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q01 - kola
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03-07-2008, 08:20 AM
an infarct causing impairment Wernicke's aphasia is likely to be secondary to occlusion of the :
a) Anterior Choroidal Artery b) Anterior Cerebral Artery c) Superior division of the MCA territory d) Inferior division of the MCA territory e) stem of the MCA territory
03-07-2008, 08:23 AM
answer is D
Explanation When the MCA is occluded at its stem, the deep penetrating lenticulostriate arteries which supply parts of the internal capsule and basal ganglia may be blocked and there is compromised flow to the more superficial branches supplying the overlying cortex. An infarction within these territories produces contralateral herniplegia, hemianesthesia and homonymous hemianopia. When in the dominant hemisphere, severe aphasia is present; and when in the non-dominant hemisphere, hemineglect or other agnostic deficits are often present. If an embolus occludes one of the first order divisions of the middle cerebral artery, deficits arise that may be difficult to distinguish from internal carotid occlusive syndromes. Superior division of the MCA territory infarction yields contralateral, dense sensory and motor appendicular and facial weakness and, if within the dominant hemisphere, severe aphasia. Inferior division infarctions may be characterized by auditory language and repetition deficits and hernianopic visual problems. When second order divisions of the MCA are occluded (usually by emboli), the stroke symptoms are less global. If the first branch of the superior division of the MCA (the ascending frontal artery) is Occluded, then the third frontal convolution is infarcted, and there is contralateral brachiofacial weakness. When this occurs in the dominant hemisphere, the damaged region includes Broca~s area; and the initial presentation also includes mutism or dysfluency with little or no difficulty in verbal comprehension. When the territory of the second branch of the superior division of the MCA (the rolandic branch) is infarcted, there is contralateral sensory and/or motor weakness accompanied by articulatory difficulties (dysarthria), but not aphasia. Occlusion of the third (ascending parietal) or fourth (posterior parietal) branches of the superior division of the MCA produces syndromes characterized by disconnected language function such as conduction aphasia and impairment of planned motor tasks (ideomotor apraxia). Often there is no concurrent primary sensory or motor dysfunction on either side of the body. The specific syndromes associated with occlusion of the branches of the inferior division of the MCA of the dominant hemisphere include Wernicke's aphasia, often in combination with contralateral superior quadrantanopia because of infarction of white matter tracts deep to the posterior sylvian region including the optic radiation. |
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