Abstract
Epilepsy is one of the oldest diseases of man recorded in history. Before Hippocrates' time it was considered to be of divine origin although Hippocrates scoffed at the idea of a supernatural cause and gave it a pathological basis. His description of the disease is classic and does not differ materially from that found in modern textbooks. Thus he recognized both the idiopathic and symptomatic forms, various types of auras, the influence of age, of temperment, menstruation, and many other factors. Little was added to our knowledge of the disease until Hughllngs Jackson (l) suggested that unilateral epileptiform convulsions were due to irritation or discharge of certain convolutions of the opposite cerebral hemisphere. This was substantiated by Fritsch and Hitzin in 1870 and by Ferrler in 1873. (2) They also demonstrated the phenomonen of electrical excitability of the cerebral cortex. The next advance was made in 1929 when Berger discovered that changes in electrical potential of cortical origin could be recorded from the cranium by means of pad electrodes applied to the scalp, or needle electrodes placed in contact with the periosteum of the skull. (3) The potentials developed at the surface of the cortex are in the range of 100 to 1000 microvolts but if they are recorded through the scalp they are only 5 to 100 microvolts. With the use of the modern vacuum tube these voltages can be amplified one to two million times without change in form and caused to drive a stylus on a continuous running paper to form a permanent record. The electroencephalogram has developed into an important instrument for the diagnosis of epilepsy, since definite wave forms characteristic of the different types of epilepsy, have now been recognized. (Fig. 1 and 2)