Dissociation Between Personal and Extrapersonal Neglect in a Crossed Aphasia Study

Several reports document crossed aphasia following a right cerebral infarct. However, few of them provide a detailed investigation of associated neuropsychological disorders. A personal neglect disorder with no difficulty in orienting attention in the contralesional space has not been frequently reported independently of lesion side for the language deficit. In most cases, the deficit is described in the acute period. We report the case of a patient who showed severe crossed aphasia several months after cerebral damage. In addition to his language deficit, he suffered from finger agnosia, acalculia, and right/left confusion. Although he was able to orient attention in the contralesional space, he had a persistent personal neglect disorder with severe difficulty in attending to his own body. Results suggest that right hemisphere language dominance does not preclude ipsilateral specialisation for other functions. Furthermore, the dissociation between the two spatial functions provides further confirmation that they are subserved by two independent systems.     

A case of crossed aphasia in a dextral patient with polycythemia]

We report a 72-year-old right-handed man who was diagnosed as having crossed aphasia. He had polycythemia, hypertension and an old cerebral infarction in the right occipital lobe. He was admitted to our hospital because of muscle weakness in the left extremities at the age of 71. In the laboratory data, red blood cells(689 x 10(4)/microliter) and platelets(87.6 x 10(4)/microliter) were increased in number. Brain CT detected a right putaminal hematoma and an old infarct in the occipital lobe on the right. After admission, he developed non-fluent speech, and impairments of auditory comprehension, writing and naming due to the infarction in his right cerebral hemisphere including the middle cerebral artery distribution. The standard language test of aphasia(SLTA) revealed marked impairments in the language function, except for reading kana and kanji words. This writing was severely impaired compared with other language dysfunctions. Auditory comprehension, repetition and reading were impaired at the sentence level rather than at the kana word level. Furthermore, he suffered from left hemiparesis and left unilateral spatial neglect. We diagnosed his impairments of language function as crossed aphasia based on his right-handedness, CT findings and the results of SLTA. His language center was considered to be located in both cerebral hemispheres. Compared with typical findings in reported cases of crossed aphasia, the presence of both non-fluent speech and mutism were consistent with previous observations. However, the marked impairments of auditory comprehension, repetition and naming were different. Polycythemia and hypertension were considered to be the risk factors of cerebral infarction in our patient.     

Personal neglect-a disorder of body representation?

The cognitive mechanisms underlying personal neglect are not well known. One theory postulates that personal neglect is due to a disorder of contralesional body representation. In the present study, we have investigated whether personal neglect is best explained by impairments in the representation of the contralesional side of the body, in particular, or a dysfunction of the mental representation of the contralesional space in general. For this, 22 patients with right hemisphere cerebral lesions (7 with personal neglect, 15 without personal neglect) and 13 healthy controls have been studied using two experimental tasks measuring representation of the body and extrapersonal space. In the tasks, photographs of left and right hands as well as left and right rear-view mirrors presented from the front and the back had to be judged as left or right. Our results show that patients with personal neglect made more errors when asked to judge stimuli of left hands and left rear-view mirrors than either patients without personal neglect or healthy controls. Furthermore, regression analyses indicated that errors in interpreting left hands were the best predictor of personal neglect, while other variables such as extrapersonal neglect, somatosensory or motor impairments, or deficits in left extrapersonal space representation had no predictive value of personal neglect. These findings suggest that deficient body representation is the major mechanism underlying personal neglect.     

Leftward movement in severe neglect

Abstract

The difficulty that patients with unilateral spatial neglect (USN) have in exploring into the contralesional space may be explained by motor or attentional disorder. We experienced a patient with severe USN following cerebral infarction in the right postrolandic region, who showed a strong resistance to leftward movement. We devised two sets of tasks using a whiteboard. In the first experiment, the patient showed great difficulty in tracing a line from the right endpoint to the left endpoint. The examiner barely made him start further tracing even by pushing the hand leftward. By contrast, he quickly erased a whole line leftward with an eraser pen. In the second experiment, he was required to erase a line with or without an attention-attracting stimulus at the right endpoint. Not only the leftward extent, but also the velocity of erasing, were decreased when there was a stimulus at the right endpoint. The results of the two experiments suggest that the ability of leftward movement itself was preserved and overattention to the right-sided stimuli impaired his leftward movement. We consider that use of the line-tracing and line-erasing tasks may contribute to a better understanding of interaction of attentional andmotor and motor factors in severe USN.     

