Pain and psycho-affective disorders.

The subject of human pain can be subdivided into two broad categories: physical pain and psychological pain. Since the dawn of human consciousness, each of these two forms of pain-one clearly physical, the other having more to deal with the mind-have played a central role in human existence. Psychological pain and suffering add dimensions that go far beyond the boundaries of its physical counterpart. In the past 50 years, one of the more remarkable accomplishments of medical science has been to increasingly enable the clinician to impact, as never before, each of these critical realms of human existence. Our intention is, therefore, to initially describe a few of the many exciting neuroscientific and neurosurgical advances that have been made in the treatment of various types of pain and to speculate on some of the emergent questions that we believe need to be addressed. After this is accomplished, we will then use this information as a kind of two-pronged philosophical entrance into questions of the mind, brain, and soul that we feel are necessary to bring back into the sphere of the modern physician's practice. The goal of this article is two-fold: 1) to share some of our exciting research and 2) to renew the interest in timeless questions, such as that of the mind-brain and the brain-mind, in the conversation of the modern neurosurgeon. The International Association for the Study of Pain divides pain into two broad functions and anatomical categories. In this framework, "nociceptive" pain is defined as the kind of physical pain that results when the tissue is damaged. Given this perspective, such pain is usually considered a consequence of one's defense against one's environment. The other pain is the "neuropathic" one resulting from a lesion or a dysfunction of the human nervous system. As such, we will take the risk of crossing beyond the boundaries of neurosurgery and venture into boundaries that, at another time, might seem more natural to the discipline of psychiatry for two reasons. The first is that psychiatry seems to be so focused on the brain-its biochemistry and pharmacology--that questions of mind and soul have become rare and almost negligible. The second is to follow the course of the results of our own clinical investigations that have taken us into that very human world where questions of physical pain, psychological pain, and the experience of suffering abound. Today, however, the strategy of neuromodulation offers the advantage of being precisely tailored in neuroanatomical terms and, even more importantly, of being altogether reversible. At both our own Istituto Neurologico C. Besta and many other neurosurgical centers worldwide, many procedures have been reported in which implant neuromodulation devices successfully treat pain. For example, long-term stimulation of the spinal cord has been fairly effective in the treatment of neuropathic pain, multiple sclerosis, and various other forms of pain. Good results have been obtained in treating peripheral vascular diseases and sympathetic reflex dystrophy syndrome. Good results have also been achieved in trigeminal nerve stimulation and peripheral nerve stimulation. In the case of thalamic stimulation, there has also been an improvement of symptoms, but a long-term degree of tolerance was noticed. Hypothalamic stimulation has also been seen to be effective in controlling trigeminal autonomic cephalalgic pain, as well as the facial pain that is known to occur in multiple sclerosis. Motor cortex stimulation was found to occasionally have good results in treating neuropathic pain, whereas occipital nerve stimulation was found to achieve good results in controlling chronic cluster headache and other chronic headaches, although with only short-term follow-up so far. Recent reports of functional magnetic resonance imaging have prompted us to propose exciting new neurosurgical targets that may be effective in treating psychoaffective disorders. Our results appear to be more than promising so far. It appears that neuropathic pain and psychoaffective disorders seem to be sharing an anatomophysiological common background at the Brodmann Area 25 of the anterior cingulated gyrus. On the basis of these exciting findings, we believe that it is reasonable to suggest that neuropathic pain and psychoaffective disorders may ultimately be managed with complementary or, at least, similar, therapeutic strategies, each of which lie within the domain of the neurosurgeon.