11/13. Progressive ideomotor apraxia: evidence for a selective impairment of the action production system.We report a patient with slowly progressive bilateral limb apraxia associated with an asymmetrical focal degenerative process of the parietal lobes. Clinical assessment of praxis production suggested a striking deficit in controlling the spatiotemporal attributes of purposeful skilled limb movements, consistent with ideomotor apraxia. The precise nature of the action production impairment was further defined by objective three-dimensional computergraphic analysis of transitive movements which demonstrated significant kinematic deficits in spatial accuracy, timing, spatiotemporal coupling, and joint coordination. Gesture comprehension and discrimination were spared. Furthermore, detailed evaluation of the conceptual praxis system revealed that despite an almost complete inability to perform transitive movements accurately, abstract knowledge of tool function and action was remarkably well preserved. The critical dissociation between intact conceptual knowledge of action and impaired movement execution documented in this case points to a fundamental competence/performance dichotomy in apraxia and provides empirical support for cognitive models of praxis that divide the action system into distinct conceptual and production subcomponents. Within this theoretical framework, our patient's severe ideomotor apraxia is interpreted to represent a selective disruption of the action production system.- - - - - - - - - - ranking = 1keywords = discrimination (Clic here for more details about this article) |
12/13. Corticobasal degeneration with primary progressive aphasia and accentuated cortical lesion in superior temporal gyrus: case report and review.A 57-year-old woman showed progressive sensory aphasia as an initial symptom, and then developed total aphasia within 6 years and, finally, severe dementia. Neuropathologically, the cerebral cortex was most severely affected in the superior and transverse temporal gyri, and subsequently in the inferior frontal gyrus, especially in the pars opercularis. The degeneration in the subcortical grey matter was most severe in the substantia nigra, and it was moderate to mild in the ventral part of thalamus, globus pallidus and striatum. Cytopathologically, in addition to achromatic ballooned neurons, massive taupositive types of cytosekeletal abnormalities were observed both in neurons and glia, mainly in the degenerating region. This cytoskeletal pathology coincided with that reported in corticobasal degeneration (CBD). On Bodian staining, only a few neurofibrillary tangles were found in the entorhinal pre-alpha layer and substantia nigra. Pick's bodies and senile plaques could not be found. This case is thought to represent a type of CBD, but with its cortical lesion focus located in the speech area instead of the frontoparietal region. A survey of 28 pathologically evaluated cases of CBD revealed two similar cases, both of which began with progressive aphasia and presented cortical degeneration in the superior temporal gyrus. An overview of CBD cases clarified the features in another group of cases, in which the cerebral accentuated focus was shifted forward from the central region, clinically resembling Pick's disease. The clinical manifestations in CBD seem to be the expression of these diverse cortical lesions. Primary progressive aphasia may include cases of CBD with involvement of the language center.- - - - - - - - - - ranking = 0.04528825415283keywords = speech (Clic here for more details about this article) |
13/13. Slowly progressive limb-kinetic apraxia.The case of a 69-year-old female with slowly progressive limb-kinetic apraxia (LKA) of the right hand over 3.5 years is reported. She did not show any other neurological or neuropsychological symptoms except for a defect in two-point discrimination, and 3.5 years after onset she developed a slight cogwheel-like muscle tone in the right wrist. brain MRI revealed atrophic changes in the left central region including the precentral and postcentral gyri and the superior parietal region, and among them, most strikingly at the postcentral gyrus. 123I-IMP SPECT revealed decreased 123I uptake in the atrophic lesion as revealed by MRI. We should suspect corticobasal degeneration as the etiology for this patient taking her symptoms and findings on MRI and SPECT into consideration. However, her symptoms and course were quite unique among the case reports of patients with slowly progressive LKA as she had only LKA and a defect in two-point discrimination for more than 3.5 years without any other symptoms. This characteristic also indicated that the simultaneous appearance of LKA and a defect in two-point discrimination may suggest a mechanism of LKA in the present patient.- - - - - - - - - - ranking = 3keywords = discrimination (Clic here for more details about this article) |
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