Lost in space--the fate of memory representations for non-neglected stimuli

Typically, spatial neglect after right-hemisphere brain damage is defined as a failure to orient towards or attend to stimuli located towards the contralesional, in this case the left, side of space. Here, we report that neglect patients have difficulty maintaining the spatial locations of vertically arranged stimuli on the right side of space. This indicates that neglect is associated with a severe deficit in the maintenance of spatial information even on the ipsilesional "good" side.     

Neuropsychological and neuroimaging findings of developmental dysphasia: A longitudinal case study

This article presents an unusual and interesting neuropsychological and neuroimaging longitudinal study of a child who showed a relatively specific developmental language disorder in the absence of any other significant cognitive, emotional or neurological disturbance. The neuropsychological assessment included tests of intelligence, memory, language and frontal lobe functions. Our patient had a marked developmental language disorder characterized by severe impairment of oral and written language and a restricted vocabulary, even though the comprehension of both spoken and written language was relatively preserved. Moreover, his non-verbal intellectual ability was normal and he showed superior visuoconstructive and visuospatial abilities which suggested good development of right temporoparietal functions. On computerized tomography and magnetic resonance imaging there were no structural abnormalities in those cerebral areas concerned with language, although both neuroimaging studies did show a feasible reversed asymmetry or further atrophy on the left sylvian. It is noticeable that at age 17 a severe deficit in the expressive aspects of language remains. In contrast, visuo-constructive functions have improved. These results suggest a functional reorganization of the brain by increasing non-verbal capabilities. The prognosis in dysphasic syndromes is worse than in acquired aphasia in children, since despite speech therapy, an important language impairment persists during adulthood.     

Neuropsychological and neuroimaging findings of developmental dysphasia: A longitudinal case study

This article presents an unusual and interesting neuropsychological and neuroimaging longitudinal study of a child who showed a relatively specific developmental language disorder in the absence of any other significant cognitive, emotional or neurological disturbance. The neuropsychological assessment included tests of intelligence, memory, language and frontal lobe functions. Our patient had a marked developmental language disorder characterized by severe impairment of oral and written language and a restricted vocabulary, even though the comprehension of both spoken and written language was relatively preserved. Moreover, his non-verbal intellectual ability was normal and he showed superior visuoconstructive and visuospatial abilities which suggested good development of right temporoparietal functions. On computerized tomography and magnetic resonance imaging there were no structural abnormalities in those cerebral areas concerned with language, although both neuroimaging studies did show a feasible reversed asymmetry or further atrophy on the left sylvian. It is noticeable that at age 17 a severe deficit in the expressive aspects of language remains. In contrast, visuo-constructive functions have improved. These results suggest a functional reorganization of the brain by increasing non-verbal capabilities. The prognosis in dysphasic syndromes is worse than in acquired aphasia in children, since despite speech therapy, an important language impairment persists during adulthood.     

Spatial-temporal anisometries following right parietal damage

Patients with right parietal damage often have a lateralized deficit of spatial attention. In addition to a spatial deficit, such patients have also been reported to have a non-spatial deficit in temporal processing. Here, we tested the hypothesis that these spatial and temporal deficits might be linked if the right temporal-parietal cortex is important in integrating spatial and temporal attention. In AF, a patient with an acute right temporal-parietal stroke, we replicated previous observations showing that he was biased to judge ipsilesional stimuli as occurring before contralesional stimuli. More importantly, for vertically aligned stimuli, AF more accurately judged the temporal order of successive ipsilesional than contralesional stimuli. Furthermore, his contralesional performance improved with stimuli with larger vertical separations. Taken together, these findings provide additional evidence that right temporal-parietal damage produces a processing refractory period for stimuli in contralesional space that extends in both space and time. These findings are in agreement with other studies that suggest that the right temporal-parietal cortex is important in integrating the where and when of stimuli.     

