1/46. Tactile morphagnosia secondary to spatial deficits.A 73-year old man showed visual and tactile agnosia following bilateral haemorrhagic stroke. Tactile agnosia was present in both hands, as shown by his impaired recognition of objects, geometrical shapes, letters and nonsense shapes. Basic somatosensory functions and the appreciation of substance qualities (hylognosis) were preserved. The patient's inability to identify the stimulus shape (morphagnosia) was associated with a striking impairment in detecting the orientation of a line or a rod in two- and three-dimensional space. This spatial deficit was thought to underlie morphagnosia, since in the tactile modality form recognition is built upon the integration of the successive changes of orientation in space made by the hand as it explores the stimulus. Indirect support for this hypothesis was provided by the location of the lesions, which could not account for the severe impairment of both hands. Only those located in the right hemisphere encroached upon the posterior parietal cortex, which is the region assumed to be specialised in shape recognition. The left hemisphere damage spared the corresponding area and could not, therefore, be held responsible for the right hand tactile agnosia. We submit that tactile agnosia can result from the disruption of two discrete mechanisms and has different features. It may arise from a parietal lesion damaging the high level processing of somatosensory information that culminates in the structured description of the object. In this case, tactile recognition is impaired in the hand contralateral to the side of the lesion. Alternatively, it may be caused by a profound derangement of spatial skills, particularly those involved in detecting the orientation in space of lines, segments and complex patterns. This deficit results in morphagnosia, which affects both hands to the same degree.- - - - - - - - - - ranking = 1keywords = hand (Clic here for more details about this article) |
2/46. Generalized auditory agnosia with spared music recognition in a left-hander. Analysis of a case with a right temporal stroke.After a right temporoparietal stroke, a left-handed man lost the ability to understand speech and environmental sounds but developed greater appreciation for music. The patient had preserved reading and writing but poor verbal comprehension. Slower speech, single syllable words, and minimal written cues greatly facilitated his verbal comprehension. On identifying environmental sounds, he made predominant acoustic errors. Although he failed to name melodies, he could match, describe, and sing them. The patient had normal hearing except for presbyacusis, right-ear dominance for phonemes, and normal discrimination of basic psychoacoustic features and rhythm. Further testing disclosed difficulty distinguishing tone sequences and discriminating two clicks and short-versus-long tones, particularly in the left ear. Together, these findings suggest impairment in a direct route for temporal analysis and auditory word forms in his right hemisphere to Wernicke's area in his left hemisphere. The findings further suggest a separate and possibly rhythm-based mechanism for music recognition.- - - - - - - - - - ranking = 0.83333333333333keywords = hand (Clic here for more details about this article) |
3/46. Dissociated active and passive tactile shape recognition: a case study of pure tactile apraxia.Disorders of tactile object recognition (TOR) may result from primary motor or sensory deficits or higher cognitive impairment of tactile shape representations or semantic memory. Studies with healthy participants suggest the existence of exploratory motor procedures directly linked to the extraction of specific properties of objects. A pure deficit of these procedures without concomitant gnostic disorders has never been described in a brain-damaged patient. Here, we present a patient with a right hemispheric infarction who, in spite of intact sensorimotor functions, had impaired TOR with the left hand. Recognition of 2D shapes and objects was severely deficient under the condition of spontaneous exploration. Tactile exploration of shapes was disorganized and exploratory procedures, such as the contour-following strategy, which is necessary to identify the precise shape of an object, were severely disturbed. However, recognition of 2D shapes under manually or verbally guided exploration and the recognition of shapes traced on the skin were intact, indicating a dissociation in shape recognition between active and passive touch. Functional MRI during sensory stimulation of the left hand showed preserved activation of the spared primary sensory cortex in the right hemisphere. We interpret the deficit of our patient as a pure tactile apraxia without tactile agnosia, i.e. a specific inability to use tactile feedback to generate the exploratory procedures necessary for tactile shape recognition.- - - - - - - - - - ranking = 0.33333333333333keywords = hand (Clic here for more details about this article) |
