1/6. The role of the dynamic body schema in praxis: evidence from primary progressive apraxia.On an influential model of limb praxis, ideomotor apraxia results from damage to stored gesture representations or disconnection of representations from sensory input or motor output (Heilman & Gonzalez Rothi, 1993; Gonzalez Rothi et al., 1991). We report data from a patient with progressive ideomotor limb apraxia which cannot be readily accommodated by this model. The patient, BG, is profoundly impaired in gesturing to command, to sight of object, and to imitation, but gestures nearly normally with tool in hand and recognizes gestures relatively well. In addition, performance is profoundly impaired on imitation of meaningless gestures and on tasks requiring spatiomotor transformations of body-position information. We provide evidence that BG's apraxia is largely attributable to impairments external to the stored gesture system in procedures coding the dynamic positions of the body parts of self and others; that is, the body schema. We propose a model of a dynamic, interactive praxis system subserved by posterior parietal cortex in which stored representational elements, when present, provide "top-down" support to spatiomotor procedures computed on-line. In addition to accounting for BG's performance, this model accommodates a common pattern of ideomotor apraxia more readily than competing accounts.- - - - - - - - - - ranking = 1keywords = hand (Clic here for more details about this article) |
2/6. Apraxia of tool use: an autopsy case of biparietal infarction.Although disorders in the use of single objects have been reported, there have been few detailed analyses. We describe the autopsy case of a 65-year-old, right-handed male patient with severe impairment of actual tool use which was caused by biparietal infarctions. He persistently and stably showed a severely defective use of actual objects, single or multiple, and relatively well-preserved pantomimes of object use and intransitive gestures. He did not have aphasia or dementia, and his ability for tool naming and function description was completely preserved. The author identified similar patterns of errors about a tool-action(-target) relationship both in single-object use and multiple-object use. Lesion analysis showed cortical infarcts mainly located in the bilateral inferior parietal lobules, extending into the temporal lobe on the right side.- - - - - - - - - - ranking = 1keywords = hand (Clic here for more details about this article) |
3/6. Ideomotor and ideational apraxia in corticobasal degeneration: a case study.Corticobasal degeneration (CBD) is a progressive disorder that can be characterised by asymmetrical akinetic rigidity, involuntary movements, cortical sensory loss, alien limb syndrome and asymmetrical apraxia (Gibb et al., 1989; Rinnie et al., 1994). diagnosis of praxic disabilities is thought to be essential for distinguishing CBD, in its early stage, from other akinetic-rigid syndromes. However, the nature of apraxia in CBD, and the relations between ideomotor and ideational apraxia, are not well understood. For example, if there is an ideational deficit in a given patient, does this deficit occur independently of any ideomotor disorder, or are the two impairments linked in some manner? In the present paper we report a case study of a patient with apraxia due to CBD. We examine whether the disorder is confined to production tasks, or whether there is also a related deficit in recognising the correct actions performed with objects (an ideational deficit). We also evaluate whether a disorder found for action with single objects dissociates from the ability to link multiple actions into more complex, everyday tasks. The performance of our patient showed an impairment in both action production and action recognition system, suggesting a component of ideational as well as ideomotor apraxia in CBD.- - - - - - - - - - ranking = 182.46494877064keywords = alien (Clic here for more details about this article) |
4/6. A single case-study of diagonistic dyspraxia.Diagonistic dyspraxia is a clinical syndrome usually characterized by involuntary and conflicting behaviors between the hands following corpus callosum lesions. In the present study, we report the case of a patient who presents such symptoms, along with a series of complex abnormal behaviors, such as carrying out an action and subsequently doing the exact opposite, or being unable to choose between two alternative decisions. The data reported in this study indicate that, at least in some patients, diagonistic dyspraxia can be associated with abnormal, antagonistic, behaviors not limited to the hands. In our view, diagonistic dyspraxia result from lesion of the posterior corpus callosum while associated complex abnormal behaviors result from concomitant anterior lesions.- - - - - - - - - - ranking = 2keywords = hand (Clic here for more details about this article) |
5/6. Corticobasal syndrome with novel argyrophilic glial inclusions.A 42-year-old, left-handed woman first noted impaired dexterity of the dominant hand, soon followed by dysarthria and cognitive decline. Over a 4-year period, she developed severe left-sided apraxia with eventual neglect of the left arm and progressive extrapyramidal signs. Cognitive testing showed progressive executive, visuospatial, fluency, and naming impairment with relative preservation of memory. Single-photon emission computed tomography demonstrated asymmetric right posterior frontal and superior parietal hypoperfusion. The clinical impression was corticobasal degeneration. At autopsy, severe atrophy was seen in the perirolandic and frontal regions. There was marked neuronal loss and gliosis in the posterior frontal and precentral regions and less severe pathology in prefrontal, temporal, and parietal areas. Mild to moderate gliosis and neuronal loss were also seen in the putamen, globus pallidus, subthalamic, and dentate nuclei. Gallyas silver stain revealed numerous inclusions adjacent to oligodendrocyte nuclei in white and gray matter of affected cortical and subcortical regions. The gracile inclusions were wavy, slender, and stained positively with antibodies to ubiquitin and alphaB-crystallin but not to microtubule-associated proteins (tau, MAP1B, MAP2), tubulin, neurofilaments, glial fibrillary acidic protein, or alpha-synuclein. The argyrophilic inclusions identified in this case are distinct from those previously described in neurodegenerative diseases.- - - - - - - - - - ranking = 2keywords = hand (Clic here for more details about this article) |
6/6. The alien hand syndrome: report of a case and review of the literature.The term "alien hand syndrome (AHS)" comprises many clinical signs of which the common features are the involuntary motor movement of the affected limb and the denial of limb ownership. It can result from several diseases involving corpus callosum or medial frontal cortex. Two major types of AHS were previously classified, callosal and frontal types. Moreover posterior subtype of which the lesions do not involve corpus callosum have been reported. In the present report, the authors describe a 57-year-old man with AHS, aggressive behavior and hemispatial neglect which are the rare manifestations of callosal damage. neuroimaging demonstrated subacute infarction of entire corpus callosum from the rostrum to splenium. A review of the literature on these abnormalities is included in the present paper.- - - - - - - - - - ranking = 23613.663170021keywords = alien hand syndrome, hand syndrome, alien hand, alien, hand (Clic here for more details about this article) |