The history of algology, algotherapy, and the role of inhibition.

Cephalalgia (1st century AD), nostalgia (1678), neuralgia (18th century), causalgia (1872) were terms followed in the 1950's by Bonica's 'algology... a disease state of its own', addressed by ever-growing numbers of pain clinics, strongly foreshadowed by Leriche's douleur maladie in the 1930's. (Hence also 'algotherapy'). Philosophers first, then early academic physiologists began to exhibit interest in pain, that all too common phenomenon, only too often unyielding to theoretical as well as practical efforts. Was it, after all, an instance of built-in self-preservation, a reflex? Identification of the nervous energy and its anatomical pathways in the 19th century, endless arguments as to their 'specificity', led to new surgical attempts to control and interpret pain, by now supported by general, then local anesthesia. Early in this century Henry Head's much-discussed notion of 'epicritic' sensation exerting some control over 'protopathic' pain was soon followed by Otfried Foerster's insistence on a central role of inhibition providing pain relief. Almost forgotten, Foerster's idea found expression in Melzack and Wall's 'gate control theory' of 1965. Gasser and Erlanger's classification of sensory nerve fibers began to dominate research in the 1930's thanks to the cathode ray oscillograph invented in 1897. The pain inhibition concept was given another boost in the seventies when the role of the midline mesencephalic and oblongata nuclei was established as both opium receptors and producers of opioids. Finally, inhibition may also be seen as the principle underlying the age-old therapeutic effect of 'counter-irritation', mostly in the form of electrical stimulation.