Neurosurgical treatment of chronic pain.

Neurosurgery is not a first-choice treatment for chronic pain. It is indicated when chronic pain is insufficiently relieved by analgesics, or when medication is effective but causes unacceptable side effects. Neurosurgical procedures may be ablative or augmentative (stimulating). An ablative procedure interrupts pain pathways at one of various levels in the central nervous system (CNS). In contrast, an augmentative procedure is non-destructive and is generally considered to activate the inhibitory system in the CNS, thereby suppressing pain perception. There is, however, no neurosurgical procedure which affords permanent pain relief. This stems from the fact that pain is not simply the result of stimulation of specific sensory fibres in the peripheral and central nervous systems. As discussed elsewhere, there are two varieties of pain: nociceptive (somatic) and dysaesthetic (deafferentation). Some neurosurgical procedures relieve both nociceptive and dysaesthetic pain, while others relieve only one or other type. Which procedure should be used in a specific case depends on many variables, including efficacy, indications for use, advantages and disadvantages, limitations and complications. These differ with each procedure. Familiarity with neuroanatomical and neurophysiological concepts of pain mediation and perception, and with a range of techniques, together with the necessary equipment, are all required for the safe and effective use of neurosurgery in the treatment of pain. It is still sometimes thought that medication is no longer necessary after neurosurgery even if the procedure has resulted in incomplete relief. This misunderstanding must be corrected. The goal of pain treatment is always to provide a pain-free state and, if necessary, it should be achieved through a multi-modality approach. The following discussion of several neurosurgical procedures is based both on my personal experiences and on data reported in the literature. Cordotomy