The anatomic basis of pure alexia

The behavioral and anatomic correlates of pure alexia were analyzed in 16 patients. Right homonymous hemianopia failed to appear in three patients, who had right achromatopsia instead. Color anomia and unilateral optic ataxia were seen in six patients. Memory defects were found in two patients. Visual agnosia was noted in two. No patient had visual disorientation. The crucial anatomic correlate of alexia was a lesion of the paraventricular white matter of the left occipital lobe, capable of compromising both interhemispheric and intrahemispheric visual pathways. The lesion associated with color anomia was in the mesial occipitotemporal junction of the left hemisphere.     

Disconnection syndrome in a right-handed patient with right hemispheric speech dominance

The callosal disconnection syndrome is characterized by unilateral (left) tactile anomia, unilateral (left) agraphia and unilateral (left) ideomotor apraxia. We report on a right-handed patient, who developed a callosal disconnection syndrome due to the rupture of an anterior communicant aneurysm. As he had right hemisphere dominance for language and praxis, the signs described above were crossed. He also featured a left alien hand sign and motor aprosody. The authors believe this is the first case of callosal disconnection in a right-hander with crossed language and praxis functions.     

Basal temporal language area demonstrated by electrical stimulation

We report on a 38-year-old patient with intractable complex partial seizures originating in the dominant left medial temporal region. In the work-up for seizure surgery, arrays of subdural electrodes were placed, and electrical stimulation revealed marked language interference in a 2 X 2-cm area in the left basal temporal fusiform gyrus (3.5 to 5.5 cm posterior to the temporal tip). Complete receptive and expressive aphasia, inability to repeat, agraphia, and alexia were elicited, but visual memory was preserved, and no constructional apraxia was noted. Stimulation of the basal temporal gyrus at lower stimulus intensities produced a relatively selective and severe anomia.     

A study of visual processes in a case of interhemispheric disconnexion

A 75-year-old right-handed woman, after a probable cerebral infarct, developed an irregular constriction of the visual fields, a left-sided agraphia, and an anomia for objects in the left hand. Subsequent testing demonstrated an inability to name, though ability to recognize, letters and objects flashed in the homonymous left visual field. An inter-hemispheric disconnexion syndrome was inferred from these findings. The present publication concerns mainly the visual aspects of this disconnexion syndrome.Tasks were devised to test the abilities of the major and minor hemisphere: (a) the left hemisphere demonstrated a complete dominance for language expression and an incomplete dominance for written language comprehension; (b) the right hemisphere appeared to be dominant for some visuo-spatial tasks including number comprehension; (c) when the hemispheres were given contradictory visual informations on a non-verbal task (chimeric stimuli) there was a predominance of the right hemisphere. The right hemisphere appeared able to process complex information. Specialization of functional activities in each hemisphere is briefly discussed.     

Callosal disconnection syndrome in a left-handed patient due to infarction of the total length of the corpus callosum

We report on a left-handed patient with an ischemic infarction affecting exclusively the total length of the corpus callosum. This lesion clinically correlated with an almost complete callosal disconnection syndrome as described in callosotomy subjects, including unilateral verbal anosmia, hemialexia, unilateral ideomotor apraxia, unilateral agraphia, unilateral tactile anomia, unilateral constructional apraxia, lack of somesthetic transfer and dissociative phenomena. Despite the patient's left-handedness, his pattern of deficits was similar to the disconnection syndrome found in right-handers. Our report focusses on motor dominance and praxis. We followed-up the improvement in left apraxia and investigated the ability to initiate and learn a new visuo-motor skill. The results permit two tentative assumptions: (1) that the improvement in left apraxia was due to a compensatory increase in ipsilateral proximal muscle control, and (2) that motor dominance, i.e. the competence to initiate and learn a new movement pattern, was hemispherically dissociable from manual dominance in the sense of praxis control.     

Limb apraxia in patients with damage confined to the left basal ganglia and thalamus.

Limb apraxia was investigated with standardised tests in 14 patients whose CT scan provided evidence of a vascular lesion confined to the left basal ganglia, or the thalamus, or both, and not involving the cortex or adjacent white matter. Five patients were severely impaired in imitating movements and pantomiming object use. Four of them also performed poorly when tested with real objects. In two patients the lesion was primarily thalamic and in three the lesion was primarily in the lenticular nucleus and the posterior limb of the internal capsule. Patients without apraxia generally had smaller injuries, but there were exceptions. Apraxia is currently conceived of as due to damage of cortical areas and their cortico-cortical connections, but the present data suggest that the model should be enlarged to include the deep nuclei and the pathways running through them.     

