engleski

Visual evoked potentials

Visual evoked potentials were analyzed in 30 patients with unilateral ischemic cerebral lesion. Their localization had been confirmed by CT. According to the intensity of brain damage, the lesion was evaluated as slight, mild or severe. 14 patients had hemianopsia as well, and in one was found upper quadrantanopsia. In spite of all advantages of potentials evoked by shaped visual stimu1i, due to the impossibility of cooperation in the course of the examination in these patients, we still frequently apply light flashes stimuli. In this way registered, relatively small asymmetries of the evoked potentials, provided that they are observed above the homologous sites of both hemispheres, can have a great significance. Because the evoked potentials amplitudes show more significant variability than their latencies, their determination is a more reliable sign painting to changes connected with a certain lesion. Important and characteristic changes are registered in the early stage of the response above the hemisphere with the lesion, and they are manifested by the absence of one or more components and/or longer latency of peaks in certain components. Changes in the later course are almost always connected with the changes in the early part of the response, but are not so pronounced and characteristic. The most marked changes are found mostly in the damages of occipital regions, then follow the lesions with mostly temporal loca1is action, while damages found in the anterior area cause minimal changes in visual evoked potentials, or they may even be normal. Taking into account the intensity of the cerebral lesion, it is necessary to say that severe damages are the cause of more pronounced changes in the visual evoked potentials.

visual evoked potentials; hemianopsia

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