4/46. auditory perception in auditory neuropathy: clinical similarity with auditory verbal agnosia.The precise features of auditory perception in patients with auditory neuropathy have not been well described. In the present study, we examined auditory perception in a patient with auditory neuropathy. The patient was a right-handed 7-year-old boy. His chief complaint was delayed speech and suspected of verbal learning disability. He could talk, read and repeat rather fluently but could not understand fully what was asked. V-IQ, P-IQ and F-IQ of Wechsler Scale for Children III-R were 53, 118 and 81, respectively. Pure tone audiogram was completely normal. His speech discrimination ability was very poor. He could identify environmental sounds with visual matching. He could differentiate intensity difference but not time difference. This phenomenon was reported in patients with hemispheric symptoms. These clinical features are very similar to verbal auditory agnosia. ABR showed no response at 90dBnHL alternating clicks and tone bursts. Click evoked and distortion product otoacoustic emissions (OAE) were normal. Electrocochleogram was also normal. Motor and sensory nerve conduction velocity was completely normal. Pa of MLR and N1 of SVR were present. His diagnosis should be "pure type" of auditory neuropathy or auditory nerve disease. Importance of both ABR and OAE examination should be widely announced and auditory neuropathy must be campaigned stressed to be clinical entity among personnel who take care of children with speech delay.- - - - - - - - - - ranking = 0.16666666666667keywords = hand (Clic here for more details about this article) |
5/46. Posterior alien hand syndrome after a right thalamic infarct.The alien hand syndrome, as originally defined, should be reserved for cases in which the hand feels foreign "together with" observable involuntary motor activity. These involuntary movements are unusual during or after acute stroke. Three varieties of alien hand syndrome have been reported, involving lesions of the corpus callosum alone, the corpus callosum plus dominant medial frontal cortex, and posterior cortical and subcortical areas. A patient with posterior alien hand syndrome of vascular aetiology is reported. Imaging studies disclosed an isolated infarction of the right thalamus sparing other cerebral regions.- - - - - - - - - - ranking = 1.3333333333333keywords = hand (Clic here for more details about this article) |
6/46. Auditory agnosia in children after herpes encephalitis.Four pediatric patients whose bilateral auditory cortices were damaged by herpes encephalitis at an early age were studied. Their brain CT and MRI scans demonstrated common bilateral lesions of the auditory cortices. Their auditory perception was investigated by means of behavioral and objective hearing tests and auditory perception tests. All four patients showed mild or moderate hearing loss in the behavioral hearing test and normal auditory brainstem responses but did not manifest total deafness. Moreover, perception tests involving speech, environmental sounds and music demonstrated that most auditory perception ability had been lost in all patients. On reaching school age, the patients were enrolled in schools for the deaf or special schools for handicapped children.- - - - - - - - - - ranking = 0.16666666666667keywords = hand (Clic here for more details about this article) |
7/46. Balint's syndrome in a 10-year-old male.A 10-year-old male was referred with difficulties at school. He had particular difficulty with reading long words, following the sequence of text down a page, writing words in the correct order, writing words in line, and copying from the blackboard. He had a history of infective endocarditis complicated by intracerebral haemorrhage at the age of three years. Detailed history taking revealed symptoms typical of 'dorsal stream' pathology, namely a deficit of 'vision for action'. This included a spatial disorder of attention (simultanagnosia), defective hand and foot movements under visual control (optic ataxia), and acquired oculomotor apraxia which are consistent with Balint's syndrome. Strategies were suggested for coping with the symptoms and one year later a distinct improvement in adapting to the disability was found.- - - - - - - - - - ranking = 0.16666666666667keywords = hand (Clic here for more details about this article) |
