Late rheoencephalographic assessment of the cerebral circulation after ligation of the common carotid artery.

A series of 17 patients was investigated following common carotid ligation. The period between operation and examination ranged from 2-7 years. Cerebral circulation was estimated by use of the rheoencephalographic method. Statistical analysis of the reg plot was performed by comparing an age-matched normal population with patients. A comparison was also made of the ligated and nonligated sides for the patients. The following results were obtained: a significant decrease in the amplitude of the reg waves, an extension in the anacrotic part of the wave, and a decrease in the angle of its inclination. This was intensified more on the side of the common carotid ligation. These findings may suggest that after common carotid ligation the cerebral circulation is changed for a long period of time. They would also seem to indicate that postoperatively, the cerebral circulation does not return to normal--if it ever does.