Cognitive disturbances with neglect-like features have been reported occasionally in patients with chiasmal disorders, so far however with no obvious substrate by conventional brain imaging. Thus, there were no right ...Cognitive disturbances with neglect-like features have been reported occasionally in patients with chiasmal disorders, so far however with no obvious substrate by conventional brain imaging. Thus, there were no right hemisphere lesions that could explain the lateralised visual inattention as observed in particular during monocular visual acuity testing. On this background, we further examined four adult patients who consented to functional 18F-fluoro-deoxyglucose (FDG) positron emission tomography (PET) scan. In three there were no significant findings. The fourth patient, a 26-year-old male with cognitive defects after surgery for craniopharyngioma, will be discussed in more detail. His PET scan demonstrated a widespread reduction of regional metabolic activity in left hemisphere primary visual cortex and higher order visual areas, despite absence of explanatory pathological signal changes on MRI. As present in only one out of four patients, however, the findings do not allow specific pathogenetic mechanisms to be suggested, nor generally to substantiate involvement of higher cerebral circuits. Obviously, even developed imaging has its limits, and in the very theory the visual dysfunctions observed might still depend on higher brain centres’ faulty adaptation to loss of pre-geniculate visual information.展开更多
Objective: By means of neuropsychologic tests, to further analyse a specific chiasmal monocular visual testing behaviour, here labelled temporal blocking because of the elective ignorance of optotypes on the temporal ...Objective: By means of neuropsychologic tests, to further analyse a specific chiasmal monocular visual testing behaviour, here labelled temporal blocking because of the elective ignorance of optotypes on the temporal side of the chart. Often it is combined with impairment of reading and other cognitive impairments. Methods: Eighteen patients with lesions to the chiasm and some degree of temporal blocking aged 24 - 76 years underwent: 1) tests for visual neglect (Gothenburg test;behavioural inattention tests: star cancellation;line bisection);2) visuo-perceptual tests;and 3) a test involving reading a crowded ten-letter and cipher bar. Results: The temporal blocking in two patients recovered after emergency neurosurgery and their results were normal when subsequently tested. Of the 16 patients with deficiencies, 14 had a poorer left eye (p Conclusions: The best neuropsychologic tests appeared to be those for visual neglect and the crowded bar test. In most cases, the right cerebral hemisphere’s lack of some crossed information from the left eye, usually needed for normative saccades and adjustment to visual space, may be a factor underlying the specific visual behaviour.展开更多
文摘Cognitive disturbances with neglect-like features have been reported occasionally in patients with chiasmal disorders, so far however with no obvious substrate by conventional brain imaging. Thus, there were no right hemisphere lesions that could explain the lateralised visual inattention as observed in particular during monocular visual acuity testing. On this background, we further examined four adult patients who consented to functional 18F-fluoro-deoxyglucose (FDG) positron emission tomography (PET) scan. In three there were no significant findings. The fourth patient, a 26-year-old male with cognitive defects after surgery for craniopharyngioma, will be discussed in more detail. His PET scan demonstrated a widespread reduction of regional metabolic activity in left hemisphere primary visual cortex and higher order visual areas, despite absence of explanatory pathological signal changes on MRI. As present in only one out of four patients, however, the findings do not allow specific pathogenetic mechanisms to be suggested, nor generally to substantiate involvement of higher cerebral circuits. Obviously, even developed imaging has its limits, and in the very theory the visual dysfunctions observed might still depend on higher brain centres’ faulty adaptation to loss of pre-geniculate visual information.
文摘Objective: By means of neuropsychologic tests, to further analyse a specific chiasmal monocular visual testing behaviour, here labelled temporal blocking because of the elective ignorance of optotypes on the temporal side of the chart. Often it is combined with impairment of reading and other cognitive impairments. Methods: Eighteen patients with lesions to the chiasm and some degree of temporal blocking aged 24 - 76 years underwent: 1) tests for visual neglect (Gothenburg test;behavioural inattention tests: star cancellation;line bisection);2) visuo-perceptual tests;and 3) a test involving reading a crowded ten-letter and cipher bar. Results: The temporal blocking in two patients recovered after emergency neurosurgery and their results were normal when subsequently tested. Of the 16 patients with deficiencies, 14 had a poorer left eye (p Conclusions: The best neuropsychologic tests appeared to be those for visual neglect and the crowded bar test. In most cases, the right cerebral hemisphere’s lack of some crossed information from the left eye, usually needed for normative saccades and adjustment to visual space, may be a factor underlying the specific visual behaviour.
