For Sudden, painless monocular blindness select the site of the lesion of cerebrovascular disease,
Correct Answer: Internal carotid aery
Description: Sudden, painless monocular blindness is a sign of carotid disease. The symptom is also called amaurosis fugax . The patient may describe a shade dropping in front of the eye or describe vision like looking through ground glass. If a thrombus propagates up the carotid to the middle cerebral aery, then symptoms seen in middle cerebral aery occlusion or embolization (hemiparesis with sensory symptoms, aphasia depending on hemispheric dominance) will also occur. Midbasilar aery disease produces weakness and sensory loss with diplopia, loss of facial sensation or movement, and ataxia. Branches of the basilar aery supply the base of the pons and superior cerebellum. The symptoms described suggest disease in the posterior circulation, whichincludes paired veebral aeries, the basilar aery, and the paired posterior cerebral aeries. The basilar aery divides into two posterior cerebral aeries that provide branches to the cerebellum, medulla, pons, midbrain, thalamus, and temporal and occipital lobes. A midbasilar aery occlusion could cause ataxia of limbs by involving pontine nuclei; paralysis of the face, arm, and leg by involving coicospinal tracts; and impairment of facial sensation by involvement of fifth nerve nucleus. Occlusion of the entire middle cerebral aery results in contralateral hemiplegia, hemianesthesia, and homonymous hemianopsia. When the dominant hemisphere is involved, aphasia is present. When the nondominant hemisphere is involved, apraxia and neglect are produced. When only a penetrating branch of the middle cerebral aery is affected, the syndrome of pure motor hemiplegia is produced, as the infarct involves only the posterior limb of the internal capsule, involving only motor fibers to the face, arm, and leg (lacunar infarct).
Category:
Ophthalmology
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