Crossed quadrant homonymous hemianopsia in a case of multiple sclerosis.

We describe the first report of crossed quadrant hemianopsia (CQHH) occurring in a patient with a well documented clinical history of Multiple Sclerosis (MS). The visual field studied by a Humphrey Field Analyzer (Mod.630, 30-2 program) showed a CQHH, involving right superior quadrants and left inferior ones. Magnetic resonance imaging (MRI) showed two lesions located in both left and right trigone area, corresponding to the geniculocalcarine pathways. CQHH is a very rare visual field defect commonly caused by vertebro-basilar ischemia and attributed to bilateral injury of the calcarine fissure. In the absence of lesions in the primary visual cortex, a direct relationship between the quadrantonopic defect and two small demyelinating lesions in posterior periventricular white matter, corresponding to the geniculocalcarine pathways, is implied.