交叉性失语

右利手者右大脑半球病变所致的失语称为交叉性失语。交叉性失语少见。我科八年来共诊断八例（占我组失语症患者２５０例的２．８％），均为男性右利手者，头颅ＣＴ扫描均证实右大脑半球单发病灶，其中脑梗塞７例，脑出血１例。均于发病三个月内作失语检查。其中交叉性Ｂｒｏｃａ失语一例，交叉性传导性失语一例，交叉性Ｗｅｒｎｉｃｋｅ失语一例，交叉性经皮质运动性失语一例，交叉性经皮质感觉性失语三例，交叉性丘脑性失语一例。此８例各型交叉性失语之临床表现与右利手左大脑半球病变产生的各相应类型失语无根本不同。产生交叉性失语是患者的大脑半球语言中枢的逆转所致（不在左侧而在右侧大脑半球的对称部位），它与遗传有关。失语症类型与患者年龄和性别的关系有待进一步研究。     

Crossed aphasia: New perspectives

Abstract

Crossed aphasia reflects an unusual latcralization pattern characterized by a dissociation between manual and language hemispheric dominance in a right-handed individual. In order to circumscribe the syndrome of crossed aphasia, authors have developed stringent exclusion criteria to define that syndrome. We believe that such an approach artificially created a homogeneous syndrome. As an alternative to the rigorous exclusion criteria approach, we propose to broaden the definition of crossed aphasia to accommodate the various demonstrated aphasic symptoms. The interest in crossed aphasia can then shift from the search for a universal symptom complex to different subgroups of patients. Indeed, there now appears to be overwhelming evidence (including Wada experiments) to indicate that crossed aphasia can cither be the mirror image of uncrossed aphasia or indicate a bilateral language representation pattern. Two patients are presented and their symptoms are discussed in the light of the literature. One of our patients is the only one to our knowledge to evidence affective prosody impairments. We argue that this latter symptom be added to the list of associated signs to be assessed as part of a crossed aphasia battery.     

Crossed Wernicke''s aphasia

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.     

Crossed aphasia: a PET follow up study of two cases.

Two cases of aphasia after right hemispheric stroke in right handed patients are described. The first patient had a severe mixed transcortical aphasia, apraxia and neglect after a lesion involving the right lenticular nucleus and periventricular white matter; aphasia was still present after three months. The second patient had a mild, transient fluent aphasia after a small right hemispheric periventricular lesion. Studies with [18F]FDG and positron emission tomography (PET) showed functional depression extending to the structurally unaffected left hemisphere in both patients in the acute stage. After three months, in the patient with persistent aphasia, metabolism was still reduced in the right hemisphere, with some recovery of hypometabolism on the left, while metabolic values had returned to normal in the patient with full language recovery. A close parallelism between glucose metabolism and clinical course in crossed aphasia is shown, as well as the presence of a functional involvement of the structurally unaffected left hemisphere in the acute stage.     

Crossed aphasia: description of a case

We describe a new case of crossed aphasia in a right-handed patient with a right hemispheric lesion. A right-handed man, 76 year-old, developed a sudden left hemiparesis with sensitive impairment and mutism. He has neither family history of left handeness or ambidexterity or vascular risk factors. CT cerebral scan showed a large infarct of the middle cerebral artery on the right side, with haemorrhagic suffusion. Cerebral MRI and EEG-cartography confirmed the indemnity of the left hemisphere. Aphasia studies confirmed a mutism with spared verbal comprehension, but alexia was present. A year later, left hemiparesis was recovered but aphasia remained. Crossed aphasia is rarely seen. It is caused by a right hemispheric lesion in right-handed subjects. Fluency is most commonly impaired. At onset, mutism is the common symptom, which evolves to expressive aphasia. Several hypothesis have been raised about the possible mechanisms involved. The few number of PET or SPECT studies performed in these patients have disclosed extensive areas of hypometabolism in the right hemisphere, that exceed the size of the image observed with CT scan or MRI.     

Crossed aphasia in a child

Aphasia due to a cortical--subcortical infarct occurred in a right-handed, five year-old boy. Twelve years later, language disturbances were still present.     

Crossed aphasia in multiple sclerosis

Aphasia is a rare sign of multiple sclerosis (MS). Several different forms of aphasia have been reported in MS. We report, to our knowledge, the first case of a MS patient with crossed aphasia during an attack.     

Crossed aphasia in a dextral

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.     

Crossed aphasia in early childhood.

A four-year-old child was admitted to hospital with an infarct of the right middle cerebral artery involving the frontoparietal area. His symptoms included left hemiplegia and aphasia. After two weeks, he had hemiparesis, word-finding and naming problems and enuresis. A year later he demonstrated elective mutism at school, had attention and short-term memory impairments, occasional enuresis and an average IQ. He was shy and withdrawn; this is interesting, since depression is usually associated with left-hemispheric lesions. It is suggested that an early period of mutism should be included among the criteria for the study of crossed aphasia in children, as this is a common occurrence in such cases. Even after recovery of speech, impairments in attention and academic skills may persist.     

Crossed aphasia in right handed patients

The very rare aphasia following damage to the right cerebral hemisphere in right-handed subjects is described, with a survey of the views on this problem and presentation of two cases of this so-called crossed aphasia in right-handed subjects. On one of these cases the lesion was cortico-subcortical in a part of the frontal lobe, temporal lobe and a part of the occipital lobe, with sparing of the deep structures of the right hemisphere and with clinical pattern resembling that of Broca aphasia. In the second case the lesion involved the subcortical and deep structures with destruction of the lentiform nucleus, anterior part of the internal capsule and part of the head of the caudate nucleus, and the clinical pattern resembled that of Wernicke aphasia.     

Crossed aphasia in a right-handed patient

A case of crossed aphasia in a right-handed patient provided evidence that cerebral dominance for speech may be located in the right hemisphere. Intravenous injection of amytal in the left carotid artery did not worsen the language disturbances. Comparison of this case with those reported shows that there is not a constant model with only one physiopathological mechanism for all cases of crossed aphasia in right-handed patients.     

Crossed aphasia with visceral situs inversus

A patient presenting the association of anomalous cerebral dominance for language, as revealed by crossed aphasia, and partial visceral situs inversus is described. Although it cannot be excluded that the two abnormalities coincided by chance, it is suggested that they both resulted from a single aberration of development.     

Crossed aphasia in a Chinese bilingual dextral

A persistent nonfluent aphasia following a right cerebral infarction developed in a 54-year-old right-handed Chinese man. Computerized axial tomography localized the lesion in the distribution of the right middle cerebral artery. The speech and language dysfunction was greater for performances in Chinese than in English, despite the fact that the patient was born in China, was schooled in Chinese until age 7, and spoke Chinese at home and in his business. It is suggested that early learning of Chinese, an ideographic language based on visual spatial percepts, might have been critical for the establishment and maintenance of language dominance in the right hemisphere.     

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.