Chronic pain and nonpainful sensations after spinal cord injury: is there a relation?

Objectives: First, to define the clinical characteristics of nonpainful sensations (NP) that commonly appear after spinal cord injury (SCI); and second, to compare the clinical characteristics of NP and chronic pain (CP) after SCI. Methods: Two sets of questions concerning CP and NP were mailed to 330 subjects. Responses from 197 persons experiencing CP as well as NP were analyzed. Results: The most common locations for CP and NP were back and lower extremities. Although the number of areas in which the subjects perceived CP and NP to be located was significantly correlated, a factor analysis showed separate groupings of areas with CP and NP, respectively. Self-reported allodynia or hyperesthesia in the lower extremities, however, was significantly associated with CP in the same areas. The number of descriptive adjectives used for CP and NP was also significantly correlated, as was the perceived intensity of CP versus NP. Additionally, significant correlations were found in onset and temporal pattern of CP and NP. Similarly to CP, NP interfered with sleep, work, and other daily activities, and the patterns of interference due to CP and NP were significantly correlated. Discussion: While many aspects of the clinical picture of CP and NP are similar after SCI, the CP and spontaneous NP are not necessarily located in the same areas. Although the observed similarities between CP and NP may be based on pathophysiologic mechanisms, the significant relations between the interference patterns suggest that psychosocial mechanisms related to coping are also involved.