CENTRAL HOMONYMOUS HEMIANOPIA WITH AN ISCHEMIC LESION OF THE ANTERIORVISUAL PATHWAY

Paracentral homonymous hemianopia is a rare form of homonymous visual field defect. Vascular disorders in the occipital cortex are the most common cause of homonymous scotomas. The authors report a case of left homonymous paracentral scotoma associated with a left facial palsy, a left arm paresis and moderate confusion. Six months later a sectorial optic atrophy appeared. The neurophysiological evaluation with visual evoked potentials and pattern-electroretinogram, showed defective par amacular afferences with repercussion on the retinal ganglion cells. M agnetic resonance imaging (MRI) showed an ischaemic lesion in the righ t parathalamic region involving the lateral geniculate nucleus and/or the optic tract; the lesion extended into the anterior limb of the int ernal capsule, explaining the motor deficits. The MRI did not disclose lesions in the posterior visual pathway nor in the occipital cortex. The pathophysiologic mechanism is discussed.