[Present state of pain surgery].

This report presented to the Société de Neurochirurgie de Langue Française is based on 34 years of unique practice in neurosurgical management of pain; during that long period the author and his associates have collected an unusually large experience in almost every field of neurosurgical management of pain; they have improved or fully devised several new techniques which allow them to ground an appreciation of the procedures still worthy to be used in various pain syndromes. The first part of the report deals with "Cybernetics of pain". This rather long chapter is based both on classical data and personal observations on man during and following operations, meant to relieve pain. Though supporting HEAD and HOLMES, theory on Control of protopathic by epicritic Stimuli, the authors consider that the type of pain associated with noxious stimulation as representative of just one among other types of pain, not induced by nociception and not associated with protection reflexes. Sensory deafferentation as can be produced by amputations, herpes zoster, dorsal column or medullary lesions, cannot be included in Sherrington's scheme of psychical mechanisms associated with protection reflexes and yet is responsible for most of the chronic unbearable and often intractable pain. Moreover, an important modulation of pain as such depends on conditioning, on inherited and acquired patterns of behaviour and on a multiplicating factor which is provisionally named "algogenic neurosis". The fact that an intact nucleus ventralis posterolateralis is a necessity for a "no pain status" tends to prove that this thalamic nucleus acts as a major inhibiting relay on the pain integrating system and for several additional reasons is the level of integration of epicritic versus protopathic stimuli in case of true nociception...