Measurement of Cerebral Glucose Metabolism in the Visual Cortex Predicts the Prognosis of Hemianopia

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.

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.

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.

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.