aphasia following a right cerebral infarction developed in a 74-year-old right-handed Chinese man. Computerized axial tomography localized the lesion in the right frontal lobe. This case is similar to a previously reported one, also with crossed aphasia in a bilingual and dextral Chinese person. Despite these two independent observations and in spite of the fact that unusual cerebral organization might be related to early learning of a nonalphabetic (ideographic) language, preliminary sampling has failed to demonstrate a greater incidence of crossed aphasia in two separate Chinese populations.

Article abetract—Severe Broca aphasia and left hemiplegia without right limb apraxia occurred suddenly in a right-handed man with no personal or family history of left-handedness. Postmortem examination showed infarction of the right hemisphere, limited almost entirely to the precentral gyrus. In this patient, cerebral dominance for speech lay in the right hemisphere, but dominance for limb praxis lay in the left. This case provides evidence that cerebral dominance for speech and handedness in dextrals may be dissociated. It also suggests that lesions of the precentral gyrus are of major importance in producing Broca aphasia.