Pain following spinal cord injury: the clinical problem and experimental studies

The problem of pain following spinal cord injury challenges the health care community to develop new treatment strategies for patients requiring pain management. A number of pain syndromes are associated with spinal injury based on the nature of the lesion, neurological structures damaged, and secondary pathophysiological changes. Efforts to identify specific characteristics of each syndrome are an important beginning to the successful diagnosis and treatment of spinal injury pain. Without research directed towards understanding the basic mechanisms of this condition, it is likely that the treatment of these patients will remain basically the same as for any other type of pain. In recent years optimism for the development of more effective treatments for central pain of spinal origin has resulted from efforts directed towards understanding the morphological, neurochemical, and physiological responses to spinal injury. Through the use of different experimental models valuable insights related to the mechanism(s) responsible for the onset of central pain following injury have been obtained. At present there are three hypothesis related to this condition: (a) imbalance of sensory channels; (b) loss of spinal inhibitory tone; and (c) the existence of central pattern generators. Future research related to these hypotheses will need to focus on the use of appropriate injury models that simulate the pathological changes associated with human injuries and which lead to clinically relevant pain-related behaviors. Continued research directed towards an examination of these proposed mechanisms will also require new research strategies and a cooperative working relationship between basic and clinical scientists. In this review the clinical characteristics of spinal injury pain and the results of experimental studies are discussed.