Contralesional neglect in monkeys with small unilateral parietal cortical ablations

Transient contralesional spatial neglect, in addition to motor impairment in the contralesional arm, is sometimes seen in patients following cerebral infarction in the right hemisphere and is seen following experimental occlusion of the right middle cerebral artery in primates. To test whether contralesional visuospatial neglect arises from a disruption of the forward flow of information from the striate cortex through the dorsal territory of the middle cerebral artery, we made a small strip suction ablation in the right parietal cortex from the medial edge of the dorsal cortical surface to the posterior ventral edge of the superior temporal gyrus in marmoset monkeys. These monkeys did not exhibit a motor impairment, or misreaching, with the contralesional arm. When they were unrestrained and free to use either arm, they were impaired at finding rewards in their contralesional space and in choosing the nearer of two rewards hidden in ipsilesional space (i.e. they had an ultra-ipsilesional bias in ipsilesional space). Comparison of performance under four conditions in a task in which the monkeys were constrained to reach into each hemispace with each arm separately indicated that they were impaired at reaching into contralesional, but not ipsilesional, space with either arm but they did not exhibit any impairment confined to the contralesional arm. These impairments in contralesional space were transient suggesting that the monkeys were able to re-align their egocentric spatial coordinates to obviate these deficits.     

Recovery of language function in Korean-Japanese crossed bilingual aphasia following right basal ganglia hemorrhage

ABSTRACT

Few studies have investigated language recovery patterns and the mechanisms of crossed bilingual aphasia following a subcortical stroke. In particular, Korean-Japanese crossed bilingual aphasia has not been reported. A 47-year-old, right-handed man was diagnosed with an extensive right basal ganglia hemorrhage. He was bilingual, fluent in both Korean and Japanese. After his stroke, the patient presented with crossed aphasia. We investigated changes in the Korean (L1) and Japanese (L2) language recovery patterns. Both Korean and Japanese versions of the Western Aphasia Battery (WAB) were completed one month after the stroke, and functional magnetic resonance imaging (fMRI) was performed using picture-naming tasks. The WAB showed a paradoxical pattern of bilingual aphasia, with an aphasia quotient (AQ) of 32 for Korean and 50.6 for Japanese, with Broca’s aphasia. The patient scored better in the Japanese version of all domains of the tests. The fMRI study showed left lateralized activation in both language tasks, especially in the inferior frontal gyrus. After six months of language therapy targeting L1, the Korean-WAB score improved significantly, while the Japanese-WAB score showed slight improvement. In this case, the subcortical lesion contributed to crossed bilingual aphasia more highly affecting L1 due to loss of the cortico-subcortical control mechanism in the dominant hemisphere. The paradoxical pattern of bilingual aphasia disappeared after lengthy language therapy targeting L1, and the therapy effect did not transfer to L2. Language recovery in L1 might have been accomplished by reintegrating language networks, including the contralesional language homologue area in the left hemisphere.     

Japanese crossed Wernicke's aphasia.

A right-handed Japanese man with no personal or family history of left-handedness developed severe Wernicke's aphasia, a mild constructional disorder, and slight left hemiparesis. MRI revealed infarction in the territory of the righ middle cerebral artery, including areas homologous to Broca's and Wernicke's areas. The cerebral blood flow in these areas remained diminished even after language activation. The most likely explanation is that language production occurred in the left Broca's area, while language comprehension occurred in the right Wernicke's area (a dissociated aphasia).     

Ipsilesional and contralesional regions participate in the improvement of poststroke aphasia: a transcranial direct current stimulation study

In the past few years, noninvasive cerebral stimulations have been used to modulate language task performance in healthy and aphasic patients. In this study, a dual transcranial direct current stimulation (tDCS) on anterior and posterior language areas was applied for 2 weeks to a patient with a possible crossed aphasia following a right hemisphere stroke. Inhibitory cathodal stimulation of the right Brodmann areas (BA) 44/45 and simultaneous anodal stimulation of the left BA 44/45 improved the patient’s performance in picture naming. Conversely, the same bilateral montage on BA 39/40 did not produce any significant improvement; finally, electrode polarity inversion over BA 39/40 yielded a further improvement compared with the first anterior stimulation. Our findings suggest that ipsilesional and contralesional areas could be useful in poststroke functional reorganization and provide new evidences for the therapeutic value of tDCS in aphasia.     

