Electroencephalography in Clinical Neurology

In 1931 Berger¹showed that impairment of cortical function resulting from high intracranial pressure in man is associated with the appearance of abnormally slow electrical potentials of about 3 a second. These potentials were recorded through the intact skull by placing electrodes on the forehead and occiput. The method he used was similar to that with which he originally demonstrated the normal 10 a second rhythm. Two years later,²he found similar slow waves confined to the affected hemisphere in 2 cases of cerebral tumor. He was unable to obtain the abnormally slow waves when the tumor was situated midway between his electrodes, but they appeared when one of the electrodes was in proximity to it. In 1935, Kornmüller³and Foerster and Altenburger⁴showed that the slow alternating potentials do not originate in cerebral tumors themselves. It appeared, therefore, that the disturbances were arising in the