Teoría Del Dolor

Pain and the Neuromatrix in the Brain
Ronald Melzack, Ph.D.
Abstract: The neuromatrix theory of pain proposes that pain is a multidimensional experience produced by characteristic
“neurosignature” patterns of nerve impulses generated by a widely distributed neural network—the “body-self neuromatrix”—in
the brain. These neurosignature patterns may be triggered by sensory inputs, but they mayalso be generated independently of
them. Acute pains evoked by brief noxious inputs have been meticulously investigated by neuroscientists, and their sensory
transmission mechanisms are generally well understood. In contrast, chronic pain syndromes, which are often characterized by
severe pain associated with little or no discernible injury or pathology, remain a mystery. Furthermore, chronicpsychological or
physical stress is often associated with chronic pain, but the relationship is poorly understood. The neuromatrix theory of pain
provides a new conceptual framework to examine these problems. It proposes that the output patterns of the body-self
neuromatrix activate perceptual, homeostatic, and behavioral programs after injury, pathology, or chronic stress. Pain, then, isproduced by the output of a widely distributed neural network in the brain rather than directly by sensory input evoked by injury,
inflammation, or other pathology. The neuromatrix, which is genetically determined and modified by sensory experience, is the
primary mechanism that generates the neural pattern that produces pain. Its output pattern is determined by multiple influences,
of which thesomatic sensory input is only a part, that converge on the neuromatrix.
Dr. Melzack is Professor Emeritus, Department of Psychology, McGill University. Direct correspondence and requests for
reprints to him at Department of Psychology, McGill University, 1205 Dr. Penfield Avenue, Montreal, Quebec, Canada H3A
1B1; 514-398-6084 phone; 514-398-4896 fax; rmelzack@ego.psych.mcgill.ca.
Key words: pain,body-self neuromatrix, stress

P

ain has many valuable functions. It often signals injury or disease and produces a wide
range of actions to stop it and treat its causes.
Toothache, for example, is usually a signal of caries,
and forces us to seek dental help. Memories of earlier pain and suffering also warn us to avoid potentially dangerous situations. Yet another effect of pain,especially after serious injury or disease, is to make
us rest, thereby promoting the body’s healing processes. All of these actions induced by pain—to seek
help, avoid, or rest—have obvious value for survival.
Yet despite these valuable features of pain, there
are negative aspects that challenge our attempts to
understand the puzzle of pain. What is the value of
persistent phantom limb pain toamputees whose
stump has healed completely? The pain, not the physical disability, prevents them from leading normal
lives. Similarly, most backaches, headaches, muscle
pains, nerve pains, pelvic pains, and facial pains serve
no discernible purpose, are difficult to treat, and are
a disaster for the people who suffer them.1,2
Pain may be the warning signal that saves the
lives of some people,but it destroys the lives of countless others. Chronic pains, clearly, are not a warning
to prevent physical injury or disease. They are the
disease—the result of neural mechanisms gone awry.
The neuromatrix concept suggests brain mechanisms
that may underlie some kinds of chronic pain and
points to new forms of treatment.

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Phantom Limbs and the
Concept of a Neuromatrix
The gatecontrol theory of pain,3 proposed in
1965, highlighted the role of spinal and brain mechanisms in acute and chronic pain, and triggered an
explosive advance in pain research and therapy. Yet,
as historians of science have pointed out, good theories are instrumental in producing facts that eventually require a new theory to incorporate them. And
this is what has happened. It is possible to...