A case of slowly progressive unilateral spastic hemiparasis, hand clumsiness, limb ataxia and constructional apraxia]

A 65-year-old woman was seen in our clinic because of a 4-year history of slowly progressive left hand clumsiness and left limping. Neurologically, she had left-side spastic hemiparasis including her tongue, hand clumsiness, limb ataxia, constructional apraxia, and memory impairment. Dementia, parkinsonism and lower motor neuron sign were not confirmed. MRI study showed diffuse cerebral atrophy and shrinkage of the right cerebral peduncle and pontine base. SPECT (99mTc-ECD) study revealed hypoperfusion of the right fronto-parietal cortex. This is a rare case presented with slowly progressive left-side spastic hemiparasis, mimicking Mills' syndrome. In addition this case had other cortical signs, such as ipsilateral hand clumsiness, limb ataxia, constructional apraxia. Neuroimaging study suspects that the right front-parietal cortex is the primary lesion. Etiologically atypical motor neuron disease with adjacent cortical involvement is suspected rather than corticobasal degeneration with severe unilateral pyramidal tract degeneration.     

Alexia with agraphia produced by localized infarction in the inferior posterior region of the left temporal lobe

There have been several reports on alexia with agraphia due to hemorrhage or trauma in the inferior posterior region of the left temporal lobe since Yamadori (1982) first reported a case of cerebral hemorrhage. We presented the first case of alexia with agraphia due to a circumscribed infarct in the inferior posterior region of the left temporal lobe. A 65-year-old right-handed man had an acute onset of inability to read Japanese "kana" letters and to write any letters. He had no difficulty in speaking or understanding. Neurological examination on admission was normal except for homonymous quadrantanopia in the right upper field. Neuropsychological findings: Spontaneous speech was fluent without dysprosody. There were no disturbances in auditory understanding or in repetition. He could read Japanese "kanji" characters correctly, however, he could not read any "kana" letters. Writing was also disturbed severely even as to his address, name or telephone number. Calculation was also difficult. There were no disturbances in naming colors, no ideomotor or constructional apraxia nor visual agnosia. X-ray computed tomography (CT) scan showed a faint low density area with ring enhancement suggesting a cerebral infarct in the inferior posterior region of the left temporal lobe. Patient's hospital course was characterized by a marked improvement of alexia, especially of "kana" letters as compared with that of "kanji" characters. Dissociative improvement of alexia compared with agraphia in this case could be explained by the fact that the lesion was in close contact with the occipital lobe and that he also had pure alexia in the early stage.     

Regional specificity of localized cortical lesions in West syndrome

West syndrome, although classified as a generalized epilepsy, is associated with localized cerebral lesions in some cases. However, similar localized cortical abnormalities usually can result in partial epilepsy, instead of West syndrome. We performed this study to determine the additional factors that result in West syndrome instead of partial epilepsy in patients with localized cerebral lesions. We reviewed the pathologic features, topographic localization, and side of unilaterally defined cerebral lesions in relation to the seizure types in 39 epileptic patients, including five patients who presented with West syndrome. The lesions of all five patients with West syndrome involved the temporal or occipital lobes (or both). Among the nine with an occipital lesion, four had West syndrome. In the 19 with a temporal lesion, three had West syndrome. However, in the 16 patients with a frontal lesion, none exhibited epileptic spasms. In four of the five with West syndrome the lesions were on the right side; 23 had lesions on the right, 16 had them on the left. Temporo-occipital lesions and lesions on the right were related to the genesis of West syndrome, which would be in close correlation with normal brain maturation.     

Alexia without agraphia: a clinico-tomographic study

The authors report the clinical findings and CT-scanning results in two cases of alexia without agraphia and review the literature on this subject. Both patients had extensive infarction in the territory supplied by the left posterior cerebral artery and developed severe alexia without agraphia, right hemianopia without color-anomia and one of them presented with transient verbal memory difficulties. In both cases the evolution was very good, with total regression of the alexia after 17 months in the first patient and almost complete recovery after there months in the second one. The authors comment on the causes and possible mechanisms of the alexias, especially of the alexia without agraphia, and suggest that every patient with right hemianopic disturbances due to occlusion of the left posterior cerebral artery be thoroughly studied from a neurological point of view, so that this syndrome can be detected since, notwithstanding its recognized rarity, it seems highly probable that many cases have been overlooked as a result of incomplete examination of the patients.     

Partial hemispheric disconnection syndrome of traumatic origin.

A patient presented left-sided apraxia, constructional disturbances with the right hand and left tactile anomia after a severe head injury. MRI showed a callosal lesion involving the middle and posterior third of the truncus. This finding supports the thesis that the posterior callosum plays a predominant role in the interhemispheric mediation for praxis, as well as in the right-left transfer of spatial information guiding constructional performance. Left-sided apraxia was evident on imitation, on verbal command and on visual presentation of an object, but not on tactual presentation and during the actual use of objects. Moreover, apraxia on imitation showed a more rapid recovery than apraxia on verbal command. These data are consistent with the hypothesis of a left-hemisphere dominance for praxis, which is almost absolute when the retrieval of the appropriate gesture requires a semantic analysis of the stimulus.     

Prosopagnosia without hemianopsia after unilateral right occipitotemporal lesion

Three atypical features were noted in a patient with prosopagnosia due to a right occipital hematoma: prosopagnosia was unassociated with achromatopsia, spatial disorientation or left visual field alexia; the right visual field was normal and the left field only slightly impaired; the lesion was apparently unilateral.     

