Electrophysiological findings in cortical blindness. Report of a case,

Abstract

Spontaneous cerebral activity and visual evoked responses have been described in a patient with post-traumatic cortical blindness who was studied over a period of 4 weeks. The resting occipital pattern was extremely small in amplitude but composed of frequencies largely within the normal alpha range. No evidence of light-induced alpha blocking could be detected. Averaged evoked responses derived from leads placed over the occipital poles were abnormal, in that they were rudimentary and inconsistent, none of the normal initial 5 waves being identifiable with certainty. The presence of a light-evoked, prominent vertex wave, dissimilar from that evoked by sound, was noteworthy in view of the virtual absence of an occipital response and severity of visual deficit.