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
The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the bloo...The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the blood supply and flow rate in the bilateral carotid arteries and the blood flow rate in the anterior cerebral and middle cerebral arteries were similar to normal controls, but the cerebral vascular resistance, critical pressure and pulsatility index were increased, and cerebral arterial elasticity and cerebral blood flow autoregulation were decreased. Compared with the lesioned hemisphere of patients with cerebral infarction, the total blood supply and blood flow rate of patients with cerebral arteriosclerosis were higher. Compared with normal subjects, patients with cerebral arteriosclerosis exhibited cognitive disturbances, mainly in short-term memory, attention, abstract capability, and spatial and executive dysfunction. Results showed that cerebral arteriosclerosis does not directly affect the blood supply of a cerebral hemisphere, but affects cognitive function. The increased cerebral vascular resistance and reduced autoregulation of cerebral blood vessels may be important hemodynamic mechanisms of arteriosclerosis-induced cerebral infarction.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.
基金the Technology Research Program of Shaanxi Province, No. 2009K18-02
文摘The present study observed hemodynamic changes in 26 patients with cerebral arteriosclerosis using a cerebral circulation dynamics detector and transcranial Doppler. In patients with cerebral arteriosclerosis the blood supply and flow rate in the bilateral carotid arteries and the blood flow rate in the anterior cerebral and middle cerebral arteries were similar to normal controls, but the cerebral vascular resistance, critical pressure and pulsatility index were increased, and cerebral arterial elasticity and cerebral blood flow autoregulation were decreased. Compared with the lesioned hemisphere of patients with cerebral infarction, the total blood supply and blood flow rate of patients with cerebral arteriosclerosis were higher. Compared with normal subjects, patients with cerebral arteriosclerosis exhibited cognitive disturbances, mainly in short-term memory, attention, abstract capability, and spatial and executive dysfunction. Results showed that cerebral arteriosclerosis does not directly affect the blood supply of a cerebral hemisphere, but affects cognitive function. The increased cerebral vascular resistance and reduced autoregulation of cerebral blood vessels may be important hemodynamic mechanisms of arteriosclerosis-induced cerebral infarction.
