The Development of Clinical Neurophysiology
As early as the second half of the 19th century a number of researchers had written that it was possible to record electrical activity of the brain in test animals with open skulls. A large percentage of this research was aimed at evoking potentials from animals. Luigi Galvani’s famous ‘frog leg’ experiment performed almost a century before, lead the way to developing the evoked potential. Not too much attention was paid to these findings because there did not appear to be any clinical use.
(If the frog leg experiment is not familiar to you, please refer to Luigi Galvani – try a Google search and see what you find).
It was not until 1929 before the first of a series of articles appeared from Dr Hans Berger, a German nerve doctor, working in Jena, where mention was made of the recording of this electrical activity from the intact, closed skull of a human with the aid of electrodes placed on the skin. He differentiated slow so-called alpha (10-11Hz) and faster, so-called beta (20-30Hz) waves. With this came the birth of a new medical investigation method, the electroencephalograph (EEG).
In the following years Berger published data about the EEG’s recorded by him of various illnesses, and about the EEG picture under various circumstances (among others, sleep narcosis).
The history of neurophysiology
After the field of electronics went through an enormous development during and after the Second World War, electroencephalography expanded into a clinical investigation method, which gradually increased in use. EEG departments were set up and furnished, and technicians were attracted and trained to record EEG’s. Accordingly as the number of technicians grew, the need for co-ordinated training and the promotion of the quality of the technician increased.
In the sixties associations and schools of training for EEG technicians were established. Many EEG departments developed over the ensuring years, and were expanded to become ‘Clinical Neurophysiology’ departments as other investigation techniques apart from EEG were included in their operations.
Following the initial discoveries in the early 1970’s by Martin Halliday, the area of evoked potentials developed very quickly over the next decade or so. By adding to those very early techniques described back in the late 1800’s three evoked potential (EP) tests have rapidly blossomed into useful clinical tools. Pattern-shift visual (PSVEP), brainstem auditory (BAEP), and short-latency somatosensory evoked potentials (SEP) are reliable diagnostic tests that yield reproducible results in the routine department.