Visuo-constructional disorders and alexia-agraphia associated with posterior cortical atrophy

A 57 year-old woman developed a slowly progressive environmental agnosia and dressing apraxia without disturbances of language, memory, orientation and social activities. Two years later, alexia, agraphia, visual agnosia, constructional apraxia, simultagnosia and imitation apraxia of nonsymbolic gestures were also noted. Ophthalmic examination demonstrated a left inferior quadranopsia. Oral comprehension was normal. There was no loss of insight, and behavioral response was appropriately concerned. Computed tomography and magnetic resonance imaging revealed bilateral cortical atrophy in parieto-occipital areas, most pronounced on the right side, with enlargement of the ventricles. Positron emission tomography demonstrated low flow and metabolism values in the right parietal, temporal and occipital regions. This case is very similar to those of posterior cortical atrophy recently reported by Benson et al. (1988). It suggests a selectively degenerative dysfunction of posterior association cortex, sparing oral language and verbal memory.     

Acquired alexia with agraphia syndrome in childhood

The acquired alexia with agraphia syndrome is a conspicuous disorder of reading and writing in the absence of significant other language impairments that has mainly been recorded in adults. Pure cases are rare, with most patients displaying mild aphasic deficits. In children, acquired reading and writing disorders are generally reported as part of more encompassing aphasic syndromes affecting oral and written language equally, for example, Broca or Wernicke aphasia. Documented instances of predominant acquired reading and writing disorders in childhood are exceptional. We report an 11-year-old, right-handed boy who sustained a left temporoparieto-occipital hematoma following rupture of an arteriovenous malformation and who consecutively presented with the acquired alexia with agraphia syndrome associated with word-finding difficulties. Neuropsychologic and neurolinguistic data showed that there was no concomitant Gerstmann and/or angular gyrus syndrome. Th e recoveryfrom the anomia was quite favorable, but recovery of written language was more protracted and acted on the patient's further scholastic achievement. This case is reminiscent of a historical childhood case reported in 1939 and is consonant with adult cases in terms of lesion location and semiologic picture.     

Slowly progressive limb-kinetic apraxia with a decrease in unilateral cerebral blood flow

We report two patients with slowly progressive motor disorders, whose principal manifestations were asymmetric limb-kinetic apraxia and muscle rigidity. In both patients MRI revealed no responsible lesion, whereas single photon emission computed tomography (SPECT) showed a decrease in cerebral blood flow (CBF) in the unilateral hemisphere. One patient with mainly right-sided apraxia had a decreased CBF in the left central region between the frontal and parietal cortices, and the other patient with left-sided apraxia in the right parietal cortex. In agreement with asymmetric clinical symptoms, the regional CBF decrease in the unilateral cortical areas including the frontal and parietal cortices may suggest a degenerative disease, presumably diagnosed as having cortico-basal degeneration.     

Reversed laterality of cerebral functions in a non-right-hander: neuropsychological and spect findings in a case of 'atypical' dominance.

A 54-year-old non-right-handed man with positive familial sinistrality showed a pure right hemisphere syndrome following a left hemisphere stroke. Severe right side hemineglect, transcortical motor dysprosodia, spatial dysgraphia and visuo-constructive impairments were observed. At no time were the expected left hemisphere abnormalities such as aphasia, alexia, right-left disorientation or finger agnosia noted. A left fronto-temporal subcortical lesion was documented on CT scan. A Tc-99m HM-PAO SPECT study revealed no cerebral blood flow changes in the right hemisphere while in the left hemisphere a fronto-temporo-parietal cerebral blood flow reduction was evident. This case of a complete reversed laterality of cognitive functions argues for a distinction to be made between 'anomalous' cerebral dominance and 'atypical' cerebral dominance.     

Naming difficulties in alexia with agraphia for kanji after a left posterior inferior temporal lesion.

The case is described of a patient with alexia and agraphia for kanji, and severe anomia after a subcortical haemorrhage in the left posterior inferior temporal area. Magnetic resonance imaging at four months after onset showed a lesion in the inferior temporal and fusiform gyri, extending from the temporo-occipital junction toward the anterior third of the temporal lobe. Comparison with other reported cases of alexia with agraphia and anomia made it clear that when accompanied by severe anomia, the lesions extended either forward to the anterior part of the middle temporal gyrus or medially to the parahippocampal gyrus. It is suggested that the disconnection of association fibres between the parahippocampal, fusiform, middle, and inferior temporal gyri, especially between the parahippocampal gyrus and the other temporal gyri, or the cortical damage to the posterior part of these gyri is essential for the production of anomia.     

Anterior choroidal artery syndrome. Neuropsychological study of 4 cases

A neuropsychological study was carried out in 4 cases of infarction in the territory of the anterior choro?dal artery. In 3 cases the lesions were on the right side. A syndrome of the minor hemisphere was present with severe visual neglect, constructional apraxia, alexia due to disorders of visuo-spatial strategy, anosognosia and motor impersistence. In the case with a left-sided lesion there was no neglect but a mild aphasia with impaired fluency, semantic paraphasias, perseveration and a decreased psycho-linguistic ability. The mechanisms of neglect in right-sided lesions are considered.