Changes in visual reaction time following cerebral angiography. Preliminary communication.

An instrument for measuring visual reaction time (VRT) was constructed and later tested on 18 control volunteers. It was established in these subjects that the mean VRT did not vary by more than 6% over a period of 5 days. The equipment was then employed to measure changes in VRT following carotid angiography under general anaesthesia in a series of 48 patients. Of these, 22 patients had no demonstrable lesion and showed no change in VRT; 26 patients had an intracranial lesion and revealed an increase in VRT on the first day after angiography. Possible causes of the changes in VRT are discussed and further investigations are suggested.