Serial regional blood flow and visual evoked responses in transient cortical blindness.

Normal regional blood flow was documented by Single Photon Emission Computed Tomograms 5 and 20 hours before the full recovery of cortical blindness in two patients, lending itself to the possibility of being a prognostic factor. Rubbing of the posterior cerebral arteries against the tentorial edges during trauma instead of traction was believed to cause blindness in one patient and embolization due to hammering bone grafts home during cervical spinal fusion, in the other. Pattern reversal visual evoked responses (PRVERs) were absent during blindness; upon recovery P 100 with full amplitude and normal latency appeared despite the presence of tunnel vision. These are consistent with the fact that the central 8-10 degrees of visual field represented in the posterior occipital poles being the main sources of P 100 in association with the x-cells in the centre of the retina.