8/46. Visuospatial deficits due to impaired visual attention: investigation of two cases of slowly progressive visuospatial impairment.Two patients with slowly progressive visuospatial impairment demonstrated a peculiar type of visuoconstructive deficit. The most prominent manifestation appeared when handling kanji (logogram) characters and other figurative patterns. The patients showed pure agraphia for complex kanji but not for kana (syllabogram) or Arabic numerals. Their abilities to read and understand kanji characters and to orally describe the structure of a kanji character were preserved. They could not draw or copy figures or symbols except for single lines or simple symbols, although they could identify and name the targets easily. They also performed poorly in such visuoconstructive tasks as the block design subtest and matching to sample tests that require the ability to simultaneously attend to multiple saliencies. When asked to copy multiple kana characters scattered on a sheet of paper, they could correctly describe the location of a particular character in relation to the others, but actually wrote each character in grossly mislocated positions. These findings suggest that when the patients start particular tasks, which require detailed visual analysis, their range of visual attention becomes extremely narrow. This task-dependent narrowing and fixation of visual attention might explain some of the visuoconstructive symptoms described in patients with slowly progressive visuospatial impairment.- - - - - - - - - - ranking = 0.16666666666667keywords = hand (Clic here for more details about this article) |
9/46. Tactile agnosia and tactile aphasia: symptomatological and anatomical differences.Two patients with tactile naming disorders are reported. Case 1 (right hand tactile agnosia due to bilateral cerebral infarction) differentiated tactile qualities of objects normally, but could neither name nor categorize the objects. Case 2 (bilateral tactile aphasia after operation of an epidural left parietal haematoma) had as severe a tactile naming disturbance as Case 1, but could categorize objects normally, demonstrating that tactile recognition was preserved. Case 1 may be the first case of tactile agnosia clearly differentiated from tactile aphasia. CT scans of Case 1 revealed lesions in the left angular gyrus, and in the right parietal, temporal, and occipital lobes. Case 2 had lesions in the left angular gyrus and of posterior callosal radiations. Our findings suggest that tactile agnosia appears when the somatosensory association cortex is disconnected by a subcortical lesion of the angular gyrus from the semantic memory store located in the inferior temporal lobe, while tactile aphasia represents a tactual-verbal disconnection.- - - - - - - - - - ranking = 0.16666666666667keywords = hand (Clic here for more details about this article) |
10/46. writing, calculating, and finger recognition in the region of the angular gyrus: a cortical stimulation study of gerstmann syndrome.OBJECT: In an attempt to gain a better understanding of the cerebral functions represented in the angular gyrus and to spare them during surgery, the authors studied patients with brain tumors located close to the angular gyrus and mapped cortical sites by using electrostimulation. methods: Before undergoing tumor removal, six right-handed patients (five with left and one with right hemisphere tumors) were studied using cortical mapping with the aid of calculating, writing, finger-recognition, and color-naming tasks in addition to standard reading and object-naming tasks (for a total of 36 brain mapping studies). Strict conditions of functional site validation were applied to include only those cortical sites that produced repetitive interferences in the function tested. Preoperatively, four of the patients exhibited discrete symptoms related to gerstmann syndrome while performing very specific tasks, whereas the other two patients presented with no symptoms of the syndrome. No patient had significant language or apraxic deficits. Distinct or shared cortical sites producing interferences in calculating, finger recognition, and writing were repeatedly found in the angular gyrus. Object- or color-naming sites and reading-interference sites were also found in or close to the angular gyrus; although frequently demonstrated, these latter results were variable and unpredictable in the group of patients studied. Finger agnosia and acalculia sites were also found elsewhere, such as in the supramarginal gyrus or close to the intraparietal sulcus. Mechanisms involved in acalculia, agraphia, or finger agnosia (either complete interferences or hesitations) during stimulation were various, from an aphasia-like form (for instance, the patient did not understand the numbers or words given for calculating or writing tasks) to an apparently pure interference in the function tested (patients understood the numbers, but were unable to perform a simple addition). CONCLUSIONS: Symptoms of gerstmann syndrome can be found during direct brain mapping in the angular gyrus region. In this series of patients, sites producing interferences in writing, calculating, and finger recognition were demonstrated in the angular gyrus, which may or may not have been associated with object-naming, color-naming, or reading sites.- - - - - - - - - - ranking = 0.16666666666667keywords = hand (Clic here for more details about this article) |
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