Crossed anomic aphasia: mild naming deficits following right brain damage in a dextral patient.

A detailed case study is reported of crossed aphasia (CA) in a dextral patient, bearing upon such controversial issues as intrahemispheric localisation of language function and hemispheric reversal of nonverbal function. DA, a man aged 37, developed a mild naming problem due to right temporal lobe haematoma. Apart from a mild acquired stutter, his continuous speech was fluent and had a normal proportion of open to closed class lexical items. His naming deficit appears to originate in the 'blocking' or 'disconnection' of the phonological lexicon: he could usually give a functional definition of un-named items and retrieve them with the help of a phonemic cue. Lexical retrieval appears his only language deficit, as he had no comprehension or phonological discrimination deficits. DA showed no visuo-spatial or auditory-nonverbal deficits, suggesting the complete reversal of hemispheric specialisation.     

A case of crossed aphasia with echolalia after the resection of tumor in the right medial frontal lobe]

We report a right-handed woman, who developed a non-fluent aphasia after resection of astrocytoma (grade III) in the right medial frontal lobe. On admission to the rehabilitation department, neurological examination revealed mild left hemiparesis, hyperreflexia on the left side and grasp reflex on the left hand. Neuropsychologically she showed general inattention, non-fluent aphasia, acalculia, constructional disability, and mild buccofacial apraxia. No other apraxia, unilateral spatial neglect or extinction phenomena were observed. An MRI demonstrated resected areas in the right superior frontal gyrus, subcortical region in the right middle frontal gyrus, anterior part of the cingulate gyrus, a part of supplementary motor area. Surrounding area in the right frontal lobe showed diffuse signal change. She demonstrated non-fluent aprosodic speech with word finding difficulty. No phonemic paraphasia, or anarthria was observed. Auditory comprehension was fair with some difficulty in comprehending complex commands. Naming was good, but verbal fluency tests for a category or phonemic cuing was severely impaired. She could repeat words but not sentences. Reading comprehension was disturbed by semantic paralexia and writing words was poor for both Kana (syllabogram) and Kanji(logogram) characters. A significant feature of her speech was mitigated echolalia. In both free conversation and examination setting, she often repeated phrases spoken to her which she used to start her speech. In addition, she repeated words spoken to others which were totally irrelevant to her conversation. She was aware of her echoing, which always embarrassed her. She described her echolalic tendency as a great nuisance. However, once echoing being forbidden, she could not initiate her speech and made incorrect responses after long delay. Thus, her compulsive echolalia helped to start her speech. Only four patients with crossed aphasia demonstrated echolalia in the literature. They showed severe aphasia with markedly decreased speech and severe comprehension deficit. A patient with a similar lesion in the right medial frontal lobe had aspontaneity in general and language function per se could not be examined properly. Echolalia related to the medial frontal lesion in the language dominant hemisphere was described as a compulsive speech response, because some other 'echoing' phenomena or compulsive behavior were also observed in these patients. On the other hand, some patients with a large lesion in the right hemisphere tended to respond to stimuli directed to other patients, so called 'response-to-next-patient-stimulation'. This behavior was explained by disinhibited shift of attention or perseveration of the set. Both compulsive speech responses and 'response-to-next-patient-stimulation' like phenomena may have contributed to the echolalia phenomena of the present case.     

Selective deficit of auditory localisation in patients with visuospatial neglect.

Possible auditory deficits in neglect were examined by comparing the performance of four right brain-damaged (RBD) patients with left visuospatial neglect, versus four RBD patients without neglect, in three auditory tasks. The first task required speeded discrimination of sound elevation, by moving a central lever up or down according to the vertical position of a peripheral target sound, regardless of its side. The other two auditory tasks were non-spatial, requiring either speeded pitch discrimination (moving the central lever up for high pitch, down for low pitch) or speeded target detection. Neglect patients' performance was impaired with respect to RBD controls only when the auditory task required spatial coding of the target sound (the up/down spatial discrimination). This demonstrates a selective deficit of auditory space perception in neglect patients. This auditory spatial deficit was more pronounced for left than right sounds. Since auditory space perception was impaired in the vertical dimension, the observed deficit cannot be attributed to a systematic rightward shift in sound localisation. Instead, the results suggest increased spatial uncertainty in sound localisation by neglect patients, particularly for auditory targets on the contralesional side. These findings are related to multimodal coding of space in the parietal cortex, which was damaged in the neglect patients, but not in the RBD controls.     

