Introduction
During routine interpretation of electroencephalographic tracings, we observed that postoperative records of patients who had been subjected to temporal lobectomy for control of convulsive seizures consistently showed alterations of the alpha rhythm. Moreover, these alterations did not seem to be directly caused by the surgical procedure per se. They involved areas of the brain which were fairly distant from the region of operation. On occasions they extended to the opposite hemisphere, in some cases being limited to it. The persistence of the alterations for several months, and sometimes even years, argued against their being produced by pathological changes due to surgical trauma.Searching for possible correlations between changes in alpha rhythm and other clinical and electrical data, we reviewed previous EEG tracings and clinical charts on patients who underwent temporal lobectomies at the University of Minnesota Hospitals during the period from 1954 to 1958. The results of this survey