Presumed Ocular Myasthenia and Micropsia A Case Report

Michaeli‐Cohen, Adi; Almog, Yehoshua; Loewenstein, Anat; Stolovitch, Chaim; Gutman, Izaac; Lazar, Moshé

doi:10.1097/00041327-199603000-00005

Cited by 2 publications

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“…Furthermore, dysmetropsia can result from a size reduction of the retinal image due to an accommodation increase of the lens in¯uenced by the distances between the object plane and the pupil and the accommodation level, which is a phenomenon called accommodative micropsia [24]. A similar mechanism may underly the cases in which dysmetropsia occurs associated with muscular diseases such as ocular myasthenia [14]. In cases of central origin, micropsia is mostly described as a transient phenomenon, occurring as prodroma of, or simultaneously with, temporal lobe epileptic seizures or migraine [21].…”

Section: Introductionmentioning

confidence: 99%

Brain imaging in a patient with hemimicropsia

et al. 1999

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Hemimicropsia is an isolated misperception of the size of objects in one hemifield (objects appear smaller) which is, as a phenomenon of central origin, very infrequently reported in literature. We present a case of hemimicropsia as a selective deficit of size and distance perception in the left hemifield without hemianopsia caused by a cavernous angioma with hemorrhage in the right occipitotemporal area. The symptom occurred only intermittently and was considered the consequence of a local irritation by the hemorrhage. Imaging data including a volume-rendering MR data set of the patient's brain were transformed to the 3-D stereotactic grid system by Talairach and warped to a novel digital 3-D brain atlas. Imaging analysis included functional MRI (fMRI) to analyse the patient's visual cortex areas (mainly V5) in relation to the localization of the hemangioma to establish physiological landmarks with respect to visual stimulation. The lesion was localized in the peripheral visual association cortex, Brodmann area (BA) 19, adjacent to BA 37, both of which are part of the occipitotemporal visual pathway. Additional psychophysical measurements revealed an elevated threshold for perceiving coherent motion, which we relate to a partial loss of function in V5, a region adjacent to the cavernoma. In our study, we localized for the first time a cerebral lesion causing micropsia by digital mapping in Talairach space using a 3-D brain atlas and topologically related it to fMRI data for visual motion. The localization of the brain lesion affecting BA 19 and the occipitotemporal visual pathway is discussed with respect to experimental and case report findings about the neural basis of object size perception.

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Section: Introductionmentioning

confidence: 99%