Dynamic aphasia: the selective impairment of verbal planning

A single case study of a patient, ROH, who had a space occupying lesion in the left frontal lobe is reported. His selective speech disorder had all the hallmarks of a dynamic aphasia. Tests of sentence completion, phrase generation and sentence generation were administered. His ability to generate sentences was significantly better given a pictorial context than a verbal context. Although he could order a sequence of pictures, he had the greatest difficulty in ordering the constituent words of a sentence. Luria's hypothesis that dynamic aphasia is due to an impairment of inner speech which provides "the linear scheme of a sentence" is discussed. It is concluded that dynamic aphasia does not reflect a deficit of language processing but rather the selective impairment of verbal planning.     

Exploratory saccades show no direction-specific deficit in neglect

In patients with spatial neglect, contralesional reflexive saccades toward suddenly appearing targets show direction-specific deficits. We examined whether these deficits also occur during free exploration of space. Neglect patients' voluntary eye movements showed reduced amplitudes for saccades in all directions but no direction-specific deficit. The results argue against an interpretation of spatial neglect as a general deficit to disengage attention or to program saccades in contralesional direction.     

An autopsied case of corticobasal degeneration with onset of nonfluent aphasia revealing symmetrical cerebral involvement

Herein we describe a patient with established corticobasal degeneration with onset of nonfluent aphasia and showing symmetrical cerebral involvement. A 64-year-old man with a speech disorder for 2 years visited our hospital. He had nonfluent aphasia (reduced spontaneous speech, loss of intonation, anomia, repetition disorder, and difficulty in speaking short sentences). He also showed right-sided motor neglect, hypertonus of the left lower limb, a mask-like facial expression, and difficulty in closing his eyes. He was restless and walked around even during examination, suggesting frontotemporal dementia (FTD). Single-photon emission computed tomography (SPECT) revealed symmetrical reduction of cerebral blood flow in the bilateral fronto-temporo-parietal lobes. His neurological condition deteriorated gradually and a year later he could not speak comprehensive sentences. Magnetic resonance imaging (MRI) of the head at age 70 showed symmetrical atrophy of the bilateral fronto-temporal lobes. He died of respiratory failure after clinical problems lasting ten years. On pathological examination, the fixed brain weighed 1,010 g and showed bilateral symmetrical atrophy of the frontal lobes. Histopathological examination revealed neuronal loss and gliosis in the frontal lobes, especially in the frontal convexity, superior frontal gyrus and precentral gyrus. Gallyas-Braak silver staining showed astrocytic plaques, argyrophilic threads and coiled bodies mainly in the frontal lobes. The substantia nigra showed severe neuronal loss on both sides and presence of free melanin. Pathological diagnosis was corticobasal degeneration (CBD). We believe that the patient had nonfluent aphasia and FTD reflected in bilateral degeneration of the frontal lobes. Some cases of CBD may present with symmetrical degeneration of the brain, even though left-hemisphere symptoms such as aphasia reveal themselves at an early stage.     

Crossed aphasia: functional studies with single photon emission computerized tomography

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 hypoperfusion three year after the onset of stroke.     

Hypnosis meets neuropsychology: simulating visuospatial neglect in healthy participants

Neglect patients are not aware of stimuli in the contralesional space. We aimed to simulate neglect-like behaviour in healthy participants, by asking them to orient their visuospatial attention in two conditions: non-hypnotic suggestion and post-hypnotic suggestion. Results showed that directing visuospatial attention to one side of space caused neglect of stimuli in the opposite side of space, but only when participants were under post-hypnotic suggestion. Furthermore, directing visuospatial attention to the right side of space caused more neglect of left-sided stimuli than directing visuospatial attention to the left side of space did for right-sided stimuli. We propose that post-hypnotic suggestion can be a useful tool for (de)activating neurocognitive mechanisms underlying visuospatial awareness, a function that is fundamental for our survival. The use of post-hypnotic suggestion could be applied to the study of many domains of cognitive neurosciences (e.g., neurocognitive rehabilitation).