Background and objective: Homonymous hemianopia caused by cerebrovascular disease may improve over time. This study investigated whether functional neuroimaging can predict the prognosis of hemianopia due to cerebral infarction.
Methods: We studied 19 patients (10 men and 9 women) with homonymous hemianopia and compared them with 34 healthy subjects (20 men and 14 women). Cerebral glucose metabolism was measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), 1 to 6 months after the onset. Bilateral regions of interest (ROIs) were selected from the posterior and, anterior striate cortices, extrastriate cortex, and thalamus. Furthermore, semi-quantitative data on cerebral glucose metabolism were obtained for ROIs and compared with the data obtained for homologous regions in the contralateral hemisphere by calculating the ipsilateral/contralateral (I/C) ratio.
Results: The I/C ratio for the cerebral glucose metabolism in the posterior striate cortex was high (>0.750) in 8 patients, and the central visual field of these patients improved or showed macular sparing. The I/C ratio for cerebral glucose metabolism in the anterior striate cortex was high (>0.830) in 7 patients, and the peripheral visual field of these patients improved. However, no improvement was observed in 9 patients with a low I/C ratio for cerebral glucose metabolism in both the posterior and anterior striate cortices.
Conclusion: Measurement of cerebral glucose metabolism in the striate cortex is useful for estimating visual field prognosis. Furthermore, FDG-PET is useful in predicting the prognosis of hemianopia.
Keywords: cerebral glucose metabolism; hemianopia; macular sparing; positron emission tomography; visual field.